Comparative Vertebrate Anatomy Lab Test

Overview Vertebrate Body: Gas Exchange Systems: -There are three modes of gas exchange represented among the vertebrates?

(1) the general body surface (2) gills (evaginations of the body surface), and (3) lungs (invaginations into the body surface).

Dissection: -towards the end of the blood flow in the necturus

*The pulmonary veins conduct blood from the lungs to the left atrium, and this blood is pumped into the ventricle to mix to some degree with deoxygenated blood from the right atrium.

Dissection: -Lateral and dorsal in each carotid a pigeon?

- is anterior vena cava returning deoxygenated blood to the heart from the body. -These two vessels join a posterior vena cava to form a remnant sinus venosus that feeds the deoxygenated blood into the dorsal side of the right atrium.

Dissection: -the heart of a pigeon?

- large heart that is completely four-chambered >the right and left brachiocephalic arteries, originating immediately from the ascending aorta >The right and left carotid arteries are the first branch off the brachiocephalic arteries

Dissection: -what part of the Necturus is not homologous

- the gills of amphibians are not homologous with those of fishes; -in Necturus the gills are only external (and covered with ectoderm), whereas in fishes the gills are located within the gill slits (and are endodermal).

Dissection: -main urinary bladder in a turtle?

- thin-walled, bi-lobed main urinary bladder that will be seen just dorsal to the pelvic girdle and the two accessory urinary bladders, one on each side of the cloaca.

SPINY DOGFISH

-(Squalus acanthias) -rough skin covered by tiny bony placoid scales. -Teeth and placoid scales are therefore homologous. -The caudal fin along with the rest of the laterally compressed tail is the principal organ of locomotion

Dissection: -vas deferens in a male pigeon ?

-A small projection on the medial border of each testis (actually the minute epididymis) leads to the vas deferens that extends to the posterior part of the cloaca -The vas deferens lies parallel to the ureters and is closely associated with them.

Dissection: -where does air enter in a turtle for gas exchange to occur?

-Air enters the gas exchange system of the turtle via the external nares. -It then passes through short nasal passages and enters the mouth through the internal nares in the anterior portion of the palate.

Dissection: -where is air drawn in a turtle during gas exchange?

-Air is drawn back to the pharynx where it enters the slit-like glottis that is located in the posterior region of the floor of the mouth in a raised area. -The glottis leads into the trachea and lungs

Overview Vertebrate Body: important invention the reptiles did ?

-An important "invention" of the reptiles was the amniotic egg. - This egg, with its protective shell and membranes, could be laid on land, thereby freeing the animal from a dependence on environmental water for reproduction. -Evolution of the amniotic egg—often called the land egg—was a major evolutionary innovation in vertebrate history

Overview Vertebrate Body: The Circulatory System: -Ancient Fish conus arteriosus also maintain(CA)?

-Because of its elasticity and contractibility, the conus also maintains a steady arterial pressure on the blood flowing to the gills.

Dissection: -blood from the right atrium in a pigeon?

-Blood from the right atrium then passes into the right ventricle and then on to the lungs via the pulmonary arteries.

Overview Vertebrate Body: The Circulatory System: -Necturus blood circulation

-Blood from the systemic circulation is collected in a sinus venosus and -flows into the right atrium, to the single ventricle, and -exits into a narrow conus arteriosus, -which expands into the base of the ventral aorta, which in some animals is replaced with a bulbus arteriosus

Dissection: -where does the atria drain and what happens to the blood in a turtle ?

-Both atria drain into the single, incompletely divided ventricle. -The vessels carrying blood away from the ventricle look like three large arteries extending anteriorly.

Dissection: kidney and ureter of a pigeon ?

-Each kidney has three distinct lobes that occupy the greater part of the roof of the body cavity and are nestled in cavities in the bone. - The ureter extends from the medial border of each kidney to the posterior part of the cloaca

Overview Vertebrate Body: The Circulatory System: -This required first adaptation for Amphibians?

-First, the veins from the lungs (the pulmonary veins) came to enter the heart independently of the sinus venosus. -To this end, pulmonary veins in vertebrates always enter the left side of the atrium away from the sinus venosus while all the other veins continue to lead to the sinus venosus, which enters the right side of the atrium.

Dissection: -bladder of a turtle living in fresh water?

-The bladders in freshwater turtles have an interesting function -- they are involved in buoyancy control, much like the ballast tank in a submarine. -Water in the bladders can be taken in or expelled through the cloaca altering the specific gravity of the body.

Dissection: -what body part of the pigeon is homologous ?

-Posterior to the heart, it expands slightly to form the proventriculus or anterior stomach. -It is homologous to the cardiac region of the stomach. This structure can be seen on the left side dorsal to the liver

Dissection: -crop function in a pigeon >

-Posteriorly, at the base of the neck, the central part of the esophagus enlarges to form the crop. -This organ is primarily for the storage of food and regulates the amount of food passed on to the stomach.

Dissection: instead of penis a turtle has?

