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Human Physiology > The Vascular System > Flashcards

The Vascular System Flashcards

(51 cards)

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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

Study These Flashcards
A

Is very low
- 10-15 mmHg

21
Q

Venous pressure

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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?

Study These Flashcards
A

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

22
Q

Arteriolar end: Outward forces

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A

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

23
Arteriolar end: Inward forces
Hydro. pressure = 1mmHg Osmotic potential = 25mmHg Total outward force = 26mmHg
24
Venule End: Outward forces
Hydro. pressure = 17mmHg Osmotic potential = 0mmHg Total outward force = 17mmHg
25
Venule End: Inward forces
Hydro. pressure = 1mmHg Osmotic potential = 25mmHg Total outward force = 26mmHg
26
Net outward pressure: Arteriolar
11 mmHg - results in ultrafiltration (more pressure out than in, fluid and gases pushed out)
27
Net inward pressure: Venules
-9 mmHg - results in reabsorption (more pressure in than out, brings fluids and gases in)
28
How much blood flows through all capillary beds in one day?
24 x 60 x 5 = 7,200 L/day - total filtered = 20 L/day - total reabsorbed = 17 L/day - unabsorbed = 3 L/day
29
What happens to this additional 3 liters?
It is picked up by the lymphatic system
30
The lymphatic system
- Has an ending, unlike blood vessels - Fluid flows one way
31
Lymphatic system: Structure
- 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
Lymphatic system: Functions
- Removal of excess fluid - Transport of fats from intestine - Assist immune response
33
How we move lymph fluid?
- skeletal muscle pump - respiratory pump
34
How the lymph gets collected?
- lymph nodes = swellings ---where wbc reside
35
Edema
Accumulation of excess fluid in the interstitial space
36
Causes of edema
- Filtration far greater than absorption - Inadequate drainage of lymph
37
Filtration far greater than absorption...
- 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
Inadequate drainage of lymph...
- Blocked lymph
39
Blood pressure regulation
Blood pressure control involves both the cardiovascular system and the renal system
40
Some factors affecting flow
*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
Blood pressure regulation
- Short-term regulation = baroreceptor reflex - Long-term regulation = Urinary system
42
Blood pressure regulation: Short-term regulation
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
Increased arterial blood pressure
- 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
Decreased arterial blood pressure
- 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
Why does your HR increase when you exercise?
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
Renin-Angiotensin-Aldosterone
- 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
Zymogen
inactive protein that needs to be activated by a protease
48
Angiotensin II
vaso-constrictor
49
Angiotensin II acts on what?
The adrenal cortex to release aldosterone - Aldosterone acts on kidney to conserve sodium

Human Physiology (8 decks)

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