Bio Bullet Notes

8/8/2019 Bio Bullet Notes

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1.Cell structure and organization

Chloroplastso Site of photosynthesis where light energy is absorbedo Consist of grana which are stacked up to increase surface area for absorptionof lighto Only present in plant cells

Cell membrane (plasma membrane)o Lipid bilayer that surrounds the cell, interspersed with protein moleculeo Presence of temporary poreso Selectively permeable:Controls movement of substanceso Diffusion, osmosis and active transport can therefore take placeo Prevent outflowing of cytoplasmo Tonoplast:Plasma membrane surrounding the vacuole Cell wall

o Made of cellulose (a polysaccharide), and may be deposited with ligino Maintain cell turgidity, provide mechanical support, protect from mechanicaldamageo Freely permeable to water and most soluteso

Only present in plant cells Cytoplasmo Protoplasm surrounding the nucleuso There are numerous organelles present in the cytoplasmo Organelle:Specialized membrane bound structures Cell vacuoleo Fluid-filled space enclosed by a membraneo In animal cells, these are present as numerous small ones, and these areusually not permanento In plant cells, there is usually a large central vacuoleo Cell sap:Fluid in vacuoles, contains sugars, mineral salts and amino acidso Tonoplast:Membrane around the vacuole Nucleuso Nucleoplasm:Small spherical mass of denser protoplasmo Nuclear membrane:Nuclear envelopeo Found in the cytoplasmo Control activities of the cell:Reproduction, repairs and maintenanceo Chromatin:Network of long thread-like structures, containing the hereditymaterialso Chromatin is made up of proteins and DNA (Deoxyribose Nucleic Acid)o Chromosomes:Condensed and highly coiled chromatin threads during cell divisiono Nucleoli:A spherical structure that plays a part in the build up of proteins Endoplasmic reticulumo A series of flattened sheetso Smooth endoplasmic reticulum:Sites of synthesis and transport of steroids and

lipidso Rough endoplasmic reticulum:Transport proteins synthesized at the ribosomestowards Golgi bodies for secretary packing. Mitochondriao Rod-shapedo Site of aerobic respirationo Powerhouse:Release energy during cellular respiration Golgi bodieso Stacks of flattened membrane sacs


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o Involved in secretion of vesicles, formation of lysosomes Ribosomeso Tiny structures concerned with the manufacture of proteinso Found on rough endoplasmic reticulum Comparison between plant cell and animal cell

Plant cell Animal cell

Cell wall XCell membrane Chloroplasts XMitochondria Golgi apparatus Endoplasmic reticulum Nucleus Shape Fixed IrregularCentriole X Vacuoles One large central Many smallGranules Starch GlycogenCilia/flagella X

o All cells have cell membrane, cytoplasm, nucleus, mitochondria, endoplasmicreticulum and ribosomes Root hair cello Function:Increase absorption of water and mineral salts from the soilo Presence of root hairo Long and elongatedo Increase surface area for greater rate of absorption Xylem vesselo Function:Conduction of water in plants as well as to offer mechanical supporto Narrow and cylindrical continuous tubeo Absence of cross wallo Water column can move easily up the lumen of the xylem vessel

o Lignified cell wallso Strengthens the wall and prevents collapse of the xylem vessel Red blood cello Function:Transport of oxygen from lungs to the rest of the bodyo Contains hemoglobin:Oxygen carriero Flat, biconcave shape (no nucleus)o This serves to increase surface area to volume ratioo Oxygen can also diffuse into or out of the cell at a faster rateo The absence of a nucleus also allow the red blood cell to squeeze through thenarrow capillaries Cello Basic structural unit of all organisms

o Functional unit of all organisms where all chemical reactions necessary tomaintain and reproduce the living system existo Arise from pre-existing cellso Contain heredity material Simple tissueo Cells of the same type grouped together to carry out special function Complex tissueo Cells of different type grouped together for the same function Organ


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o Different tissues working together and enabling the organ to perform itsfunction Organ systemo Different organs working together for a special purpose

2.Movement of substances

Diffusiono The random movement of molecules of a substance from a region of higherconcentration to a region of lower concentration Osmosis

o The movement of water (or solvent) molecules from a region of higherconcentration to a region of lower concentration across a partially permeablemembrane Active transport

o The movement of substances into or out of cells against a concentrationgradient Water potentialo The measure of the free kinetic energy of water in a system, or the tendencyfor water to leave a systemo High water potential = high tendency for water to leave the system/lowtendency for water to enter a system/high concentration of water Osmotic potentialo Low osmotic potential = low tendency for water to enter a system/hightendency for water to leave the system/high water potential/high concentration ofwater Hypertonic environmento Cell has high water potentialo Cell has low osmotic potentialo Water leaves the cell Hypotonic environmento Cell has low water potential

o Cell has high osmotic potentialo Water enters the cell Isotonic solutiono Cell gains and lose water at the same rateo No net loss or gain in waterBiological molecules

Importance of watero Use as a biological solvent:Medium where chemical reactions occuro As a reagent in the digestion or hydrolysis of foodo As a transport medium for digested food like glucose, amino acids in animalso As a transport medium for wastes like CO2, urea and other nitrogenouswastes like creatinine in animalso

As a transport medium for hormones from the glands to the target organso For heat loss since water has a high specific heat capacityo As a major component of body fluids such as blood, tissue fluid and digestivejuiceso Replaces water lost from the body in sweat, urine and in breatho Act as a lubricant in mucus and synovial fluido Essential constituent of protoplasmo Essential for photosynthesis in green plantso Maintains turgidity of plant cells and to keep plants upright


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o Transport medium for mineral salts and manufactured sugars in plants

Carbohydrates

o Chemical constituents

Carbon

HydrogenOxygen Fatso Chemical constituents

CarbonHydrogenOxygen Proteinso Chemical constituents

CarbonHydrogenOxygen

Nitrogeno Other possible constituentsSulfurPhosphorus Starch testo Drops of iodineBlue-black color if starch is presentBrown color if starch is present Reducing sugars testo Benedicts solutionGreen color mixture means traces of reducing sugarsYellow or orange color precipitate means moderate amounts of reducing sugarsBrick-red or orange-red color precipitate means large amount of reducing sugars Protein testo Biuret solutionSodium hydroxideCopper (II) sulfateo Color changeBlue to violet (proteins)Blue to pink (short-chain polypetides) Fat testo Ethanolo Watero Observation:Cloudy white emulsion if fats are present Synthesis

o Glycogen from glucoseo Polypetides and proteins from amino acidso Lipids such as fats from glycerol and fatty acids

