ANS 2: Week 4 Notes
ANS 2: Week 4 Notes ANS 002
Popular in Introductory Animal Science
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This 9 page Class Notes was uploaded by Mackenzie Hayes on Saturday April 23, 2016. The Class Notes belongs to ANS 002 at University of California - Davis taught by Dr. James Murray in Spring 2016. Since its upload, it has received 46 views. For similar materials see Introductory Animal Science in Animal Science and Zoology at University of California - Davis.
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Date Created: 04/23/16
ANS 2: Week 4 Notes (4/18) ● Mammary Gland Anatomy ○ Exocrine gland - secretes to outside of body ■ Developmentally like salivary + sudoriferous (sweat) glands ○ Defines the class mammalia ■ Range from skin surface milk patch (monotremes) ■ To variable number of defined glands ○ Number of glands varies with species: ■ Cow: 4 glands; 4 teats ■ sheep/goats: 2 glands; 2 teats ■ Mare: 4 glands; 2 teats ■ Sow: 6-20 glands; same # teats ● Doesn’t have cistern like a cow to store milk ● Must nurse more frequently b/c can’t hold as much ○ Kangaroo young born very immature ■ Continue to nurse/grow in pouch ■ Each nipple produces totally different milk (different glands) ● Stages of Mammary Development: ○ 1 - at puberty ■ Ductal elongation promoted by estrogen + IOF-I ■ Minimal alveolar development (progesterone) ○ 2 - lactogenesis - at pregnancy ■ Ductal and alveolar growth (progesterone) ■ Late pregnancy production of milk + secretion initiated ○ 3 - galactopoiesis = lactation ○ 4 - involution - at end of lactation ■ Regression to pre-pregnancy state ● Composition of milk varies across species ○ Caseins most abundant protein in cow milk + whey is less (reverse in humans) ○ 9 of the 20 amino acids are essential ○ Over 500 different fat molecules have been found in cow milk ■ Changes in diet affect it ■ Food doesn’t have a composition it has a “range” of composition ● No two steaks are alike ○ Changes based on: ■ Breed ■ Stage of lactation ● Colostrum vs. milk ● Early vs. mid vs. late pregnancy ■ Parity of dam ■ Type of feed ■ Age of young ● Newborn vs. young at foot in kangaroos ● Colostrum: ○ First milk produced after parturition ■ High protein content ■ High material antibody content ● Important for passive immunity ● Neonatal gastrointestinal tract epithelium is porous to large molecules immediately after birth ● Not true for all mammals (rabbits) ● Anatomy: *be able to label* ○ True secretory alveoli develop under hormonal control during pregnancy ■ Increasing estrogen - duct and cistern development ■ High progesterone - alveolar growth ○ Structure’s been modified over time (selective breeding) ■ Conformation to fit milking machine ○ Tree-like structure in ductal system (quarters) ○ Mammary epithelial cells - produce + secrete milk ○ Meilol epithelial cells - respond to oxytocin to contract ■ Oxytocin release caused by physical stimulation of hypothalamus ○ Parenchyma - glandular tissue (alveolar tissue) makes milk (progesterone) ○ Alveolus ■ Lumen holds milk ■ Epithelial cells produce milk ■ Stroma = connective tissue ○ Lobule - 200-250 alveoli ■ Lobe = multiple lobules ○ Mammogenesis - mammary gland development ○ Lactogenesis - induction of lactation ○ Galactopoiesis - maintenance of lactation ● *500 gallons of blood / 1 gallon milk* ○ Massive blood supply and flow to mammary system ● Lymph nodes = passive system throughout body ○ Will swell with white blood cells to fight infection ● More living organisms per unit area in small intestine than anywhere else on earth ● Hypothalamus - responds to nerve signals + releases hormones (4/22) ● Digestive Anatomy ● Functions of the GI tract ○ All animals are hollow tubes ■ Some tubes are more specialized than others ○ Receiving ■ Mouth ■ Way of getting food in (ingesting food) ■ Teeth / lips / tongue / jaw ● Able to determine lots about the diet ● Distinctive for different purposes ○ Dog - jaw moves up and down (shearing) ○ Ruminant - jaw moves side to side (grinding) ○ Conduction, storing ■ Foregut - not a lot of digestion ■ Not all systems have a storage function ■ Birds have crop to store food ● Allows it to pick up lots of food fast + digest later ○ Digestion, absorption ■ Acid digestion ● Acidic environment + enzyme breakdown ● Hydrochloric Acid + pepsin ● Stomach, abomasum, ■ Basic Absorption ● Basic environment ● Small intestine - absorbs amino acids, nucleotides, etc. ● Rumen as well (microbes need neutral environment) ○ Absorbing water, defecating ■ Large intestine ■ Some animals have storage for waste (birds do not) ● GI Tract overall same idea for all animals all throughout time ○ Hagfish = almost just a simple hollow tube ○ Complexity and length will vary depending on diet ** ■ Obligate carnivore : simpler GI tract (meat easy to digest) ■ Ruminant / herbivore : more complex (harder things to digest) ● Have to incorporate fermentation ● Cecum = appendix ○ No known function for us ■ Vestigial structure ○ Plant eaters = helps them withdraw nutrients ● Fish + Birds are “constrained” ○ Fish = small compact body to fit GI tract into ■ Small intestine is VERY SMALL ● Pyloric cecum helps to hold food before SI ● Allows time to digest and absorb fat ■ **diagram appears on tests** ■ Distal Stomach = acid stomach ■ Sprial intestine = increase surface area ● Folds inside take up short distance ● Allows more absorption of water (large intestine) ○ Bird = need to be light for flight ■ Beaks instead of lips ● Designed for type of food the bird eats ■ Darwin in the Galapagos - finches ● Differentiate entirely upon diet ■ Crop = storage ■ Proventriculus = acid stomach ● Breaks down and softens food ■ Gizzard = grinds hard food ● Little rocks held inside to crush food ● Birds in wild “eat” rocks for their gizzard ■ Small intestine: ● Inside small intestine = outside of body ○ Most concentrated area of living organisms on earth ● Duodenum, Jejunum, Ileum (3 parts) ● Duodenum = loop that contains the pancreas (beginning) ○ Pancreas produces enzymes and buffers ■ Exocrine organ: ● Counteracts acidity of stomach ● Sodium Bicarbonate ■ Endocrine organ: ● Insulin ○ Where gallbladder drains bile into small intestine ● Can’t really define line between Jejunum and Ileum ● Ileo-cecal junction ○ 2 ceca (paired ceca) no known function ● Large intestine = extremely small ○ Doesn’t absorb nearly as much water or hold waste ○ Water + waste are heavy so get rid of it ○ Pig: ■ Salivary glands ■ Esophagus = just for transportation ■ Single acid stomach ● Cardiac sphincter ○ Prevents stomach contents from going up into esophagus ○ Leads to acid reflux (burning of esophageal lining) ● Pyloric sphincter ○ Allows food out of stomach and into small intestine ■ Very large large intestine ○ Dog: simple (carnivore) ○ Horse: larger cecum for hindgut fermentation ● Bacteria = friend and enemy ○ Coliform = fecal contamination measurement ● Coprophagy = eat own feces ○ Hind-gut fermentors ● Saliva = minor component of digestion (more of a buffer) ○ Produce lots of it ○ Moisten food for swallowing ■ Bolus = food being swallowed ○ 3 groups of salivary glands ● Epiglottis - closes and blocks the trachea so food forced down esophagus ● Ruminant ***diagram on many tests*** ○ 1 stomach (4 chambers) ○ Fermentation requires larger digestive tract ○ Rumen + reticulum ■ Open to each other ■ Fermentation ○ Omasum ○ Abomasum ■ True acid stomach
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