A&P Test 2
A&P Test 2 ABAS 3450
Popular in Anatomy and Physiology of Domestic Animals
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This 36 page Study Guide was uploaded by Allison Collins on Sunday April 3, 2016. The Study Guide belongs to ABAS 3450 at Middle Tennessee State University taught by Dr. Kevin Downs in Winter 2016. Since its upload, it has received 51 views. For similar materials see Anatomy and Physiology of Domestic Animals in Agricultural & Resource Econ at Middle Tennessee State University.
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Date Created: 04/03/16
Monogastric Digestive Anatomical Terminology • Salivary glands – produce salivary amylase, which begins digestion o Not present in all species o Saliva = mucus + water (serous fluid) o 4 types of salivary glands § Parotid – largest glands • Produces only serous fluid • Located just in front of each ear § Mandibular – medium-‐sized • Produces mix of mucus and serous • Located along jawline § Sublingual – medium-‐sized • Produces mix of mucus and serous • Located beneath tongue § Buccal – small • Produces only mucus • Branches off of parotid gland toward nose – multiple branches • Esophagus – transportation of ingesta from mouth to stomach by means of peristalsis (peristalsis works in a variety of systems) • Cardiac sphincter – prevents chyme from re-‐entering esophagus o Low pH from stomach would burn esophagus o Opens and closes o Opens to esophageal region • Esophageal region of stomach – produces nothing • Cardiac region of stomach -‐ food enters from esophageal region o Expanding pouch o Produces mucus, stores chyme (stomach contents) • Fundic region of stomach -‐ food enters from cardiac region o Largest portion of stomach o Produces mucus, pepsinogen, HCl o Has thick tissue (more cells) that aids in acid production • Pyloric region of stomach – food enters from fundic region o Chief cells – produce pepsinogen o Parietal cells – produce HCl o Pepsinogen inactive until it combines with HCl § Pepsinogen + HCl = pepsin § Pepsin breaks peptide bonds, thereby digesting protein • Pyloric sphincter – controls movement of chyme into duodenum o Between pyloric region and duodenum o Too much chyme will overload the neutralizing system • Stomach mucosa – lining • Duodenum – digestion of nutrients o Closer to right body wall o Attached to pancreas and gallbladder – chyme enters here • Pancreas o Produces NaHCO (sodi3m bicarbonate) which acts as a buffer by neutralizing chyme § Discharges into duodenum o Produces enzyme that digests carbs, proteins, lipids o Much smaller than liver, yellowish in color , has one or two lobes 2 o Endocrine component produces insulin and are also important in carb digestion • Liver o In most cranial part of the abdomen o Largest gland in the body, reddish-‐brown in color o Produces bile and plays in protein, carb, and fat metabolism o Products of digestion pass through hepatic cells before entering into bloodstream o Discharges into duodenum • Gall bladder – stores bile, emulsifies fat – i.e. suspends/separates lipids to increase surface area • Small intestine o Mesenteric fat § Mesentery conveys vessels and nerves o Jejunum – absorption of nutrients § Identifiable by mesenteric fat and villi (tiny projections that increase surface area for absorption o Ileum – absorption of nutrients § Identifiable by villi o Jejunum and ileum tissue layers (deep to artificial): § lumen à epithelial cells à villi à mucosa à muscularis mucosae à submucosa à circular smooth muscle à cells of Auerbach’s nerve plexus à longitudinal smooth muscle à serosa • Muscularis mucosae – thin, weak muscle that moves villi 3 • Cells of Auerbach’s nerve plexus – coordinates circular and longitudinal smooth muscle to contract – i.e. controls peristalsis • Submucosa – produces NaHCO 3 • Large intestine o Cecum – fiber fermentation § Dead-‐end pouch at junction of ileum and colon § Much larger in horses and rabbits (fibrous diets) o Ascending coil of large intestine – shorter – first part of colon o Descending coil of large intestine -‐ longer – last part of colon o Ileo-‐colonic-‐cecal junction – regulates, by particle size, where particles should go § Large particles go to large intestine § Fine particles go to cecum o Rectum – most dorsal of GI tract – opens to anus • Anal sphincter o Internal – thickening of circular smooth muscle – involuntary o External – striated muscle – voluntary control 4 5 6 7 8 9 Ruminant Digestive System Terminology Esophagus • Function: transports