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SF3 > Cardiovascular Regulation and Coronary Circulation > Flashcards

Cardiovascular Regulation and Coronary Circulation Flashcards

1
Q

During emergency situations, which organs have the greatest need for blood supply?

A

Brain

Heart

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2
Q

What are the major functions of the heart?

A
  • Generating blood pressure
  • Routing blood
  • Ensuring one-way blood flow
  • Regulating blood supply
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3
Q

What are the two major mechanisms of blood flow control?

A
  • Acute control
    • Local
    • Humoral
  • Long term control
    • Vascular remodeling
    • Formation of new vessels
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4
Q

What is autoregulation?

A

It is a manifestation of local blood flow regulation defined as the instrinsic ability of an organ to maintain a constant blood flow despite changes in perfusion pressure

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5
Q

Individual organ flow is under the control of resistive vessels (arterioles). What part of the autonomic system controls these vessels?

A
  • Mainly sympathetic
  • Very few parasympathetic system
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6
Q

Blood flow is regulated by tissue needs. What are the major needs to tissue supplied by blood flow?

A
  • Oxygen
  • Nutrients
  • Removal of CO2, hydrogen and other metabolites
  • Transport of hormones
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7
Q

Flow is closely related to _______ rate of tissues.

A

Metabolic

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8
Q

What are the two major theories for control of local blood? What does each state?

A
  • The vasodilato theory
    • Increases in tissue metabolism lead to increases in blood flow
  • Oxygen demand theory
    • Decreases in oxygen availability to tissues increases tissue blood flow
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9
Q

Tissue metabolic rate and tissue blood flow are _______ (directly/indirectly) proportional.

A

Directly

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10
Q

What are the major vasodilators implicated in increasing blood flow?

A

Adenosine

CO2

Lactic acid

ADP compounds

Histamine

K ions

H ions

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11
Q

What is the mechanism of the vasodilator theory for blood flow control?

A
  1. Increase in tissue metabolism
  2. Release of vasodilators
  3. Decrease in arteriole resistance
  4. Increase in blood flow
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12
Q

What is the mechanism of the oxygen demand theory of blood flow control?

A
  1. Decrease in oxygen delivery to tissues
  2. Decrease in tissue oxygen concentration
  3. Decrease in arteriole resistance
  4. Increase in blood flow
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13
Q

The _______ (sympathetic/ parasympathetic) nervous system is most important in regulating the vessels, while the _________ (sympathetic/parasympathetic) nervous system is most important in regulating heart function.

A

Sympathetic; parasympathetic

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14
Q

Arteriole diameter is controlled by the tonic release of ____________.

A

Norepinephrine

*This means that arterioles are tonically constricted

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15
Q

Increase in norepinephrine release onto alpha-receptors causes blood vessels to ___________ (dilate/constrict)

A

Constrict

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16
Q

Decrease in norepinephrine release onto alpha-receptors causes blood vessels to ___________ (dilate/constrict)

A

Dilate

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17
Q

What roles does the nervous system have in regulation of circulation?

A
  • Regulates via the autonomic nervous system
  • Rapid control of arterial pressure
  • Redistribution of blood flow
  • Increasing pumping activity of the heart
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18
Q

Sympathetic nerve fibers innervate all vessels except __________.

A

Capillaries

NOTE: Capillaries are NOT innervated

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19
Q

Parasympathetic nervous system is mainly important in control of _______.

A

Heart rate

*This done via the vagus nerve

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20
Q

What is the vasomotor center?

A

The VMC is a portion of the medulla oblongata that, together with the cardiovascular center and respiratory center, regulates blood pressure and other homeostatic processes.

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21
Q

Where is the vasomotor center located?

A

Bilaterally in the reticular substance of the medulla

Lower third of pons

NOTE: The vasomotor center transmits impulses downward through the cord to almost all blood vessels

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22
Q

What are the components of the vasomotor center?

A

Vasoconstrictor area

Vasodilator area

Sensory area

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23
Q

How does the nervous system control arterial pressure?