-Rather than a true penis, turtles (and some other reptiles) have a hemipenis. -A hemipenis is an elongated, pigmented thickening of the cloacal floor with a raised glans at the caudal end.

Dissection: -how sperm travels in sharks

-Sperm move from the testes through these ducts into modified kidney tubules in the anterior portion of the kidneys. -These ducts conduct the sperm through the modified kidney and converge to form a sperm duct.

Dissection: -ovary duct in a turtle ?

-The anterior openings of the oviducts lie near the anterior end of the ovary. -The oviduct continues as a broad ribbon-like tube lying along the posterior side of each ovary. - Parts of the oviduct are differentiated for egg packaging. It ends at the cloaca just dorsal to the large urinary bladder.

Overview Vertebrate Body: The Circulatory System: -Turtles aortae carries

-The aortae then carry oxygenated blood from the left side. -When the turtle is submerged in water, however, it too has the ability to alter the path of the blood so that the aortae carry deoxygenated blood directly from the right side of the ventricle thus bypassing the lungs for increased efficiency

Overview Vertebrate Body: The Circulatory System: -adult frog blood flow

-The arteries going to the lungs (the pulmonary arteries) came to exit separately from the ventral aorta, -which exited on the left (and which still lead to all the other arteries and so to the rest of the body).

Dissection: -pancreas and the liver of the turule?

-The elongate pancreas lies on the anterior border of the duodenum near where it begins at the stomach. -The left lobe of the liver nearly covers the stomach and extends to the right, dorsal to the ventricle of the heart

Dissection: -esophagus in a turtle

-The esophagus may be seen just underneath the cartilaginous trachea.

Dissection: -what portion of the body of the necturus is homologous ..?

-The genital portion of the kidney is actually homologous to the epididymis in reptiles and mammals. -Thus, in the male the urinary duct conducts both sperm and urine to the cloaca

Dissection: -the genital portion in males in the necturus ?

-The genital portion of the kidneys is modified for the storage and transport of sperm; transverse ducts conduct the sperm through the kidney to the urinary duct

Dissection: the shell of a turtle ?

-The girdles are wedged tightly within the shell providing strong support -There are also plates of keratin on the outside of the shell that overlap two or more bones of the shell, locking them together. -The plates, then, are homologous to feathers and, in a general sense, analogous to bony fish scales.

Dissection:' -Kidneys in sharks

-The kidneys and gonads lie under the lobes of the liver and digestive tract. -The kidneys are thin, elongated organs that lie along the length of the dorsal body wall on either side of the midline behind the peritoneum

Dissection: -larges intestines of a turtle ?

-The large intestine empties into the cloaca, which opens to the outside via the vent. -The spleen is a spheroid gland that lies in a mesentery just anterior to the cecum and is dorsal in position.

Dissection: -why is the mixing of blood not important in the necturus?

-The mixing of blood is unimportant in Necturus because all blood leaving the ventricle passes through the gills before going to the rest of the body.

Dissection: -blood flow in necturus

-The narrow, tubular conus arteriosus is continuous with the bulbus arteriosus which lacks cardiac muscle and is the swollen base of the ventral aorta -Follow the ventral aorta anteriorly until it divides into two branches

Dissection: -where do the mature eggs end up?

When the eggs are mature, they break through the wall of the ovary, pass into the coelom, and enter the anterior ends of the paired oviducts.

Overview Vertebrate Body: The Circulatory System: Circulatory system of the ancestral fish?

a collecting chamber for venous blood, the sinus venosus (SV), the atrium (A), the ventricle (V), and the conus arteriosus (CA)

Dissection: -turtle's carapace and plastron?

expanded and fused with other bones to form the upper shell (the carapace). The pectoral and pelvic girdles are connected to both the carapace and the lower shell (the plastron).

Overview Vertebrate Body: The Circulatory System: -In some fishes

first portion of the ventral aorta is known as the bulbus arteriosus which lacks cardiac tissue and valves

Overview Vertebrate Body: Gas Exchange Systems: One difficulty the first terrestrial vertebrates?

had in using lungs for gas exchange was that they could not hold or chew food and breathe at the same time because both air and food had to pass though the oral cavity

Overview Vertebrate Body: The Circulatory System: -The function of the bulbus arteriosus in Necturus ?

help neutralize the pressure waves of ventricular contraction.

Overview Vertebrate Body: The Circulatory System: -Birds and mammals are both?

homeothermic, that is, they maintain a high body temperature through metabolic processes

Dissection: -what is homologous in a shark

portion of the kidney is actually homologous to the epididymis in reptiles and mammals

Overview Vertebrate Body: The Circulatory System: -ventral aorta in Necturus?

-The ventral aorta divides immediately and sends the blood to the three pairs of gills. -Blood leaving the gills is collected in the efferent gill arteries, which converge to form the right and left aortae, which then fuse to form the dorsal aorta

Overview Vertebrate Body: The Circulatory System: -first requirements of homeothermy are?

