BIOLOGY COMPARATIVE VERT. ANATOMY WEEK 8, Shark Cardiovascular & Respiratory Systems

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1 BIOLOGY COMPARATIVE VERT. ANATOMY WEEK 8, Shark Cardiovascular & Respiratory Systems Assignments Readings Kardong & Zalisko Chapter 7: ; 8: Tuesday Each team will present their shark cardiovascular system to another team that did a different dissection. Half of the Participation team will expose the heart & the other half will expose the efferent branchial arteries in the roof of the mouth. Work Use my notes as a guide for what you should see & examine, but you must use the lab manual or text for explanatory information & supplementary images. You will be expected to know the terms used in my laboratory notes; use my notes as the guide for what to learn in Kardong & Zalisko. Dissect your shark as described below. Share the work amongst your team so you can take time to read & do your coloring too. Compare your shark with other specimens. Coloring Test yourself & color code the blood vessels in these unlabeled images in the Student Art section: Fig. 8.2, 8.3 & 8.7 Quiz You will be given a take home assignment as your quiz for this week. Learning Goals 1. Know the clades listed below & the shared derived traits for their cardiovascular & respiratory systems. 2. Identify the peritoneal (pleuroperitoneal) and pericardial cavities & their associated membranes (visceral pericardium, parietal pericardium, visceral peritoneum & parietal peritoneum. 3. Know & identify the types of gills, pouched (in lamprey) (septal (in sharks) vs. aseptal (in perch). 4. Know the parts of a shark gill as listed. 5. Identify the spleen & know 1 function for this organ. 6. Know the chambers of the heart & which chamber is the strongest. 7. Know the pathway of blood through the heart chambers. 8. Which blood vessels bring blood to the heart? Which blood vessel(s) exit the heart? 9. Identify the systemic arteries, systemic veins, visceral arteries & hepatic portal veins as listed. 10. Know 1 organ that each artery delivers blood to. 11. Know 1 organ that each vein receives blood from. 12. Be able to trace the flow of blood from any starting point to another part of the path. This is a common lab practical question, where you are given 2 marked positions & then are asked to name or trace the pathway between the points. Type of Material lucite block dried skulls fluid preserved Specimens to Examine lamprey miscellaneous bony fish lamprey, shark skulls, shark head dissections, whole shark & skate, perch Additional Sources of Information Carvalho M Dissection Gallery. Sharks & Rays: Myth & Reality. Amer. Museum of Natural History. Derting T Squalus Circulatory System. Comparative Vertebrate Anatomy, Murray State Univ. Martin RA Heart of an Athlete. Biology of Sharks & Rays. Millen Lab 8: Circulatory and Respiratory Systems. Biology 204. Univ. of British Columbia. Heart.html Millen Lab 9: The Systemic Circulatory System. Biology 204. Univ. of British Columbia. Systemic_blood.html Moscarella RA Circulation Diagrams. Zool. 328, Comparative Vertebrate Anatomy, Michigan State Univ. Orange County Community College Cardiovascular Home. Comparative Anatomy. Online Biology Library. PBS Great White Shark Dissection. Inside Nature s Giants. Pepe P Shark Lab, Activity 4: Circulatory System. Phoenix College, Maricopa.

2 Major Clades & Shared Derived Traits in Respiratory & Cardiovascular Systems of Fishes (Features in living taxa, observed in lab) Vertebrata Gnathostomata Osteichthyes Cyclostomata Chondrichthyes Actinopterygii Actinopterygii (Lamprey) (Sharks) (Bowfin) (Teleostii) Swim Bladder Pouched gills Lost lungs? Opercular gills Pulmonary Artery Paired nostrils Septal gills Paired ventral lungs? 5 pairs of aortic arches Internal gill lamellae Complex chambered heart: SV, Atrium, Ventricle & CA Dorsal & ventral aorta > 6 pairs of aortic arches Hepatic portal circuit Olfactores (Tunicates & Vertebrates): closed circulatory system & ventral heart

