How Do You Build the Molecules of Life? Better Known as Organic Molecules and Digestion…
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Transcript of How Do You Build the Molecules of Life? Better Known as Organic Molecules and Digestion…
Living Creatures Have Organization
• All organisms are made of the same collection of chemicals, which are organized into…• Molecules
• Made up of proteins, fats, carbohydrates, and nucleic acids
• Molecules are then organized into…• Organelles & Cells, specifically…
• Plant Cells & Animal Cells
Living Creatures Have Organization
• Going from a cell to baby…. • The original fertilized egg has to divide into
groups of cells• The groups of cells work together to perform
the same function and form tissue
Living Creatures Have Organization
• Tissue is then organized into…• Organs & Organ systems
• Respiratory, Circulatory, Digestive, etc.
Living Creatures Have Organization
Making the Body Systems Work
• Animals make energy using food and oxygen
• Animals build bodies using:• Food for raw
materials • Amino acids,
sugars, fats, nucleotides
• ATP energy for synthesis
But where do we get the raw material from? Food we eat!
O2
Food
ATP
Getting & Using Food• Ingest: Taking in food• Digest
• Mechanical digestion• Breaking up food into
smaller pieces• Chemical digestion
• Breaking down food into molecules small enough to be absorbed into cells
• Enzymes are proteins that help to speed up the breaking down process
• Absorb: Absorb across cell membrane• Diffusion• Active transport
• Eliminate: Undigested material passes out of digestive system
intracellulardigestion
extracellulardigestion
Ingestion Starts Digestion
• Mouth• Mechanical Digestion• Chemical Digestion
• Saliva -Enzyme digests starch• Slippery protein• Protects soft lining of digestive system• Lubricates food for easier swallowing
Salivary Glands
• Scattered throughout oral cavity• Functions:
• Hydrolysis• Dissolve things• Moisten food and mouth
• Composition of saliva• pH 6.35-6.85 (Slightly acidic)• Produce 1000-1500 ml a day• 99% of saliva is water
• Salivary amylase begins breakdown of starch
Esophagus• Moves both air and food• Epiglottis, a flap of tissue, prevents food from
entering the trachea• Food enters the esophagus instead• Muscular contractions and relaxations called
peristalsis moves food through the esophagus
Stomach• Can stretch to hold 2 L of food• “Growling” is contracting of stomach muscle• Three layers of muscle churn the food• Gastric pits in the stomach secrete acidic digestive fluid• Mucus protects the stomach lining – ulcers are a breakdown of this
protective lining• Mixed food particles and gastic fluid is called chyme
Fundus
Duodenum
Esophagus
BodyPylorus
Stomach
• Disinfect food• HCl = pH 2, will kill bacteria
• Chemical Digestion• Digestion of proteins by pepsin, a gastric
protease, into peptides. • Gastric lipase- pH 5-6, splits lipids
Liver • Produces bile to break up fats
• Bile is composed of bile acids and salts, phospholipids, cholesterol, pigments, water, and electrolyte chemicals
• Bile stored in gallbladder until needed• Large organ right of the stomach• Stores glucose, makes proteins, breaks down toxins – including
alcohol
Pancreas
• Lies behind the stomach• Produces sodium bicarbonate, to neutralize
stomach acid to protect the small intestine• Produces insulin in the Islets of Langerhans,
specialized cells in the pancreas• Pancreatic juices:
• Pancreatic amylase – breaks down all starches
• Trypsin, Chymotrypsin – separates amino acids (proteins)
• Pancreatic lipase - breaks down lipids• Nucleases - break down nucleic acids
Islet of Langerhans
Gallbladder
• A pear shaped sac on underside of the right lobe of the liver. • About 7-10cm long. • Ducts
• Hepatic ducts• Cystic ducts• Common bile ducts
• Function• Store and concentrate bile by absorbing water• Contracts and releases bile to duodenum when
needed
Small Intestine• Nearly 7 m in length• Three sections:
• Duodenum (25 cm), Jejunum (2.5 m) and Ileum (4 m)
• Intestinal Juices• Maltase, sucrase, lactase – break down
carbohydrates• Aminopeptidase, Dipeptidase – break down amino
acids (proteins)• Deoxyribonuclease, ribonuclease- break apart
sugars and nucleic acids
Duodenum
• First section of small intestines• Receives acid food from stomach • Mixes with digestive juices from:
• Pancreas• Live• Gallbladder
Absorption by Small Intestines• Highly folded lining of the small intestine is called villi, which are
covered in microvilli• Give a surface area about 250 square meters (area of a tennis
court)• 90% of all nutrients are absorbed in the small intestine, 10% in
stomach and large intestine. • Carbohydrates: absorbed on surface of villi. • Proteins: amino acids are transported by active transport into
the capillaries • Water absorption: absorption accomplished by osmosis• Lipids: lipase breaks down glycerol
Circular creaseswith villi
Colon• Also known as large intestine• Four parts – ascending colon, transverse colon,
descending colon and sigmoid colon• Waste solidifies into feces and >90 % water is reabsorbed
• Diarrhea: not enough water absorbed • Constipation: too much water absorbed
Rectum
Sigmoid
Descendingcolon
Transversecolon
Ascendingcolon
Anus
You’ve Got Company!• Living in the large intestine is a community of
helpful bacteria• Escherichia coli (E. coli)
• produce vitamins • vitamin K; B vitamins
• generate gases• by-product of bacterial metabolism • methane, hydrogen sulfide
stomachkills germs break up fooddigest proteinsstore food
mouthbreak up fooddigest starchkill germsmoisten food
small intestinesbreakdown food
- proteins- starch- fats
absorb nutrients
pancreasproduces enzymes to digest proteins & carbs
liverproduces bile
- stored in gall bladderbreak up fats
large intestinesabsorb water
Appendix
• Vestigial organ located behind the ascending portion of colon
• Darwin suggested it might been used to digest cellulose
• Scientists are now studying how it might influence the immune system
Rectum • Last section of colon • Eliminate feces which are undigested materials
• extracellular waste• mainly cellulose from plants
• masses of bacteria
Length of Digestive System
• Herbivores & Omnivores• Long digestive
systems• Harder to
digest cellulose • Carnivores
• Short digestive systems
• Protein easier to digest
Teeth
• Carnivore• sharp ripping teeth• “canines”
• Herbivore• wide grinding teeth• molars
• Omnivore• both kinds of teeth
Vegetarian Diets
• Need to make sure you get enough protein• 20 amino acids to make protein
• 10 amino acids humans can produce • 8 “essential amino acids” come from food
• Grains (like corn) have 6 (missing 2)• Beans (like soybean & red beans) have 6 (missing
different 2)• Mix beans & grains for complete group of amino
acids• Rice & Beans• Tofu & Rice• Peanut Butter & Bread