-high blood pressure and rapid blood flow which both birds and mammals have. -A consequence is that the ventricle of these organisms must be completely divided to prevent mixing of oxygenated and deoxygenated blood.

Dissection: -immature females in necturus species

-immature females, the ovaries are small, irregularly shaped structures. -They may bear clusters of undeveloped eggs that give them a spongy look. -The oviducts, which extend from near the pectoral girdle to the cloaca, may be undeveloped

Dissection: -difference in mature and immature oviducts of sharks

-immature females, the oviducts are slender, straight tubes lying close to the ventral surface of the kidney. -mature females, the oviducts and uterus are much larger and are suspended from the ventral surface of the kidney by a well-developed mesentery.

Overview Vertebrate Body: The Circulatory System: -second requirements of homeothermy are?

-is a reduction of the number of blood vessels wherever possible so as to reduce the resistance to blood flow. -This led to the loss of one aorta in each of these two groups

Overview Vertebrate Body: Gas Exchange Systems: -Lungs originated in the ancestral?

-jawed fishes as a branch off the esophagus just behind the pharyngeal slit -The opening from the pharynx into the passageway leading to the lungs is the glottis

Dissection: -digestive portion of the necturus

-liver, the largest organ of the body. Pull the liver to the left side of the animal and find the thin-walled gall bladder embedded on its lower undersurface. -The short esophagus lies dorsal to the base of the liver. -It leads into the slightly larger, tubular stomach, which is unusual in that it is straight rather than J-shaped, and in that it lies parallel to the long axis of the body. -The dark-colored spleen is located in the mesentery along the left side of the stomach

Dissection: -Males necturus ducts

-male there are no ducts leading directly from the testes to the cloaca. -Instead, minute ducts lead from the testes to genital portion of the kidneys.

Dissection: -how is gas exchange affected in a pigeon ?

Gas exchange is affected in large part by contraction and relaxation of abdominal and pectoral muscles; birds, like reptiles and mammals, use negative pressure breathing

Overview Vertebrate Body: The Circulatory System: -Necturus small portion of blood goes

However, a portion of the blood that leaves the gills is shunted to the lungs for additional gas exchange and returns to the heart before being again pumped out to the gills.

Dissection: -pigeons gonads?

In birds, the gonads are generally reduced as a means of diminishing the overall body weight so to increase flight efficiency.

Overview Vertebrate Body: Gas Exchange Systems: -secondary palate structure in birds?

In birds, the secondary palate does not reach the midline and is incomplete.

Dissection: -afferent portion of a shark

In gill breathing aquatic vertebrates, these afferent portions carry blood into the capillary beds of the five gills.

Dissection: -Necturus female and male difference in producing ...

In the female both portions produce urine, but in the male the genital portion is modified to transport sperm and does not produce urine.

Dissection: -in a female sharks urine is collected

In the female dogfish, urine is also collected by the urinary ducts (not easily found) that empty into the cloaca at the urogenital sinus

Dissection: -ovaries in a turtle ?

In the female, ovaries containing eggs of various sizes and of spherical shape will be seen lying just posterior to the liver and against the dorsal body wall.

Overview Vertebrate Body: The Circulatory System: -what does the blood flow adult frog supply?

In this way, the supplies of deoxygenated and oxygenated blood that have been held separate in the heart are picked up and carried to the appropriate destinations.

Overview Vertebrate Body: The Circulatory System: -why isn't the ventral aorta not needed in older frogs?

It can also be noted that the ventral aorta, which is no longer needed to conduct blood to the gills, divides into two, with a single aorta on each side (the left and right aortae) which later join to form the dorsal aorta

Dissection: -how are male turtles recognized ?

Male turtles can be recognized by the much longer claws on the front feet and by the larger, elongate cloacal region, which contains the penis (sometimes protruding from the cloaca). -The claws are adapted for stimulating and holding onto the female during copulation.

Dissection: -digrestive system in a shark> pyloric located?

Near the posterior end of the left lobe of the liver the stomach bends abruptly forward and diminishes in diameter

Overview Vertebrate Body: The Circulatory System: -The principal difference between the heart of a shark and that of Necturus

Necturus is that an incomplete septum divides the atrium into right and left atria.

Perch class

Osteichthyes -In the modern ray-finned fishes the ancestral lung has evolved into the swim bladder -

Lamprey class

Petromyzontida

Turtle and pigeon class

Reptilia -One branch was a lineage that gave rise to the therapsids. -Therapsids, called the "mammal-like reptiles," were transitional to mammals. The turtles represent a second lineage. -Turtles, though specialized to fit inside a shell, are in some other aspects of their morphology quite similar to ancestral reptiles. -The other modern reptiles, the lizards and snakes, evolved from a third lineage. -The fourth lineage (archosaurs) were the last important lineage of reptiles to originate from the stem reptiles. -The archosaurs include: pterosaurs (flying reptiles), dinosaurs, crocodilians, and birds.

Dissection: -what kind of veins does the necturus have

The Necturus has both a postcava and cardinal veins, but in most higher vertebrates the vena cavae replace the cardinal veins.

