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Animal Physiology
Digestion, Secretion, and Absorption
| Term | Definition |
|---|---|
| Types of Gut tracts | Intracellular: Protists, sponges extracellular: ---Incomplete Gut tract: 1 opening not as efficient, small meals. ex.) Corals ---Complete Gut tract: 2 openings, efficient, assembly line, larger body size. |
| Food compounds | Proteins=Large Lipids=not water soluble starch, cellulose= large and not very water soluble. |
| Ways to Digest | 1.) Hydrolysis- Negative free energy but slow (favorable) 2.) Enzymes- Faster |
| Secretions (Mouth)- Saliva | 1.) Mucin -glycoprotein, helps lubricate 2.) Lysozyme- break down cell walls of bacteria 3.) Alpha Amylase- breaks down carbohydrates (starch) |
| Secretions (stomach) | 1.) mucus- Goblet cell Soluble- (thin) Visible- (not soluble, thicker) 2.) Intrinsic factor- parietal cell b12 for RBC Shortage= Pernicious anemia |
| Secretions (stomach) Cont. | 3.) pepsinogen- from chief cell proenzyme: not in active form. becomes active when HCl present (pepsin when HCl is around) 10-20% protein in meal digested Regulation: Vagus, Secretin, low pH |
| Vagus Nerve | 10th cranial Nerve, regulates pepsinogen |
| Secretin | Hormone that initiates release of pepsin If pepsin was directly made it would destroy the cells. |
| Secretions (HCl from Parietal cell) | 1.) CO2 +H2O= H2CO3 2.) H2CO3--> HCO3- + H+ (HCO3- out blood) ( Exchange Cl- in) 3.) Cl- passively diffuses out into lumen 4.) H+ out to lumen, K+ exchange in (active) 5.) K+ leaks out passively |
| HCl secretion Phases | Cephalic, Gastric, Intenstinal |
| Cephalic | See, smell, Taste, Imagine |
| Gastric | Stretch, caffeine, alcohol, protein |
| Intestinal | Peptides, Chyme |
| HCl Secretion Regulation | Ceaphalic= vagues nerve (Nervous system) Gastric= Vagus, gastrin (Hormone) Intestinal= Gastrin (-) feedback: very low pH, fatty acids. |
| Pancreas( Endocrine) | 3%, secrete straight to blood stream. Insulin- Lowers blood sugar Glucagon- Raises blood sugar |
| Pancreas (exocrine) | 97% mass of organ, has ducts Aqeuous fraction Enzymatic fraction |
| Aqeuous fraction (intestine) | H2O, HCO3- ( neutralize acid) stimulated by secretin --> pepsinogen secretion |
| Enzymatic fraction | Trypsin, chymotrypsin, carboxypeptidase, a-amylase, lipases. Stimulated by CCK ( Cholecystokinen) ----> hormone |
| Gall bladder | Stores bile from liver |
| Bile | regulated by CCK, concentrated 5-20X, Emulsifies lipids (physical digestion), acts as a detergent big droplets---> small droplets. |
| BIle acid | Very important for emulsification |
| Lecithen | lipid helps mobilize cholesterol. Ex.) soybeans, egg yokes. |
| Cholesterol | Excretion |
| Billirubin | Heme group of hemoglobin comes from old red blood cells. |
| Bicarbonate and water | makes aqueous and neutralizes. |
| Bile pigments | Billrubin: Green/black in bile, brown in feces, yellow in urine. |
| Problems | Gallstones can lead to obstructive jaundice, Hepatitis A, Hepatitis B, Cirrhosis |
| Obstructive jaundice | Yellow tinge to skin and eyes |
| Hepatitis A | Sewage, contaminated water, shellfish |
| Hepatits B | Blood |
| Cirrhosis | Alcohol abuse, liver death |
| Digestive physiology (feeding strategy case studies) | Wax- aquatic (more common), terrestrial Cellulose- Invertebrates, Foregut, and hindgut fermentation |
| Aquatic wax | Primary consumers: copepod crustaceans , store wax Secondary consumers: fish and birds, eat copepods. |
| Marine birds- Petrel | Feed on marine animals containing wax, less than 1 % of wax excreted |
| Albatross and petrel stomach adaptations | Lipid layer ( top), and water later (bottom) , lipids stored, used when bird is on nest. |
| Terrestrial Wax | Beeswax, wax glands, honeycomb |
| Honey guide birds | Eats wax and larvae |
| Ratel Or honey badger | East honey |
| Mbuti Tribe of Pygmies | Follow honeyguides, eat honey |
| Experiment: Domestic chicks | 1.) feed wax: dont survive 2.) feed wax + bacteria: survive |
| Cellulose digestion | Large, insoluble, yet used as an energy source. |
| Invertebrates | Cellulase enzyme ( silverfish) or Symbiotic protists and bacteria (termites) |
| Termite Experiment | Expose Flagellates to O2, termites cant digest their food |
| Cellulose Digestion ( Foregut Fermentation) | Cows, Camels, kangaroo, hoatzin. Rumen: stomach chamber, chew cud, Anaerobic fermentation with symbionts, 70 % of energy needs from bacteria Cellulose--> glucose---> 2 ATP + lactic acid Bacteria use glycolytic pathway |
| what if bacteria were aerobic? Would it be better? | No, because the bacteria would receive all the energy(ATP). |
| Calf stomachs | Enlarged rumen on hay-fed animal compared to milk fed. |
| Fistulated Cow | Can sample rumen microbes |
| Cellulose Digestion ( Hindgut Fermentation) | Horse, rabbit, lemming, willow ptarmigan. |
| Hindgut anatomy: Human | Colon- large intestine, Small intestine Cecum w/appendix- blind pouch |
| What is more efficient Hindgut or foregut | Foregut fermentaion is more efficient, because it is earlier in the process, small intestine, has more time for absorption. Hindgut more water is conserved, doesnt digest/ break down food all the way. Ex.) cow poop vs. Horse poop. |
| Rabbit Coprophagy | Feces (ignored) Cecal pellets) Consumed |
Created by:
Neiller4