CV 3 (2) Flashcards

1
Q

Veins have all — distinct layers (tunics). The walls are thinner than arteries, so they often appear — in histological slides.

A

three

collapsed

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2
Q

Compared to arteries, veins have (3)

A

 less smooth muscle
 less elastic tissue
 higher compliance

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3
Q

Veins are highly distensible, so they are called — — that act as

A
capacitance vessels
blood reservoirs (60% of TBV)
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4
Q

Venous Pressure (2)

A

 Pressure gradient available for venous return ~15 mm Hg. This is not sufficient to move blood back to the heart
 Mechanisms supporting Venous Return

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5
Q

echanisms supporting Venous Return (4)

A
  1. Venous Valves
  2. Respiratory pump (thoracic pump): Pressure changes in the
    central cavity due to the pressure changes due to breathing. This
    helps to propel blood back to the heart.
  3. Skeletal muscle pump: When muscles contract they squeeze the
    veins. This results in blood moving toward heart. Venous valves
    prevent backflow when the muscle relaxes.
  4. Venoconstriction: The smooth muscle in the veins is under SNS
    control (α adrenergic receptor) and contracts when stimulated.
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6
Q

Varicose Veins

 Veins have one-way valves that prevent the

A

backflow of blood.

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7
Q

Varicose veins are

A

veins that have become
dilated and tortuous resulting in incompetent
(leaky) valves.

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8
Q

who suffers from varicose veins?

A

15% of adults suffer from this condition,

mainly in the lower limbs.

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9
Q

Capillaries

Anatomy (2)

A

 Single layer endothelial cells

 Basement Membrane

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10
Q

Mechanisms of Capillary Exchange (6)

A

Narrow water filled spaces
Movement of fluid and dissolved substances via Bulk Flow (decrease ΔP)
Vesicle fuse to form water filled channel
Movement of fluid and dissolved substances via Bulk Flow (decrease ΔP)
 Transcytosis and Transepithelial Transport
 Simple Diffusion

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11
Q

What is the difference between Plasma and Interstitial Fluid?

A

plasma has more proteins

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12
Q

Metarteriole/Thoroughfare Channel (2)

A

 Intermittent Smooth Muscle
 Most direct route between
arteriole and venule

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13
Q

Capillaries (1)

A

Branch off Arteriole and Metarteriole

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14
Q

Precapillary Sphincters (2)

A

 Smooth Muscle

 Control entrance to capillaries

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15
Q

Arteriovenous Anastomosis (2)

A

 Direct connection between arteriole and Vein

 No Exchange

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16
Q

Amount of blood and pathway blood travels through capillary bed
varies moment to moment based on

A

tissue’s metabolic activity

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17
Q

Capillary Network

Regulation (4)

A
 Metarteriole and Precapillary 
sphincters fluctuate between 
contracted and relaxed state
 Rate of fluctuation controlled 
primarily by [O2 ] in tissue
 [O2] low, smooth muscle spends 
more time in relaxed state and 
blood takes convoluted path 
through capillary bed
 [O2] high, smooth muscle spends 
more time in contracted state and 
blood takes most direct path 
through capillary bed
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18
Q

Velocity is slowest in

A

capillary
beds because they have a
greater cross-sectional area

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19
Q

Diffusion Across the Capillary Wall: Exchange of (2)

A

Nutrients and Metabolic End Products

20
Q

Bulk Flow (2)

A

 Water distribution between plasma and interstitial fluid

 Movement of protein free fluid between plasma and interstitial fluid

21
Q

bulk flow occurs through

A

water filled channels

22
Q

bulk flow function

A

Distribution of ECF volume (not exchange of
nutrients and metabolic products which occurs more rapidly
via diffusion).

23
Q

Two Directions Fluid Movement (2)

A
  1. Filtration

2. Absorption

24
Q

**Magnitude and Direction of fluid movement determined by

25
1. Hydrostatic Pressure of Capillary (PC)
``` Force exerted by the fluid pressing against a capillary wall (Capillary Blood Pressure) Filtration Force (30 mmHg arterial end; 10mmHg venous end) ```
26
2. Colloid Osmotic Pressure in Capillary (ΠC) (2)
``` Osmotic force created by impermeable plasma proteins Absorptive Force (28 mmHg) ```
27
3. Hydrostatic Pressure of Interstitial Fluid (PIF) (2)
Force exerted by the fluid in the interstitial space | Absorptive Force; (-3mmHg)
28
4. Colloid Osmotic Pressure of Interstitial Fluid (ΠIF) (2)
Force exerted by the impermeable proteins in the interstitial space Filtration Force; (8 mmHg)
29
Net Filtration Pressure =
PFiltration – PAbsorption | Pc + πif) – (πc + Pif
30
The Starling Equation also accounts for the
water permeability of the capillary (Kf) Net Filtration Pressure = Kf [(Pc + πif) – (πc + Pif)] + value = net filtration - Value = net absorption
31
Filtered fluid returned | to CV system by
lymphatic system
32
Overall Net Filtration Pressure (2)
 Varies based on status of arterioles feeding capillary bed |  Arteriolar dilation and constriction alter PC and overall net filtration pressure
33
Lymphatic System | Functions: (3)
1. * Return filtered fluid and proteins to circulation 2. Transporting absorbed fat from small intestine to circulation 3. Immune System (fluid percolates through lymph nodes as returns to circulation)
34
1. * Return filtered fluid and proteins to circulation (5)
a. Normally produce ≈ 3L filtrate/day b. Escaped Proteins Normally small amount filtered Injury Hormones and Paracrines (ex. Histamine, Bradykinin)
35
Mechanism of Lymph Flow (3)
Smooth muscle in the wall of the lymphatics exerts a pumplike action. Lymphatic vessels have valves similar to those in veins. Skeletal muscle pump and Thoracic pump
36
Edema
Fluid accumulation in interstitial space
37
Edema causes loss of (2)
1. Loss of normal lymph drainage | 2. Loss of normal balance between PC and ΠC
38
1. Loss of normal lymph drainage (2)
 Blocked by parasites (ex. Bancroftian Filariasis (Elephantiasis))  Removal/Damage during surgery
39
2. Loss of normal balance between PC and ΠC (3)
A. increase PC B. decrease ΠC C. increase Πif
40
Causes & Examples of Edema Formation (4)
Increased Pc Decreased πc Increased capillary permeability Impaired lymphatic drainage
41
Cause: Increased Pc Ex: (5)
``` Arteriolar Dilation Venous Constriction Increased Venous pressure Heart failure NOT increased MAP ```
42
Cause: Decreased πc Ex: (4)
Decreased plasma protein concentration Severe liver failure (lack of plasma protein) Protein malnutrition Nephrotic syndrome
43
Cause: Increased capillary permeability Ex: (2)
Burn | Inflammation
44
Cause: Impaired lymphatic drainage Ex: (3)
Standing Removal of lymph nodes Infection of lymph nodes
45
Edema Treatment (3)
1. Ice 2. Elevation 3. Compression