Dissection: -how the kidneys work in sharks for males/females

-In both males and females the anterior portion of the kidney has lost its urinary function and does not produce urine. -The posterior kidneys are drained by accessory urinary ducts, which are difficult to find. -The urine empties into the cloaca at the urogenital sinus. -A small rectal gland lies near the colon and is attached to it by a duct. The rectal gland excretes excess sodium and chloride ions.

Dissection: -kidneys of a turtle

-In both sexes, the kidneys are lobed structures closely flattened against the extreme posterior dorsal wall of the body cavity. -The kidneys are very obvious in the dorsal dissection of the turtle. -They drain into the cloaca via ureters (difficult to find).

Dissection: -immature female sharks

-In immature females, the ovaries are relatively small and smooth.

Dissection: -mature female sharks?

-In mature females, they contain eggs in various stages of maturity. -When the eggs are mature, they attain a diameter of nearly three centimeters and contain an enormous amount of yolk.

Overview Vertebrate Body: Gas Exchange Systems: -structure of most vertebrates

-In most vertebrates, the gills are located in pharyngeal slits, openings through the body wall in the pharynx. Muscle action moves water in through the mouth and out through the pharyngeal slits to ventilate the gills

Dissection: -what is present in an embryo and what are the three blood vessels it divides?

-In reptiles the conus arteriosus is present in the embryo but is then divided into three trunks by longitudinal ridges. -The three blood vessels are, from the animal's left to right, the pulmonary trunk, left aorta, and right aorta.

Dissection: -differences between immature and mature in male sharks?

-In sexually immature specimens, the sperm duct is a straight, thin tube lying on the ventral surface of the kidney. -In sexually mature specimens, it is intricately coiled, covering most of the ventral surface of the kidney

Overview Vertebrate Body: The Digestive System: -the liver in sharks

-In sharks, the liver is quite large. -This is because it is filled with an oil to make the shark more buoyant. -Thus, the shark liver is an analog of the swim bladder of ray-finned bony fishes.

Overview Vertebrate Body: Lamprey Urogenital structure

-In the ancestral vertebrates, such as the lamprey, the kidneys were drained by urinary ducts that carried urine to a urogenital papilla opening into a cloaca . -A cloaca is a chamber at the end of the digestive tract that receives the intestine, urinary, and reproductive tracts and is found in all vertebrates except mammals and some bony fishes. -The opening of the cloaca to the outside, the vent, serves as a common exit for the urinary, digestive, and reproductive systems. -In the ancestral vertebrate, there were no tubes or ducts to carry sperm or eggs from the gonad to the cloaca. Instead the gametes were shed directly into the body cavity and eventually entered the urinary ducts through two genital pores located at the junction of the urinary ducts to the cloaca. -They are then discharged into the cloaca through the urogenital papilla and out the vent.

Dissection: -females reproductive system of a pigeon

-In the female, the single left ovary lies somewhat anterior and ventral to the left kidney. -The ovary consists of many ova bound by a membrane and attached to the dorsal body wall by a short mesentery.

Dissection: -females and males gonads of a pigeon?

-In the male, the right testis is generally less developed than the left. -Female birds typically lose the right ovary altogether. -The gonads of both sexes vary considerably in size according to the time of year and also the maturity of the individual bird.

Overview Vertebrate Body: The Circulatory System: -details how turtle circulation works if they don't have a gill circulation?

-It no longer has a conus arteriosus; instead, the pulmonary trunk (a single vessel emerging from the heart -which then divides to provide the pulmonary arteries) and the left aorta each exit the ventricle independently from the ventral aorta (which still leads to all other arteries including the right aorta).

Dissection: -sinous venous Necturus function

-It receives venous blood in two large channels that are supplied by veins from the liver, the cardinal veins, and the posterior vena cava. -All venous blood from the body flows into the sinus venosus, which functions as a collecting sac, before traveling to the right atrium.

Overview Vertebrate Body: The Circulatory System: -mammals heart from what animal did they evolve

-Mammals branched off from the reptiles before reptiles had developed a heart more advanced than that of the amphibians -Therefore, mammals have independently lost the conus arteriosus and acquired the septum in the ventricle during their evolution. -Furthermore, apparently by chance, they lost the right aorta rather than the left

Dissection: -sharks what process do they use for breathing

-Many sharks utilize ram ventilation, a process in which they keep their mouths open during forward locomotion so that water flows in and out through gills; -others actively ventilate their gills by taking water into their mouths and close the mouth forcing water down the pharynx and across their gills.

Dissection: -what does the Necturus rely on for gas exchange

-Necturus rely on their external gills and body surface for gas exchange -but do occasionally go to the water surface and gulp in air, forcing it into the lungs by positive pressure breathing.

Dissection: -the septum of the necturus?

-Necturus the septum is perforated by several openings, permitting considerable blood flow between the two atria.

Dissection: -The principal difference between the heart of a fish (shark) and Necturus is...

-Necturus there is a septum that divides the atrium into two chambers, the right and left atria. *The heart consists of five parts: a sinus venosus, two atria, a ventricle, and a conus arteriosus

Dissection: -where does oxygenated blood come from ?

-Oxygenated blood from the lungs enters the dorsal side of the left atrium via small pulmonary veins.

Overview vertebrate body: -What evolved in the reptiles and bird in the urogenital system ?

-The new sperm ducts that evolved in reptiles, birds, and mammals do not connect to the kidneys; instead they connect to the epididymis on the testes and conduct sperm from the testes to the urine tube or, in some cases, directly into the cloaca. -Since this change evolved independently in each of these different groups, sperm ducts are not always homologous. -Also, for this reason the names ureter and vas deferens for the urine tube and sperm tube respectively apply only in reptiles, birds, and mammals.

Dissection: -sharks oral cavity?

-The oral cavity is the area enclosed by the jaw, an evolutionary innovation not found in the ancestral fish. Note the many rows of sharp bony teeth

Dissection: -what a oviduct produces in a female pigeon ?

-The oviduct produces the albumen and hard shell of the eggs as the already fertilized ovum passes through. -A small remnant of the right oviduct as it enters the right side of the cloaca may persist.

Dissection: -male testes in a pigeon ?

-The paired testes of the male are located in the same position relative to the kidneys as the ovaries of the female.

Dissection: -pericardium of a turtle ?

-The pericardium has been removed to expose the heart. -The transversely expanded ventricle whose blunt apex points posteriorly is the most conspicuous part, but dorsal to this lie the right and left atria and the sac-like sinus venosus.

Overview Vertebrate Body: The Circulatory System: -pulmonary artery and vein in Necturus?

-The pulmonary arteries actually branch off the efferent gill arteries. -The pulmonary veins return the blood to the left atrium.

Dissection: -pulmonary vein in the necturus

-The pulmonary vein from each lung conducts oxygenated blood from the lung anteriorly to a point under the heart where the right and left pulmonary veins fuse -This vessel then enters directly into the left atrium.

Dissection: -pulmonary artery function in the necturus

-The right and left pulmonary arteries actually branch off the efferent gill arteries before they join to form right or left aortae.

Dissection: -in the turtle the aorta branches off too?

-The right aorta branches immediately to give rise to the brachiocephalic artery and continues posteriorly to the lower body where it joins with the left aorta to form the dorsal aorta, just dorsal to the stomach. -The brachiocephalic artery branches into the right and left carotids and subclavian arteries.

Dissection: -in the turtle what does the right aorta supply?

-The right aorta supplies blood to the head, limbs, and lower body; and the left aorta to the viscera. The pulmonary trunk divides into left and right pulmonary arteries.

Dissection: --pulmonary vein of a turtle function?

-The right atrium is much larger than the left atrium which receives blood from the lungs via the pulmonary veins. -The pulmonary veins are sometimes difficult to distinguish.

Overview Vertebrate Body: -shark urogenital system evolution?

-The shark shows the intermediate condition -In the shark, tiny ducts lead from the testis into the anterior portion of the kidney (genital kidney), which is modified into tubules used for the storage and transport of sperm (this portion of the kidney does not produce urine). -These modified kidney tubules are actually homologous to the epididymis, which is found in reptiles, birds, and mammals. -The modified kidney tubules converge to form a large sperm duct, which, in the shark, leads from the anterior kidney directly to the cloaca. A urinary duct drains the posterior kidney of the shark

Dissection: -skin, feathers, scales of a pigeon?

-The skin of birds is thin and loose when compared to most other tetrapods. -Keratin scales, structurally similar to those of reptiles, are found on the legs and feet. -Feathers, though covering almost the entire body, are rooted only in a few well-defined tracts.

Dissection: -In a pigeon what is arrangement of the lungs?

-The special arrangement of the lungs and their associated air sacs permits a continuous unidirectional flow of air through the lungs during both inhalation and exhalation.

Dissection: -spiracle of a shark

-The spiracle has a rudimentary gill and its function is unknown in most sharks. -sharks and in rays, however, the spiracle is used to draw water in for gas exchange since the mouth may be partially buried as the animal lies along the floor of the ocean.

Dissection: -stomach of the turtle

-The stomach, a curved tubular organ leading into the duodenum of the small intestine, runs from the far left side horizontally toward the right side of the animal. -The anterior portion is the cardiac stomach while the posterior portion is termed the pyloric stomach.

Dissection: -the tail of the necturus?

-The tail is provided with a dorsal and ventral tail fin. -When Necturus swims, its locomotion is still fishlike; the limbs are held close to the body and the tail provides the main thrust.

Dissection: male reproductive system of turtle ?

-The testes in the male are compact, round structures attached to the ventral side of each kidney by a mesentery. -Attached to each testis is a conspicuous mass of coiled tubes, the epididymis, which conducts the sperm from the testis to the vas deferens (difficult to find), which leads to the cloaca. -The two spongy ridges in the ventral wall of the cloaca is the penis.

