Compare/Contrast

• Comp/Cont: angiogenesis

  Amphibia

  • proteins in the frogs skin can switch angiogenesis on and off as needed

  Mammalia

  • the process of angiogenesis is controlled by activator and inhibitor molecules that the animal cannot control.
• Comp/Cont: afferent branchial arteries

  Fish

  • deoxygenated blood to their gills for oxygenation

  Mammals

  • the most important source of blood to the upper arm and hand.
• Comp/Cont: aorta

  Mammals and Birds

  • the aorta directly comes out of the left ventricle to supply the body with oxygenated blood.

  Reptiles

  • the aorta emerges from the right ventricle meaning that the aorta receives deoxygenated blood directly from the heart. 
• Comp/Cont: arteries

  Mammals

  • circulatory systems are closed and have developed muscular walls.

  Reptiles

  • muscular walls around arteries are less developed, which is reflective of differing metabolic rates between reptiles and mammals.
• Comp/Cont: atrioventricular node

  Birds

  • AV ring of P-cells that is located on the right side of their hearts

  Fish

  • Sinus venosus which is found in the heart of a fish.
• Comp/Cont: atrium

   Amphibians

  • three chambered hearts consisting of two atria and one ventricle, this means when deoxygenated and oxygenated blood are pumped in the single ventricle, then there is a mixture of blood the flows through out their bodies alongside deoxygenated blood.

  Mammals

  • four separate chambers to prevent mixing, this having the largest heart in the world, a heart specimen is on display in Royal Ontario Museum and measures around 5 feet in length and estimated to pump around 58 gallons of blood. 
• Comp/Cont: blood islands

  Both fish and birds embryos have blood islands that form within the yolk sac and rely on it for initial nutrient and oxygen supply during early development. 
• Comp/Cont: brachiocephalic

  Birds

  • this artery is important because it supplies blood to the wing arteries.

  Fish

  • very simplified circulatory system. Their system consists of a 2 chambered heart, veins, and arteries.
• Comp/Cont: bulbus arteriosus


   The bulbous arteriosus is found primarily in teleosts and chondrichthyes species. Their shape can vary depending on species. The smooth muscle composition of this structure was compared to smooth muscle arterial trunks in embryonic birds and mammals. The study found the presence of a nitric oxide indicator for smooth muscles in both birds and fish embryos, indicating that the bulbous arteriosus is homologous to the arterial trunk of terrestrial vertebrates. However, the arterial trunk of birds does not have any dilating control over their blood pressure.
• Comp/Cont: capillaries


   Most animals have very similar capillaries in their body. Even though reptiles and birds have different numbers of chambers in their hearts, their capillaries still have very similar functions. Reptiles have larger spaced capillaries to help with their blood flow. 
• Comp/Cont: capillary bed

   FIsh

  • two types of capillary beds, one type is in the gills and the other type is in the rest of their body.

  Mammals & Reptiles

  • One capillary bed
• Comp/Cont: capillary plexus

   Birds

  • the primary capillary plexus in the median eminence is single or divided into an anterior and posterior plexus.

  Mammals

  • capillary plexus expansion is driven by vessel regression to optimize network passage of blood. 
• COMP/CONT: cardiac muscle

  Birds

  • Have striated cardiac muscles that pump blood through the body
  • Have closed circulatory system
  • Four chambered heart

  Fish

  • Have striated cardiac muscles that pump blood through the body
  • Have closed circulatory system
  • Two Chambered Heart
• COMP/CONT: cardiovascular system

   Fish

  • Consists of a two chambered heart and uses their gills to circulate their blood. Unlike in other vertebrates, their oxygenated and deoxygenated blood do not mix.

  Amphibians

  • Deoxygenated and oxygenated blood does mix. Their blood is not circulated by gills and they have a three chambered heart.
• COMP/CONT: carotid ducts

  Amphibians

  • carotid ducts (arches three and four) have been lost in most adults as it becomes part of the external carotid structure and part of the ventral aorta.

  Birds

  • arch four is the main passageway for blood and arch three is a shunt for internal and external carotids.
• COMP/CONT: cisterna chyli

  Mammals

  • The thoracic duc arises for the cisterna chyli as a single trunk as part of their lympatic system,

  Fishes

  • The lympatic system, which includes the cisterna chyli is not well defined that some characterize their lymphatic system as a second circulatory system.
• COMP/CONT: closed circulatory system

  Fishes

  • two chambered heart consisting of one ventricle and one atrium

  Mammals & Birds

  • 4 chamber heart consisting of two ventricles and two atria. The more chambers an organism has, the more effective the circulatory system is at separating oxygenated and deoxygenated blood, which aids in the organism's oxygen supply. 
• COMP/CONT: clotting

  Mammals

  • Coagulation cascade mechanism which leads to the conversion of fibrinogen into fibrin creating a platelet plug to form an efficient blood clot. In dogs, clotting factors include plasma, fibrinogen, and prothrombin.

  Birds

  • Fibrinogen also gets converted into fibrin but they have different clotting features such as nucleated thrombocytes (blood cells that act in clotting).
• Comp/Cont: contraction

   Birds

  • Contract their muscles at high frequencies so that they can lift and fly around. This takes place in the upper body mainly.

  Reptiles

  • In snakes case they have to contract the muscles up and down the lengths of their body to initiate movement forward.
• Comp/Cont: conus arteriosus

  Amphibians

  • Frogs use this to distribute blood throughout the body by using a spiral valve

  Fish

  • This part of the heart uses the contractions of the heart muscles to push the blood throughout the body.
• COMP/CONT: cutaneous artery

  Reptiles

  • Often flush their skin with blood while sunbathing to help heat themselves.