3 RESPIRATORY SYSTEM In fish, the pharynx contains the visceral or branchial arches and gill pouches. The pharynx is a transitional region used for the passage of food & for gas exchange. The visceral arches contain: branchiomeric & hyobranchial muscles, aortic arches, branchial bar (gill cartilage) & gill lamellae. The first gill pouch is differentiated in sharks to form a spiracle. The spiracle forms between the jaws & the hyoid arches & is a remnant of the 1 st pouch that was present in Agnathans. Use these terms interchangeably to refer to the splanchnocranium cartilage that support the gills: branchial bar = visceral bar = gill bar = gill arch. Gill rays are internal cartilaginous supports for the gill lamellae that form on the lateral sides of the branchial bars. Gill rakers prevent debris or food entry to gills and form on the medial/internal sides of the branchial bars. Gill filaments or gill lamellae [lamell = small plate] are actually the primary lamellae or plates that support the secondary lamellae where actual gas exchange occurs. Sharks have septal gills with a partition dividing demibranchs on each half of a gill. Teleosts have aseptal gills lacking this division. Coronal Section Diagrams of Gills Upper diagram showing the parts of a septal gill. B: Pouched, C: Septal & D: Aseptal (Opercular) Lower diagram: pathways of water flow in septal & aseptal gills. Images from: Cyclostomata (Lamprey) Locate the lamprey's small, pouched gill chambers in the lucite block of a lamprey or the fluid preserved sections on demo table. Lamprey Pouched Gills - sagittal section Lamprey gills - transverse section Exits for pouched gills:

4 Chondrichthyes (Shark) Look at the fluid-preserved skulls & find branchial arches, gill rakers & remnants of the gill rays that supported the gill lamellae. Follow the dissection instructions & find the septa that divide the gills into a series of separate compartments. Identify the gill lamellae. Then scrape away gill lamellae from the surface of one gill to expose the cartilaginous gill rays. Locate the gill rakers inside the pharyngeal cavity. Locate the spiracle & external gill slits on the preserved skate & sharks. What is an important function of the skate s spiracle in relationship to the location of the other gill slits that is not typical of the dogfish shark s spiracle? Shark Spiracle Shark Septal Gills showing gill rakers Shark Septal gills Shark Gill Rakers Actinopterygii (Preserved Perch & Dried Bony Fish Skulls) Look at the cut section to see the gill lamellae & gill rakers on the gill bars(arches). Look at the other side of the head to examine the opercular region covering the gills. Their gills are called opercular (aseptal) gills because the septum that divides the gill chambers is absent. Trout gills showing long, gill rakers Perch Opercular (Aseptal) Gills

