Lecture 10 Flashcards
Amphibians, reptiles, birds and mammals have circulatory systems with
Pulmonary + systemic circuits
Describe Amphibian hearts:
Three chambered heart: Two atria and One ventricle
What happens due to the Amphibian heart having one ventricle?
Oxygenated and deoxygenated blood mixes in this one ventricle
Describe Reptile hearts:
Five chambered heart: 2 Atria and 3 Ventricles (or Cavums - interconnected chambers)
The Cavum Pulmonale functions to
Pump blood through the pulmonary circuit
The Cavum Arteriosum functions to
Pump blood through the systemic circuit
Describe Bird and Mammal hearts
Four chambered hearts
What is the function of the right side of the heart?
Pumps deoxygenated blood to the lungs and then returns oxygenated blood from the lungs to the heart (via the pulmonary circuit)
What is the function of the left side of the heart?
Pumps oxygenated blood through all the body tissues before returning deoxygenated blood to the heart (via the systemic circuit)
Left ventricle pumps blood through this circuit so it is need of
Much more force compared to the right ventricle, so it has added muscle
Pressure is higher in the
Systemic circuit
Pressure is lower in the
Pulmonary circuit
Why does pressure need to be lower in the Pulmonary circuit?
Pressure needs to be lower in the latter because blood does not need to travel far (destination is the lungs) and in the lungs, the blood vessels are very thin-walled due to gas exchange
Why does pressure need to be higher in the Systemic circuit?
Pressure needs to be higher in the former because it carries blood to all parts of the body (besides the lungs), so the heart needs to contract very forcibly to ensure blood can reach places very far from the heart
Oxygenated blood from lungs (via the pulmonary circuit) returns to the
Left atrium
Deoxygenated blood from body (via the systemic circuit) returns to the
Right atrium
What is the disadvantage to completely separated pulmonary and systemic circuits?
Circulatory system is inflexible
Reptiles can selectively distribute blood between the two circuits with the use of a
Shunt
What happens when there is a shunt?
The blood is prevented from entering the pulmonary circuit and recirculates only in the systemic circuit
What is the shunt controlled with?
A valve in the heart (that separates the Cavum Venosum and Cavum Pulmonale)
What happens when the valve for Reptiles is closed?
The blood can only flow through the systemic circuit
What is the valve in reptiles controlled by?
Epinephrine
Epinephrine levels decrease when
Underwater, resulting in closed valves
Epinephrine levels increase when
Traveling, so valves open and blood can travel through both circuits
