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Physiology > Heart and Blood Vessel Physiology > Flashcards

Heart and Blood Vessel Physiology Flashcards

1
Q

Where is the heart?

A

In the mediastinum between 3rd and 4th rib

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2
Q

What are desmosomes?

A

Intercolated discs that keep muscle cells together and uniform

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3
Q

Why is it important for the heart to have gap junctions?

A

Ions can pass more quickly from cell to cell, making depolarization faster

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4
Q

Why is the left wall of the heart thicker?

A

It needs to generate greater contractive force for higher pressure in vessels

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5
Q

True or False: Blood requires a lot of ATP to move throughout the body

A

False. Blood requires bo energy to move throughout the body. It follows pressure gradients

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6
Q

True or False: The right side of the body and left side pump equal amounts of blood.

A

True

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7
Q

On average, how much blood does the human body contain and how often is it circulated through the body?

A

5L; once a minute

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8
Q

What are the two kinds of myocardial cells?

A

Contractile (99%) and Autorhythmic

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9
Q

Describe autorhythmic cells

A

1% of myocardial cells
Able to generate APs spontaneously
Found in nodes, bundles, and fibers
Never rest (reach -70mV), go to about -60mV via slow depolarization due to leaky Na+ channels

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10
Q

Describe the electrical activity of contractile cells

A

Rest at -90mV and remain at constant membrane potential for a long time in a plateau phase because voltage-gated Ca2+ channels stay open

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11
Q

Are cardiac action potentials voluntary or involuntary?

A

Involuntary

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12
Q

How does the absolute refractory period of the heart compare to skeletal muscles? Why is this significant?

A

The heart has a relatively long refractory period, which allows it to relax, lower pressure, and allow blood back into it

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13
Q

What is the intrinsic conduction system?

A

Siniatrial Node (SA), 70-75bpm
Atrioventircular Node (AV) 50bpm
AV bundle (intraventricular space) 35bpm
-Goes left to right
Bundle Branches
Purkinje Fibers (30bpm)
Individual fibers can generate their own rhythm as a last resort

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14
Q

What is arrhythmia?

A

An irregular heartbeat

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15
Q

What is fibrillation?

A

Rapid irregular contractions, which are useless for pumping blood

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16
Q

What is the pacemaker of the heart?

A

The Sinoatrial Node

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17
Q

What happens if the SA node fails?

A

Ecoptic focus: the AV takes over and the heart assumes slowed junctional rhythm

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18
Q

What happens if the AV node is defective?

A

Heart block

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19
Q

What is tachycardia?

A

An abnormally fast heartrate (more than 100bpm)

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20
Q

What is bradycardia?

A

An abnormally slow heartrate (less than 60bpm)

Note: This is desirable result of endurance training

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21
Q

What’s ectopic focus?

A

Abnormally excitable areas depolarize faster than the SA node (can lead to accelerated heartrate)

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22
Q

What is the difference between systole and diastole?

A

Systole: Contraction
Diastole: Relaxation

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23
Q

When does ventricular filling occur?

A

Mid to late diastole, when ventricles are relaxes and AV valves are open

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24
Q

What is EDV?

A

End Diastolic Volume: The blood left in the ventricle after diastole, about 20% of capacity

25
Q

When do Ventricular Systole and Atrial Diastole take place?

A

At the same time.

26
Q

What causes AV valves to close?

A

Rising ventricular pressure during systole exceeding atrial pressure

27
Q

What is true about valves during the isovolumetric phase?

A

They are closed

28
Q

What causes the semilunar valves to open?

A

Ventricular pressure exceeds pressure in the large arteries during “Ejection Phase”

29
Q

What is ESV?

A

End Systolic Volume - Blood remaining in ventricles at end of ejection phase

30
Q

What causes a dicrotic notch?

A

Backflow of blood in aorta and pulmonary trunk when SL valves close

31
Q

What are the heart sounds and when do they occur?

A

Lub - When AV valves close, beginning of systole

Dubb - When SL valves close, beginning of diastole

32
Q

What are heart murmurs and what do they indicate?

A

Abnormal heart sounds – most often indicate valve problems

33
Q

What is Cardiac Output (CO)?

A

Heart Rate x Stroke Volume

(xxx bpm) x (70mL/beat)

34
Q

What is the cardiac reserve?

A

The difference between resting and maximal CO

35
Q

What are the effects of the SNS on heartrate?

A

Hormones & Autonomic Innervation
-Emotional or Physical stressors activate
-NE causes pacemaker to fire more rapidly
-Epinephrine depolarizes autor. cells and increases contractility and HR
-Positive cronotropy
-Thyroxine enhances effects of NE/Ep

36
Q

What are the effects of the PSNS on Heart Rate

A

ACh hyperpolarizes pacemaker cells by opening ligand-gated K+ channels
Negative cronotropy

37
Q

What is Starling’s Law?

A

The heart will pump out whatever volume is pumped in

38
Q

What are the factors affecting stroke volume?

A

Preload
Contractility
Afterload

39
Q

What is “Preload”?

A

Ventricular stretching during diastole, specifically the degree of stretch of cardiac muscle cells before they contract

40
Q

True or False: At rest cardiac muscles are shorter than optimal length

A

True

41
Q

What is contractility?

A

The force produced during contraction at a given preload

The contractile strength at a given muscle length independent of muscle stretch and EDV

42
Q

What can increase contractility?

A

Increased Ca2+
Hormones (thyroxine, glucagon, epinephrine)

43
Q

What can decrease contractility?

A

Negative intropic agents
Acidosis
Extracellular K+
Ca2+ blockers

44
Q

What is afterload?

A

Blood pressure in major arteries which must be overcome to eject blood from heart

45
Q

What effect does hypertension have on Stroke Volume?

A

Increases afterload, decreasing stoke volume

46
Q

What are the results of increased venous return?

A

Distended ventricles, therefore increased contraction force, therefore increased Stroke Volume

47
Q

What is the Bainbridge Reflex?

A

Atrial walls stretch and stimulate SA node and atrial stretch receptors

48
Q

What factors affect heart rate?

A

Age, Sex, Exercise, Body Temp

49
Q

True or False: The heart can only use glucose as an energy source?

A

False, it is adaptable to a number of food sources including fatty acids and lactic acid

50
Q

What is Congestive Heart Failure?

A

A progressive condition where cardiac output is so low that circulation is inadequate for tissue needs

51
Q

What are some possible causes of Congestive Heart Failure?

A

Coronary Atherosclerosis
Persistent Hypertension
Multiple Myocardial Infarctions
Dilated Cardiomyopathy

52
Q

True or false: arteries have thicker muscle, veins have a wider diameter

A

True

53
Q

True or False: The wider the diameter if a blood vessel the faster the flow

A

True

54
Q

Where are the elastic arteries, why are they important?

A

Nearer to the heart, can expand as heart expels blood, accommodating for pressure changes

55
Q

What is tissue perfusion?

A

Blood flow. Rate of flow is important to provide proper function:

Important for delivery of O2, removal of waste, absorption of nutrients, urine formation

56
Q

True or False: Blood travels at a rate inverse to the total cross-sectional area?

A

True. (Wider/Bigger = Faster)

57
Q

What is blood flow?

A

The volume in a vessel organ or system during a given period, measured in ml/min

Equivalent to the total cardiac output of the entire vascular system

58
Q

How is blood flow calculated?

A

Flow Rate = deltaP/R

As resistance increases flow rate decreases

P - Pressure Gradient
R - Vascular Resistance (opposition to flow through a vessel)

Physiology (13 decks)

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