5 BODY CAVITIES The visceral organs of the shark are located in one of the coelomic cavities called the pleuroperitoneal (or peritoneal) cavity. The organs are covered with a shiny, thin transparent membrane called the visceral peritoneum while the body wall is covered with a similar membrane called the parietal peritoneum. These membranes were formed by hypomere mesoderm. The pericardial cavity is another coelomic cavity. It is separated from the peritoneal cavity by a transverse septum. The heart is covered with a transparent thin membrane called the visceral pericardium. A similar membrane called the parietal pericardium covers the outer wall of the pericardium. Within both coelomic cavities, the organs are free to move independently of their surroundings & a small amount of coelomic fluid reduces any friction produced by those movements. CARDIOVASCULAR SYSTEM Spleen The spleen is an accessory circulatory organ that produces red blood cells and filters out old red blood cells. It also produces & releases white blood cells during infections. Heart Sharks have a 4-chambered heart. All chambers are formed of cardiac muscle tissue & are found within the pericardial cavity. Blood flows in a one-way path through the heart so they have a "single-circuit", low-pressure circulation. The heart pumps deoxygenated blood toward the gills: low O2 blood --> sinus venosus --> atrium --> ventricle --> conus arteriosus --> low O2 blood The sinus venosus is a very thin sac that tears easily when exposing the heart or the liver. The atrium is large, but very soft or spongy in texture. The ventricle will feel hard and muscular, but looks smaller than the atrium because of its contracted state. The ventricle generates most of the pressure that moves the blood forward. There are 1-way valves at the junction between the heart chambers to control the flow of blood. The conus arteriosus is a small, narrow tube that contains a series of semilunar valves to prevent back flow of blood. The conus contracts or recoils slowly, regulating pressure in the ventral aorta & keeps the flow of blood more uniform. Blood Vessels The heart is ventrally located. The first vessel that exits the heart is called the ventral aorta. The ventral aorta divides into a series of paired afferent branchial arteries. These arteries are ventral to the gills & take deoxygenated blood up into the gills for gas exchange, thus they "arrive" at the gills. Oxygenated blood leaves the gills dorsally via a series of paired efferent branchial arteries (blood "exits" the gills). One small branch forms the commissural artery that leads directly to the heart. When this vessel enters the pericardium it divides into a pericardial artery on the parietal pericardium wall & into the coronary artery that supplies cardiac muscle tissue with oxygen. The efferent branchial arteries merge dorsally into the dorsal aorta. Branches off of the dorsal aorta may be divided into several categories: Somatic branches that are typically paired (R & L) will go to the body wall or limbs & include: R & L subclavian arteries that enter the pectoral fins, R & L iliac arteries that enter the pelvic fins and a caudal artery that is an unpaired somatic branch into the tail via the hemal canal. Unpaired, visceral branches go to digestive system organs & include: celiac artery with its branches, anterior mesenteric artery, gastrosplenic artery, and a posterior mesenteric artery. There are 3 major venous circuits that return deoxygenated blood via separate pathways to the sinus venosus. Paired, lateral abdominal veins takes blood from the fins & muscle tissue of the body wall. This vein empties into the subclavian vein that then empties into the common cardinal sinus just before blood enters the sinus venosus. Blood from the caudal vein is split into small, paired vessels, called renal portal veins, on the lateral sides of the kidney tissue. This blood flows through capillary beds in the kidney tissue & then enters paired, posterior cardinal veins. The posterior cardinal veins carry blood up into large, sac-like chambers called posterior cardinal sinuses & then into the common cardinal sinuses. The hepatic portal circulation is a special subdivision of the venous blood flow. The venous blood from all of the digestive system organs & spleen goes into the liver before it goes back to the heart. Find out why. The blood in the hepatic portal vein merges with blood from the hepatic artery to ensure that the liver receives some oxygenated blood. A portal circuit takes blood from 1 capillary bed (e.g. stomach) carries blood in vein(s) to another capillary bed (e.g. liver). The processed blood exits the liver in paired hepatic sinuses that empty directly into the sinus venous through the transverse septum. See the details of the venous circuits in your lab manual or below.

