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
What is the general mechanism by which the nervous system increased arterial pressure?
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
26
How does the arterial baroreceptor reflex regulate arterial pressure?
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
27
Carotid sinus baroreceptors respond to pressures between ____ and \_\_\_\_\_\_\_\_.
60; 180 **NOTE:** Baroreceptors respond to changes in arterial pressure
28
Baroreceptor reflex is most sensitive at a pressure of \_\_\_\_\_\_\_\_\_\_.
100 mmHg
29
How do the baroreceptors respond to changes in arterial pressure?
* As pressure increases the number of impulses from carotid sinus increases which results in: * **Inhibition** of the vasoconstrictor * **Activation** of the vagal center
30
A decrease in pressure at the carotid sinuses results in a ________ (decrease/ increase) in arterial pressure.
Increase **NOTE:** Constriction of common carotids results in a decrease in pressure at carotid sinuses
31
What are chemoreceptors sensitive to?
Oxygen lack CO2 excess H ion excess
32
Where are chemoreceptors located?
**Carotid bodies** near the carotid bifurcation Arch of aorta
33
Activation of chemosensityve receptors results in ___________ (excitation/inhibition) of vasomotor center.
Excitation **NOTE:** Chemoreceptors are not stimulated until pressure falls *below* 80 mmHg
34
What is the mechanism by which chemoreceptor affect arterial pressure?
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
What is the mechanism by which CNS ischemic response effects arterial pressure?
1. Reduced cerebral blood flow 2. CO2 buildup 3. Activation of vasomotor center 4. Increase in sympathetic activity 5. Increase arterial pressure
36
Where are low pressure receptors located? What is there major function?
**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
Activation of low pressure receptors enchance ________ and ________ excretion.How?
**Na and water** **​Mechanism:** * Decresasing rate of ADH * Increasing glomerular filtration rate * Decreasing Na reabsorption
38
Bainbridge reflex
**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
Due to the bainbridge relfex, an increase in ______ pressure increases heart rate.
Atrial
40
Stretch atria sends signals to vasmotor center via _______ to increase heart rate and cotnractility.
Vagal afferents
41
Muscle blood flow can increase ______ fold during exercise
20 **NOTE:** During exercise capillary density incrreases markedly
42
Decrease in oxygen levels during exercise affects vascular smooth muscle directly, leading to \_\_\_\_\_\_\_.
**Vasodilation** **NOTE:** Pottasium, adenosine, CO2, and NO are vasodilators
43
Beta receptors induce vasodilation mainly in _________ and \_\_\_\_\_\_\_\_\_.
Muscle; liver
44
What is the normal mean arterial pressure during excercise?
20-80 mmHg **NOTE:** MAP will also stretch the blood vesels and cause vasodilation
45
What are some hemodynamic and humoral changes that occur during exercise?
* 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
46
The cardiac muscle is supplied by the first two branches of the \_\_\_\_\_\_\_\_.
Aorta \*Right and left coronay arteries
47
The superifical venous system drains the \_\_\_\_\_\_\_\_\_\_\_\_
Left ventricle **NOTE:** The deep system drains the rest of the heart
48
What are the components of the superficial venous system?
Coronary sinus Anterior cardiac veins **NOTE:** These vessels empty into the right atrium
49
What are the components of the deep venous system?
Basian veins Arteriosinusoidal vessels **NOTE:** These vessels open directly into the heart chamber
50
What is normal resting coronary flow?
225 ml/min
51
The left and right coronary arteries and their branches are sometimes referred to as\_\_\_\_\_\_\_\_\_\_
Epicardial vessels
52
The coronary arteries that run deep within the myocardium are referred to as \_\_\_\_\_\_\_\_\_\_\_.
subendocardial
53
Coronary inflow occurs mainly during diastole. Why?
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
54
Normal _______ blood pressure is important for coronary filing becuase filling of cornary arteries occurs mainly during ventricular diastole.
Diastolic
55
Coronary circulation is regulated mainly by \_\_\_\_\_\_\_\_.
**Metabolites** **NOTE:** Coronary circulation is very short and very rapid
56
What characteristic of coronary circulation makes the left ventricle more liable to ischemia and infarction?
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
57
The cornary vessels are susceptible to __________ and \_\_\_\_\_\_\_\_.
Degeneration; artherosclerosis
58
What happens during atherosclerosis?
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
59
What are the effects of atherosclerosis?
* Angina * Heart attack * Stroke
60
What positive contibutions does coronary circulation provide to patients with ichemia?
* Minute anastomoses * Angiogenesis * Enlargement
61
Cause of ischemic heart disease
* Atherosclerosis * Thrombus * Coronary artery spasm
62
What factors can lead to atherosclerosis?
* Intimal damage (damage to tunica intima) * Increased permeability of intima possibly to monocytes * Subintimal deposit of cholesterol and fats * Necrosis * Calcification
63
What factors can lead to coronary artery spasm?
* Emotional stress * Sympathetics
64
\_\_\_\_\_\_\_\_\_ is the most critical vessel in ischemia.
Left anterior descending artery (LAD)
65
What are the results of ischemic heart disease?
* Partial obstruction * Cannot autoregulate * Not too noticeable during rest, but exercise, results in pain * Mortality * Much worse if **left main coronary** is affected
66
What the stages of recovery for ischemia?
* Collateral circulation * Replacement of dead muscle by the scar tissue * Normal areas of the heart gradually hypertrophy
67
What are possible surgical treatments for coronary artery disease?
* Coronarya rtery bypass graft * Coronory angioplasty * Either with or without stent * Laser beam (experimental)