  Mammals

  • Their ears contain a great number of blood vessels, but they're used to keep cool. Elephants flap their ears to force air over these blood vessels, and cool of their entire body.
• COMP/CONT: diastolic pressure

  Mammals

  • the diastolic pressure is generally between 60 and 90.

  Reptile

  • the diastolic pressure is generally 21-55.

  This difference could be due to a number of different physiological reasons, such as the elasticity of the arterior walls. 
• COMP/CONT: double circulation

  Fish

  • Single circulatory system

  Amphibians, Reptiles, Mammals, Birds

  • A double circulatory system is seen in all vertebrates except for fish. Although reptiles and amphibians have double circulation, there is still some mixing of the blood since they have a 3 chambered heart while in birds and mammals there is no mixing of the blood.
• COMP/CONT: ductus arteriosus

   Fish

  • bulbus ateriosis, which is located in the heart and functions to control the flow of their blood to maintain a stable/constant and controlled the flow into their gills.

  Bird

  • ductus ateriosis that allows for the bypass of blood to non functional lungs in embryonic birds. It typically closes after hatching of the birds egg.
• COMP/CONT: edema

  Fish

  • Typically occurs when issues arise in their osmoregulation. Problems with the regulation of water and the amount of solute in the body can cause swelling and lead to edema. Edema can affect a fish's ability to swim by affecting their buoyancy and more.

  Reptiles

  • Can have issues with swelling and edema when it comes to issues in osmoregulation and can have edema result from other factors like heart disease, and liver and kidney dysfunction. Edema can affect mobility and overall health.
• COMP/CONT: efferent artery

  Mammals

  • Have the function of carrying filtered blood away from the glomerulus to the other parts of the kidney.

  Fish

  • 4 different efferent arteries that provide oxygenated blood back to the body from the gills. 
• COMP/CONT: endocardial tubes

  Amphibians

  • Splanchnic mesoderm at the region of pharynx proliferates and the cells aggregate to form two small masses called endocardial cells. They become into the endocardial tubes.

  Mammals

  • A pair of endocardial tubes appear in the cardiac crescent and fuses along the ventral midline to form a heart tube, consisting of an internal layer of endocardial cells and an external layer of myocardial cells, separated by the extracellular matrix. 
• COMP/CONT: endocardium

  Birds

  • Provides a barrier to protect the inner cardiac tissue to prevent blood clotting and allow blood flow in the heart chambers.
  • In flight metabolic rate is higher so their endocardium are adapted to increase capillaries in the endocardium.

  Reptiles

  • Provides a barrier to protect the inner cardiac tissue to prevent blood clotting and allow blood flow in the heart chambers.
  • Thinner compared to other taxa, because they have a lower metabolic rate. Since their heart is less complex the endocardium can aid in efficient blood flow.
• COMP/CONT: endothelium

  Mammals

  • The endothelium controls the vascular relaxation and blood fluidity. There may be differences in the structure of the endothelium due to sizes of the mammals and their evolutionary paths.

  Cats

  • Endothelium supports bursts of vascular activity.

  Dogs

  • the endothelium to support endurance.
• COMP/CONT: erythrocytes

  Birds

  • Bigger erythrocytes for more oxygen delivery during flight as atmosphere is low in oxygen

  Mammals

  • Smaller erythrocytes than in birds
• COMP/CONT: external carotids

   Fish

  • Helps support the oral cavity and pharynx

  Amphibians, Reptiles, Birds, Mammals

  • Provides blood flow to the face and neck
• COMP/CONT: foramen of Panizza

  This structure is found only in animals of the order Crocodilia. All other animal hearts have separate left and right aorta’s that do not connect.
• COMP/CONT: glomerulus

  In amphibians and reptiles, the glomerulus is located inside the renal cortex, but amphibians have a less developed kidney structure that causes less efficient water conservation compared to reptiles.
• COMP/CONT: heart

  Reptile

  • three chambered heart that consists of two atria and a singular ventricle

  Birds

  • four chambered heart that consists of an additional ventricle. (Cockroaches have 13 chambers). 
• COMP/CONT: hemodynamics

  Reptiles

  • Small blood vessels that work together to take oxygenated blood to tissues and pump deoxygenated blood towards the lungs. This is called double circulation.

  Fish

  • Blood flows one way from a two chambered heart through the gills and the rest of their body. This is called single circulation.
• COMP/CONT: hemoglobin

  Reptiles

  • Have a less amount of hemoglobin due to their less energetic lifestyles means they do not need as much oxygen

  Birds

  • Have a larger amount of hemoglobin for more oxygen carrying capacity as their lifestyle requires more oxygen usage
• COMP/CONT: hemopoiesis

  Birds

  • primarily undergo hemopoiesis in bone marrow

  Fish

  • exhibit blood cell production in various tissues, like the kidney and spleen.
• COMP/CONT: hepatic portal system

  Mammals

  • hepatic portal system and it takes the blood from the digestive tract to the liver

  Fish

  • hepatic portal system collects blood from the spleen and swim bladder rather than the digestive tract and sends it to the liver
• COMP/CONT: hepatic veins

  Birds

  • Come from the liver, and a small vein from the ligament of the gizzard.

  Reptiles

  • specifically snakes, only terrestrial species have hepatic portal veins that resembles a corkscrew morphology posterior of the liver. 
• COMP/CONT: hypotensive shock

  Hypotensive shock occurs in all taxa when an extreme amount of fluid is lost in the body but can be exhibited in different ways.

  Fish, hypotensive shock can be a symptom of scombroid fish poisoning (SFP) if left untreated, which is the most common fish related illness.