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Physiology (MPP 3202) > Ch. 13/14 Day 3 > Flashcards

Ch. 13/14 Day 3 Flashcards

1
Q

Functional Model of CV System

A

Closed system in series

Each side of heart functions as an independent pump

  1. Arterioles: sites of variable resistance
    - -biggest drop in pressure occurs here
  2. Capillaries: exchange between blood and cells
  3. Postcapillary venules: exchange and support leukocyte adhesion and emigration
  4. Systemic Veins: expandable volume reservoir
  5. Valves in veins and heart assure one-way flow around closed loop system
  6. Elastic Systemic Arteries: pressure reservoir; maintain blood flow during ventricular relaxation
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2
Q

How much cardiac output do the lungs get?

A

100% from every heartbeat

–distributed to left and right heart

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3
Q

How much of the cardiac output do the kidneys get?

A

~20% from every heartbeat

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4
Q

How much of the cardiac output does the skeletal muscle get?

A

~20% from every heartbeat

–can radically change during exercise

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5
Q

Velocity of Blood Flow

A

Slows down as it passes through smaller structures (arterioles, capillaries, venules).

Total blood flow over all those capillaries is basically equal to blood flow in a single aorta.
–blood flow is relatively constant throughout the whole system, but velocity drops down

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6
Q

Blood Vessel Structure

A

All blood vessels have endothelial layer

  1. Artery
    - -tremendous amount of elastic tissue
    - -lots of smooth muscle
  2. Arteriole
    - -lots of smooth muscle
  3. Capillary
    - -single layer of endothelial cells
    - -no muscle since it’s an exchange vessel
  4. Venule
    - -fibrous tissue
    - -no muscle since it’s an exchange vessel
  5. Vein
    - -collapsable (very little elastic tissue)
    - -some smooth muscle
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7
Q

Elastic Arteries

A

closer to the heart; stretch as blood is pumped into them and recoil when ventricles relax

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8
Q

Muscular Arteries

A

farther from the heart; have more smooth muscle in proportion to diameter; also have more resistance due to smaller lumen

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9
Q

Arterioles

A

20−30 µm in diameter; provide the greatest resistance; control blood flow through the capillaries

Resistance vessels
–control of BP

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10
Q

Ventricular Contraction

A
  1. Ventricle contracts
  2. Semilunar valve opens; blood ejected from ventricles flows into arteries
  3. Aorta and arteries expand and store pressure in elastic walls
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11
Q

Ventricular Relaxation

A
  1. Isovolumic ventricular relaxation
  2. Semilunar valve shuts, preventing flow back into ventricle
  3. Elastic recoil of arteries sends blood forward into rest of circulatory system
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12
Q

Pulse Pressure

A

Systolic pressure minus diastolic pressure

Reflects actual amount of blood that the heart has been able to pump

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13
Q

Mean Arterial Pressure

A

Diastolic pressure + 1/3 (pulse pressure)

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14
Q

Systemic Circulation Pressures

A

Pressure waves created by ventricular contraction travel into the blood vessels. Pressure in the arterial side of the circulation cycles but the pressure waves diminish in amplitude with distance and disappear at the capillaries.

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15
Q

Capillary Blood Flow

A

Blood flow to capillaries is regulated by:

  • -vasoconstriction and vasodilation of arteries
  • -precapillary sphincters (can close off capillaries in response to local signals)
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16
Q

Exchange Function

A

Takes place in capillaries and postcapillary venules

Capillaries—smallest vessels: 7-10 µM diameter; have thinnest walls (single layer of flattened endothelial cells supported by basal lamina)

No smooth muscle, no elastic tissue reinforcement facilitates exchange, as does the large aggregate surface area thin walls and huge total surface area diffusion distance from lumen to tissue cells is small

Plasma and cells exchange materials across thin capillary walls

Capillary density related to metabolic activity of cells in the tissue

17
Q

Types of Capillaries

A

Continuous, Fenestrated, Discontinuous (sinusoidal)

18
Q

Continuous Capillaries

A

Adjacent ECs close together (muscles, heart, skin, adipose tissue, and CNS)
–very little leakage (tight)

Have tight/close junctions

Transcytosis may be only mechanism for exchange within CNS—blood-brain barrier

19
Q

Fenestrated Capillaries

A

Pores in vessel wall (kidneys, intestines, and endocrine glands)
–leakage possible

Have large pores

Basement membrane: mucoprotein which restricts passage of large molecules (especially proteins)

20
Q

Discontinuous (sinusoidal) Capillaries

A

Gaps between cells (bone marrow, liver, and spleen; allow passage of proteins, cells)
–leaky vessel

21
Q

Capillary Exchange

A

Exchange between plasma and interstitial fluid via paracellular pathway or endothelial transport

Small dissolved solutes and gases move by diffusion, depending on lipid solubility and concentration gradient

Larger solutes and proteins move mostly by vesicular transport and by bulk flow—mass movement in response to hydrostatic or osmotic pressure gradients

22
Q

Capillary Filtration

A

Fluid movement out of capillaries

Caused by hydrostatic pressure

Net filtration at arterial end –> fluid pushed out of system

23
Q

Capillary Absorption

A

Fluid movement into capillaries

Net absorption at venous end –> fluid back into vesicle

Caused by colloid osmotic pressure

24
Q

Starling forces and Transmicrovascular Exchange

of Fluid

A

Net Driving Force (NDF):

  1. when NDF > 0  Filtration
    - -hydrostatic pressure greater than oncotic pressure
  2. when NDF
25
Q

Net Pressure Formula

A

Net Pressure = hydrostatic pressure minus colloid osmotic pressure

26
Q

Veins

A

Most of the total blood volume is in veins

Lower pressure (2 mmHg compared to 100 mmHg average arterial pressure)

Thinner walls than arteries, larger lumen; collapse when cut

27
Q

What helps blood in veins return to the heart?

A

Skeletal muscle pumps:
–contraction of muscles surrounding veins help force blood towards heart

Venous valves:
–ensure one-way directional flow

Breathing:
–diaphragm flattens upon inhalation: increases abdominal pressure compared with thoracic pressure, also moving blood –> heart

28
Q

Lymphatic System

A

Returns fluid and proteins to circulatory system [lymphatic endothelium has very porous junctions, and so is much “leakier” than vascular endothelium]

Transports absorbed fat from intestines to blood

Serve as filter for pathogens

Produces and houses lymphocytes for the immune response

29
Q

Thoracic Trunk and Right Lymphatic Trunk

A

Merging lymphatic ducts; deliver lymph into right and left subclavian veins (so fluid can be returned to heart)

30
Q

Lymph Ducts

A

Formed from merging capillaries

Similar in structure to veins

Lymph is filtered through lymph nodes

31
Q

Lymphatic Capillaries

A

Smallest; found within most organs; interstitial fluids, proteins, microorganisms, and fats can enter.

32
Q

Edema

A

Fluid buildup

Two main causes:
1. Inadequate drainage of lymph

  1. Filtration far greater than absorption
    - -Increase in capillary hydrostatic pressure
    - -Decrease in plasma protein concentration
    - -Increase in interstitial proteins
    - -Increased permeability

Physiology (MPP 3202) (32 decks)

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