Unit 1 - CV System The Heart 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

The heart is a fascinating organ in that begins beating after only…

Answer 2

3-6 weeks after fertilization

Question 3

It will beat on average ______ times before we die

Answer 3

3 billion

Question 4

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

Answer 4

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

Question 5

Where does the heart lie?

Answer 5

in the center of the thorax, sandwiched b/t the lungs

Question 6

Must contract from the _____ so that blood is squeezed out of the ____

Answer 6

BOTTOM UP

TOP

Question 7

List the 4 features of the heart structure?

Answer 7

a. Four chambers
b. Walls of each chamber are composed of 3 layers
c. Pericardial sac
d. Heart Valves

Question 8

What are the 4 chambers?

Answer 8

i. Left and right atria

ii. Left and right ventricles

Question 9

What are the 3 layers that walls of each chamber are composed of?

Answer 9

i. Endocardium
ii. Myocardium
iii. Epicardium (= visceral pericardium)

Question 10

Endocardium

Answer 10

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

Question 11

Myocardium

Answer 11

• cardiac muscle cells joined together by intercalated disks that contain gap junctions that allow ions to flow directly between cells (electrical coupling)
• 99% of cells are normal contractile cells
• 1% of cells are non-contractile cells referred to as “autorhythmic cells” that form a network called the conduction system.

Question 12

____ of cells are normal contractile cells

Answer 12

99%

Question 13

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

Answer 13

1%

autorhythmic cells

conduction system

Question 14

Cardiac muscle cells contract…

Answer 14

without innervention

Question 15

Epicardium (= visceral pericardium)

Answer 15

• epithelial lining covering the outer surface of the heart

Question 16

1st, ____ contract together, then the _____ contract together

Answer 16

ATRIA

VENTRICLES

Question 17

“Autorhythmic cells”

Answer 17

form a network called the conduction system

• specialized to generate APs spontaneously
• has a special ability (specialized myocardial cells) to contract without any outside signals
• AKA pacemakers b/c they set the rate of the heartbeat
• don’t contribute to the contractile force of the heart

Question 18

Surrounding and protecting the heart =

Answer 18

Pericardial sac

Question 19

Where is the pericardial sac formed from?

Answer 19

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

Question 20

What does the pericardial sac prevent?

Answer 20

Prevents overdistension of the heart and anchors it to surrounding structures

Question 21

Where is the pericardial cavity space?

Answer 21

between pericardial sac and epicardium

Question 22

What does the pericardial cavity space contain?

Answer 22

contains serous fluid that reduces the friction resulting from contractions

Question 23

Heart Valves

Answer 23

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 24

What do heart valves open in response to?

Answer 24

open in response to changes in pressure

Question 25

What are the 2 kinds of heart valves?

Answer 25

i. Atrioventricular valves (between atria and ventricles) | ii. Semilunar valves (between ventricles and larger arteries)

Question 26

Where are the Atrioventricular valves located?

Answer 26

between atria and ventricles

Question 27

What are the 2 types of Atrioventricular valves (AV)?

Answer 27

- TRIcuspid valve | - BIcuspid valve

Question 28

Where is the TRIcuspid valve located?

Answer 28

between right atrium and right ventricle

Question 29

Where is the BIcuspid valve located?

Answer 29

between left atrium and left ventricle

Question 30

For Atrioventricular valves, ____ pressure in the ventricles due to ventricular ________ CLOSES them

Answer 30

HIGH CONTRACTION *when a ventricle contracts, blood pushes against the bottom side of its AV valve & forces it upward into a closed position

Question 31

For Atrioventricular valves, when ventricles _____, pressure in the ventricles falls below that in the atria and the valves ___.

Answer 31

RELAX OPEN

Question 32

Where are the Semilunar valves located?

Answer 32

between ventricles and larger arteries

Question 33

What are the 2 types of Semilunar valves?

Answer 33

- aortic semilunar valve | - pulmonary semilunar valve

Question 34

Where is the aortic semilunar valve located?

Answer 34

between left ventricle and the aorta

Question 35

Where is the pulmonary semilunar valve located?

Answer 35

between right ventricle and pulmonary trunk

Question 36

The Semilunar valves...

Answer 36

DON'T need connective tendons as the AV valves do

Question 37

For Semilunar valves, HIGH pressure in the ventricles due to ventricular ________ _____ them

Answer 37

CONTRACTION OPENS

Question 38

For Semilunar valves, when the ventricles RELAX, pressure in the ventricles ____ _____ that in the large vessels, and the HIGHER pressure in the aorta/pulmonary trunk _____ the semilunar valves.

Answer 38

FALLS BELOW CLOSES

Question 39

During ventricular CONSTRICTION, the ____ _____ remain ______ to...

Answer 39

AV VALVES CLOSED PREVENT BLOOD FLOW BACKWARD INTO THE ATRIA

Question 40

During ventricular RELAXATION, the ______ ______...

Answer 40

SEMILUNAR VALVES PREVENTS BLOOD THAT HAS ENTERED THE ARTERIES FROM FLOWING BACK INTO THE VENTRICLES

Question 41

What is the Chordae tendineae and the Papillary muscles?

Answer 41

Chordae tendineae: - collagenous tendons - AV valves connects to this - prevent valve from being pushed back into the atrium (if it fails, prolapse is the result) Papillary muscles: - provide stability for the chordae

Question 42

Fibrous skeleton

Answer 42

4 fibrous CONNECTIVE TISSUE RINGS that surround the 4 heart valves

Question 43

What do the Fibrous skeleton do?

Answer 43

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). - acts as an electrical insulator - blocking most transmission of electrical signals b/t the atria & the ventricles