A
  • Constricting almost all arterioles of the body which increases total peripheral resistance (TPR)
  • Constricting large vessels of the circulation thereby increasing venous return and cardiac output
  • Directly increases cardiac output by increasing heart rate and contractility
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24
Q

The __________ secretes epinephrine and norepinephrine which contrists blood vessels via ______ receptors.

A

Adrenal medulla; alpha adrenergic receptors

NOTE: Epinephrine can also dilate vessels through a potent Beta2 receptor

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25
Q

What is the general mechanism by which the nervous system increased arterial pressure?

A
  1. Excercise/ fright
  2. Activation of vasomotor center
  3. Increase in sympathetic and decrease in parasympathetic activity
  4. Increase in total peripheral resistance, venous return, heart rate, and heart strength
  5. Increase in arterial pressure
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26
Q

How does the arterial baroreceptor reflex regulate arterial pressure?

A
  1. A rise in pressure stretches baroreceptors, causing them to transmit signals to the vasomotor center
  2. Feedback signals are sent, via the autonomic system, to circulation
  3. Arterial pressure is reduced back to normal
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27
Q

Carotid sinus baroreceptors respond to pressures between ____ and ________.

A

60; 180

NOTE: Baroreceptors respond to changes in arterial pressure

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28
Q

Baroreceptor reflex is most sensitive at a pressure of __________.

29
Q

How do the baroreceptors respond to changes in arterial pressure?

A
  • As pressure increases the number of impulses from carotid sinus increases which results in:
    • Inhibition of the vasoconstrictor
    • Activation of the vagal center
30
Q

A decrease in pressure at the carotid sinuses results in a ________ (decrease/ increase) in arterial pressure.

A

Increase

NOTE: Constriction of common carotids results in a decrease in pressure at carotid sinuses

31
Q

What are chemoreceptors sensitive to?

A

Oxygen lack

CO2 excess

H ion excess

32
Q

Where are chemoreceptors located?

A

Carotid bodies near the carotid bifurcation

Arch of aorta

33
Q

Activation of chemosensityve receptors results in ___________ (excitation/inhibition) of vasomotor center.

A

Excitation

NOTE: Chemoreceptors are not stimulated until pressure falls below 80 mmHg

34
Q

What is the mechanism by which chemoreceptor affect arterial pressure?

A
  1. Decrease in O2, decrease in pH, and increase in CO2
  2. Chemoreceptor activated (only under 80 mmHg)
  3. Vasomotor center activated
  4. Increase in sympathetic activity
  5. Increase in arterial pressure
35
Q

What is the mechanism by which CNS ischemic response effects arterial pressure?

A
  1. Reduced cerebral blood flow
  2. CO2 buildup
  3. Activation of vasomotor center
  4. Increase in sympathetic activity
  5. Increase arterial pressure
36
Q

Where are low pressure receptors located? What is there major function?

A

Atria and pulmonary arteries

  • Minimize arterial pressure changes in response to changes in blood volume

NOTE: Increases in blood volume activates low pressure receptors which in turn lower arterial pressure

37
Q

Activation of low pressure receptors enchance ________ and ________ excretion.How?

A

Na and water

​Mechanism:

  • Decresasing rate of ADH
  • Increasing glomerular filtration rate
  • Decreasing Na reabsorption
38
Q

Bainbridge reflex

A

An increase in heart rate due to an increase in central venous pressure. Increased blood volume is detected by stretch receptors located in both atria at the venoatrial junctions.

39
Q

Due to the bainbridge relfex, an increase in ______ pressure increases heart rate.

40
Q

Stretch atria sends signals to vasmotor center via _______ to increase heart rate and cotnractility.

A

Vagal afferents

41
Q

Muscle blood flow can increase ______ fold during exercise

A

20

NOTE: During exercise capillary density incrreases markedly

42
Q

Decrease in oxygen levels during exercise affects vascular smooth muscle directly, leading to _______.

A

Vasodilation

NOTE: Pottasium, adenosine, CO2, and NO are vasodilators

43
Q

Beta receptors induce vasodilation mainly in _________ and _________.

A

Muscle; liver

44
Q

Alpha receptors induce vasodilation mainly in where?