Enzymes

o Lock and key

Highly specificOnly substrates with shapes complementary in shape to that of the enzymes canfit into the enzyme active site and be acted upon by the enzymes


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o Active site

Site with a specific shape where substrate will bind onto enzymeo Enzyme-substrate complex

Formed only long enough for the reaction to be completeSame enzyme molecule can then catalyze the reaction with another substratemolecule

o Activation energyReduces activation energy so that it is possible for chemical reactions to takeplace in cells at normal body temperatureo Enzyme specificity

Only substrates with shapes complementary to that of the enzyme canfit into enzyme active site and be acted upon by the enzymeo Effects of temperature

Enzymes have an optimum working temperature often but not alwaysclose to that at which they usually functionAn enzyme is inactive at low temperaturesThis is because enzyme-substrate complexes are formed slowlyAs temperature rises, it activity increases

The rising temperature increases the rate of metabolic reactions as the heatincreases molecular motionThus the molecules move more quickly and frequency of collision betweensubstrate and enzyme molecules increasesHence, there is a greater possibility of a reaction taking placeQ10 The rate of reaction double for every 10C rise in temperature until optimumtemperature is reached The temperature coefficient Q10 varies between enzymes, depending on theactivation energy of the catalyzed reactionOptimum temperature The temperature at which maximum reaction occurs Beyond optimum temperature, enzyme activity will decrease until it is completely

deactivated or destroyed As enzymes are made of proteins, when they are heated to too high atemperature, they are denaturedDenaturation The breaking of the secondary tertiary structures of proteins/enzymes due to hightemperatures An irreversible (60C) destruction of an enzyme can be brought about by extremeheating Each enzyme has its own optimum temperature Most enzymes work best between 30-37C Enzymes in the human body have an optimum temperature of 37Co Effects of pH

Extreme changes in pH of the solutions destroy the enzymesOptimum pH The pH at which the maximum rate of reaction occurs When the pH is altered above or below the optimum pH, the rate of enzymeactivity decreases as changes in pH alter the ionic charge of the acidic and the basicgroups that help maintain the specific shape of the enzyme pH changes lead to alterations in enzyme, particularly at the active site extreme pH changes can cause denaturation of the enzyme


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3.Animal nutrition

Digestiono Mouth

The presence of food in the mouth or thoughts of food stimulates thethree pairs of salivary glands to secrete salivaFood is mixed with saliva and is softened by mucin

Mastication breaks down food into smaller pieces (increase in surfacearea/physical digestion)The enzyme amylase, present in saliva, digests starch to maltoseBolus Small, spherical mass of food formed by mastication andthe rolling of the tongueBolus is swallowed via the pharynx into the esophaguso Esophagus

Bolus passes down the esophagus into the stomach through gravity aswell as peristalsisNo digestion takes place in the esophaguso Stomach

Food in the stomach stimulates the secretion of gastric juices into thestomach cavity by the gastric glandsPeristaltic movement in the stomach churns the food and mixes it wellwith gastric juice (as well as to break down the food substances into smaller pieces)Gastric juice A dilute hydrochloric acid (pH 2), prorenin and pepsinogenThe functions of hydrochloric acid Stops action of salivary amylase Converts inactive forms of gastric enzymes to active formso Pepsinogen pepsino Prorenin rennin Provides a slightly acidic medium for the action of digestiveenzymes Kills germs and certain potential parasitesExcess production of hydrochloric acid may erode the stomach wallsand thus result in gastric ulcersPepsin causes the breakdown of proteins to peptones or polypeptides Proteins + pepsin peptonesSince pepsin breaks down proteins, these need to be formed in the inactive statebefore being released, otherwise they will breakdown the proteins found in the cellsthat produces themRenin is an enzyme characteristic of mammalsRenin clots or curdles milk proteins by converting the soluble protein caseinogeninto insoluble casein, a process that requires calcium ions Caseinogen (soluble) + renin/Ca2+casein (insoluble)The insoluble casein would remain long enough in the stomach to be digested bypepsinProtein digestion would be completed in the ileumFood normally remains in the stomach for about three to four hoursChyme Liquefied, partly digested food that passes in small amountsinto the duodenum through the pyloric sphincter Small intestine

The presence of chyme stimulates


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Secretion of intestinal juice (succus entericus (which contains enzymesenterokinase), erepsin (peptidase), maltase, sucrase (or invertase), lactase andintestinal lipase by the intestinal glands) Secretion of pancreatic juice (pancreatic amylase, pancreatic lipase, trypsinogen,an inactive form of protease) by the pancreas into the duodenum Release of bile by the gall bladder into the duodenum

Acidic chyme comes into contact with intestinal juice, pancreatic juiceand bile and is neutralizedAn alkaline environment is now created to provide a suitable alkaline medium forthe action of pancreatic and intestinal enzymesCarbohydrate digestion in small intestine Digestion of starch in the mouth is minimal Also, there is no digestion of starch in the stomach Remaining starch that enters the small intestine are digested by pancreaticamylase to maltose, then to glucose by maltase Simple sugars are the end-products of carbohydrates digestionFat digestion in small intestine Bile emulsifies fat by breaking fats up into minute fat globules suspended in water

to form a stable emulsion Emulsification increases the surface area of fats for digestion Digestion of fats sped up Emulsified fats are converted by lipases to fatty acid and glycerolProtein digestion in small intestine Some protein digestion occurs in the stomach Undigested proteins in the small intestine are converted by trypsin to peptones,which are converted erepsin to amino acids.o Trypsinogen + enterokinase trypsino Proteins + trypsin peptoneso Peptones + erepsin amino acids Absorptiono Digested food substances are absorbed by the villi of the small intestine, especially

in the jejunum and ileumo The wall of the small intestine is well adapted for the absorption of digested foodsubstancesInner walls of the small intestine thrown into many transverse folds and furrowsVilli Minute finger-like projections found on the wall of thesmall intestineNumerous villi are found on the folds and furrows of the smallintestineMicrovilli Minute finger-like projections found on villiThe presence of folds and furrows, as well as villi and microvilli, serve to increase

surface area for absorptionThe long length of the small intestine also increases surface area for absorption totake placeThe epithelium is only one cell thickThe intestinal wall and the villi are richly supplied with blood vessels andlymphatic vesselsThe presence of these vessels serve to carry away digested food substancesLacteal A lymphatic vessel present in a villi which is surrounded by blood capillaries


