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									Comparative Anatomy Notes – Set 10
CIRCULATORY SYSTEM - Chapter 12 - Blood vessels - in embryo have homologies in vessels - inside pharyngeal arches are aortic arches and all embryos have them - primitive patches are in shark with afferent and efferent arteries Arteries - carry blood away from heart - muscular, elastic fibrous walls - regulates blood pressure - terminate in capillary beds Veins - cant function in blood pressure regulation - not fibrous or muscular - carry blood toward heart Heart - modified blood vessel - some systems in vertebrate body whose veins don’t go to heart, but drain some organs and dump blood into other organs = Portal System 3 portal systems found in vert. 1. Hepatic 2. Renal 3. Hypophyseal - these are all veins Hepatic Portal System - drains intestine and dump into liver Renal Portal System - drains tails and dumps into kidneys Hypophyseal - smallest - capillaries in hypothalmus that dump into anterior pituitary Heart - typical tetrapod blood is pumped from heart to lungs via pulmonary arteries and back to heart by pulmonary veins Fish Heart - tube like heart - 4 chambers - sinus venosus, atrium, ventricle, conus arteriosus - Sinus Venosus - thin walled venous chamber - recieves blood from large veins returning to heart - ducts of cuvier - coronary veins - hepatic veins - Atrium - large and thin walled - dorsal to ventricle - in situ - Ventricle - dumps into conus artriosus - continuous with aorta - Valves separate these chambers - sino-atrial node - sino-ventricular node - semi-lunar valve - Conus arteriosus - short in bony fish and amphibians - not found in adult amniotes Heart of Lungfish and Amphibians vs. Dogfish 2 notable differences 1. Modification of partial or complete partition with in atrium - left and right atria 2. Advent of Lungs - double circulation forms


- modification in conus arteriosus - semi-lunar valve becomes modified so as to shunt into pulmonary vessels, deoxygenated blood = spiral valve - modified semi lunar valve - allows blood to go to lungs - structure of frog heart - most deoxygenated blood goes to lungs - little blood mixes with in ventricle - spiral valve directs oxygenated blood entering ventricle from left atrium into other channels or vessels - conus is more prominent in anurans than in tailed salamanders - conus is also called truncus arteriosus - is also called bulbus cordis - salamander heart - bulbus arteriosus - this is a muscular swelling of ventral aorta - smooth muscle not cardiac - from generalized fish heart, get partitions ----lung fish - Urodela - right and left atrium - sinus venosus dumps into RA - pulmonary veins leave LV - one ventricle - after conus and ventral aorta are vessels - bird is now pulled away and placed with reptiles in a cleidistic digagram - reptilian heart is unusual Amniotes - exhibit 2 atria and 2 ventricles - birds and mammals - 2 ventricles are completely seperated from each other - 2 atria and 2 ventricles = 4 chambers th - Sinus venosus - represents a 5 chamber in reptile heart - birds and mammals exhibit SV during early embryonic life - doesnt keep pace with development of atria (right) - it is incorportated into RA - becomes sino-atrial node - pacemaker region of heart - in adult amniote, RA and LA are seperated - doesnt close until after birth - hole there is called foramen ovale - fossa there is called fossa ovalis Auricle - sometimes used to equal atrium - in higher vertebrates refers to flap of tissue that allows expansion of atrial chamber - get more blood Heart of Mammals and Birds - blood flow **** Aortic Arches - pull out bottom part makes it more ventral - pull out last three - basic pattern has 6 aortic arches - Major Atrioral channels - embryonically seen 1. Ventral aorta emerges from heart and passes forward beneath pharynx 2. Dorsal Aorta, paired anteriorly, passes caudally above digestive tract and pharynx 3. 6 Pairs of AA connects ventral and dorsal aorta - get modification of AA system - in Reptiles, get additional arch stuck in there Aortic Arches st nd - most Teleost 1 and 2 disappear - the dorsal aortae are now individual vessels


- become internal carotids - extensions extend to head - in lung fish - pulmonary artery develops - off of arch #6 - they have gills and also posses lungs th - in Tetrapods - have pulmonary artery from 6 arch - most - arch #5 is lost - exceptions - terrestrial tailed salamanders Tetrapods as a whole ex Frog -arches 1 and 2 disappear - in addition, dorsal segment between arches 3 and 4 is dropped - this part may be retained = ductus caroticus - when this is dropped, arch #3 has common base that extends to internal carotids - ventral aorta extension = external carotid rd - 3 arch = carotid arch - common carotid is at base between 3 and 4 - arch 5 has been lost - dorsal segment of 6 has been lost ex. Frog - arch 4 has no connection anteriorly = systemic or aortic arch - arch 6 = pulmonary arch - adult anuran gives basic pattern of tetrapods Urodele - have ductus caroticus th - dorsal segment of 6 arch = ductus arteriosus Reptiles - general - 1 and 2 disappear - Ducuts caroticus is lost - 5 is lost - ductus arteriosus is lost - innovation is introduced in heart and dorsal aorta nd = 2 aortic arch - independent - arch from left side comes from right side and loops left - arch from right side does the opposite - additional aortic arch - 2 arches in reptiles Heart of Reptile Turtle - in addition there is internal pocket inside heart = Cavum venosum blood flow - collected from post cava through sinus venosus to precava - venous blood - goes to RA - venous blood goes to cavum venosum - valve mechanism that shifts back and forth when blood enters in - venous blood is diverted to cavum pulmonale (RV) - pump into pulmonary artery - goes to lungs - returning to heart is oxygenated blood through pulmonary veins to LA - from LA - oxygenated blood goes to Cavum arteriosum - goes back to CV - shift skin - goes to left and right aortic trunk - other mechanism involved in other reptiles