foodstuffs from mouth to reticulorumen • Splits reticulum and rumen Esophageal-‐reticulo-‐rumen orifice • At ending of esophagus – the opening between esophagus, reticulum, and rumen – only exists during swallowing and regurgitating • When animal is not swallowing or regurgitating, the sphincter keeps closed and an orifice exists only between reticulum and rumen – i.e. becomes the reticulo-‐rumen orifice 10 o When this is the case, food passes between reticulum and rumen (through the reticulo-‐rumen orifice) and does not pass back into or from esophagus Reticulum • Food enters from esophagus • Function: mixes rumen contents and forms bolus by means of passing foodstuff back and forth through reticulo-‐rumen orifice • Mucosa of reticulum is distinctive honeycomb patterns o Cellulae reticuli -‐ the “ground” of the four-‐, five-‐, or six-‐sided cells of the honeycomb pattern o Crests – walls of the cells; about 1 cm high o Cornified papillae – small, stiff projections in reticulum that line the crests and floors of the cells § Work with the cellulae reticuli to grasp incoming food/objects 11 Rumen • Food enters from esophagus • Houses bacteria, protozoa, and yeast • Function: fermentation of fibrous material o High fiber feed generally correlates with lower quality feedstuffs, so a ruminant must consume a large amount of feed for sufficient nutrients 12 § This is the reason that the ability to ferment fibrous material is essential to wild ruminant survival o The animal itself doesn’t make the fiber-‐digesting enzymes – the microbes do § Symbiotic relationship: microbes receive food and shelter, host benefits from the byproduct of microbial digestion of fiber • Closely related to reticulum in structure and function o Reticulorumen has pH of about 7 – an acidic environment would kill microbes • Blindsacs – 2 chambers at caudal end of rumen; dorsal and ventral o Septa – walls of blindsacs • Rumen papillae – increases surface area for absorption of the byproducts of fiber fermentation o Carpet-‐like appearance Reticulo-‐rumen-‐omasal orifice – opening located at dorsal end of omasum Omasum • Absorbs water in digesta – when opened, contains dry digesta • Has a putty-‐like consistency on palpation • Floor of omasum is smooth except for tooth-‐like projections that guard the opening o These are called the omasal horn papillae • Omasal laminae – layers within the omasum – increase surface area for water absorption • pH of about 7 Omasal-‐abomasal orifice – opening to abomasum at ventral end of omasum and dorsocaudal end of abomasum 13 14 Abomasum • Function: protein digestion o Protein comes from the microbes that die from the acidity of the abomasum (pH of about 2) – walls of microbial cells break down, exposing the protein within and making it available for absorption by the ruminant • Produces HCl and pepsinogen (like the monogastric stomach) o Pepsinogen has no purpose until it is combined with HCl – combination produces pepsin, which aids in protein digestion • Digesta in abomasum is wet • Function is closest of the 4 chambers to the monogastric stomach Rumination • A ruminant’s modified (compartmentalized) stomach is vital to its survivability • Constant grazing during the day to fill rumen with food as quickly as possible – very little chewing • At night, grazing ceases while animal hides from predators o At this time, rumination occurs and food is digested • Rumination: ingesting feedstuffs very quickly, regurgitating bolus into mouth, chewing, swallowing again, repeating • Breakdown of food increases surface area for microbe digestion Steps of rumination 1. Prehension – taking food into mouth by means of tongue, lips, teeth, etc. -‐ varies by species 2. Mastication (chewing) – very little occurs at initial intake of food 3. Deglutition – swallowing 15 4. Regurgitation 5. Remastication – more thorough than first time 6. Deglutition – swallowing again 7. Repeat Fermentation of feedstuffs in rumen Feedstuffs include: carbs, proteins, lipids, vitamins, minerals, water • When feedstuffs enter rumen, they are immediately attacked by microbes Carbohydrates – 2 types • Starch (complex)/sugar (simple)– not much is typically consumed by ruminants o That which is consumed is broken into glucose (monosaccharides) • Fiber o Composed of cellulose (digestible) and lignin (not digestible) o Most of a ruminant’s diet is fibrous o Breaks down into glucose (monosaccharides) • Byproducts of fiber fermentation o Certain vitamins, such as Vitamin K and B complex § Pass