Unit 1: CV System Part C

Question 1

Why is a hydraulic pump required?

Answer 1

In order to sustain the pressure gradients needed to create the blood flow necessary to transport material (nutrients, gases, wastes, etc.) throughout the body

Question 2

Even when the heart is removed from the body, it can…

Answer 2

continue to beat on its own, without any need for nervous stimulation

Question 3

List the 5 features of the heart structure?

Answer 3

a. Four chambers

b. Walls of each chamber are composed of 3 layers

c. Pericardial sac

d. Heart Valves

e. fibrous skeleton

Question 4

What are the 4 chambers of the heart?

Answer 4

i. Left and right atria
ii. Left and right ventricles

Question 5

List the 3 layers that compose the walls of each chamber

Answer 5

i. Endocardium

ii. Myocardium

iii. Epicardium (= visceral pericardium)

Question 6

Endocardium

Answer 6

inner epithelial lining of the heart (continuous with lining of blood vessels)

Question 7

Myocardium

Answer 7

cardiac muscle cells joined together by intercalated disks that contain gap junctions that allow ions to flow directly between cells (electrical coupling)

Ø 99% of cells are normal contractile cells

Ø1% of cells are non-contractile cells referred to as “autorhythmic cells” that form a network called the conduction system

Question 8

Epicardium

Answer 8

= visceral pericardium)
Øepithelial lining covering the outer surface of the heart

Question 9

Pericardial sac

Answer 9

Surrounding and protecting the heart

Question 10

____ of cells are normal contractile cells

Answer 10

99%

Question 11

____ of cells are non-contractile cells referred to as “_________” that form a network called the ___________.

Answer 11

1%

autorhythmic cells

conduction system

Question 12

What is the pericardial sac formed from?

Answer 12

formed from parietal pericardium fused to the fibrous pericardium (thick layer of connective tissue)

Question 13

What does the pericardial sac prevent?

Answer 13

Prevents overdistension of the heart and anchors it to surrounding structures

Question 14

Where is the pericardial cavity space?

Answer 14

between pericardial sac and epicardium)

Question 15

What does the pericardial cavity space contain?

Answer 15

contains serous fluid that reduces the friction resulting from contractions

Question 16

Heart Valves

Answer 16

passive unidirectional valves (open in response to
changes in pressure) that prevent the backflow of blood from the ventricles to the atria or from the large vessels to the ventricles

Question 17

What do heart valves open in response to?

Answer 17

(open in response to changes in pressure)

Question 18

Where are the Atrioventricular valves located?

Answer 18

between atria and ventricles

Question 19

What are the 2 kinds of Atrioventricular valves and where are they located?

Answer 19

Ø tricuspid valve between right atrium and right ventricle.

Ø Bicuspid valve between left atrium and left ventricle

Question 20

Describe how pressure causes valves to open and close in the ventricles

Answer 20

High pressure in the ventricles due to ventricular contraction closes them.
When ventricles relax, pressure in the ventricles falls below that in the atria and the valves open

Question 21

Where are the semilunar valves located?

Answer 21

between ventricles and larger arteries

Question 22

What are the 2 kinds of semilunar valves and where are they located?

Answer 22

aortic semilunar valve between left ventricle and aorta.

pulmonary semilunar valve between right ventricle and pulmonary trunk

Answer 23

High pressure in the ventricles due to ventricular contraction opens them.
When the ventricles relax, pressure in the ventricles falls below that in the
large vessels, and the higher pressure in the aorta/pulmonary trunk closes
the semilunar valves

Question 24

Fibrous skeleton

Answer 24

connective tissue rings

Question 25

Describe the function of the Fibrous skeleton

Answer 25

i. Prevent collapse of valve openings. .

ii. Physically and electrically separate atria from the ventricles, allowing atria to contract as a unit to push blood down into ventricles, and allow ventricles to contract as a unit to push blood upwards into the major
blood vessels (aorta and pulmonary trunk/arteries.