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Human Physiology > The Vascular System > Flashcards

The Vascular System Flashcards

1
Q

Arteries & Arterioles

A
  • Thick walls, smooth muscle w/ elastic tissue to withstand pressure
  • Carry blood away from heart
  • thickest
    “rubber band”
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2
Q

Capillaries

A
  • Tiniest vessels, single-cell thick for easy diffusion
  • Exchange of materials b/t blood and body cells
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3
Q

Venules & veins

A
  • One-way valves in thin-walled vessels surrounded by thin layer of smooth muscle giving low resistance to blood flow
  • Returns blood to heart
    “Reserve” (more or less blood to the heart)
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4
Q

Tunic adventitia

A

Outermost layer

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5
Q

Tunica media

A

Intermediate layer

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6
Q

Tunics intima

A

Interior lining

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7
Q

Compliance

A

The ability of a vessel to stretch
- not the same as recoil
- high compliance = high stretch

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8
Q

Veins are more compliant, but less…

A

Elastic than arteries

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9
Q

High compliance allows?

A

Blood to pool (sit) in the veins
- ab 3.2 liters

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10
Q

High elasticity allows?

A

Arteries to keep blood flowing
- even when the heart isn’t active atm

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11
Q

Hardening arteries

A

Increase in bp
- why bp increases with age

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12
Q

Flow is proportional to

A

Change in pressure
- Fluid flows only if there is a positive pressure gradient (delta P1- delta P2)
- No pressure gradient, so NO flow
- Flow depends on change in pressure, NOT ABSOLUTE PRESSURE
—-systemic vs pulmonary = diff pressures, but same flow

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13
Q

Flow is irreversibly proportional to

A

Resistance (aka 1/R)
- Resistance is caused by friction
- Resistance is proportional to 1/radius^4, so doubling the radius increases the flow 16x
—constricting = decrease in blood flow
- pressure falls over distance as energy is lost bc of friction

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14
Q

Hydrostatic pressure

A

Pressure exerted on the walls of the container

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15
Q

Distribution of blood flow

A
  • Regulated by muscular walls of the arterioles (due to highest level of resistance)
    —-spend more time closer to 80 (120/80) due to longer diastole (passive filling)
  • Regulation of calcium levels of arteriolar smooth muscle
    —-smooth muscle does not have troponin & tropomyosin
    —-amnt of calcium still is an affect
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16
Q

Distribution of blood flow: Extrinsic control

A
  • Autonomic nervous system (primarily sympathetic NS)
    — increase input = increase contraction
    — decrease input = increase dilation
  • Hormones (Epi)
    — increase levels = constriction
    — decrease levels = dilation
    ex: Angiotensin, vasopressin, ANF
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17
Q

Distribution of blood flow: Intrinsic (local) control

A

Happening in a particular tissue
- Active hyperemia = vasodilation leads to increased blood flow after increased metabolic activity
ex: O2, CO2, pH, lactate, adenosine K+ (all local metabolic factors
- Reactive hyperemia = vasodilation leads to increased blood flow due to flow blockage
ex: increase resistance, decreases flow
- Flow autoregulation = changes in response to changing blood pressure to maintain constant flow
— low pressure = dilation (decreases pressure, but then changes delta P so regulates flow)
— high pressure = contraction (Drives flow, but also increases resistance)
* takes place in kidney
- Injury = increased blood flow stimulated by chemical release from injured cells leading to inflammation
ex: histamine

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18
Q

As blood flows through capillary beds, the flow should be slow enough to allow?

A

Transfer of nutrients & wastes (via diffusion)

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19
Q

Some factors affecting flow

A
  1. pressure gradient (CO)
  2. vessel radius
  3. blood viscosity
  4. vessel length
  5. total blood volume
  6. temperature
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20
Q

How is blood returned to the heart with such a low venous blood pressure?

A

gravity

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20
Q

Venous pressure

A

Is very low
- 10-15 mmHg

21
Q

Venous pressure

A
  • Decrease compliance: by stimulating muscles (nerves, hormones, etc.)
  • One-way valves: critical in veins
  • Skeletal muscle pump
  • Respiratory pump: inhalation + exhalation
  • Cardiac suction: heart itself can aid in blood return, atria
21
Q

The key role of circulatory system is?