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Aid in the transport of fatBlood vessels carry sugars and amino acidsThis continuous transportation of digested materials away aids to maintainconcentration gradientProcess Simple sugars and amino acids, since they are relatively small in size, diffuse

through the walls of the villi into the blood capillaries Mineral salts and vitamins, since they are relatively small in size, also diffusethrough the walls of the villi into the blood capillaries Transport of digested food substances into the blood capillaries can be throughdiffusion or by active transport Fats are broken down into glycerol and fatty acidso Glycerol is soluble in water and it diffuses through the epitheliumo Fatty acids reacts with bile salts to form soluble soaps so that it can diffuse throughthe epitheliumo In the epithelium, glycerol and the soluble soaps recombine to form minute fatglobules which are absorbed by the lacteals Water and mineral salts are also absorbed by the large intestines

The epithelium layer of the villi is one cell thicko This allows digested food substances to diffuserapidly over a short distance into the blood capillaries or lacteal Undigested food substances and unabsorbed digested matter are storedtemporarily in the rectum before being discharged as feces through the anus Egestiono Removal undigested matter from the body Transportation and utilization of absorbed foodso Sugars

Blood capillaries in the villi unite to form a large vein, the hepatic portal veinThe hepatic portal vein is linked to the liverSimple sugars are transported to the liver, where most of these are converted toglycogen and storedConversion of glucose to glycogen is carried out in the presence of the hormoneinsulin, produced by the pancreas Glucose + insulin (from pancreas) glycogenThe unconverted sugars are transported to the other parts of the body as glucosefor assimilationGlucose is needed for cellular respirationHence, when the body is in need of glucose, glycogen is converted back intoglucose in the liver and transported away to other parts of the bodyThe conversion of glycogen to glucose is under the action of the hormoneadrenaline Glycogen + glucagon (from pancreas) glucoseo Amino acids

The route of transport for amino acids is similar to that of simplesugars (after being transported to the liver, it is transported in the blood stream to

otherparts of the body)Amino acids are assimilated for New protoplasm Growth and repair Formation of hormones Formation of enzymes


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Excess amino acids not utilized are brought back to the liverDeamination Removal of the amino groups (-NH2) and conversion intoammonia, then urea of excess amino acidsUrea is transported to the kidneys to be removed in the urineThe remains of amino acids are converted into glucose (and then to glycogen) in

the livero Fats

Lymph A colorless fluid in lactealsChyle Milky fluid obtained when fats in the lacteals are mixed withlymphLacteals linked together into larger lymphatic vessels, discharging into thethoracic duct, and ultimately opening into the subclavian veinFats are then carried to the liver and assimilatedWhen there is an inadequate supply of glucose, the fats are oxidized to provideenergy

Under normal conditions, fats are used to build protoplasmExcess fats are stored in adipose tissuesAdipose tissues A layer of tissues beneath the skin, around the heart, thekidneys and in the mesenteries binding the intestines, where fats are stored Peristalsis

o Rhythmic, wave-like contractions of the alimentary canal wall to move food alongthe alimentary canalo Brought about by the antagonistic actions of the circular and longitudinal musclesDilation Circular muscles relax, longitudinal muscles contractConstriction Circular muscles contract, longitudinal muscles relax Functions of livero Carbohydrate metabolism:Glycogen is converted to glucose in the liver in thepresence of glucagon from the pancreaso Fat metabolism

Lipids are removed from the blood and broken downE.g. cholesterol is excreted in the bileo Breakdown of red blood cells

The red blood cells become worn out after a period of time and are destroyed bythe spleenThe hemoglobin of red blood cells are brought back to the liver where it is brokendown and the iron released is storedBile pigments are formed from the breakdown of hemoglobin

o Metabolism of amino acids and the formation of ureaThe amino group is converted into urea and is removed from the body in the urineThe remains of the deaminated amino acids are converted to glucose in urea4.Plant nutrition

Adaptations of dicotyledonous leaf

Upper epidermis Structure Function


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One cell thick layerWaxy cuticleNo chlorophyllStomata may be present in smallnumbers

Cuticle reduces loss of waterthrough evaporationCuticle also protects the leaf fromMechanical injury.The upper epidermis and thecuticle is transparent, thus

allowing light to pass througheasily

Palisade mesophyll Densely packed cylindricalshaped cells arranged at rightangles to the upper epidermisof the leaf in one or two layersCells have thin walls andcontain many chloroplasts

Palisade mesophyll cellsare the main sites wherephotosynthesis takes placedue to high concentrationof chlorophyll.Thin cell wall andcytoplasm allows rapiddiffusion of water andcarbon dioxide into thechloroplasts.

Spongy mesophyll Irregularly-shaped cellscontaining fewer chloroplastsCells are loosely packed withlarge intercellular air spacesbetween cells

Air spaces are connected with thestomata (serves as passage wayfor diffusion of carbon dioxide andoxygen, as well as water vapor)Some photosynthesis occurs andthis causes the cells to be turgid(support)

Vascularbundles

Lignified xylemvessels andtracheidsPhloem tissueswith sieve tubesand companioncells

Xylem aids in the conduction of water and mineralsalts from the roots to the leaves. Provides supportfor the leaf laminaPhloem aids in transport of products ofphotosynthesis from the leaves to other parts of theplant, especially to the roots, in the form of sucrose

Lowerepidermis

One cell thick layerWaxy cuticlePresence of many

stomata

Stomata allow gaseous exchangebetween external environmentand the intercellular air spaces in

the spongy mesophyllStomata A pair of curvedguard cellssurrounding astomatal pore

Gaseous exchange occurs throughthe stomatal pore. Opening or closure of guardcells regulates gaseous exchange

Photosynthesiso EquationsWord equation


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Carbon dioxide + water =glucose + oxygen + waterChemical equation 6CO2 + 12H2O =C6H12O6 + 6O2 + 6 H2Oo Intake of carbon dioxide