directly into omasum o Volatile Fatty Acids (VFA’s) § Include propionate, acetate, and butyrate § Used to generate ATP – absorbed across rumen wall into bloodstream § At cellular level: VFA’s enter cell respiration at Krebs Cycle 16 • Don’t go through glycolysis as there is not much glucose in a ruminant’s diet o CO 2 and CH 4 (methane) – released through mouth as a belch (eructation) § Loss of energy (heat) – benefit of heat regulation Protein • Some protein bypasses rumen degradation and goes direc tly to omasum • When degraded, microbes break protein into peptides , then further into amino acids o Microbes further break amino acids into carbon skeletons and nitrogen o Nitrogen then combines with hydrogen to form NH3 (ammonia) § Some NH3 passes to the liver then to the kidneys and is disposed in urine as excess nitrogen § Some NH3 is recycled through the salivary glands o Microbes put carbon and NH3 back together, re -‐forming the amino acids § Amino acids combine to form polypeptides, then protein • Protein passes into omasum • This process allows ruminants to consume low-‐quality protein and convert it to better-‐quality protein • Another source of protein is the microbes themselves, which burst and release their own protein when they enter the acidic abomasum Lipids – limited in the ruminant diet • The small amount that does exist in ruminant diet is converted by microbes into VFAs, which pass across the rumen wall and eventually aid in Krebs Cycle NPN (non-‐protein nitrogen) 17 • Combines with carbon and is converted by microbes to NH3 • Microbes use NH3 in reconstruction of amino acids à protein • By this method ruminants are able to glean protein from non -‐protein sources • Excess nitrogen enters the nitrogen pool and exits the body in urine Summary of food’s passage through a ruminant Rumination: prehension à mastication à deglutition à bolus formed as food passes between rumen and reticulum (esophageal-‐reticulo-‐rumen orifice exists at this point) à regurgitationà re-‐mastication à deglutition à repeat Digestion: Rumen à reticulo-‐rumen orifice à reticulum à reticulo-‐rumen-‐ omasal orifice à omasum à omasal-‐abomasal orifice à abomasum à pyloric abomasum à duodenum à jejunum à ileum à cecum à ascending coil of large intestine à descending coil of large intestine à ileo-‐ colonic-‐cecal junction à rectum à anus **A ruminant’s GI tract would be the same as a monogastric’s if the rumen, reticulum, and omasum were replaced with the cardiac region of the stomach** 18 19 Embryology Purpose of the egg: to protect and nourish the embryo Embryos incubate for 21 days (remember: incubation, not gestation) Protection – the shell • Made of calcium; formed in the uterus • Arch shape – difficult to break from outside, easy from inside • First line of defense against microbes – however, they can still enter through the pores • Inner and outer shell membrane o Fused together; formed in isthmus o Made of protein o Second line of defense against microbes • Air cell – only place inner and outer membrane aren’t fused o At wide end of the egg o Gets larger as incubation progresses o Embryo breaks into it and starts to breath air, then continues to break through cell when hatching 20 • Cuticle – light outer protein layer that dries quickly after the cell is laid Nourishment – the yolk • Was originally a follicle in the ovary • Majority of composition: nutrients for the embryo • Albumen – egg white – composed of protein and water o Thick albumen: from magnum o Thin albumen: from uterus • Chalazae – on either pole of yolk – spun-‐out protein fibers from thick albumen, formed when yolk twists 21 • Vitelline membrane – thin membrane that surrounds the yolk, is inside the yolk sac • Germinal disc – where embryo develops if fertilized 22 o Blastoderm – fertile disc – looks like a donut with a dark middle o Blastodisc – infertile disc – indescript white spot • Dark/light yolk layers – daytime/nighttime – hen eats during the day and the nutrients give pigmentation to the yolk • Latebra – tunnel created from germinal disc to center of yolk – unsure of function 3 extra-‐embryonic membranes • Amnion – very thin fluid-‐containing membrane surrounding embryo o Protects embryo by absorbing shock o Not as important for human embryos – only needed before implantation of egg cell o Gets tighter around embryo as incubation progresses 23 • Yolk sac – enables embryo to absorb nutrients from the yolk o Meckel’s diverticulum – remnant of yolk sac attachment o Retains shape and size