Today

• Looking at “Form fits function”– Human Body Review

• Have out notes, etc. that you need

Form fits function

Examples

• Enzyme specificity• Viral specificity• Pollinators/flowers• Pollen/stigma• Adaptations/environment

Nervous System

Action potential

• http://outreach.mcb.harvard.edu/animations/actionpotential.swf

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.html

Transmission across synapses

• http://outreach.mcb.harvard.edu/animations/synaptic.swf

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__transmission_across_a_synapse.html

Muscular System

Muscle Tissue

• Skeletal – attached to bone (Ex. Biceps)

• Smooth – blood vessels and internal organs (stomach)

• Cardiac – heart• Reflex arc – pictured

to the left

Vertebrate Skeletal Muscle• Contract/relax: antagonistic pairs

w/skeleton• Muscles: bundle of….• Muscle fibers: single cell w/ many nuclei

consisting of….• Myofibrils: longitudinal bundles composed

of….• Myofilaments:

•Thin~ 2 strands of actin protein and a regulatory protein •Thick~ myosin protein

• Sarcomere: repeating unit of muscle tissue, composed of….

• Z lines~sarcomere border• I band~only actin protein• A band~actin & myosin protein overlap• H zone~central sarcomere; only myosin

Muscle contraction

• http://bcs.whfreeman.com/thelifewire/content/chp47/4702001.html

Muscular contraction

• Action potential travels from neuron to muscle• Action potential is generated on the

sarcolemma• Sarcoplasmic reticulum releases Ca++• Ca++ binds to troponin on the actin filaments

– Conformational change exposes myosin binding sites

Muscular Contration

• ATP binds myosin head (high-energy head)• If Ca++ present, myosin binding sites on the

actin are exposed (myosin heads bind to actin filaments) – form cross bridges

• ADP and P are released, causes conformational change in myosin, causes sliding movement towards center of sarcomere (2 Z lines come together)

• Muscle fibers contract

Muscle contraction regulation, I

• Relaxation: tropomyosin blocks myosin binding sites on actin

• Contraction: calcium binds to troponin complex; tropomyosin changes shape, exposing myosin binding sites

Muscle contraction regulation, II

• Calcium (Ca+)~ concentration regulated by the….

• Sarcoplasmic reticulum~ a specialized endoplasmic reticulum – releases Ca+

• Stimulated by action potential in a motor neuron

• T (transverse) tubules~ travel channels in plasma membrane for action potential

• Ca+ then binds to troponin

Endocrine System

Mode of Action: Chemical Signaling• 1- Plasma membrane reception •

signal-transduction pathways (neurotransmitters, growth factors, most hormones)

• 2- Cell nucleus reception • steroid hormones, thyroid hormones, some local regulators

TROPIC HORMONES

T3/T4 Calcitonin

TestosteroneEstrogen

ProgesteroneShort-termEpinephrine

Long-termGlucocorticoids

QuickTime™ and aCinepak decompressor

are needed to see this picture.

Respiratory

• Countercurrent exchange – allows diffusion to occur along the entire length of capillary

• 80% efficient• On land, gills would dry out and collapse (need

moist surface for diffusion)

Regulating breathing• Regulation: monitors CO2

levels in blood (medulla oblongata)

• CO2 + water = carbonic acid = lowers pH

• Slight drop in pH triggers a breathing response

• O2 levels have little effect on breathing unless O2 is severely depleted

Respiratory pigments: gas transport• Needed for efficient transport of

oxygen• Oxygen transport-• Hemocyanin: found in hemolymph of

arthropods and mollusks (Cu) – blue blood

• Hemoglobin: vertebrates (Fe)

• Carbon dioxide transport-• Blood plasma (7%)• Hemoglobin (23%)• Bicarbonate ions (70%)• Deep-diving air-breathers-• Myoglobin: oxygen storing protein

Protein review• Cooperativity – the

binding of one oxygen to hemoglobin, causes the other 3 active sites to have a HIGHER AFFINITY for oxygen

• Similar to allosteric activation

• What do you think the optimal pH is for hemoglobin?