Carbon dioxide from the atmosphere diffuses into the leaf through the stomataOnce the carbon dioxide enters the leaf, it dissolves in the thin film of water

surrounding the spongy mesophyll cells and palisade mesophyll cells and finallydiffuse into the chloroplasts within the cells and used in photosynthesiso Effects of varying light intensity

In the absence of light, photosynthesis does not occur and only respirationcontinuesAs light intensity increases, the rate of photosynthesis increases until the amountof carbon dioxide released from respiration is equal to the amount of carbon dioxideabsorbed for photosynthesisAs higher light intensities, a net uptake of carbon dioxide and release of oxygen isreached and the amount of sugar in the plant will increaseThe rate of photosynthesis increases with increasing light intensity up to the lightsaturation point

Beyond the light saturation point, further increase in light intensity has no effecton the rate of photosynthesisAt very high light intensities, the rate of photosynthesis slows down as excessiveamounts of ultraviolet rays damages chlorophyll moleculesBlue light and red light are most strongly absorbed by chlorophyll pigmentsThus, the highest photosynthetic rate is obtained when leaves are illuminated withblue and red lighto Effects of temperature

The reaction in dark stage of photosynthetic process are catalyzed by enzymeIncreasing temperature up to 40C will increase the rate of photosynthesis due toincreased enzyme activityAt temperatures above 40C, the rate of photosynthesis slows down as theenzymes are denatured gradually

o Effects of carbon dioxideThe normal percentage of carbon dioxide in atmospheric air is 0.03%Increasing carbon dioxide level increases the rate of photosynthesis upto the carbon saturation pointFurther increase in carbon dioxide levels had no effect on the rate ofphotosynthesisCarbon dioxide levels of greater than 0.1% have no effect on rate ofphotosynthesiso Limiting factor

Definition Any factor that directly affects a process if the quantity of this factor is changedIn the case of photosynthesis

Light Carbon dioxide concentration Temperature


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Graphs show the effect of light and carbon dioxide concentration onphotosynthesis ratesIn each case, the rates increase rapidly at first, then reach a ceiling, indicatingthat they are being affected by another limiting factor, for example, temperature

For example, in the first graph, by increasing the temperature, the rate ofphotosynthesis showed only a small increaseIt is likely that temperature may not be an important limiting factor in thisexampleIn the second graph, carbon dioxide concentration is increased insteadThere is a significant increase in the rate of photosynthesisIt is likely that carbon dioxide is an important limiting factor in this example

This is true in nature as there only is 0.03% CO2 in airThus, carbon dioxide concentration is the limitation factorCarbon dioxide levels can only be raised under laboratory conditionsThe constant rate of photosynthesis even when carbon dioxide concentration israised implies that there is another limiting factor at workIn the third graph, with raised carbon dioxide concentration, temperature isincreasedAgain, there is a significant increase in the rate of photosynthesisThis shows that temperature was a limiting factorCompensation point At certain light intensity, the rate of photosynthesis and the rate of respiration isequal This means that the amount of CO2 taken in and O2 released is the same.

5.Transport in flowering plants

Xylemo FunctionsConducts water and its dissolved mineral salts from the roots to the stemsProvide mechanical support to the plant Phloem


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o FunctionsConducts manufactured nutrients (sucrose and amino acids) from the leaves toother parts of the plant Rooto Structure

The root consists of various regions or zones

Growing zone Small young cells that are actively dividing to form new cellsZone of elongation Cells elongate here to bring about increase in length of the rootRoot cap Several layers of protective cells to protect the young cells from injury duringelongationZone of root hairs/maturation Absorption of minerals and water occurs hereThe region of the root about the zone of root hairs has an outer skin which isimpregnated with suberinThis allows it to be air proof as well as waterproof

o Structure of a young dicotyledonous rootXylem and phloem are not bundled togetherCortex present as a storage tissuePiliferous layer Epidermal layer of the root which bears root hair cellsRoot hairs serve to increase surface area to volume ratio for the adaptation ofabsorbing water and mineral saltsCuticle is missingo Movement of water

Absorption of water and mineral salts takes place mainly in the zone of root hairsRoot hairs increase surface area for uptake of waterSap in root hair is a relatively concentrated solution of sugars and various saltsThus the sap has a lower water potential than the soil waterWater enters the root hair cells by osmosisCell sap and soil water is separated by a partially-permeable plasma membraneEntry of water dilutes the root hair cell sapThis causes water to move into the inners cell by osmosisAs water moves into these cells, they have a higher water potential than cellsfurther in, thus water will move in further into the rootsThe process continues until the water enters the xylem vessels and moves up theplanto Pathway of water from root to leaves

Root hair cells epidermis of root cortex of root endodermis xylemvessels Transpiration

o DefinitionThe loss of water vapor from the aerial parts of a plant, especially through thestomata of the leaveso A consequence of gaseous exchangeThere are numerous mesophyll cells present within a leaf, and these aresurrounded by intercellular air spacesWater continually moves out of the mesophyll cells to form a thin film of moistureover their surface


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From the wet cell walls, water evaporates into the intercellular spaces, and fromthere it diffuses through the stomata to the drier air outside the leafo Effects

Air movement The higher the air movement, the higher the rate of transpirationTemperature

A rise in temperature will result in a rise in rate of evaporation (transpiration)Humidity of air The more humid the air, the slower the rate of transpirationLight intensity High light intensity will cause stomata opening This will increase the rate of transpirationo Wilting

The turgor pressure in the mesophyll cells in the leaf Supports the leaf Keep the leaf firm and widely spread out to absorb sunlight for photosynthesisIn strong sunlight, excessive transpiration causes the cells to lose their turgorThey become flaccid and the plant wilts

o TranslocationDefinition The transport of manufactured substances like sugars and amino acids in plantsTranslocation of sugars and amino acids occurs in the phloem Experiment with aphids Ringing experiment Use of14C isotopes6.Transport in humans

Main blood vessels

o Pulmonary arteryHeart to lungso Pulmonary veinLungs to hearto Hepatic arteryHeart to livero Hepatic veinLiver to hearto Renal arteryHeart to kidneyso Renal veinKidneys to arteries Functions of bloodo Red blood cells