as incubation progresses • Chorio-‐allantois – lines the shell o Enables embryo to breathe – oxygen/carbon dioxide exchange § Gases travel through pore à chorio-‐allantois à blood à embryo o Store waste and absorb calcium o Spreads over entire inside of shell as incubation progresses 24 Hatch position: assumed at 18 days • Correct: head toward air sac (wide end of egg), head under right wing 25 Shell/yolk layers from outside to inside: Cuticle à shell à outer shell membrane à inner shell membrane à chorio-‐allantois à albumen à yolk sac à yolk à amnion à amnionic fluid à embryo 26 ß 5 days 27 28 CARDIOVASCULAR SYSTEM Physiology of the heart – flow of blood 4 chambers in the heart • 2 pump blood: ventricles – left and right o Contract at the same time o One is very thick, one very weak • blood goes through valves • 2 return blood: atria – left and right – sit on top of ventricles Flow of blood through the heart and body • When blood moves through the heart, it’s happening all at the same time – constant motion • For the purpose of notes, we are starting at one point and working our way through 1. Start: left ventricle – very thick – bigger pump – pumps oxygenated blood to the body 2. Oxygenated blood leaves left ventricle through aortic semilunar valve – • semilunar: looks like 3 half moons into aorta 3. Oxygenated blood leaves the heart through the aorta • Split in aorta: large diameter split to the right (blood to body) small diameter split to the left (blood to head) – 4. Blood loses oxygen when it reaches the body tissues 5. Deoxygenated blood returns to the right atrium through the two vena cava (veins) – cranial (from the head) and caudal (from the body) 6. Deoxygenated blood leaves right atrium through the right atrioventricular valve into the right ventricle 29 7. Right ventricle contracts, deoxygenated blood goes through pulmonary semilunar valve into pulmonary artery 8. Pulmonary artery has two major branches, one for each lung • This is the only time an artery carries deoxygenated blood 9. Blood picks up oxygen in the lungs 10. Oxygenated blood returns to left atrium through pulmonary veins • This is the only time when veins carry oxygenated blood 11. Oxygenated blood returns to left ventricle through left atrioventricular valve Cardiac cycle Contractile state of ventricles or atria and of the valves – typical heart sounds (lub dub) • Diastole – bottom number, relaxation • Systole – top number, contraction, ventricle contraction mainly o Atria do contract but not nearly as much • Happening at same time on left and right sides • Atrioventricular valves are open when blood is flowing into the ventric le, semilunar valve is closed • Loud sounds created when valves close 1. Isometric relaxation: atrioventricular valves closed, semilunar valves closed, diastole in ventricles and atria 2. Rapid filling of left atrium: diastole in ventricles and atria, AV valves open, SL valves closed – 3 heart sound 3. Diastasis: diastole in ventricles and atria, AV valves open, SL valves closed 30 4. Atrial systole (emptying of atria): diastole in ventricles (blood flows into ventricles), systole in atria, AV valves open, SL valves closed – 4 heart sound 5. Isometric contraction (ventricles contract, pushing blood out): systole in ventricles, diastole in atria, AV valves closed to prevent backflow, SL valves open and blood exits to aorta/pulmonary arteries– 1 heart sound 6. Ejection part one (blood flows out of ventricles) – ventricles systole, atria diastole, AV valves closed, SL valves open 7. Ejection part two – ventricles systole, atria diastole, AV valves closed, SL valves open nd 8. 2 heart sound: pressure from backflow of blood sh uts the semilunar valves 8. Repeat cycle Orientation of the heart Surface vasculature – heart needs its own blood supply for oxygen to keep it pumping • Left/right coronary artery – sit in AV groove – branch out, branches service the heart itself o Heart attack – clot/plaque blocks an artery o Bypass surgery – take vein from leg and bypass the blocked vein • 2 branches of coronary artery – left and right (left includes apex of heart) Orientation: surface anatomy – ventricles: tough is left, soft is right Aorta vs coronary arteries • Aorta is in back of the heart – always very stiff – if facing the aorta the left ventricle/atrium is on the right side • Coronary artery is in front of the heart – goes through to the right side of the heart 31 Vocabulary Pericardium – sac surrounding the heart; contains pericardial fluid to prevent