Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

PHYS 150: physiology > cardiovascular physiology > Flashcards

cardiovascular physiology Flashcards

1
Q

What are the characteristics of cardiac muscle tissue?

A
  • excitability
  • automaticity
  • rhythmicity
  • refractoriness
  • conductivity
  • contractility
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the term for the ability of the cardiac muscle to respond to an electrical stimulus by contracting?

A

excitability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What channels open during depolarization?

A

Na+ & Ca2+
* on sarcolemma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What occurs during the plateau phase?

A

Ca2+ channels stay open longer
* 200 msec
* remains depolarized
* purpose = prevents tetany; prolongs duration of the action potential; sustains heart contraction; allows for efficient pumping

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the events of a cardiac action potential

A
  1. Depolarization = Na+ & Ca2+ channels open
  2. Na+ channel closes
  3. Ca2+ channels remain open = plateau phase & K+ channels open
  4. Repolarization = Ca2+ closes & K+ continues to flow in
  5. Returns back to resting potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Can stimulate the cardiac muscle continuously even if the previous action potential isn’t done?

A

No
* there is a refractory period
* action potential must finish before another action potential is initiated
* purpose = prevent tetany & allow for efficient & complete pumping of the heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is automaticity?

A
  • ability of some cardiac muscle to initiate its own stimulus
  • autorhythmic cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the purpose of leaky membranes in the cardiac cell?

A

regulates & maintains the pacemaker activity (SA node)
- initiates depolarization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the pacemaker’s potential?

A

-60 mV to -40 mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the threshold potential? How is it reached?

A

-40 mV
* leaky channels = aways open & letting in ions
* leaky channels allows for the cardiac membrane to reach its threshold
* nervous stimulation is not required

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is rhythmicity?

A
  • regularity of beat
  • pacemaking activity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is refractoriness ?

A
  • cardiac cells has a refractory period where = cell is unable to generate another action potential for a specific amount of time
  • contraction & excitation occurs by the end of the refractory period
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What connects cardic cells together?

A

intercalated discs
* allows for ions to diffuse from one cardiac muscle cell to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a functional syncytium?

A

group of cells acting as if they were one
* cardiac cells beat as one
* action potential spreads through entire myocardium via intercalated discs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the wall of conective tissue between atria & ventricles?

A

fibroskeleton

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the functions of the fibroskeleton?

A
  • supports the AV valves
  • high electrical resistance –> controls direction of electrical impulses
  • directs impulses to AV node
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do electrical impulses go from the atria to ventricle?

A

via the AV node
* this is the only way for an impulse to get to the ventricle from the atria
* ensures proper timing of atrial & ventricular contractions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Does the atria & ventricle contract at the same time?

explain

A

No
* there is a delay between atrial contraction & ventricular contraction
* purpose = allows tiem for ventricles to fill with blood before entering the systemic circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Wat would happen if atria & ventricles contracted at the same time?

A
  • less blood would be pumped from atria to ventricles & to the systemic circulation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the electrical events that occur when the heart is stimulated?

A
  1. SA node = depolarizes (starts the electrical signal) –> 100 times/min
  2. AV node –> depolarizes 40-60 times/min
  3. Bundle of His –> depolarizes 20-35 times/min
  4. Spreads to right & left bundle branches –> depolarizes 20-35 times/min
  5. Purkinje fibers –> depolarizes 20-35 times/min
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What sets the heart rate?

which cells in the heart?

A

the cells that depolarize most rapidly
* heart is a functional syncytium - so when it beats, that means all the cardiac cells are beating together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is an EKG?

A

electrocardiogram
* consist of 5 waves that reflects cardiac events

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Where would you place a 3 lead EKG?

A

left arm, right arm, left leg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Explain the components of an EKG

segments, intervals, waves, complex

A

2(+1) segments:
1. PR segment = atrial depolarization is complete & impulse is delayed at the AV node
2. ST segment = time between ventricular depolarization and repolarization
3. TP segment = period between ventricular repolarization and the onset of the next P wave

2 intervals:
1. PR interval = 0.12-0.20 s
2. QT interval = 0.32-0.38 s

QRS complex = part of QT interval
* onset of ventricular depolarization

P wave = atrial depolarization (SA node)