Dissection: -trachea of a turle

-The trachea branches into right and left bronchi that lead deep into the substance of the lungs.

Dissection: -pigeon trachea and larynx?

-The trachea extends from the glottis to the lungs. -The anterior end of the trachea near the glottis is called the larynx. Unlike the larynx of mammals, this structure does not produce sounds, though it can modulate them.

Dissection: -the ureter of a turtle

-The ureter is a short, uncoiled tube that enters the cloaca just anterior to the reproductive tubes. -The ureter is an outgrowth of the cloaca and found only in amniotes

Dissection: -the urinary bladder of a turtle ?

-The urinary bladders have separate openings into the cloaca. -Thus the urine goes down the ureter to the cloaca, and then into the bladders for storage.

Overview Vertebrate Body: The Circulatory System: -ventral aorta in ancestral fish

-The ventral aorta leads from the heart anteriorly and gives rise to a series of paired aortic arches that form the afferent gill arteries carrying blood to each gill on each side. -After oxygenation, blood continues on from each gill and collects in the dorsal aorta. -Blood is then distributed to all parts of the body.

Dissection: -what does necturus not have?

-There are no gills in the gill slits of Necturus. -Gas exchange in amphibians takes place over the surface of the external gills (if present), in lungs, and over the entire body surface.

Dissection: -ventral aorta branches it divides in the Necturus?

-These branches will subdivide and give rise to three pairs of afferent gill arteries, which conduct blood to the capillaries of the gills.

Overview Vertebrate Body: Gas Exchange Systems: -secondary palate structure/function?

-This structure separates the nasal cavity from the oral cavity. -As a result, air goes through the nasopharynx, the space between the palates, before entering the mouth and then does so directly opposite the glottis. -Breathing therefore can occur even while food is being processed in the front of the mouth .

Dissection: -how turtles use their lungs to breathe ?

-Turtles ventilate their lungs by negative pressure breathing, -using their pectoral muscles to raise the pectoral girdle to expand the thoracic/abdominal cavity and therefore the lungs.

Overview Vertebrate Body: Gas Exchange Systems: -solved the problem with gas exchange ?

-Two lines of reptiles, the crocodilians and therapsids (the lineage leading to the mammals), solved the problem by evolving a secondary palate.

Dissection: -water passes in sharks...

-Water passes in through the mouth and out through the gill pouches, passing over the gills. -As a result, gases can be exchanged across the thin gill capillary walls. - Note the cartilaginous bars supporting the posteriorly directed gill filaments and the hard anterior gill rakers that guard the openings into the gill pouches

Dissection: -mature females in necturus species

-When mature, the eggs burst out through the thin membranous walls of the ovaries and fill the abdominal cavity. -Through ciliary action of the lining of the coelomic cavity, the eggs are propelled forward to the openings of the oviducts in the anterior part of the coelom and pass through them to the cloaca. -The oviducts by this time are large and highly coiled.

Overview Vertebrate Body: The Circulatory System: -Necturus all blood goes

-all the blood from the heart goes to the gills for gas exchange, and then to the rest of the body via the dorsal aorta.

Overview Vertebrate Body: The Circulatory System: -what did the birds retain and what did the mammals reduce

-birds retained the sinus venosus in a vestigial form while mammals possess a reduced sinus venosus which functions as the sinoatrial node.

Overview Vertebrate Body: The Circulatory System: -what is the fold in tissue in older amphibians (frog)

-called the spiral valve forms in the conus arteriosus and serves to direct oxygenated and deoxygenated blood into the appropriate vessels

Overview Vertebrate Body: The Digestive System: -vertebrates have one or more blind pouches off their digestive tracts?

-ceca. -If a cecum branches off at or near the stomach, it is called a pyloric cecum. *Ceca are quite variable in size and shape though generally prominent in herbivores or omnivores while less so in carnivores.

Overview Vertebrate Body: The Circulatory System: -Amphibians faced a new problem?

-establishing a satisfactory circulation: accommodating air breathing. -keeping the oxygenated blood that was coming into the heart from the lungs separate from the blood coming in from the other parts of the body; -could then be sent in its turn to the lungs for oxygenation while the blood from the lungs went on to the rest of the body.

Overview Vertebrate Body: Gas Exchange Systems: -how amphibians facilitate breathe?

-evolved internal nostrils (nares); are openings in the palate (the roof of the mouth), which connect to the external nostrils, -so providing an independent passageway for the entry of air into the pharynx. *All higher vertebrates have these as well.

Dissection: -how do Necturus breathe?

-external nares are small but better developed than the shark since they extend posteriorly and open into the mouth, an adaptation for air breathing. -This permits air and olfactory stimuli to enter the mouth even when the mouth is closed.

Dissection: -the forelimb of the necturus ?

-forelimb the elbow is rotated so the foot is directed slightly forward.> -This permits the animal to lift itself slightly above the ground, a position that is much further developed in reptiles and mammals.

