Heart

Question 1

What is the cardiac cycle?

Answer 1

Events occuring from one heartbeat to the next.

Question 2

Define end diastolic volume

Answer 2

Amount of blood in ventricles before systolic ( or filling in )

Question 3

Define end systolic volume

Answer 3

Lowest volume of blood in ventricle during cardiac cycle, at end of contraction.

Question 4

Ejection fraction

Answer 4

fraction of EDV ejected per cardiac cycle

Question 5

Describe the electrical conduction pathway in the heart

Answer 5

SA node –> AV node –> Bundle of His –> Bundle Branch –> purkinje fibers

Question 6

Describe intercalated disc:

Answer 6

Heart cells connected by discs working as one functional organ in synchronization.

Question 7

Describe a gap junction

Answer 7

Intercellular connection between cells that connects cytoplasm of 2 cells to allow electrical impulses to pass directly.

Question 8

What is the Frank-Starling Mechanism?

Answer 8

Heart automatically pumps incoming blood . The amount pumped is determined by the rate of blood flow into the heart.

Increase volume of blood stretches ventricles causing cardiac muscle to contract more forcefully.

Question 9

What is preload?

Answer 9

Pressure as ventricles fill with blood at end of diastole.

Question 10

What is afterload?

Answer 10

Afterload refers to the forces that oppose ejection of blood out of the chamber.

Question 11

Name 2 similarities of Cardiac and Skeletal Contraction

Answer 11

Both striated with myosin/actin.

Both have the t-tubule mechanism acting on sarcoplasmic reticulum.

Question 12

Name 3 differences of Cardiac and Skeletal Contraction

Answer 12

T tubule Mechanism has direct diffusion of Ca++ for larger amounts of storage.

Action potential has cardiac muscle plateau for longer time of contraction than skeletal mm.

Strength of contraction varies and is dependent on extracellular Ca++.

Question 13

Ability of cardiac muscle to depolarize and contract is extrinsic or intrinsic?

Answer 13

Intrinsic

Question 14

Does the SA node have small or large fibers?

Answer 14

Small diameter

Question 15

Are there contractile muscle fibers in the SA node?

Answer 15

Almost none.

Question 16

Where does the SA node connect to?

Answer 16

Atrial muscle fibers.

Question 17

Cell membranes of the SA node are naturally ____ to NA+ and CA++? Why?

Answer 17

LEAKY. Less negative resting membrane potential for easier SELF excitation.

Question 18

SA node and AV node make up which part on an ECG?

Answer 18

P-wave

Question 19

Bundle branches make up which part on an ECG?

Answer 19

Q aspect

Question 20

Purkinje fibers make up which part on an ECG?

Answer 20

QRS

Question 21

Events that occur within the cardiac cycle are..

Answer 21

1) Chamber and vessel blood volume changes
2) Chamber and vessel blood pressure changes
3) Electrical activity
4) Heart sounds occur
5) Valve opening/closing

Question 22

What is the p-wave?

Answer 22

depolarization of atrial tissue

Question 23

What is the QRS complex?

Answer 23

depolarization of ventricular tissue, repolarization of atrial tissue

Question 24

What is the t-wave?

Answer 24

repolarization of the ventricles; relaxation

Question 25

Atrial contraction causes how much additional ventricle filling? Also known as a primer pump

Answer 25

20%, unnecessary except during vigorous exercise

Question 26

Define both isolvolumnic contraction and isovolumnic relaxation.

Answer 26

Periods of time when the ventricles have no net change of volume during contraction and relaxation due to the AV valves being closed.

Question 27

What type of energy metabolism does the heart use primarily?

Answer 27

Heavy reliance on aerobic (oxidative) @ 70-90% coming from fatty acids.

Lactate and glucose (10-30%) as well.

Question 28

Heart pumps how much liters per minute? And how much does this number increase by during heavy exercise?

Answer 28

4-6 liters, 4-7x increase during heavy exercise

Question 29

Blood volume pump controlled by what 2 factors?

Answer 29

Intrinsic cardiac regulation (Frank Starling) , and Extrinsic Autonomic Nervous system

Question 30

What is released to regulate the cardiac pump in the ANS

Answer 30

Sympathetic Nervous System affected by norepinephrine for fight/flight response. –> increases cardiac output and pacemaker fires faster.

Question 31

What inhibits cardiac output as a part of the ANS?

Answer 31

Parasympathetic Nervous system. Acetylcholine hyperpolarizes membrane of cells by opening K+ channels. Reduces HR

Question 32

Heart SA node receives ANS innervation when?

Answer 32

Continuously.

Question 33

Heart is said to have _____ tone

Answer 33

Vagal; dominant influence is inhibitory.

Question 34

What allows the SA node to self-excite?

Answer 34

ANS

Question 35

Does the heart pump out all of the blood from the ventricles per beat?

Answer 35

No, roughly 2/3 of the EDV

Question 36

If afterload is increased, what happens to stroke volume?

Answer 36

Stroke volume will decrease, as their is more pressure against the outgoing blood from the heart.

Question 37

If afterload is decreased what happens to stroke volume?

Answer 37

Stroke volume will increase, more blood ejected per beat.