6 Chondrichthyes (Cardiovascular System) Sharks that have poorly dissected throat muscles can expose the shark hearts. The heart is located in front of the pectoral girdle and deep to the hypobranchial muscles. If your hypobranchial muscles are good you should NOT attempt this dissection. Teams that dissected the heart can show their dissections to the neighboring students. Other teams should follow the directions in their lab manual to look at the gills & expose the arteries in the roof of the mouth. Be sure to cut through the side of your shark that does NOT have the muscles exposed. You want to leave the ventral throat muscles intact, but you will cut through the the gills on one side. Students who dissect out these dorsal arteries should show their dissection to others. Most arteries will be injected with red latex, however, the ventral aorta & the afferent branchial arteries will not be injected so they are harder to find, and are easily torn. The efferent arteries & the arterial circulation that branches off of the dorsal aorta should be filled with red latex. Some arteries are never injected with latex. These arteries are marked with a * in the list below & carry deoxygenated blood. Look at the dissected shark head in Plexiglas. They have the major blood vessels & the heart exposed. One specimen has labels for many of the major blood vessels. Use these models to understand the 3-dimensional aspects to the pathway of blood flow into & out of the gills & heart. Often the latex fails to enter some of the vessels you need to find. If this happens (its especially common in the hepatic artery branch off of the celiac artery), look at another student's shark that does have visible blood vessels. Major Arterial Pathways Conus arteriosus Ventral Aorta Afferent Branchial arteries gill capillaries Efferent Branchial arteries Efferent Branchial artery Commissural artery Coronary artery heart muscle capillaries Commissural artery Pericardial artery parietal pericardium capillaries Efferent Branchial arteries Dorsal Aorta numerous branches as listed: Paired, somatic Unpaired, to visceral organs: Unpaired, somatic R & L Subclavian a.: pectoral fin R & L Iliac artery: pelvic fin Celiac artery has 3 main branches: Pancreaticomesenteric a.: pancreas, intestine Gastric a.: stomach Hepatic a.: liver Anterior (Superior) Mesenteric a.: intestine (ventrally) Gastrosplenic a.: stomach & spleen Posterior (Inferior) Mesenteric a.: rectal gland & intestine (dorsal) Caudal a.: tail Major Systemic Vein Pathways: filled with blue latex. The renal portal veins are not injected & are too small to find. The common cardinal vein is too small to find. Caudal vein Renal Portal veins Posterior Cardinal vein Posterior Cardinal sinus Common Cardinal veins - Sinus Venosus Lateral Abdominal veins Posterior Cardinal sinus Common Cardinal veins Sinus Venosus Hepatic veins Sinus Venosus Major Hepatic Portal Vein Pathways: filled with yellow latex & may look a bit "greenish" rather than yellow. Posterior Intestinal vein Lienomesenteric vein Hepatic Portal vein liver capillaries Hepatic veins Pancreaticomesenteric vein Hepatic Portal vein liver capillaries Hepatic veins Gastric vein Hepatic Portal vein liver capillaries Hepatic veins Compare with Kardong Fig pg 460 & Fig pg. 471

7 Chondrichthyes (Circuit Diagrams) Not all of the vessels shown are required for you to find & know on your specimens. Some of these extra vessels are included to accurately complete pathways.

8 Chondrichthyes (Heart & Coronary Vessels) Large arrows are used to indicate anterior or rostral regions. Labeling codes for the heart: parietal pericardium (PP), visceral pericardium (not labeled, shiny surface over the heart chambers). The fou heart chambers (made of cardiac muscle), in order of blood flow are: sinus venosus (SV), atrium (A), ventricle (V) & conus arteriosus (CA). Lateral diagram of a shark s heart (anterior to the left) Ventral views of the shark s heart. Commissural artery CA A CA PP V A V SV Pericardial artery, Coronary Artery Sinus venosus A Pericardial artery Commissural Arteries V Liver Falciform ligament & transverse septum CA A V Coronary Arteries

9 Chondrichthyes (Branchial Circulation) Afferent Branchial Artery, Efferent Branchial Artery Dorsal aorta, Celiac Artery, Subclavian A., Efferent Branchial A. Dorsal Lateral view Ventral aorta, Afferent branchial artery Ventral view Label this one on your own! Ventral aorta & afferent branchial arteries will not be injected in your sharks, but they carry deoxygenated blood. Ventral view

10 Chondrichthyes (Peritoneal Cavity Arteries & Veins) Gastric A. & V. Pancreaticomesenteric A. & V. Intestine Spleen Post. Mesenteric a. Ant. Mesenteric a. Gastrosplenic a. Celiac Artery, Hepatic Artery & Hepatic Portal Vein, Posterior Cardinal Vein Lienomesenteric vein Posterior Intestinal vein Iliac Artery Rectal gland Posterior Cardinal Vein & Posterior Cardinal Sinus Lateral Abdominal Vein Caudal Artery Caudal Vein (opening below artery)

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