Cardiac Cycle

Question 1

what is longer, Cardiac muscle action potential or skeletal muscle action potential/

Answer 1

cardiac muscle action potential

• Expand time necessary to develop force for the entire heart to contract
• Also includes Ca++ involvement in the process

Question 2

Systole

Answer 2

period of ventricular contraction (pumping)

Question 3

Diastole

Answer 3

period of ventricular relaxation (filling)

Question 4

what are the 5 stages of the cardiac cycle?

Answer 4

1. atriole systole begins: atrial contraction forces blood into ventricles
2. ventricular systole (1st phase): ventricular contraction pushes AV valves closed
3. Ventricular systole (2nd phase): semilunar valves open and blood is ejected
4. ventricular diastole (early): semilunar valves close and blood flows into atria
5. ventricular diastole (late): chambers relax and blood fills ventricles passively

Question 5

Electrocardiogram

Answer 5

ECG: process of recording the electrical activity of the heart over a period of time

detects:
1. Irregular or abnormal heartbeats due to problems in the conduction system
2. Identify where in the heart muscle damage has occurred

Question 6

Einthoven’s triangle

Answer 6

P-wave: atrial depolarization
QRS complex: ventricular depolarization
T wave: ventricular repolarization

Question 7

Normal cardiac action potential is conducted through

Answer 7

the atria and ventricles, a characteristic sequence of voltage differences is created between the left forelimb and the right forelimb

Question 8

PR interval

Answer 8

• atrial depolarization
• The cardiac action potential is being conducted through the AV node
• Time between depolarizations. PP interval can be used to measure atrial contractions per minute

Question 9

RR interval

Answer 9

Time between ventricular depolarization. Used to measure ventricular contractions per minute

Question 10

QT interval

Answer 10

ventricular action potential

Question 11

Cardiac arrhythmias

Answer 11

caused by lack of the FORMATION of action potentials (sick sinus syndrome) or the conduction of action potentials (AV blocks)`

Question 12

what are 2 cardiac arrhythmias?

Answer 12

1. Bradycardia = slow heartbeat
2. Tachycardia = fast heartbeat

Question 13

what movements does action potentials make in the heart?

Answer 13

circular movement due to damage or blockage of the tissue. Can happen in both the atria and ventricles, can lead to fibrillation in with parts

Question 14

Defibrillators

Answer 14

stimulates the entire heart to go into the refractory period

Question 15

Tachycardia

Answer 15

• heart “palpitations”, dizziness, fainting or near-fainting, lightheadedness
• Can lead to ventricular or atrial fibrillations (irregular or fast HR)

Question 16

Bradycardia

Answer 16

• fatigue, dizziness, lightheadedness, fainting or near-fainting spells
• Blood can pool in chambers and potentially start to clot
• Most pacemakers implanted are for too slow of a heartbeat

Question 17

Parasympathetic acetylcholine

Answer 17

• binds to muscarinic receptors on the heart muscle
• Activation of the muscarinic receptor causes opening of additional K+ channels, making the cell “hyperpolarize” taking longer to reach threshold

Question 18

Sympathetic norepinephrine

Answer 18

• binds to beta receptors
• Increases Ca++ channels and their permeability, decreasing the time it takes to reach threshold

Question 19

Mechanical properties of the heart

Answer 19

Heart rate
Stroke volume
Cardiac output (CO)
Ejection fraction
Preload
Afterload
Contractility
Frank-starling mechanism
Factors on cardiac output

Question 20

Adrenergic neurons

Answer 20

release norepinephrine (NE), sympathetic neuron

Question 21

Adrenergic receptors

Answer 21

• alpha and beta receptors are on visceral effectors

Alpha 1 and beta 1 are excitatory
Alpha 2 and beta 2 are inhibitory
Beta 3 is on brown adipose tissue and involved in thermogenesis

Question 22

Cholinergic neurons

Answer 22

• release acetylcholine (Ach)
• All sympathetic and parasympathetic preganglionic neurons, all parasympathetic postganglionic neurons

Question 23

Cholinergic receptors

Answer 23

Nicotinic receptors are present in postganglionic neurons and motor endplate

Muscarinic receptors are present in membrane of all effectors (smooth, cardiac muscles, and glands)

Question 24

Which of the following statements is true?

The period of contraction (systole), the heart pumps out blood through the arteries; during the period of relaxation (diastole), the heart fills with blood

The period of contraction (diastole), the heart pumps blood out through the arteries; during the period of relation (systole), the heart fills with blood

Answer 24

The period of contraction (systole), the heart pumps out blood through the arteries; during the period of relaxation (diastole), the heart fills with blood

Question 25

During the early repolarization phase of cardiac muscles which of the following ion channels open and close?

K+ channels open and Na+ channels closed

Na+ channels open and K+ channels closed

Answer 25

K+ channels open and Na+ channels closed

Question 26

Ventricular depolarization occurs during

P wave
QRS complex
T wave

Answer 26

QRS complex

Question 27

Activation of the SV (sinoatrial) node would result in the:

P wave
QRS complex
T wave

Answer 27

P wave

Question 28

Ventricular repolarization occurs during:

P wave
QRS complex
T wave

Answer 28

T wave

Question 29

Atrial contraction occurs:

P wave
QRS complex
T wave

Answer 29

P wave

Question 30

Memorize the ECG chart!

Answer 30

Memorize the ECG chart