Dissection: -sjarks blood cirulation

-four-chambered heart -The sinus venosus receives venous blood from all parts of the body and conducts it to the atrium. -When the atrium contracts, blood passes from the atrium into the thick-walled muscular ventricle, and is pumped by the ventricle into the last chamber, the conus arteriosus. -The conus arteriosus extends as far as the anterior end of the pericardial cavity; it then continues as the ventral aorta

Overview Vertebrate Body: The Digestive System: -esophagus in birds?

-greatly enlarged to form the crop. -The anterior (cardiac) and posterior (pyloric) stomachs are likewise modified in birds to form the proventriculus and gizzard respectively.

Overview Vertebrate Body: The Circulatory System: -most adult amphibians different from Necturus b/c?

-have lost the gills and modified the circulatory plan to accommodate lung breathing. >ex: the adult frog has a complete separation of the left and right atria and has lost the gills and the gill circulation.

Overview Vertebrate Body: The Circulatory System: -Ray-finned bony fishes and cartilaginous fishes have..

-hearts and circulatory systems very similar to that of the ancestral fish. -Inside the bodies of fish, the parts of the heart are arranged in various ways. In general, they are folded so that the atrium is dorsal to the ventricle

Dissection: -what does the necturus lack in compared to the skin of fish, reptiles, birds, and mammals

-particular the lack of any bony or keratinized scales. -These characteristics are important since a portion of the Necturus' gas exchange occurs through its moist surface. The skin is well supplied with glands that produce copious amounts of mucus

Dissection: -posterior vena cava in the necturus ?

-posterior vena cava, which conducts venous blood from the posterior part of the body. -Follow it anteriorly until enters the liver where it joins with the hepatic veins to convey the blood to the sinus venosus.

Dissection: -brachiocephalic arteries in a pigeon? -dorsal aorta?

-providing oxygenated blood to the neck and head regions. -The dorsal aorta branches almost immediately upon exiting the left ventricle,

Overview Vertebrate Body: The Circulatory System: -This required second adaptation for Amphibians?

-the atrium was subdivided to form a right and left side -so that the deoxygenated blood entering the right side of the atrium via the sinus venosus - sinus venosus was kept separate from the oxygenated blood coming into the atrium from the pulmonary veins on the left.

Dissection: -female reproductive system in sharks?

-the ovaries lie on either side of the esophagus at the anterior end of the pleuroperitoneal cavity. -Each ovary is suspended from the dorsal body wall by a mesentery.

Dissection: -In a Necturus who has thew larger oviduct female or male?

-the oviduct is larger in the female and the anterior end of the oviduct has an enlarged funnel; this is lacking in the male's urinary duct. -However, the male does have a vestigial oviduct that is homologous to the female oviduct. *It may be seen as a dark line of pigmented cells along the lateral edge of the urinary duct.

Dissection:' -Reproductive structure in sharks for males

-the testes are located near the anterior end of the abdominal cavity adjacent to the anterior end of the kidneys. -Each testis is held in place by a mesentery through which minute ducts pass.

Overview Vertebrate Body: The Circulatory System: -turtle circulation with ventricles ?

-the ventricle is partially divided by a septum. -The pulmonary trunk as you would then expect exits from the right side of the ventricle so as to carry deoxygenated blood to the lungs.

Dissection: -the voice organ of a pigeon ?

-the voice organ of birds (the syrinx) is located at the posterior end of the trachea, where it divides to form the bronchi.

Overview Vertebrate Body: The Circulatory System: -Reptiles have hearts and circulatory systems similar too..

-those of adult amphibians, but they can differ in certain ways. >ex: The turtle has a complete separation of the left and right atria and no longer has a gill circulation.

Overview Vertebrate Body: The Circulatory System: -something different in the turtles heart

-turtle heart is that the left aorta actually attaches to the heart to the right of the ventral (and hence right) aorta. -This is a result of the particular evolutionary pathway taken to establish the reptilian heart

Overview Vertebrate Body: The Digestive System: -pharynx in aquatic chordates?

-where the pharyngeal slits are found. -In higher vertebrates, it is the region that the gut tube and the respiratory tract have in common. -ex: apply to lobe-finned bony fishes and most amphibians

Overview Vertebrate Body: The Digestive System: -small intestine?

-where the principal digestive and absorptive functions occur. -The first loop of the small intestine is called the duodenum. -The pancreas in virtually all vertebrates lies in a mesentery near the bend of the duodenum

Dissection: -do necturus have urinary bladder?

A shrunken urinary bladder is attached to the ventral surface of the cloaca. There are no ceca in Necturus.

Dissection: -where does oviduct of a female pigeon come from ?

A single coiled oviduct originates at a point slightly behind and lateral to the ovary and extends to the posterior part of the cloaca.

Necturus and frog class

Amphibia

Dissection: -what other animal has same veins?

As in fishes, there are also cardinal veins that return venous blood to the sinus venosus.

Dissection: -where is blood returned in a shark

Blood is returned to the sinus venosus by the anterior and posterior cardinal veins. The posterior cardinal veins can be seen on either side of the dorsal aorta in the abdominal cavity

Shark (dogfish) class

Chondricthyes -Most members of this group have internal fertilization; males have evolved "claspers" for introducing sperm into the female's body. For these and other reasons, it is most inappropriate to regard sharks and other cartilaginous fish as more primitive than the bony fish

Dissection: -where does the deoxygenated blood come from in a turtle ?

Deoxygenated blood from the limbs is returned to the right atrium via the posterior vena cava.

Overview Vertebrate Body: The Circulatory System: -Ancient Fish conus arteriosus (CA)?

The conus arteriosus is a narrow chamber that connects the ventricle with the ventral aorta. -It contains a series of semilunar valves that prevent backflow into the ventricle.

Dissection: -efferent portion of a shark

The freshly oxygenated blood then passes from the gill capillaries into the efferent (away from) portions of the gill arteries that join to form the dorsal aorta and so into the general body circulation.

Dissection: -pigeons gas exchange system?

The gas exchange system of birds consists not only of the lungs, but also a number of air sacs located among the viscera and in spaces within certain bones.

Overview Vertebrate Body: Gas Exchange Systems: One difficulty the first terrestrial vertebrates how the internal nostril function?

The internal nostrils generally opened near the front of the mouth whereas the glottis was in the back (as you will see in the Necturus), and while breathing, air had to traverse the length of the mouth.

Dissection: -lips of the male and female in necturus cloaca

The large vent (the opening into the cloaca) is located at the junction of the trunk and tail. lips surrounding the vent; in the male the lips are very swollen and have tiny papillae inside, in the female the lips are small, smooth folds

Dissection: -Turtle's peritoneum?

The large vessels forming an H-shaped design in the ventral peritoneum are veins carrying blood from the posterior part of the body. They join the hepatic portal vein to enter the liver

Dissection: -pulmonary arteries in a pigeon?

The left and right pulmonary arteries are branches of the pulmonary trunk, which, like the aorta, leaves the ventricles and splits while still surrounded by heart tissue

Dissection: -what body part in necturus is inefficient ?

The limbs are mechanically inefficient for support and movement, but are sufficient for crawling up on the banks of streams

Dissection: -turtles lungs?

The lungs are broad, flat, spongy organs lying against the carapace on each side just posterior to the pectoral girdle. They extend quite far posteriorly.

Dissection: -where is oxygenated blood is pumped?

The oxygenated blood is pumped to the left ventricle from the left atrium and so on to the aorta, thus completing the cycle of blood transport through the pigeon heart.

Overview Vertebrate Body: The Digestive System: -pancreas structure un shark

The pancreas can be a discrete, obvious structure or structures as in the shark

Dissection: -do sharks also have vena cava?

The posterior vena cava is a new invention; in the shark venous blood returns to the heart through the cardinal veins and there is no vena cava.

Dissection: -how to tell if a shark is male?

The sex of a shark is shown by its pelvic fin. That of the male is pointed backward and modified into a clasper with rolled edges for sperm transfer

Dissection: -sinus venosus of a turtle ?

The sinus venosus, which contains the "pacemaker", receives blood from various veins on the dorsal side and delivers it to the right atrium.

Dissection: -the small intestines of the turtle

The small intestine continues into the large intestine. Note the cecum, a round nub at the junction of the large and small intestines.

Dissection: -ventral aorta in sharks?

The ventral aorta gives rise to three pairs of branches that in turn branch to produce the five aortic arches that form the afferent (towards) gill arteries on each side.

Dissection: -the silts of Necturus compared to fish?

These are the third and fourth gill slits; the first and second do not break through the skin in Necturus as they do in fishes. Behind the tongue on the floor of the pharynx is a small raised area where a tiny slit, the glottis (the opening to the larynx and trachea) is located.

Overview Vertebrate Body: Gas Exchange Systems: -Lungs were retained ?

lobe-finned bony fishes and in tetrapods but evolved into swim bladders in ray-finned bony fishes

Overview Vertebrate Body: The Circulatory System: -The ancestors of birds resembles heart?

of a reptiles. As you might guess, the aorta that was lost was therefore the left.

Dissection: overview blood flow in the necturus heart?

sinus venosus → right atrium → ventricle → conus arteriosus → ventral aorta (bulbus arteriosus) → afferent gill arteries → capillaries of the gills → efferent gill arteries (branch forming pulmonary artery) → right or left aorta → dorsal aorta → various parts of the systemic circulation.

Dissection: -digrestive system in a shark> pylorus

stomach terminates at the pylorus, a sphincter muscle that regulates the flow of food from the stomach to the intestine.

Dissection: -which artery carries oxygenated blood in the Necturus

the left and right aortae are formed from arteries draining the gills and therefore carry oxygenated blood.

Dissection: -what oral structure does the turtle lack in

turtle lacks teeth, which are functionally replaced by a keratin reinforced beak, as in birds.

Overview Vertebrate Body: Gas Exchange Systems: -All fish and many amphibians exchange gases?

using gills.

Dissection: five external gill slits in a shark?

water exits during gas exchange