11/30/2003
Lab is open today - email me when you get here; the outer door is locked
This should interest some of you. We will need lab assistants for the Fall of 2004, so if some of you are interested talk to Campbell or me at the end of next semester and in the summer.
You have to return your dissection kits next week or I will be forced to hold your grades
We will have the test as scheduled on the 1 and 3 December 2003 (NO CHANGE IN THESE DATES)
I have put up some pointers, for which reading your prescribed text will be sufficient (Hildebrand and Goslow, 2001)
Read and know Campbell's notes and the lab text and the (Hildebrand and Goslow, 2001) - I will ask questions from these.
you can begin your dissections at anytime and do not require to begin only during the scheduled lab.
some of the information on this page might only be information (not for the test)
What I want you to know --
Coelom and Mesenteries
Read and know Campbell's notes and the lab text and the (Hildebrand and Goslow, 2001) - I will ask questions from these.
The Coelom is the body cavity that encloses the internal organs. In invertebrates the coelom may be segmented. The coelom has its origin in the hypomere (mesoderm), its outer wall is known as the somatic peritoneum and the inner membrane around the gut is the visceral peritoneum. Together with the gut wall and the endoderm it is known as the splanchnopleure; the somatopleure is similarly the outer group of membranes - somatic peritoneum + body wall + ectoderm. In the primitive vertebrate and in the embryonic condition the mesenteries divide the coelom into a right and left half. The mesenteries are the hypomeral layers that extend down (dorsal to ventral) the medial portion of the coelom. The dorsal mesentery is that portion that extends down from the dorsal wall of the coelom to the splanchnopleure, the ventral mesentery is the ventral portion. the ventral mesentery is lost in in various parts of the coelom, thus making it one large confluent cavity. The dorsal mesentery usually remains intact through its length and is usually strengthened by collagen; it carries blood vessels and nerves of the viscera.
the following are different portions of the mesentery and named differently.
Greater omentum is the dorsal mesentery connecting the stomach from the dorsal coelom. also called mesogaster (what is an omentum)
Mesoduodenum is that portion around the duodenum; Mesointestine is around the small intestine; Mesocolon around the colon; Mesorectum is around the rectal region of the gut
The ventral mesentery in jawed vertebrates is greatly reduced and persists as specialized ligaments. The lesser omentum is a portion of the ventral mesentery connecting the stomach to the liver.
In mammals the dorsal mesentery is a sight of fat deposition.
None of the organs of the viscera lie in the coelom, rather they are enclosed within the mesentery walls; except the anterior funnels of the oviducts and the anterior kidney tubules of some vertebrates (larval lampreys).
Thus classifying organisms based on the coelom condition, vertebrates along with many invertebrates are known as Coelomate or Eucoelomate
The coelom is divided transversely by the transverse septum into a - Pericardial cavity & Pleuroperitoneal cavity. (what is the sight of formation of the transverse septum). The transverse septum is incomplete in the elasmobranchs and in hagfishes.
what is the arrangement of the pericardial, pleural, peritoneal and pleuroperitoneal cavities in the anurans (and some reptiles), in crocodiles, snakes and some lizards and birds, and in mammals.
Digestive System
Read and know Campbell's notes and the lab text and the (Hildebrand and Goslow, 2001) - I will ask questions from these.
observe the sectioned jaw on my cat
The mouth in chordates (Branchiostoma) is supposed to have arisen by fusion of gill slits. The tongue is an important organ serving to capture and handle prey/food besides other functions in different organisms. The tongue of the lamprey is an example of homoplasy, evolved parallel to the tongues of higher vertebrates. The musculature of the tongue is derived from the hypobranchial musculature (there was a question on this on the last test; do you know the primary function of this muscle group in the shark), and the skeletal support is provided by the hyoid. Not all vertebrates have a tongue and they are variously adapted to diverse feeding habits, ecology and physiology.
The liver is related in development to the transverse septum mentioned above. The liver is mesodermal in origin, and originates in the small intestine and grows out into the transverse septum. Here it becomes large due to association with the major veins that enter the heart through the septum and then grows posteriorly into the peritoneal cavity. In this event it takes the posterior wall of the septum with it that is subsequently known as the serosa of the liver. Further in development, only its anterior and ventral connection to the liver persist and these are known as the coronary (anterior) and falciform (ventral) ligaments. Both have been observed in lab under the mesenteries section. The coronary ligament is circular and suspends the liver from the transverse septum (or its derivatives) in all vertebrates. The transverse septum is thus composed of the posterior wall of the pericardial cavity, the anterior wall of the peritoneal cavity, the falciform and coronary ligaments, the serosa and the mesoderm of the liver.
