Physiology of Circulation Flashcards

1
Q

Circulation is primarily influenced by what?

A

tissue needs

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2
Q

3 characteristics of arteries?

A

1) transport blood under high pressure
2) strong vascular walls
3) rapid blood flow

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3
Q

4 characteristics of arterioles?

A

1) final small branches of arterial system
2) act as control conduits - blood released into capillaries
3) strong muscular walls that vasoconstrict/dilate
4) innervated by SNS only

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4
Q

4 characteristics of capillaries?

A

1) exchange site for nutrients, wastes, electrolytes, fluid
2) very thin walls
3) contain small capillary pores
4) permeable to small molecular substances, H2O

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5
Q

3 characteristics of venules?

A

1) gathers low oxygenated blood
2) collects blood from capillaries
3) gradually merge into larger veins

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6
Q

Major function of veins?

A
  • serve as a blood reservoir (64% of total blood volume)

- transport blood from tissues to heart

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7
Q

Distribution of blood volume?

A
  • veins = 64%
  • arteries = 15%
  • capillaries = 5%
  • pulmonary = 9%
  • heart = 7%
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8
Q

What is the volume of blood flowing through a vessel, an organ, or the entire, circulation in a given period (ml/min)?

A

blood flow

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9
Q

What is the force per unit area exerted on a vessel wall by the contained blood (mmHg)?

A

blood pressure

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10
Q

What is the opposition to flow; amount of friction blood meets when passes through the vessels?

A

resistance

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11
Q

Blood flow is affected by what 2 factors?

A
  • pressure gradient

- vascular resistance

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12
Q

What is the calculation of flow through a vessel?

A

Ohm’s law:

blood flow = change in pressure between 2 ends of vessel/ resistance

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13
Q

What is the normal adult overall blood flow?

A

5,000 ml/min = cardiac output

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14
Q

What are the two descriptions of blood flow?

A
  • laminar

- turbulent

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15
Q

What is known as the measure of blood flow through a vessel for a given pressure difference? Also known as the reciprocal of resistance?

A

conductance

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16
Q

What plays the greatest role in determining rate of blood flow?

A

diameter

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17
Q

What controls most of the blood flow through the vessels?

A

arterioles

18
Q

An increase in viscosity does what to blood flow?

A

decreases blood flow

- inverse relationship

19
Q

What is known as the percent of blood that consists of cells (RBC and WBC)?

A

% of blood that consists of cells

20
Q

What tightly controls blood flow?

A

needs of tissue

21
Q

What is controlled independently of local blood flow or cardiac output?

A

arterial pressure

22
Q

What is known as the pressure that propels blood to tissues?

A

mean arterial pressure (MAP)

23
Q

equation for MAP?

A

MAP = DBP + (pulse pressure/3)

24
Q

What is pulse pressure?

A

difference between systolic and diastolic pressure

25
Q

MAP and pulse pressure decrease with and increase in what?

A

increasing distance from the heart

26
Q

2 effects of pressure on blood flow?

A
  • increases force on blood flowing through vessels

- distends vessel (expands or stretches the vessel which increases blood flow)

27
Q

Veins have a _______ distensibility than arteries?

28
Q

What is known as the total quantity of blood that can be stored in a given portion of the circulation for each mmHG pressure rise?

A

compliance (capacitance)

29
Q

equation for compliance?

A

distensibility x volume

30
Q

What is another name for right atrial pressure?

A

central venous pressure

31
Q

What are the 5 blood reservoirs of the body?

A
  • veins
  • spleen
  • liver
  • heart
  • lungs
32
Q

Do different tissues have different metabolic needs over time?

A

YES (blood flow/100g of tissue)

33
Q

What are the 2 phases of local blood control?

A
  • acute

- long term

34
Q

What is the effect on blood flow with decreased oxygen?

A

increased blood flow

35
Q

What is stated by the vasodilator theory?

A
  • vasodilator substance released from local tissue when there is low oxygen in that particular area
  • causes more blood flow to that local tissue area
36
Q

What is stated by the Oxygen Lack Theory?

A
  • the precapillary and metarteriole sphincters constrict the vessels
  • but once you start moving, oxygen reduces and now the sphincters open and allow for dilation to increase blood flow
37
Q

What are the effects of nitric oxide?

A

vasodilator that allows for more blood flow which allows for more nutrients to get to the tissues

38
Q

2 other methods affecting local blood flow?

A
  • reactive hyperemia

- active hyperemia

39
Q

Do tissues have the ability to autoregulate?

A

YES – after increase in BF to a tissue due to increase in arterial pressure, BF returns to near normal levels

40
Q

4 vasoconstrictors?

2 vasodilators?

A
Vasoconstrictors:
- norepinephrine/epinephrine
- angiotensin II
- vasopressin
- endothelin
Vasodilators:
- bradykinin
- histamine