Hearts Flashcards
What are the 4 tissue layers in a heart?
Pericardium, epicardium, myocardium, endocardium
What does the pericardium do?
Sac that surrounds the heart
What does the epicardium do?
Contains nerves that regulate the heart
What does the myocardium do?
Contractile muscles
What does the endocardium do?
The connective tissues surrounding the atria and ventricles
What type of myocardium do fish and amphibians have?
Spongy
How many chambers do bony fish hearts have?
4 compartments arranged in a series
What are the 4 chambers in a bony fish heart? What is the order that blood flows through them?
Sinus venosus -> atrium -> ventricle -> bulbus arteriosus
Which chamber is replaced by the conus arteriosus in elasmobranchs? Why?
The bulbus arteriosus. The conus is contractile and muscular, while the bulbus is elastic and non-contractile
How many chambers do amphibian hearts have?
3, two atria and one ventricle
How does blood flow through an amphibian heart?
Deoxygenated blood enters into the right atrium, and oxygenated blood enters into the left atrium. The ventricle pumps both into the conus arteriosus and into the pulmonary and systemic circuits
Does mixing of oxygenated and deoxygenated blood occur in amphibians?
Yes
How many chambers do non-crocodilian reptiles have?
5: the left atrium, the right atrium, the cavum arteriosum, the cavum pulmonale, and the cavum venosum
How does blood flow through a non-crocodilian reptile heart?
The cavum pulmonale receives blood from the right atrium then pumps it to the pulmonary artery. The cavum arteriosum receives blood from the left atrium and pumps it to the right and left aorta
What mechanism lets non-crocodilian reptiles bypass either the pulmonary or systemic circuit?
Shunt
What are the two types of the shunt mechanism?
Right to left and left to right
Which circuit is being bypassed in a right to left shunt? Why would the animal use this?
Bypasses the pulmonary circuit. Used during diving to send more blood to the tissues instead of to the lungs that aren’t doing anything
Which circuit is being bypassed in a left to right shunt? Why would the animal use this?
Bypasses the systemic circuit. Used while resting on land
How are crocodilian hearts different than the hearts of other reptiles?
It has 4 completely divided chambers, which 2 atria and 2 ventricles and no shunt mechanism
How many chambers do mammalian hearts have?
4 chambers, 2 atria and 2 ventricles that are completely separated
How does blood flow through mammalian hearts?
Deoxygenated blood flows from the vena cava into the right atrium then into the right ventricle, then through the pulmonary artery to the lungs. Oxygenated blood flows from the pulmonary veins into the left ventricle, into the left ventricle, into the aorta to the body