- what is the function of the spiral valve
- what kind of muscles does the digestive system possess - smooth / striated
- what is a sphincter
- what are the functions of the liver
Respiratory System
Read and know Campbell's notes and the lab text and the (Hildebrand and Goslow, 2001) - I will ask questions from these.
- how is the blood supply to the gills in the gill breathers
- how is the blood supply to the lungs in the different groups
- what is the function of the diaphragm in respiration, what nerves control it and which part of the brain controls it (which bones and muscles are involved in respiration)
- gill breathers can increase oxygen uptake by increasing the surface area of the gills (but this can be mechanically unfeasible) or they can increase the rate of flow of water over their gills. In smaller gill breathers, physical movement of the gills is possible, but becomes cost inefficient for larger size gills (Necturus however can move its gills). Many fishes instead have more sturdy and rigid gills and swim at high speeds thereby increasing the rate of flow of water over their gills.
- Plethodontid salamadrers have neither lungs nor gills, and respire only through skin
- Alveoli are small sacs within the mammalian lung that increase the surface area for oxygen uptake. In Birds, these structures (parabronchi) are open on both ends. Amphibians have a single sac lung.
- respiratory control is facilitated by oxygen concentration in the blood of poikilotherms (cold blooded animals) , In homeotherms (warm blooded animals) this is facilitated by the concentration of CO2 .
Circulatory System
Read and know Campbell's notes and the lab text and the (Hildebrand and Goslow, 2001) - I will ask questions from these.
- what are the functions of blood???
- structure of the heart in the shark, necturus and cat; and the oxygen composition of the blood vessels entering or leaving the heart
- which blood vessels carry oxygenated and de-oxygenated blood (blood circuit)
- control of the heart beat - what is the heart's natural pacemaker called
- arteries have a thicker tunica media that has circular muscle fibers and elastic fibers in the larger arteries that allow them to handle the high blood pressure
- define systole and diastole
- does amphioxus have a heart??
- what are erythrocytes and do they have a nucleus in all organisms??
- know the arteries and veins that supply different regions
- what is the carotid duct??
- how many aortic arches are present in the primitive condition and what are their homologies in the three groups we have examined??
- does the liver receive arterial or venous blood?? -- mostly venous blood is supplied here as it may contain compounds that are not suitable or required in the general circulation, that could be processed enroute in the liver.
- do mammals have a renal portal system? a non-mammalian feature is the renal portal system - where the kidneys receive venous blood. This feature is retained in the birds (which are a clade nested within the reptiles) which also have a four chambered heart like the mammals (reptiles have an incomplete separation of their ventricles except crocodiles).
- what is the source of coronary arteries between gill and lung breathers??
- in the single circuit system of fishes the blood pressure is not very high and the blood that flows to the heart is low in oxygen. this is acceptable in the fishes as the high buoyancy allows the low pressure blood to still supply the cephalic region, and flexion of posterior-lateral myomeres aids in propelling the blood to the caudal ends.
- Amphibians have a 3 chambered heart that can maintain separation of the systemic and pulmo-cutaneous flow. thus oxygen rich blood passes from the left atrium through the conus arteriousus to the systemic arch; this returns to the sinus venosus and right atrium, that pumps it throught the single ventricle into the pulmo-cutaneous arch. Part of this blood is partly oxygenated by the skin and returns to the sinusvenosus, the rest enters the pulmonary system and returns to the left atrium.
- among mammals Man has arterial blood pressure of 50 and 100 mmHg (millimeters of mercury) in the head and heart respectively. Giraffe has arterial blood pressure of 100 and 260 mmHg (millimeters of mercury) in the head and heart respectively. the difference is due to the effect of gravity.
Nervous system
Read and know Campbell's notes and the lab text - I will ask questions from these.
- know the pattern of spinal nerves from the amphioxus onward
Urinogenital System
Read and know Campbell's notes and the lab text and the (Hildebrand and Goslow, 2001) - I will ask questions from these.
- what is a renal portal system
- what are the functions of the kidney
- what is the blood supply to the kidneys
- what are the excretory products of the shark, necturus and the cat and the birds and reptiles
- what constitutes the cortex and the medulla of the kidney
- the glomerulus is the capillary network within the mapighian tubules. in birds not all the nephrons have henles loop.
Links
Collection of Vertebrates - UTA
Amphibian Species of the World
Chordata - University of Michigan page (explore the different groups of Chordates here. you can also find information on invertebrates from their page)
Classification of living organisms (Animalia)
references (including illustrations on this page):
Kent, G.C. and L. Miller. 1997. Comparative Anatomy of the Vertebrates (8th edition). Wm. C. Brown Publishers.
Schmidt-Nielsen, K. 1990. Animal Physiology: Adaptation and Environment (4th edition). Cambridge University Press.
Wake, M.H. (editor). 1979. Hyman's Comparative Anatomy (3rd edition). The University of Chicago Press.