A

In almost most organs

45
Q

What is the normal mean arterial pressure during excercise?

A

20-80 mmHg

NOTE: MAP will also stretch the blood vesels and cause vasodilation

46
Q

What are some hemodynamic and humoral changes that occur during exercise?

A
  • Mass sympathetic discharge
  • Decrease in parasympathetic impulse
  • Increase HR
  • Increase MAP
  • Increase heart stretch
  • Local vasodilation
  • Global venoconstriction, leading to increase in venous return and CO
47
Q

The cardiac muscle is supplied by the first two branches of the ________.

A

Aorta

*Right and left coronay arteries

48
Q

The superifical venous system drains the ____________

A

Left ventricle

NOTE: The deep system drains the rest of the heart

49
Q

What are the components of the superficial venous system?

A

Coronary sinus

Anterior cardiac veins

NOTE: These vessels empty into the right atrium

50
Q

What are the components of the deep venous system?

A

Basian veins

Arteriosinusoidal vessels

NOTE: These vessels open directly into the heart chamber

51
Q

What is normal resting coronary flow?

A

225 ml/min

52
Q

The left and right coronary arteries and their branches are sometimes referred to as__________

A

Epicardial vessels

53
Q

The coronary arteries that run deep within the myocardium are referred to as ___________.

A

subendocardial

54
Q

Coronary inflow occurs mainly during diastole. Why?

A

Because during systole the coronary arteries are mechanically compressed by the contracting myocardium

NOTE: Coronary outflow occurs mainly during systolic due to compression of the coronary veins by the cotnracting myocardium

55
Q

Normal _______ blood pressure is important for coronary filing becuase filling of cornary arteries occurs mainly during ventricular diastole.

56
Q

Coronary circulation is regulated mainly by ________.

A

Metabolites

NOTE: Coronary circulation is very short and very rapid

57
Q

What characteristic of coronary circulation makes the left ventricle more liable to ischemia and infarction?

A

The subendocardial myocardial layer in the left ventricle receives less blood, due to myocardial compression. This renders this area mroe liable to ischemia and infarction

58
Q

The cornary vessels are susceptible to __________ and ________.

A

Degeneration; artherosclerosis

59
Q

What happens during atherosclerosis?

A
  1. LDL cholesteral accumulates
  2. Macrophages enter
  3. A lipid core accumulates
  4. Fibrous scar tissue forms
  5. Calcifications are deposited within the plaque
  6. Platelets inters
  7. Plaque becomes vulnerable

NOTE: When atherosclerosis affects coronary arteries then it is called coronary artery disease

60
Q

What are the effects of atherosclerosis?

A
  • Angina
  • Heart attack
  • Stroke
61
Q

What positive contibutions does coronary circulation provide to patients with ichemia?

A
  • Minute anastomoses
  • Angiogenesis
  • Enlargement
62
Q

Cause of ischemic heart disease

A
  • Atherosclerosis
  • Thrombus
  • Coronary artery spasm
63
Q

What factors can lead to atherosclerosis?

A
  • Intimal damage (damage to tunica intima)
  • Increased permeability of intima possibly to monocytes
  • Subintimal deposit of cholesterol and fats
  • Necrosis
  • Calcification
64
Q

What factors can lead to coronary artery spasm?

A
  • Emotional stress
  • Sympathetics
65
Q

_________ is the most critical vessel in ischemia.

A

Left anterior descending artery (LAD)

66
Q

What are the results of ischemic heart disease?

A
  • Partial obstruction
  • Cannot autoregulate
  • Not too noticeable during rest, but exercise, results in pain
  • Mortality
    • Much worse if left main coronary is affected
67
Q

What the stages of recovery for ischemia?

A
  • Collateral circulation
  • Replacement of dead muscle by the scar tissue
  • Normal areas of the heart gradually hypertrophy
68
Q

What are possible surgical treatments for coronary artery disease?

A
  • Coronarya rtery bypass graft
  • Coronory angioplasty
    • Either with or without stent
  • Laser beam (experimental)

SF3 (15 decks)

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