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KINE 2P09 - Final Exam Review > Lecture 6 - Cardiovascular Physiology Part 1 > Flashcards

Lecture 6 - Cardiovascular Physiology Part 1 Flashcards

1
Q

What is the Function and Purpose of the Cardiovascular System

A

The circulatory system facilitates transport of oxygen and nutrient-rich to active cells and transport of byproducts of metabolism away from cells

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2
Q

What are the components of the cardiovascular system

A

Blood, Heart, Arteries, Capillaries, veins

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3
Q

What are the components of blood

A

Formed elements = erythrocytes and Leukocytes
Cell Fragments = Platelets
Plasma

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4
Q

What is Hematocrit? What are the key values for males and females.

A

Measures the % of total blood volume comprised by erythrocytes
45% in males, 42% in females

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5
Q

What is plasma mostly comprised of?
What is the purpose of plasma?

A

Mostly water (>90%(
Carries ions, nutrients, waste, gases, hormones and plasma proteins

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6
Q

What is serum(hint: has to do with plasma)

A

Plasma with fibrinogen and other clotting proteins removed

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7
Q

What are Erythrocytes?

A

Red blood cells

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8
Q

Where are erythrocytes produced? What is the precursor cell?

A

Produced in red bone marrow
Precursor cell = reticulocyte

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9
Q

Design of RBCs

A

No nucleus, few organelles, no ribosomes or mitochondria

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10
Q

What are the functions of RBCs

A

Carry oxygen and carbon dioxide

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11
Q

What is hemoglobin?

A

an iron containing protein that binds oxygen and carbon dioxide
major role in gas transport

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12
Q

Do RBCs reproduce? How long do they last? Where are they destroyed?

A

Do not divide and reproduce
Last ~120 days
Destroyed in spleen and liver

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13
Q

What are RBCs concave in shape?

A

To increase surface area for gas exchange

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14
Q

What is required for production of RBCs?

A

Iron, folic acid, and vitamin B12

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15
Q

What is Erythropoiesis? What is it regulated by?

A

Erythropoiesis: Production of erythrocytes
Regulated by the hormone erythropoietin

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16
Q

What are the two different types of circulation?

A

Pulmonary Circulation - carries oxygen-poor blood from the right ventricle -> lungs -> left atrium
Systemic Circulation - carries oxygen-rich blood from the left ventricle -> all organs and tissues of the body -> right atrium

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17
Q

What is the Aorta, Pulmonary Trunk, Conduit Arteries, capillaries and veins

A

Aorta - large artery that the left ventricle pumps blood into
Pulmonary Trunk - large artery that carries deoxygenated blood to the lungs; right ventricle pumps blood into it
Conduit Arteries - smaller arteries that deliver blood to different systemic regions(femoral artery)
Capillaries - key site of nutrient/gas/waste exchange between blood and tissues
Veins - carry blood to the heart

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18
Q

What is microcirculation?

A

Vessels that interact with organs, tissues and cell
contains series of branching and progressively smaller arterioles and capillaries

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19
Q

Flow of blood through circulation - what is critical for flow direction?

A

Cardiac valves and pressure gradient

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20
Q

What are the key points for resting blood flow to systemic circulation? Cardiac output?

A

Cardiac output = 5L/min
majority of blood goes to the kidneys/abdominal organs
brain receives 13%

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21
Q

What is hemodynamics?

A

Relationship between blood pressure, blood flow and resistance to blood flow

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22
Q

What is the equation of Ohm’s law with blood flow?

A

Blood flow = ΔP / R
ΔP - pressure difference
R - resistance

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23
Q

How does Blood flow change with pressure differential bewteen two points?

A
  • blood flow increases as pressure differential increases
  • Blood Flow decreases as pressure differential decreases
  • if pressure doubles, blood flow will double
    (when resistance stays the same)
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24
Q

How does Blood Flow change with resistance?

A

Blood flow decreases as vascular resistance increases
Blood flow increases as vascular resistance decreases
(with same pressure)

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25
Q

When does vascular resistance increase?

A

When vessel length increases
Blood viscosity increases
Vessel radius decreases

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26
Q

What is the most important factor affecting vascular resistance?

A

Vessel radius this is because in Poiseuille’s Law, radius is held to the 4th power

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27
Q

What is the resistance equation(simplified). What does this mean?

A

R = 1 / r^4
- small changes in vessel radius produce large changes in vascular resistance

28
Q

What are the 4 chambers of the heart?

A

Left and right atria and ventricles

29
Q

What are the valves of the heart and where are they located?

A

Atrioventricular Valves - allow blood blood from the atria to ventricles
- Tricuspid Valve - right side of heart

30
Q

What are the valves of the heart and where are they located?

A

Atrioventricular Valves - allow blood to flow from the atria to the ventricles
- Tricuspid Valve - right side of the heart
- Bicuspid Valve - Left Side of Heart
Pulmonary Semilunar Valve - allows blood to flow from the right ventricle to the pulmonary trunk/arteries
Aortic Semilunar valve - Allows blood to flow from the left ventricle to the aorta

31
Q

Layers of the Heart

A

Pericardium - fibrous sac surrounding and protecting the heart
Epicardium - closely affixed to the heart
Myocardium - layer of cardiac muscle cells
Endothelium - sing cell layer of endothelial cells in contact with blood

32
Q

How does the heart exchange nutrients and waste?

A

Via the coronary arteries that branch off the aorta

33
Q

What enables the spread of action potentials between cardiac cells?

A

Gap Junctions

34
Q

What does the conduction system of the heart do?

A

it is responsible for initiation and spread of cardiomyocyte depolarization which leads to contraction

35
Q

What is the pathway of the conducting system?