T wave = ventricular repolarization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the condition if there is an ST-segment elevation?
MI
26
What is the condition if there is more P waves than QRS?
AV block
27
What is the condition if there is rapid/large voltage fluctuations?
v fib
28
Describe the events of the cardiac cycle
1.all 4 chambers are relaxed * SL vlaves closed * AV valves open --> blood passively flows through atria * 70% goes straight to ventricles * 30% stays in atria 2.SA node fires * atria contract --> 30% of blood goes to ventricles * depolarizations spreads to atrial walls to AV node * ventricles are relaxed 3.AV valves close (lub); SL valves open * due to increased intra-ventricular pressure * blood goes to aorta & pulmonary trunk 4.SL valves close (dub); AV valves open * due to decreased intra-ventricular pressure * cycle restarts
29
How many times does the cardiac cycle repeat per minute? | normal
**60-100 times/minutes** * intense exercise = >200 times/min * conditioning = <60 times/min
30
What is bradycardia? | HR
<60 beats/min
31
What is tachycardia? | HR
>100 beats/min
32
What is cardiac output?
**CO = HR X SV** HR = number of cardiac cycles /min SV = volume of blood pumped out of one ventricle in one heart beat * mL/beat * average = 75 mL * relaxed ventricle holds 130 mL CO = volume of blood pumped by one ventricle in one minute * mL/min
33
What are the factors that affect heart rate?
* ANS * temperature * hormones * ions * age, biological sex, physical fitness * drugs, toxins
34
What center is activated by emotional or physical stress? | ANS regulation
**cardiac accelerator center** * stimulates sympathetic neurons ---> innervate SA & AV nodes result = **increase in rate & force of contraction**
35
What center decreases heart activity when stressors are removed? | ANS regulation
**cardiac inhibitory center** * parasympathetic fibers pass via the **vagus nerve** to SA & AV nodes result = **decrease in rate & force of contraction**
36
Where is the cardiac center located in the brain?
medulla oblongata
37
What neurons dominate under relaxed conditions?
**parasympathetic neurons** * inhibitory impulses dominate = vagal tone * decreases HR & vagal inhibition
38
What neurons dominate under stressful conditions?
**sympathetic neurons** * vagal tone is overcome * increases HR & force of contraction
39
What are the effects of temperature?
* increased temp = increased HR * decreased temp = decreased HR
40
What hormones regulate the heart? Explain their effects
**Epinephrine** (adrenal medulla) * mimics SNS * increases hr & contraction **Thyroxine** (thyroid) * slower & longer lasting effect * increase HR * enhances effects of NE & E
41
What ions influence the cardiac cycle?
**Calcium** (depolarization) * **hyperclcemia** = increased strength & prolonged contraction; decreased rate * **hypocalcemia** = decreased strength **Potassium** (repolarization phase) * **hyperkalemia** = bradycardia, cardiac arrest, heart block * **hypokalemia** = fibrillation/arrhythmias
42
What are the factors affecting stroke volume?
1. Preload 2. Contractile strength of each cardiac muscle fiber 3. Afterload
43
What is preload and how does it affect stroke volume?
degree of streth in heart before it contracts **Starling's law of the heart** = force of contraction increases with the degree of cardiac muscle cell stretch * increased end diastolic volume --> increased preload (bc lots of blood) --> increased stroke volume = increased cardiac output
44
What is contractile strength & how does it affect stroke volume?
ability of cardiac muscle fibers to shorten * increased when Ca2+ and epinephrine are present & when SNS is activated
45
What is afterload and how does it affect stroke volume?
load or resistance against which the left ventricle must pump its blood during contraction * increased afterload --> decreased stroke volume
46
What are the blood vessels & their functions?
1. **Arteries** = carry blood away from the heart 2. **Veins** = carry blood towards the heart 3. **Capillaries** = gas exchange
47
What happens to arteries during ventricular systole?
* blood entering arteries are under high pressure * artery walls stretch * **artery characteristics** = larger diameter, elastic walls
48
What happens to blood vessels during ventricular diastole?
* stretched arteries recoil * **continuous flow** is maintained by driving blood through arteries & capillaries --> **prevents pulsatile flow**
49
What is blood pressure & the types?
force of blood pressing against the inner walls of the blood vessels types: 1. **ABP** = arterial blood pressure --> high bc close to heart 2. **capillary pressure**/hydrostatic pressure 3. **venous vlood pressure**--> almost nothing
50
What is the normal value of ABP?
120/80 mmHg * determined by CO, peripheral resistance & blood volume
51
Equation for pulse pressure
**systolic pressure - diastolic pressure** normal = **40 mmHg**
52
What is the normal value for mean arterial pressure (MAP)?
**(S+2D)/3** * closer to diatsolic bc heart spends more time in diastole compared to systole * normal = **95 mmHg**
53
What is the normal value for capillary pressure?
30 mmHg (arterial end) to 15 mmHg (venous end)
54
What is the normal value of venous blood pressure?
**2 mmHg** * almost nothing
55
What are the physical determinantsof arterial blood pressure?
Arterial blood pressure * **BP = CO X PR** **Peripheral resistance** = opposition to flow * cause = friction as blood flows throguh vessels * factors: diameter, length, viscosity
56
What factors can we change to change our peripheral resistance?
diameter & blood volume
57
What increases peripheral resistance?
* decreased arteriole diameter * increased blood vessel length * increased blood viscosity
58
What factors control arterial BP?
1. Baroreceptors 2. Cardiac centre 3. Vasomotor centre
59
How do baroreceptors work?
location = carotid sinuses & aortic arch * **respond to pressure by stretching** * sends impulses to medulla oblongata
60
How does the cardiac centre regulate arterial BP?
location = medulla oblongata * receives impulses from baroreceptors, hypothalamus, cerebral cortex * regulates: **HR and contractility of the heart **via SNS & PNS * innervates SA node
61
How does the vasomotor centre regulate arterial BP?
location = medulla oblongata * receives impulses from baroreceptors, hypothalamus, and cerebral cortex * controls **diameter of blood vessels** via SNS
62
What occurs when BP is elevated? How is it regulated ?
* afferent impulses go towards the cardiac centre --> increases rate of APs * decreases HR & force of contraction = decreased BP
63
What occurs when BP is low? How is it regulated?
* fewer afferent impulses to the cardiac centre & vasomotor centre * vasoconstriction & venoconstriction * increases HR & copntractility force = increases BP
64
What is the renin-angiotensin mechanism?
* activated by **low BP** * **renin** is secreted by kidneys * renin converts **angiotensinogen to angiotensin I** * **angiotensin I is converted to angiotensin II by ACE** * angiotensin II brings BP back up
65
How does angiotensin II elevate BP?
* vasocnstrictor = increases peripheral resistance * stimulates aldosterone secretion = increas Na+ reabsorption, blood volume, blood pressure
66
What are ACE inhibitors? and what conditions are they useful in treating?
inhibit conversion of angiotensin I to angiotensin II * examples = vasotex (enalapril), zestril (lisinopril), lotensin * decreases BP * conditions = hypertension, MI, heart failure, decrease workload of heart

PHYS 150: physiology (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions