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Physio: Cardiovascular > Arterial, Venous Systems & Microcirc. > Flashcards

Arterial, Venous Systems & Microcirc. Flashcards

1
Q

What are the tissue layers of the blood vessels?

A
  • intimida: inner most layer
  • media: middle layer
  • Adventist: outermost layer
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2
Q

What is the intima?

A
  • innermost layer of the blood vessel
  • can secrete chemicals to dilate or constrict vessels
  • endothelial cells
  • connective tissue
  • intercelllular matrix
  • internal elastic lamina
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3
Q

What is the media of a blood vessel?

A

Middle layer

  • elastic tissue
  • connective tissue
  • smooth muscle *
  • external elastic lamina
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4
Q

What is the adventitia of a blood vessel?

A

Outer layer

  • connective tissue
  • nerves
  • nutrient capillaries in large vessels
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5
Q

Is there smooth muscle in veins?

A

Yes, there is much more smooth muscle in arteries but veins still have some—> large veins can contract

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6
Q

What are arterioles?

A

Small arteries

  • ** bulk or resistance occurs here **
  • ** “STOP COCKS” of vascular system **
  • regulate distribution of blood flow to various capillary beds **
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7
Q

Where is the lowest pressure in systemic circulation?

A

RIGHT ATRIUM

Not the capillaries: capillaries must generate enough pressure to return blood to the heart

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8
Q

What is pulse pressure?

A

SBP - DBP

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9
Q

How do you calculate an approximate MAP?

A

DBP + 1/3 (SBP-DBP)
Or
(CO + SVR) + CVP

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10
Q

How do you calculate precise MAP?

A

Calculate area under arterial line tracing for 1 cardiac cycle
- requires calculus

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11
Q

Why is the highest BP found in the feet when supine?

A

SUMMATION WAVES: wave hits something and bounces back, another wave hits, and creates a bigger wave (higher pressure)

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12
Q

What is another name for dicrotic notch, and what does it signify?

A

Incisura: aortic valve closure and the beginning of diastole

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13
Q

What is the purpose of the vena cava?

A
  • return blood to the heart

* ** ACT AS A BLOOD RESERVOIR: ~ 70% of blood volume resides in big veins at any time *****

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14
Q

What is bovine circulation?

A
  • when left carotid comes off of the right subclavian artery (opposite side)
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15
Q

As vessels go further from the heart what happens?

A
  • Delay in onset of initial pressure rise
    3 major changes:
    1.) the high frequency components of pulse (dicrotic notch) are damped out and eventually disappear
    2.) systolic portions of pressure wave become narrowed and elevated
    3.) a hump may appear on diastolic portion of wave
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16
Q

What does the arterial system do in terms of flow?

A

Converts pulsatile flow to continuous flow

- pulse dampening: aorta can expand as blood flows out of the heart

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17
Q

How is pulsatile flow converted to continuous flow?

A

Part of energy of cardiac contraction is dissipated as forward flow—> kinetic energy, the rest is stored as potential energy

  • much of stroke volume is retained by stretching distensible arteries
  • during diastole, elastic recoil of arterial walls converts this potential energy into capillary blood flow
  • if arterial walls were rigid this would not take place- would create more work for the heart
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18
Q

Why is it important to convert pulsatile flow to continuous flow?

A

Minimized workload of the heart

More work is required to pump intermittently

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19
Q

What is the purpose of the arterial system?

A

Distribute blood supply to capillary system

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20
Q

What increases pulse pressure?

A

Decreased aortic compliance?

- age, atherosclerosis, HTN

21
Q

What is the equation for compliance?

A

(Change in volume)/(change in pressure)

* low compliance increases SBP and decreases DBP both ** —> wider pulse pressure

22
Q

Why do arteries get stiffer (less compliant) as we age?

A

Loss of elastic tissue

23
Q

What is Ohm’s law?

A

Q= change in pressure/resistance

24
Q

How do you calculate Cardiac output (CO)?

A

= (MAP - CVP)/SVR

25
Q

How do you calculate SVR?

A

=[(MAP - CVP)/CO] x 80

26
Q

What are specific blood reservoirs in the body?

A 
Spleen
Liver
Heart 
Lungs 
* large abdominal veins *
Venous plexus beneath the skin-> respond to temperature
27
Q

Why do veins make such great reservoirs?