Contains hemoglobin A red pigment

Special kind of protein containing iron Oxygen carriero White blood cells

Two main kinds Lymphocyteso Produces antibodies Phagocyteso Phagocytosiso Tissue rejection


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o PlateletsAids in the clotting of blood Fibrinogen fibrino Plasma

Transport medium Blood cells Ions Soluble food substances Hormones Carbon dioxide Urea Vitamins Plasma proteins Blood groupso TypesABABOo Possible combinations for the donor and recipient

O (donor) A (donor) B (donor) AB (donor)

O (recipient) A (recipient) B (recipient) AB (recipient) Arterieso Arteries have walls that are thick, muscular and elastic to withstand the highpressure of blood coming out from the hearto Strength of an artery to resist the pressure comes largely from its elastic fibreso Thick elastic walls also help to maintain the high blood pressure in the arteryo Elastic layer is much thicker in arteries near the hearto Elasticity allows the arteries to stretch and recoil, thus propelling the blood alongthe blood vesselo The constriction and dilation of an artery is brought about by the contraction andrelaxation of the muscles in the arterial walls Veinso Blood in veins are at a lower pressure and flows more slowly and smoothlyo The walls of veins are not as thick and muscular as those of arterieso Veins contains less elastic tissueo Semi-lunar valvesFolds of the inner walls in veins that aids in preventing back flow of bloodo Prevention of back flow is important in returning the blood to the hearto Presence of semi-lunar valves ensures unidirectional blood flow of bloodo The movement of blood along the veins is assisted by the action of the skeletalmuscles on the veinsmuscular contractions and relaxation exert a pressure on the veins, thus moving

blood along Capillarieso Microscopic blood vessels found between cells of almost all tissueso EndotheliumA single layer of flattened cells that makes up the wall of capillarieso The endothelium is partially permeable to ensure rapid diffusion of substancesthrough ito Capillaries branch repeatedly to increase surface area for exchange of substances


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o Blood pressure in capillaries is also lowered, thus blood flow is slowed down,allowing more time for exchange of substances Transfer of materials between capillaries and tissue cellso High blood pressure at the arterial end of capillaries forces out blood plasma intospaces between cellso White blood corpuscles can also squeeze through, but no red blood corpuscles

o Tissue fluidDiluted plasma containing white corpuscleso Tissue fluid is a colorless liquido Some cells do not have direct contact with blood vesselso However, these cells are bathed by tissue fluido Tissue fluid carries substances in solution between the tissue cells and the bloodcapillarieso Dissolved food substances and oxygen diffuse from the blood into the tissue fluidand then into the cellso Waste products diffuse from the cells into the tissue fluid and then through thecapillary walls into the bloodo As capillaries are small, erythrocytes can only move through them in single file

Red blood cells may even become bell-shapedo The advantages of this areThe diameter of the erythrocyte is decreased so that it can pass easily throughthe lumen of the capillariesThe cell increases its surface area to speed up absorption of waste products andrelease of oxygenRate of blood flow is reduced, giving more time for efficient gaseous exchange Hearto Size is about the size of a clenched fist in mano Lies in the thorax, behind the sternum and between the two lungs, displaced to theleft side of the bodyo Conical in shape and slants with its apex directed slightly towards the left side ofthe body

o PericardiumA two-layered bag surrounding the heartThe inner membrane being in contact with the heart while the pericardial fluid liesbetween the two membraneo Made up of four chambers

Two upper atria and two lower ventricleso Median septumMuscular wall that separates the right chambers from the left chambers, thuspreventing mixing of oxygenated and deoxygenated bloodo Blood is returned to the right and left from the vena cava and the pulmonary veinrespectivelyo Contraction of the atria will cause the blood in the atria to be pumped into the right

and left ventricles accordinglyo Blood is pumped out of the heart by the ventriclesPulmonary arch and pulmonary arteries carry blood to the lungs, aortic archcarries blood to the other parts of the bodyo Backflow is prevented due to the presence of valvesTricuspid valve in the right side, bicuspid valve on the left side Blood clotting

o Clotting of blood seals up a wound to prevent excessive loss of bloodo Clotting also prevents entry of foreign particles into the blood stream


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o HemophiliaA genetic disease where the clotting mechanism is greatly impaired, thushemophilics may bleed to deatho Damaged tissues and platelets =thrombokinaseo Prothrombin + thrombokinase + Ca2+=thrombino Fribinogen + thrombin =insoluble fibrin threads

o When blood vessels are damaged, an enzyme (thrombokinase) is released bythe damaged tissues and blood plateletso Thrombokinase converts the protein prothrombin normally present in the plasma tothrombin, which is an enzymeo Calcium ions are required for the conversion of prothrombin to thrombino Thrombin catalyzes the conversion of the soluble protein fibrinogen to a meshworkof insoluble threads of fibrino Fibrin threads entangle blood corpuscles and the whole mass forms a cloto Vitamin K is also essential for the process of blood clottingo In undamaged blood vessels, the blood does not clot due to the presence ofheparin, an anti-clotting substance produced by the livero During blood clot, thrombokinase released neutralizes the action of heparin so that

clotting can take placeo When blood clots, serum is left behindo SerumA yellowish liquid that has the same composition as plasma exceptthat it lacks the clotting constituents Cardiac cycleo Contraction of the atria will cause the blood in the atria to be pumped into the rightand left ventricles accordinglyo Ventricular contraction is also known as ventricular systole (producing lubb sounddue to the closing of the tricuspid and bicuspid valves)o Semi-lunar valves are present to prevent back flow of blood into the ventricleso Ventricular relaxation is also known as ventricular diastole (producing the dubbsound due to the closing of the semi-lunar valves)o A systole and a diastole makes up one heartbeato The rate of heartbeat varies between people Coronary heart diseaseo Two coronary arteries bring oxygen to the cardiac muscleso Obstruction to blood flow in these two arteries may bring about cardiac arrest orangina pectoriso Coronary thrombosisFormation of blood clot in the arteryo If thrombosis occurs in the coronary arteries, blood is prevented from reaching theheartcardiac arresto Heart attack/heart failureSudden slowing or stoppages of the heartbeat due to severe damage or death ofcardiac muscles

o Coronary thrombosis is more likely to occur in narrow arteries with fatty depositso Atherosclerosis

The narrowing and hardening of artery due to fatty deposits on the walls of thearteryo Walls of artery with atherosclerosis are thick and hard, with the rough innersurfaces increasing the risk of thrombosiso What happens leading up to coronary heart disease


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Cholesterol and polysaturated fats are deposited on the walls of the artery,narrowing and hardening the arteryAs the narrowing of lumen would result in rougher inner surfaces, a blood clot islikely to be formedThe blood clot would inhibit the blood from reaching the heart and cause heartattacks or heart failure

o Coronary heart disease can be caused byDiet Diet rich in cholesterol and saturated animal fats results in high blood cholesterollevelLack of exercise/being overweightStress Hormone adrenaline secreted under stress conditions increases heart beat rate andblood pressureDrinkingSmoking Nicotineo Increases the rate of heart beat by increasing secretion of the hormone adrenalineo

Causes the blood vessels to constrict, increasing the blood pressureo Causes blood to clot more easily Carbon monoxideo Increases the rate of fatty deposition on inner surfaces of the arteries anddecreases oxygen supply to the hearto Preventive measures can be taken as atherosclerosis begins early in lifeAvoid diets rich in saturated animal fats Substitute with polyunsaturated vegetable fats Regular exercisingo Strengthens the heart and maintains elasticity of thearterial walls Minimal or no smoking and drinking Low-stress lifestyle or proper stress management.7.Respiration Alveoli

o The walls of the alveoli are the respiratory surfaces, and these are one cellthicko Numerous capillaries are closely wrapped around outside of the alveolio Oxygen can diffuse across the walls of the alveoli into the bloodo Carbon dioxide can diffuse the other way Removal of carbon dioxide from the lungs

o Blood entering the lungs is rich in carbon dioxide in the form of hydrogencarbonate ionsH2O + CO2 ->H2CO3


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o Carbonic anhydrase will catalyze the backward reaction and hydrogen carbonatesare converted to water and carbon dioxide in the red blood cellso Carbon dioxide will diffuse out of the blood in the alveoli to be exhaled out tothe external environmento Some moisture and heat will also be exhaled out in this manner Cilia

o Cilia are hair-like structures which lines the trachea, moves to and fro in a wave-like rhythm to sweep the dirty mucus up the larynx and into the pharynx to beswallowed down the esophagus Diaphragmo To increase volume of the thorax during inspiration (inhalation)o To decrease volume of the thorax during expiration (exhalation) Ribso Ribs are pulled upwards and outwards during inspiration (inhalation) toincrease volume of the thoraxo Ribs are dropped to its normal position during expiration (exhalation) todecrease volume of the thorax Intercostal muscleso

During inspiration (inhalation), the external intercostal muscles contract, while theinternal intercostal muscles relax, pulling the rib cage upwards and outwards, andpulling sternum upward and forwardo This is done to increase volume of the thoraxo During expiration (exhalation), the external intercostal muscles relax, while theinternal intercostal muscles contract, causing the rib cage to drop again to its normalpositiono This is done to decrease volume of the thorax Effects of tobacco smoke

o Cigarette smoke contains more than 4000 chemicals, many of which arecarcinogenico Smoking can cause harmful diseases in mano Chemicals in tobacco smoke

NicotineCarbon monoxideTaro Effects of nicotine on the body

Increase in heartbeat and blood pressureIncreased risk of blood clots in arterieso Effects of carbon monoxide on the body

DeathIncreased risk of atherosclerosisIncreased risk of blood clots in arterieso Effects of tar on the body

Blockage in alveoli reduces gas exchange efficiencyMucus cannot be removedIncrease risk of chronic bronchitisIncreased risk of emphysema Aerobic respirationo The breakdown of food substances in the presence of oxygen with the release of alarge amount of energyo Word equationGlucose + oxygen =carbon dioxide + water + energyo Chemical equation


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C6H12O6 + O2=CO2 + H2O (38 ATP) Anaerobic respirationo The breakdown of food substances with the release of a comparatively smallamount of energy in the absence of oxygeno Word equationGlucose =carbon dioxide + ethanol + energy

o Chemical equationC6H12O6=2CO2 + 2C2H5OH (2 ATP) Effects of lactic acid on muscleso This will cause muscle fatigue and the body will need to rest to recover.8.Excretion

The process by which metabolic waste products are removed from the body of anorganism Importance of removing nitrogenous and other compoundso Ensure that chemical reactions proceed in the correct directiono Certain metabolic wastes are toxic Ultrafiltrationo Blood from the renal artery brings metabolic wastes and useful substances to the

kidney tubuleso Most of the blood plasma is forced out of the glomercular blood capillaries into theBowmans capsuleo Is the process of small molecules being forced into the nephron due to high bloodpressureo Factors of ultrafiltration

Hydrostatic blood pressure Blood pressure in the glomerulus is high because the efferent arteriole is narrowerthan the afferent arteriole, hence providing the main force required for filtrate to leakthrough the porous capillary wall of glomerulusPartially permeable membrane Allowing only small molecules to diffuse acrosso Filtrate

Glucose, vitamins, amino acids, hormones, bicarbonate ions, mineral salts andother nitrogenous waste productso Remnants

Blood cells and all large molecules like blood platelets, blood corpuscles, proteinsand fatso The filtrate trickles down into the proximal convoluted tubule, the loop of Henleand then to the distal convoluted tubule, then down into the collecting duct Selective reabsorptiono About 120cm3 of filtrate are formed in the kidney every minuteThere is a need to reabsorb useful materialsSelective reabsorption takes place to take back useful materialso At the proximal convoluted tubule, mineral salts, glucose, amino acids, and other

useful substances are reabsorbed through the walls of the tubules into the bloodcapillaries through active transport and diffusiono Highly selectiveReceptors only pumps in those that are needed by the bodyo The large molecules that remain in the blood capillaries act osmotically to reabsorbwater in the tubuleo Most of the water is reabsorbed mainly by osmosiso Some of the water is reabsorbed in the loop of Henle, distal convoluted tubule andcollecting duct into the surrounding blood capillaries


