Heart Physiology

Question 1

Heart Coordination

Answer 1

movement of blood is determined by the sequence of muscle contractions
- atria contracts first then the ventricles

Question 2

Do muscle contractions happen in a certain order?

Answer 2

yes

Question 3

What happens in the contraction of the cardiac muscle?

Answer 3

it compresses the chamber increasing the pressure and the blood flows from high to low pressure

Question 4

stimulation of the heart

Answer 4

1.heart at rest
2. atria stimulated
3. atria contract
4. ventricles stimulated
5. ventricles contract

Question 5

Cardiac muscle action potentials

Answer 5

changes in membrane permeability are responsible for producing action potentials and called pacemaker potential

Question 6

Depolarization Phase

Answer 6

• Na+ channels open
  -Ca2+ channels open

Question 7

Plateau Phase

Answer 7

-Na+ channels close
- some K+ channels open
Ca2+ remain open

Question 8

Repolarization Phase

Answer 8

-K+ channels are open
-Ca2+ channels close

Question 9

what does the plateau phase do?

Answer 9

prolongs action potential by keeping Ca2+ channels open

Question 10

action potential for cardiac and skeletal muscles

Answer 10

cardiac- 200-500msec
skeletal- 2msec

Question 11

Conduction system

Answer 11

Contraction of the atria and ventricles is coordinated by specialized cardiac muscle cells in the heart wall that form

Question 12

can all cells of the conduction system produce spontaneous action potential?

Answer 12

Yes

Question 13

conduction system include

Answer 13

sinoatrial node ,atrioventricular node , atrioventricular bundle, right and left bundle branches, and purkinje fibers

Question 14

SA node

Answer 14

• in RA
  -where action potential originates
  -functions as a pacemaker
  -large number Ca2+ channels

Question 15

AV node

Answer 15

-located in the lower portion of the right atrium
-action potentials from SA node sent to this node
-slow rate of action potential conduction

Question 16

Atrioventricular bundle

Answer 16

-action potentials from AV node travel by the AV bundle to the ventricles
- AV bundle divides into a left and right bundle branches to left and right ventricles

Question 17

Purkinje fibers

Answer 17

• at the tips of left and right bundle branches , are purkinje fibers
• purkinje fibers pass to the apex of the heart and then extend to the ventricle walls
• action potentials are rapidly delivered to all the cardiac muscle of all the ventricles

Question 18

AP path through the Heart

Answer 18

1. SA node
2. AV node
3. AV bundle
4. Right and left bundle branches
5. Purkinje fibers

Question 19

what keeps a record of electrical events in heart, and uses electrodes

Answer 19

ECG (EKG)

Question 20

p wave

Answer 20

depolarization of atria

Question 21

QRS complex

Answer 21

-depolarization of ventricles
-contains QRS waves

Question 22

T wave

Answer 22

depolarization of ventricles

Question 23

what is the summative description of all events that occur during one single heartbeat?

Answer 23

cardiac cycle

Question 24

Cardiac muscle contractions produce pressure changes within OR outside of the heart chambers?

Answer 24

within

Question 25

Are the pressure changes responsible for blood movement?

Answer 25

Yes

Question 26

does blood move from low to high pressure?

Answer 26

No (high to low pressure)

Question 27

atrial systole

Answer 27

contraction of atria

Question 28

ventricle systole

Answer 28

contraction of ventricles

Question 29

atrial diastole

Answer 29

relaxation of atria

Question 30

ventricular diastole

Answer 30

relaxation of ventricles

Question 31

true/false: heart sounds are produced due to the opening of the heart valves

Answer 31

False: it is the closure

Question 32

first heart sound

Answer 32

Lubb

Question 33

second heart sound

Answer 33

dubb

Question 34

look at the heart valve locations

Question 35

stroke volume

Answer 35

- volume of blood pumped per ventricle per contraction - 70 milliliters/ beat

Question 36

heart rate

Answer 36

- number of heart beats in 1 min. -72 beats/min.

Question 37

cardiac output

Answer 37

-total volume of blood pumped by the heart in 1 min. -5 liters/min.

Question 38

CO=SV*HR

Answer 38

cardiac output = stroke volume * heart rate

Question 39

how is the heart regulated?

Answer 39

autonomic nervous system innervation of the SA node parasympathetic- CN X sympathetic- sympathetic chain

Question 40

heart reflexes

Answer 40

the body senses changes in internal conditions and signals to the heart through the ANS to either increase or decrease heart rate

Question 41

baroreceptors

Answer 41

- monitor blood pressure in the aorta and carotid arteries -involves the medulla oblongata

Question 42

baroreceptors reflex when bp increases

Answer 42

HR and SV decrease

Question 43

baroreceptors reflex when bp decrease

Answer 43

HR and SV increase

Question 44

Chemoreceptor refles

Answer 44

-involves chemical regulation of the heart function -chemicals can affect HR & SV -medulla oblongata has chemoreceptors for changes on pH and CO2

Question 45

coronary artery disease

Answer 45

-decreases blood supply to the heart -coronary arteries are narrowed for some reason

Question 46

myocardial infarction ( heart attack)

Answer 46

-due to closure of 1+ coronary arteries, thrombus or blockage -area of cardiac muscle lacking adequate blood supply die, and scars (infarct)

Question 47

angioplasty

Answer 47

procedure opens blocked blood vessels

Question 48

stent

Answer 48

structures inserted to keep vessels open

Question 49

bypass

Answer 49

procedures reroutes blood away from blocked arteries