A

SA node -> Internodal pathways -> AV node -> bundle of His
-> right and left bundle branches -> purkinje fibres

36
Q

Function and location of the SA node

A

Origin of depolarization
pacemaker for heart rate
left and right atria contract simultaneously
Located at the right atrium

37
Q

Function of the internodal pathways

A

relays action potentials between SA and AV nodes

38
Q

AV node function

A

links the depolarization at the atria to ventricular depolarization
responsible for ventricular excitation

39
Q

Why do the atria and ventricles not contract at the same time?

A

The AV node conducts action potentials slowly(0.1s delay) allowing atrial contraction to finish before ventricular contraction starts

40
Q

Function of the bundle of His

A

Carries the action potential down the intraventricular septum

41
Q

Function of the Bundle branches

A

Split into a right and left branch at the bottom of the heart and enter the walls of the ventricles

42
Q

Function of the purkinje fibres

A

a branching network that allows depolarization to spread rapidly through the heart
Ventricles depolarize simultaneously beginning at the bottom of heart

43
Q

What is an ECG and what is the function?

A

An electrocardiogram
- used to examine electrical events in the heart
- reflects the spread of currents from the simultaneous depolarization of many cardiac cells

44
Q

What are the different sections of the ECG and what do they represent?

A

P wave - atrial Depolarization
QRS complex - 0.15s after p wave, ventricular depolarization
T wave - ventricular repolarization

45
Q

What are the two types of action potentials in the heart?

A
  1. action potential in myocardial cells
  2. action potentials in nodal cells
46
Q

What are the major features of the nodal cell action potentials?

A
  • No steady resting membrane potential
  • slow depolarization phase(pacemaker potential) that brings membrane potential potential to threshold causing an action potential
  • no plateau phase
47
Q

What cause the pacemaker potential?

A
  • progressive reduction in K+ permeability due to gradual closure of K+ channels
  • F-type Na channels that open when the membrane is negative allowing Na influx
  • Brief opening of T-type Ca+ channels allowing Ca influx
48
Q

What is the difference between L-type and T-type Ca channels?

A

L-type channels are open longer during the action potential
T-Type channels are only open briefly to support diastolic depolarization

49
Q

What causes the action potential and repolarization?

A

Opening of L-type Ca channels brings the membrane to threshold.
Repolarization is caused by the closing of the L-type Ca channel and the opening of the K+ channels allowing K+ efflux

50
Q

Resting heart rate should be ~100 bpm. Why is the resting HR slower than this?

A

Due to parasympathetic neural influence

51
Q

What is partial repolarization in myocardial cell action potential caused by?

A

caused by transient opening of one subtype of K+ channel opening allowing K+ efflux

52
Q

What is the depolarization plateau? What causes this?

A

membrane potential sits around 0mV for a prolonged period
Caused by reduction in K+ permeability and a large increase in Ca permeability. Ca influx = K efflux

53
Q

What are the two major phases of the cardiac cycle?

A

Systole - corresponds to ventricular contraction and blood ejection
Diastole - corresponds to ventricular relaxation and blood filling

54
Q

What are the 2 phases within the systolic phase?

A

Isovolumetric ventricular contraction - ventricles contract without changing length, to build pressure while valves are closed
Ventricular ejection - ventricular pressure exceeds pressure in aorta and pulmonary trunk
- aortic and pulmonary valves open

55
Q

What is the Stroke volume?

A

Volume of blood ejected from the ventricles

56
Q

What are te 3 phases of Diastole?

A

Isovolumetric ventricular relaxation - ventricles relax but AV valves are still closed
Ventricular filling phse 1 - AV valves open and blood flows from atria to ventricles passively with no atrial contraction
Ventricular Filling phase 2 - AV valves open and atria contracts to assist with ventricular filling

57
Q

What is cardiac output?

A

Volume of blood each ventricle pumps out over time(L/min)
Cardiac output = HR x Stroke volume

58
Q

What is the average resting cardiac output?

A

5L/min

59
Q

What kind kind of innervation does the heart receive?

A

Sympathetic and parasympathetic

60
Q

What does the sympathetic nervous system innervate on the heart? What does it do?

A

Innervates the whole heart
Releases norepinephrine which binds to beta-adrenergic receptors
increases heart rate and stroke volume

61
Q

What does the parasympathetic nervous system innervate on the heart? What does it do?

A

Innervates the atria only
releases acetylcholine, which binds to muscarinic receptors
Reduces heart rate

62
Q

What is chronotropy?

A

Sympathetic and parasympathetic systems exert chronotropic effects on heart by altering SA node action potential

63
Q

How do sympathetic and parasympathetic alterations look on a graph?

A

Sympathetic - increased slope of pacemaker potential, faster depolarization, HR increases, steeper upstroke
Parasympathetic - decreases slop of pacemaker potential, slower depolarization, HR decreases, flatter upstroke

64
Q

What 3 factors affect ventricular contraction and stroke volume?

A

Preload - changing end-diastolic volume
Inotropic effects of sympathetic nerves - changing force of contraction
Afterload - changing the pressure opposing ejection

65
Q

What is preload and how does it affect stroke volume?

A

More blood fills the heart during diastole, more blood will be ejected during systole

66
Q

Inotropic Effects of Sympathetic nerves

A

sympathetic nerves increase norepinephrine and epinephrine levels, they bind to beta-adrenergic receptors
The receptors activate intracellular pathways that increase intracellular Ca
Greater intracellular Ca levels increase cardiac contractility

67
Q

What is afterload?

A

Increased arterial pressure reduces stroke volume because there is greater opposition to the ventricular ejection of blood

KINE 2P09 - Final Exam Review (4 decks)

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