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o Some salts are also reabsorbed from the distal convoluted tubuleo Excess water, mineral salts and nitrogenous waste products are allowed to passthrough along the uriniferous tube and out through the collecting tubule into therenal pelvis and into the ureter as urineo Blood that flows away from the kidney tubule contains very little urea and lessexcess water

o The fluid in the nephron flows in one direction while the capillaries flow in theopposite directiono This is known as countercurrent flowo Countercurrent flow occurs to allow for maximum reabsorption of substanceso Most water is reabsorbed by diffusion, followed by osmosis according to the controlof the anti-diuretic hormone (ADH) made in the hypothalamus of the braino ADH is stored in the pituitary gland of braino The osmoreceptors in the hypothalamus of the brain monitors the osmoticpressure of the blood passing througho If the osmotic pressure of the blood rises, more ADH released from the pituitarywill increase the permeability of the tubule wall and more water will be reabsorbed,hence less urine will be formedo The production of a large quantity of water urine is known as diuresiso ADH serves to counter this condition, and thus the name Kidney dialysis

o An artery is joined to a vein, creating a arteriovenous fistulao Blood is then drawn from the vein in the arm of a patient and allowed to flowthrough the dialysis tubing in the machineo This tubing is narrow, long and coiled to increase surface areao Its walls are selectively permeableo The dialysis tubing is bathed in a dialysis liquid similar to blood plasmao Small molecules that are waste products like urea diffuse out of the tubinginto the dialysis liquido Big particles like blood cells and plasma protein remain in the tubingo The blood is not only cleansed but the amount of salt and water is adjusted

before it is returned to the patiento The cleansed blood is returned to the patient through a tube connected to avein in the armo Countercurrent flow is observed to maintain concentration gradient.9.Homeostasis

Definitiono The maintenance of a constant internal environment Process of homeostasiso A change in the internal environment (stimulus)o A corrective mechanismo A negative feedbacko In general, if some factor becomes excessive or too little, a control system initiates

a feedback mechanism, which consists of a series of changes that return the factortoward a certain mean value, thus maintaining homeostasiso Negative feedback serves to prevent the self-regulatory corrective mechanism fromover-compensation Maintenance of body temperature

o Insulation

The thicker ones skin is, the higher the insulation, thus he or she loses or gainsheat at a slower rateo Temperature receptors in the skin


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The temperature receptors in the skin sense changes in the environment andtransmit a signal to the hypothalamus to start the corrective mechanism to effect achange

o Sweating

Another characteristics of mammalsEach sweat glands is a coiled tube formed by a down-growth of the epidermisIt forms a tight knot in the dermis and is richly surrounded by blood capillariesThese secrete a liquid called sweatSweat is mostly water, with small amounts of salt and urea dissolved in itIt travels up the sweat ducts, and out onto the surface of the skin through thesweat poresSweat is secreted continuously but sometimes in very small quantities whichevaporate almost immediatelySweat helps in temperature regulation (removal of latent heat)o Shivering

A very fast random contraction and relaxation of muscles, which generates heatto warm the bloodo Blood vessels near the skin surfaceWhen one is too warm Vasodilation is brought abouto More blood is brought to the surface of the skin andmore heat is lost through radiation, conduction and convention Constriction of shunt vessels to allow more blood to be brought to the surfaceWhen one is too cold Vasoconstriction is brought abouto This prevents blood from flowing to the surface of the skino Instead it has to go through the capillaries which lie below the fat layero This reduces the amount of heat lost by radiation from the blood to the air Dilation of shunt vessels to direct blood away from the surface

o Coordinating role of brainThe hypothalamus in the brain is responsible to prevent overcompensationIn other words, the brain controls when compensation is to be ceased.10.Co-ordination and response

Relationship between receptors, central nervous system and effectorso The receptors send impulses to the central nervous systems, which transmitsanother impulse to the effectors, which response to the stimuli Structure of the eyeo Cornea

Dome-shaped transparent layer continuous with the scleraSpecialized form of conjunctivaRefracts light rays into the eye

Causes most of the refraction of lighto IrisCircular sheet of muscles that controls the amount of light into the eyePigmented to give the eye its color (it may vary from blue to grey or green tobrown)Two sets of involuntary muscles present Circular muscles and radial muscles

o Pupil


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Hole in the centre of the irisAllows light to enter into the eyeo Sclera

Outermost layer, tough, white, fibrous coatForms a protective layer round the eyeball and continues as a transparent corneawhich forms a small bulge at the front of the eye

Cornea Transparent part of the scleraThe cornea allows light to enterThe cornea is denser than the air medium, thus light rays falling onto it arerefracted inwards towards the lenso Conjunctiva

A thin transparent membrane covering the exposed part of the eyeballIt is a mucous membrane that secretes mucus to keep the eye moistThe conjunctiva is continuous with the skin of the eyelidso Eyelids

Serve to protect the eyeball against mechanical injuryAct as a shutter and help control the amount of light intensity entering

the lighto Lachrymal glandSecretes tears to lubricate the conjunctivaThe tear gland lies in the outer corner of the upper eyelidTears flow between the eyelids and the exposed part of the eyeball, helping toreduce friction when the eyelids moveDust particles entering the eyes will cause a great production of tears to washthem awayTears contain an enzyme called lysozyme, which can kill bacteriaBlinking spreads tears over the cornea and conjunctiva and wipes dust particlesoff the corneao Naso-lachrymal duct

Duct where excess tear drains intoThe naso-lachrymal duct runs from the inner corner of the eye to the noseEmotion may cause excess tears to be secreted and passed into the naso-lachrymal ducto Eyelashes

Help to shield the eye from dust particleso Choroid coat

The middle layer of the eyeballContains a network of blood capillaries that nourishes the eye as well as removeswastePigmented black to prevent internal reflection of lightAnterior end of the choroid is modified to form the ciliary body and theirisCiliary body Thickened region at the front end of the choroids that contains many involuntarycircular muscles called ciliary muscles Intrinsic eye muscles since they are inside the eyeball Ciliary muscles control the curvature or the thickness of the lens Ciliary muscles pay an important part in focusing and accommodationIris Circular sheet of muscles with a round hold in the centrePupil


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The central hole in the iris which allows light to pass into theeyeLens Transparent, elastic, biconvex crystalline lens Situated behind the iris and in contact with the iris The lens is attached to the ciliary body by the suspensory ligaments