Crocadillian - mechanism for breathing then diving - lungs arent utilized - mechanism allows for blood not to be pumped to lungs - so vessels constrict around RV - there is a valve between aortic trunks that allows blood to be diverted = Foramen of Panizza - more effectively use its blood - if RV is closed, LV can pump to both arches because of this hole - one of aortic trunks leads to head - innovation is not carried Bird - right portion is retained and left aortic region is dropped (3, 4, 5,6) - opposite in mammals - Birds have a right AA - mammals have Left AA Mammals - 3, 4, 5, 6 are retained embryonically - in adult mammals, 1 and 2 are dropped - external, internal carotids and carotid arch - 4 arch is systemic - 5 is lost - dorsal segement of 6 is lost - embryonically, we retain dorsal segment of 6 = ductus arteriosus Venous System - basic pattern - sinus venosus - all blood returns here - two vessels enter SV = common cardinals - have subclavian veins coming in - drains lateral abdominals and brachials - blood from tail goes to cardinal or may go to embryonic vessels to go to liver Shark - post cardinals has lost a part - blood from tail must go through kidneys before it goes to post cardinal = renal portal system - Major Venous channels - Cardinals - anterior, posterior, and common - Renal Portal - Lateral Abdominals - drains lateral wall of body - Vitellines - associated with hepatic portal system - Coronary 2 other characteristics of higher vertebrates 1. Pulmonary 2. Post Cava - Embryonic shark has basic venous channels - adult shark is just slightly modified - shark is a good representative vertebrate Common Cardinals - direct blood to sinus venosus - Anterior Cardinals - receives blood from parts of head - Post Cardinals - receives blood from kidneys - Renal Portal - from caudal vein - lateral Abdominals - blood from abd. stream all way back to illiacs - hepatic veins - associated with liver - hepatic portal system - drains intestine into liver - Modifications occur from basic pattern


ex. Adult Anurans - post cardinal lost - new vessel - post cava - during embryonic development of man, how does post cave form? - vessels anastomoste - gives rise to post cava ex. Turtle - post cava drains kidneys - lateral abdominals - retains renal portal system - lateral abdominals and renal portal are connected by external illiac vein Bird - 2 precava - big post cava - renal portal system still functioning - begins to divert - either to or not to kidneys - can go directly to heart - All mammals, except monotremes, have lost renal portal system - common cardinals are known as pre-cava - in higher vertebrates - anterior cardinal veins = internal jugular - most mammals retain left and right precava - cat and man retain only right precava - anterior vena cava - left doesnt disappear - portion becomes coronary sinus that dumps into LA - post. cardinal veins becomes azygous - remnant of left post cardinal is present = hemiazygous - hepatic portal system drains intestine dumping into liver - found in all vertebrates Mammalian Fetal Circulation - Blood Flow - oxygenation is taking place at placenta - oxygenated blood is going to fetus through umbilical veins - veins carry oxygenated blood = umbilical veins - vein passes through liver and unites with postcava - oxygenated blood enters heart at RA and has 2 directions to go 1. It can go to RV 2. It can pass through an interatrial apperature = foramen ovale - goes to LA st - going to RV 1 - blood is pumped to pulmonary artery - leads to lungs, but nonfunctional - oxygenated blood must be diverted away from lungs = ductus arteriosus - diverts blood from pulmonary artery to aorta - oxygenated blood goes to all parts of body - eventually blood goes to placenta through umbilical arteries At birth - placenta shuts down - umbilical vein collapses - interatrial apperature close - flap of skin allows it - blood no longer goes to LA - ductus arteriosus closes - blood not going through this duct - now deoxygenated blood enters RV to pulmonary arteries to lungs for


oxygenation Fossa ovalis -place where interatrial flap closes - if not closed, you get mixing of blood - infant becomes discolored - ductus arteriosus becomes ligamentum arteriosum - umbilical veins through liver also collapse = ductus venosus - this collapses into ligamentum arteriosum - collapsed umbilical vein can still be seen near falciform ligament = round ligament of liver


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