A

Distensibility: it takes a large volume of blood before you begin to see a change in venous pressure

 - the volume prior to pressure change is called “unstressed volume” - during shock states you rely on unstressed volume to keep you alive
28
Q

What are things that increase CVP?

A
  • decrease in CO (blood gets backed up)
  • increase in total blood volume
  • venous constriction
  • gravity- going from standing to supine
  • arterial dilation
  • respiratory activity: increased rate, and + pressure ventilation decreases venous return
  • skeletal muscle pump- exercise
29
Q

Is CVP a good measure of volume status?

A

NO
Body will try to maintain normal CVP despite substantial volume loss of unstressed reservoir
- this is done by sympathetic constriction of splanchnic venous compartment

30
Q

What is something to be aware of in a tachycardic patient who has experienced large volume blood loss?

A

Their body is dependent on sympathetic tone to maintain BP

- if you give a med that reduces that tone, nothing will keep the BP up—> a whole stick of propofol will kill them

31
Q

While standing, pressure of veins may be:?

A
  • 90mmH in the feet
  • -10mmHg in the head (Sagital veins = veins in head)
  • in a sitting craniectomy: pressure in head is so low it can suck air into circulation
  • ** can get air emboli anytime surgical incision is above the level of the heart ****
32
Q

What are varicose veins caused by?

A

Incompetent valves

Caused by too much pressure or blood clots

33
Q

What does spontaneous respiration do to venous return?

A

Decreases intra-thoracic pressure —> decreases RA pressure—> enhances venous return

34
Q

What does mechanical ventilation do to venous return?

A

Increases intra-thoracic pressure—> increases RA pressure—> decreases venous return

35
Q

What does a valsalva maneuver do to venous return?

A

Causes large increase in intra-thoracic pressure—> impedes venous return to RA
* if you forget to turn APL valve on after incubating it will cause a valsalva maneuver
—> patient’s BP will tank (giving all 50 psi to their lungs)

36
Q

What is true regarding arterioles?

A

Thick smooth muscle

Give rise to metarterioles, then capillaries

37
Q

What is true about metarterioles?

A
  • precapilary sphincters regulate flow into capillaries

- local conditions in tissues regulate opening and closing of sphincters

38
Q

What are some facts about capillaries?

A

Thin walled
Greater cross sectional area because so numerous
Greatest surface area for exchange
Devoid of smooth muscle—> CANNOT CONSTRICT

39
Q

What is the intercellular cleft?

A

Place on capillary wall where capillaries meet

- 1 place exchange can occur

40
Q

Capillary distribution varies by tissue needs. Where are the densest capillary distribution areas?

A

The heart

Metabolically active tissues

41
Q

What is the law of la place?

A

Wall stress= (pressure x radius)/wall thickness
Smaller radius=smaller pressure
Larger radius=larger pressure
* this is why capillaries don’t burst *

42
Q

What are the mechanisms of action across capillary endothelium?

A
  • diffusion:
    • O2, CO2, lipid soluble substances
  • bulk flow:
    • via intercellular clefts or “pores”
    • H2O, electrolytes, small molecules
  • vesicular transport
    • large proteins
  • active transport:
    • ions, glucose, amino acids—> requires a carrier and ATP
43
Q

What is vesicular transport?

A

Proteins are too large to go through pores of cell membrane
- they bump against the cell wall and it wraps around them creating a capsule, then releases them through the membrane and to the other side

44
Q

Is the permeability of a capillary endothelial membrane the same in all body tissues?

A

NO

45
Q

What is the difference between a continuous, fence started or discontinuous membrane?

A
  • Continuous: no gaps in membrane, still allows for diffusion, bulk flow, vesicular and active transport
  • Rene started: holes in membrane things can slip right through
  • discontinuous: breaks in membrane allow things in
46
Q

What tissues make up the wall of an artery?

A
  • endothelium
  • smooth muscle
  • elastic fibers
  • fibrous tissue
47
Q

What tissues make up the wall of an arteriole?

A

smooth muscle and endothelium

48
Q

What tissues make up the wall of a vein?

A 
Endothelium
Elastic 
Smooth muscle 
Fibrous 
(Same as an artery, but artery will have more smooth muscle)
49
Q

What factors regulate CVP?

A

Venous return and right ventricular function

Physio: Cardiovascular (5 decks)

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