Divides the eyeball into two chamberso The small chamber in front of the iris and the lens is filled with a water fluid knownas aqueous humouro The larger chamber behind the lens is filled with a transparent jelly-like fluid, thevitreous humour Both aqueous humour and vitreous humour serve to keep the eyeball firm and torefract lighto Retina

Innermost layer of the eyeballLight-sensitive layer on which images are formedPresence of photoreceptors Rods and cones

These cells are connected to the nerve-endings from the optic nerveo RodsContains visual purple The pigment concerned with vision in dim lightLight causes bleaching of visual purple which is involved in light detectionIn bright light, all the visual purple is bleachedIt takes a short time for visual purple to be formed again in the rodsThus, when a person enters a dark place from a bright one, he may not be able todistinguish the objects around him for some timeFormation of visual purple requires Vitamin AA person with deficiency in Vitamin A may not be able to see in dim light, acondition known as night-blindnessRods are sensitive to dim light, but only let one see in black and whiteo ConesLess sensitive than rods, thus it is inefficient in dim lightConcerned with bright light and color visionThree types of cones, each possessing a different pigment Red, green and blueThus, cones enable one to see light at different colorsFovea centralis (yellow spot) A shallow yellow depression in the retina in line with or on the optical axis of thelens Place where images are normally focused Contains only cones Thus vision is keenest in bright light when images are focused onto the yellow spotOptic nerve Nerve that transmit impulses to the brain when the photoreceptors are stimulatedBlind spot On the retina immediately over the optic nerve Absences of any photoreceptors, thus this area is insensitive to light Accommodation for near objectso Light rays from a near object are divergingo Refraction by cornea and aqueous humour into the pupilo Contraction of the ciliary muscles


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o Pull on the suspensory ligaments is releasedo Lens becomes thicker and more convex contractedo Light rays from near objects are sharply focused on the retinao Photoreceptors stimulatedo Nerve impulses transmitted to brain via the optic nerveo Brain interprets the impulses and near object is seen

o The nearer the objects, the more the circular muscles will contract and the thickerthe lens will beo Near point

Point where the object is so close to the eye that in order to see it, the ciliarymuscle must contract fully and the lens become most convexIf the object is moved nearer to the eye, the image formed on the retina will beblurred as the lens cannot adjust any further Accommodation for a distant vision (7m)o For a distant object, the light rays are almost parallel to each other when theyreach the eyeo Parallel rays are refracted by cornea and aqueous humour into the pupilo Relaxation of ciliary mscleso

Pull on suspensory ligaments increase

becomes taut, pulling on the edge of theelastic lenso The lens become flatter and less convex relaxo Light rays from the distant object are sharply focused on the retinao Photoreceptors stimulatedo Nerve impulses transmitted to brain via the optic nerveo Brain interprets the impulses and far object is seen Light and pupil reflexo The size of the pupil changes to allow a suitable amount of light to pass into theeyeThis protects the inner layer of the eye from damageAnd in dim light, allows more light to enter the eye in order to see clearlyo The size of the pupil is controlled by two sets of involuntary muscles in the irisCircular muscles and radial muscleso When the circular muscles contract, the radial muscles relax pupil becomessmallero When the circular muscles relax, the radial muscles contractpupil becomeslargero Thus, the size of the pupil will control the amount of light entering the eyeo The pupil becomes smaller in light of high intensityo The pupil becomes larger in low light intensityo This is a reflex actionContraction and relaxation of these involuntary muscles are automatic andimmediate in response to the stimulus of lighto Sometimes, the light intensity is so bright that decreasing the size of the pupil is

not enougho The eyelids have to come closer together to screen off part of the lighto The pupil reflex arcStimulus (change in light intensity) receptor (retina) sensory neurone inoptic nerve brain motor neurone effector (iris) Nervous systemo Function

Co-ordinate and regulate bodily functions Sensory neurons


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o Afferent/receptor neuronso Transmit impulses from the receptors to the central nervous system Relaying neurons

o Intermediate neurons

o Transmit impulses from the afferent neurons to the efferent neurons and are foundwithin the central nervous system

Efferent neuronso Motor/effector neuronso Transmit impulses from the central nervous system to the effectors Reflex actionso The nervous pathway for reflex action is the reflex arco A stimuli stimulates the nerve endings (receptor/sense organ) in the skino Impulses are producedThese travel along the sensory neurone to the spinal cord or the braino In the spinal cord or the brain (reflex centre), the impulses are transmitted firstacross a synapse to the intermediate or relaying neurone, and then across anothersynapse to the motor neurone (an impulse may also be transmitted to the brain atthe same time)o

Motor impulses leave the spinal cord along the motor neurone to the effectoro The effector (muscles or glands) brings about a respond to the stimuli Hormoneo Chemical substances produced in minute quantities by certain parts of the bodyand transported in the bloodstream to other parts where they exert an effect Endocrine glando Glands without ducts or glands of internal secretionso The islets of Langerhans in the pancreas secrete the hormone insulin into theblood stream Adrenalineo It increases the rate of conversion of glycogen to glucose in the liver, thusincreasing blood sugar level so that more glucose is available for energy productiono Stimulus includes fear, anger, anxiety or stress Insulino Stimulates absorption of glucose by cells so that they can break it down to releaseenergyo Directing the conversion of excess glucose to glycogen for storage in liver ormuscleso Increasing oxidation of glucose during tissue respirationo Thus, decreasing blood glucose concentration Glucagono Conversion of glycogen into glucoseo Conversion of fats and amino acids into glucoseo Conversion of lactic acid into glucoseo Thus, increasing blood glucose concentration

Diabetes mellituso Symptoms

High blood glucose level Lack of secretion of insulin, the body cannot use or store glucose This brings about a rise in blood glucose concentrationGlucose in urine As insulin is not secreted, blood glucose is not reabsorbed by the body and is lostin the urineo Treatment


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People with Type 1 diabetes have to inject insulin into their bodies daily.They also need to ensure that they have a ready supply of sugary food as theirblood glucose concentration can drop drastically (either from over-dosage of insulin,exercising too much or eating too little)People with Type 2 diabetes need to control their blood glucose concentration byregulating intake of carbohydrates in their diet and by regular exercising

If lifestyle changes fail, then the patients may need to take medication (e.g.metformin tablets) or insulin injection.

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