A

The exchange of gases, fluids, and nutrients at the tissues
- this takes place in the microcirculation

22
Q

Arteriolar end: Outward forces

A

Hydro. pressure = 37mmHg
Osmotic potential = 0mmHg
Total outward force = 37mmHg

23
Q

Arteriolar end: Inward forces

A

Hydro. pressure = 1mmHg
Osmotic potential = 25mmHg
Total outward force = 26mmHg

24
Q

Venule End: Outward forces

A

Hydro. pressure = 17mmHg
Osmotic potential = 0mmHg
Total outward force = 17mmHg

25
Q

Venule End: Inward forces

A

Hydro. pressure = 1mmHg
Osmotic potential = 25mmHg
Total outward force = 26mmHg

26
Q

Net outward pressure: Arteriolar

A

11 mmHg
- results in ultrafiltration (more pressure out than in, fluid and gases pushed out)

27
Q

Net inward pressure: Venules

A

-9 mmHg
- results in reabsorption (more pressure in than out, brings fluids and gases in)

28
Q

How much blood flows through all capillary beds in one day?

A

24 x 60 x 5 = 7,200 L/day
- total filtered = 20 L/day
- total reabsorbed = 17 L/day
- unabsorbed = 3 L/day

29
Q

What happens to this additional 3 liters?

A

It is picked up by the lymphatic system

30
Q

The lymphatic system

A
  • Has an ending, unlike blood vessels
  • Fluid flows one way
31
Q

Lymphatic system: Structure

A
  • Complex network of thin-walled vessels in proximity to the capillary network
    —-thin-walled = not a lot of pressure
  • Composed of cells with openings b/t the, that act as one-way valves
32
Q

Lymphatic system: Functions

A
  • Removal of excess fluid
  • Transport of fats from intestine
  • Assist immune response
33
Q

How we move lymph fluid?

A
  • skeletal muscle pump
  • respiratory pump
34
Q

How the lymph gets collected?

A
  • lymph nodes = swellings
    —where wbc reside
35
Q

Edema

A

Accumulation of excess fluid in the interstitial space

36
Q

Causes of edema

A
  • Filtration far greater than absorption
  • Inadequate drainage of lymph
37
Q

Filtration far greater than absorption…

A
  • increase arterial blood pressure (hydrostatic pressure)
  • increase venous pressure
  • increase interstitial proteins (osmotic pressure)
    — not supposed to have a lot of proteins here
    — proteins came from breaking cells apart
  • increase permeability
    — damage to other cells increases permeability; release histamine, loosen tight junctions
  • decrease plasma proteins
    — malnutrition, edema in GI tract (abdominal)
38
Q

Inadequate drainage of lymph…

A
  • Blocked lymph
39
Q

Blood pressure regulation

A

Blood pressure control involves both the cardiovascular system and the renal system

40
Q

Some factors affecting flow

A

*1. Pressure gradient (CO)
*2. Vessel radius
3. Blood viscosity
4. Vessel length
5. Total blood volume
6. Temperature
* = what our body uses min by min, sec by sec; controlled by ANS

41
Q

Blood pressure regulation

A
  • Short-term regulation = baroreceptor reflex
  • Long-term regulation = Urinary system
42
Q

Blood pressure regulation: Short-term regulation

A

Baroreceptor reflex
- baroreceptors = cells loaded with mechanosensitive receptors located predominantly at the aortic arch and carotid sinus
- Mean arterial pressure (MAP) = diastolic + 1/3 pulse pressure
- pulse pressure = difference b/t systolic & diastolic

43
Q

Increased arterial blood pressure

A
  • Increase firing of baroreceptors
  • Increased activation of parasympathetic nervous system NS
    — Increase release of Ach from vagus nerve
    — Decrease HR, increase CO
  • Decreased activity of sympathetic NS
    — Decrease vasoconstriction, decrease total peripheral resistance (TPR)
    — Decrease HR (decrease CO)
    — Decrease contraction force (decrease CO)
44
Q

Decreased arterial blood pressure

A
  • Decreased firing of baroreceptors
  • Decreased activation of parasympathetic NS
    — Increase release of Ach from vagus nerve
  • Increased activity of sympathetic NS
    — vasoconstriction
    — Increase TPR
    — Increase venous return
  • Increase HR (increase CO)
  • Increase contraction force (increase CO)
45
Q

Why does your HR increase when you exercise?

A
  1. ATP breakdown
  2. Increase metabolism, decreases Oxygen levels, CO2 increases
  3. pH drops drastically
  4. Local factors initiate muscles to vaso-dilate
  5. Hyperemia
46
Q

Renin-Angiotensin-Aldosterone

A
  • Renin is secreted by the kidneys in response to chronic low arterial blood pressure
  • Angiotensinogen is always present (secreted by liver) and is converted to angiotensin I by renin
  • Angiotensin I is converted to angiotensin II by angiotensin converting enzyme (ACE)
    —-ACE = where covid binds
47
Q

Zymogen

A

inactive protein that needs to be activated by a protease

48
Q

Angiotensin II

A

vaso-constrictor

49
Q

Angiotensin II acts on what?

A

The adrenal cortex to release aldosterone
- Aldosterone acts on kidney to conserve sodium

Human Physiology (8 decks)

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