friction during the heartbeat Epicardium – very thin epithelial layer on outside of heart Apex – most caudal point of the heart • Placed close to the sternum • Lies to the left of the median plane • The long axis that joins the center of the base to the apex slopes caudoventrally Left ventricle – a bottom section of the heart • Much thicker walls (myocardia) than right ventricle • Circular, forms the entire apex of the heart • Sends out oxygenated blood through the medially located aorta Right ventricle – a bottom section of the heart • Thicker walls than atria, thinner walls than left ventricle • Wrapped around the right and cranial aspects of the left ventricle • Receives oxygenated blood • Auricle vs atrium: auricle is structure on the outside of the atrium, flowerlike appearance, atrium is open space on the inside – not interchangeable terms! Left atrium (auricle) – a top section of the heart • To the left of the medial plane • Thin walls 32 • Receives deoxygenated blood from the veins including vena cava Right atrium (auricle) – a top section of the heart • Mostly to the right of the medial plane • Thin walls • Receives deoxygenated blood • Greater part forms a chamber into which the main systemic veins discharge – including the caudal vena cava, which enters the caudodorsal part of the right atrium Aorta – largest artery in the body • Extends from left ventricle and branches into two coronary arteries Cranial vena cava – large vein that carries blood from the head and upper body; Attaches to right atrium; carries deoxygenated blood Caudal vena cava – large vein that carries blood from the lower body; attaches to right atrium; carries deoxygenated blood Pulmonary arteries – carry blood from the right ventricle to the lungs for oxygenation Pulmonary veins – receive oxygenated blood from the lungs and drain into the left atrium • Open variously into the roof of the left atrium; do not have valves Paraconal interventricular groove – shallow groove that descends cranially toward the apex and externally divides the ventricles Paraconal artery – one of three branches of the coronary artery • Crosses ventrally across the heart in the paraconal interventricular groove • Branches from this artery supply the left and right ventricles Subsinuosal interventricular cavity – shallow groove that descends caudally toward the apex and externally divides the ventricles 33 Subsinuosal artery – one of three branches of the coronary artery; lies in the subsinuosal interventricular cavity Atrioventricular groove – groove along the external surface of the heart that divides the right atrium and right ventricle • Contains a branch of the right coronary artery Right coronary artery – branches from the aorta • Carries oxygenated blood • Branches further into arteries along the atrial and ventricular walls Left atrioventricular valve – bicuspid/mitral valve • Composed of 2 flaps (cusps) but is otherwise comparable to that of the right side Right atrioventricular valve – tricuspid valve • Composed of 3 flaps (cusps) that attach to a fibrous ring that encircles the opening Chordae tendinae – fibrous strands that join the cusps of the valves • Generally arranged so that they connect each cusp to two muscles and each muscle to two cusps • This prevents cusps from turning inside out into the atrium during ventricular contraction Papillary muscle – located in the ventricles; attach to the cusps of the atrioventricular valves via the chordae tendinae Pulmonary semilunar valve – covers the opening of the pulmonary trunk • Situated on the left side of the heart • Closed by backflow of blood during ventricular relaxation (diastole) • Composed of 3 semilunar cusps that fit together tightly when the valve is closed Aortic semilunar valve – generally resembles the pulmonary valve 34 • Centrally positioned Pectinate muscle – parallel ridges in the walls of the atria • Resemble the teeth of a comb Moderator band – muscular band of tissue found in the right ventricle • Vary in size among individuals • Provides support in right ventricle, necessary because the walls are so weak – prevent walls from exploding during contraction Myocardium – thick middle layer of the outer wall of the heart; composed of cardiac muscle Endocardium – covers the internal side of the myocardium • A thin smooth-‐surfaced layer continuous with the lining of the blood vessels Interventricular septum – short wall separating the ventricles from each other 35 36
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