Module 6: Comparative Anatomy Of The Cardiovascular System

Question 1

The heart

Answer 1

A muscular organ that pumps blood throughout the body → keeps the animal alive

Question 2

Mammalian heart

Answer 2

Made of 4 chambers: 2 atria and 2 ventricles
One atrium and one ventricle on each side of the heart: right and left sides → separated by a septum
AV valves → separate the atria and ventricles

Question 3

Atrio-ventricular (AV) valves

Answer 3

Separate the atria and ventricles from each other

Question 4

Interventricular septum

Answer 4

The septum that separates the ventricles
Thicker than the septum that separates the atria

Question 5

Why is the heart a unique organ?

Answer 5

1. Made of cardiac muscle, which is specialized muscular tissue
2. Has intrinsic contracting ability without having a stimulus
3. Heart rate increased or decreased via autonomic nerves and other mediators
4. Nutrient supply to the heart is via a small fraction of the blood that it pumps → distributed via the coronary blood vessels

Question 6

Syncytium

Answer 6

The network that the cardiac muscles arranged to form
Makes all the fibers contract together at the same time → how the atria and ventricles can contract in a coordinated way to pump blood

Question 7

The heart’s intrinsic contracting ability without a stimulus

Answer 7

1. Impulse for contraction originates from the Sino-atrial node →
2. It’s transmitted to the AV node →
3. It’s propagated to the rest of the heart via specialized fibers that form the “Bundle of His” (purkinje fibers)

Question 8

Papillary muscles

Answer 8

Specialized muscles that make up the inside walls of the heart → especially in the ventricles that are attached to the AV valves

Question 9

Chordae tendinae

Answer 9

Thick chords that attach the papillary muscles to the valves

Question 10

Endocardium

Answer 10

A thin membrane that covers the inside of the heart

Question 11

Myocardium

Answer 11

The heart muscle itself

Question 12

Epicardium

Answer 12

A thin membrane that covers the outside of the heart

Question 13

Difference in thickness between the right and left ventricular walls and Why

Answer 13

The difference: the right ventricular wall is very thin compared to the left ventricular wall
Why: the left ventricle works the hardest to push blood at high pressure to the rest of the body

Question 14

Coronary groove

Answer 14

The groove that runs around the heart separating the atria from the ventricles
It contains the coronary blood vessels

Question 15

Left vs. Right ventricles

Answer 15

Left ventricle = very large vs. the right ventricle
The left ventricle has to be strong enough to pump blood through the aorta to the rest of the body → causes the left ventricle to extend to both the right and left side of the heart
2 grooves on either side of the heart that separate the right from the left ventricle → the paraconal and subsinosal grooves

Question 16

Paraconal groove

Answer 16

Located beside the conus arteriosus that’s on the right ventricle

Question 17

Conus arteriosus

Answer 17

A come- shaped prominence on the right ventricle from which the pulmonary trunk arises

Question 18

Subsinosal groove

Answer 18

Located below the coronary sinus (in the right atrium)

Question 19

Coronary sinus

Answer 19

A “pool” that collects venous blood from the heart muscle

Question 20

Pericardial sac

Answer 20

A fibrous sac that covers the heart → contains a few millimeters of a thin, watery fluid called “pericardial fluid”
It’s a protective covering for the heart

Question 21

Blood vessels

Answer 21

Form a critical part of the circulatory system → transport blood throughout the body
Major types → arteries, veins, arterioles, venules, capillaries

Question 22

Arteries

Answer 22

Carry blood from the heart to various organs and tissues
Made of 3 layers: tunica intimate, tunica media, tunica adventitia

Question 23

Tunica intima

Answer 23

Thinnest layer of an artery
Made of endothelial cells surrounded by connective tissue

Question 24

Tunica media

Answer 24

Thickest layer of an artery
Made of elastic fibers, connective tissue vascular smooth muscles

Question 25

Tunica adventitia

Answer 25

Outermost layer of an artery
Made of connective tissue
Contains nerves that regulate the vessels

Question 26

Characteristics