Bohr shift• Hemoglobin releases oxygen (has less affinity

for oxygen) at lower partial pressure for oxygen and at lower pH’s (more CO2)

Circulation system evolution, I • Gastrovascular cavity (cnidarians, flatworms)• Open circulatory •hemolymph (blood & interstitial fluid) •sinuses

(spaces surrounding organs)• Closed circulatory: blood confined to vessels• Cardiovascular system •heart (atria/ventricles) •blood vessels

(arteries, arterioles, capillary beds, venules, veins) •blood (circulatory fluid)

Circulation system evolution, II• Fish: 2-chambered heart; single circuit of blood flow• Amphibians: 3-chambered heart; 2 circuits of blood flow-

pulmocutaneous (lungs and skin); systemic (some mixing)• Mammals: 4-chambered heart; double circulation; complete separation

between oxygen-rich and oxygen poor blood

The heartbeat• Sinoatrial (SA) node (“pacemaker”): sets rate and timing of cardiac

contraction by generating electrical signals• Atrioventricular (AV) node: relay point (0.1 second delay to ensure

atria empty) spreading impulse to walls of ventricles• Electrocardiogram (ECG or EKG)

Why do the blood vessels have different structure?

• Capillaries•endothelium (lining of smooth cells = less resistance to blood flow); basement membrane – cell attachment & selective permeability

• Arteries•thick connective tissue;

thick smooth muscle; endothelium; basement membrane

• Veins •thin connective tissue; thin smooth muscle; endothelium; basement membrane

Blood• Plasma: liquid matrix of blood in which cells are suspended (90% water)• Erythrocytes (RBCs): transport O2 via hemoglobin• Leukocytes (WBCs): defense and immunity• Platelets: clotting• Stem cells: pluripotent cells in the red marrow of bones• Blood clotting: fibrinogen (inactive)/ fibrin (active); hemophilia; thrombus

(clot)

Digestion

Feeding mechanismsSuspension-feeders

Bulk-feedersFluid-feeders

Substrate-feeders

Deposit-feeders

Intracellular Digestion

• Ingestion – phagocytosis, pinocytosis

• Digestion – hydrolytic enzymes contained in lysosomes

• Absorption – simple diffusion

• Elimination - exocytosis

Extracellular Digestion – can eat larger preyGastrovascular cavity

Complete digestive tracts(alimentary canals) – allow for systematicFood processing in specialized regions

1 opening2 openings

Gastric Pits

Positive feedback mechanism

Hormonal Regulation• Gastrin - found in stomach

– released when we sense food– Stimulates gastric juice production

• Secretin – found in duodenum– Acid chyme stimulates production of secretin– Secretin stimulates the pancreas to release bicarbonate

(offset acid)• CCK (cholecystokinin) – duodenum

– Presence of fatty acids/amino acids stimulates release of CCK

– CCK stimulates the gall bladder to release bile and the pancreas to release other enzymes

– CCK slows peristalsis if meal is high in fat (fat takes longer to digest)

• Excretion

OsmoregulatorsSaltwater fish – lose water to the environment, need to drink salt water, actively transport salt out of gills & release salt in urineFreshwater fish - opposite

Aquatic organisms can afford to

lose water ammonia

• most toxic• Able to dilute it

Terrestrial need to

conserve water urea

• less toxic/can store at high conc. (ENERGY)

• Energy tradeoff Terrestrial egg

layers need to conserve

most water uric acid

• least toxic• Less soluble• Waste in paste-form

Nitrogen waste – toxic ammonia vs energy loss

Mammalian System• Key functions

– filtration• fluids from blood collected • includes water & solutes

– reabsorption• selectively reabsorb needed

substances back to blood– secretion

• pump out unwanted substances to urine

– excretion• remove excess substances & toxins

from body

blood filtrate

urine

Excretory SystemsProduction of urine by 2 steps: • Filtration (nonselective) • Reabsorption (secretion of solutes)Protonephridia ~ flatworms (“flame-bulb” systems)Metanephridia ~ annelids (ciliated funnel system)Malpighian tubules ~ insects (tubes in digestive tract)Kidneys ~ vertebrates

Osmotic control in nephron• How is all this re-absorption achieved?

– tight osmotic control to reduce the energy cost of excretion

– use diffusion instead of active transportwherever possible

the value of acounter current exchange system

Kidney regulation: hormonesAntidiuretic hormone (ADH) ~ secretion increases permeability of distal tubules and collecting ducts to water (H2O back to body); inhibited by alcohol and coffee, caused by osmolarity changesJuxtaglomerular apparatus (JGA) ~ reduced salt intake--->enzyme renin initiates conversion of angiotension (plasma protein) to angiotension II (peptide); increase blood pressure and blood volume by constricting capillaries Angiotension II also stimulates adrenal glands to secrete aldosterone; acts on distal tubules to reabsorb more sodium, thereby increasing blood pressure (renin-angiotension-aldosterone system; RAAS)