CV 3 (2)

Question 1

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

Answer 1

three

collapsed

Question 2

Compared to arteries, veins have (3)

Answer 2

 less smooth muscle
 less elastic tissue
 higher compliance

Question 3

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

Answer 3

capacitance vessels
blood reservoirs (60% of TBV)

Question 4

Venous Pressure (2)

Answer 4

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

Question 5

echanisms supporting Venous Return (4)

Answer 5

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.

Question 6

Varicose Veins

 Veins have one-way valves that prevent the

Answer 6

backflow of blood.

Question 7

Varicose veins are

Answer 7

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

Question 8

who suffers from varicose veins?

Answer 8

15% of adults suffer from this condition,

mainly in the lower limbs.

Question 9

Capillaries

Anatomy (2)

Answer 9

 Single layer endothelial cells

 Basement Membrane

Question 10

Mechanisms of Capillary Exchange (6)

Answer 10

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

Question 11

What is the difference between Plasma and Interstitial Fluid?

Answer 11

plasma has more proteins

Question 12

Metarteriole/Thoroughfare Channel (2)

Answer 12

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

Question 13

Capillaries (1)

Answer 13

Branch off Arteriole and Metarteriole

Question 14

Precapillary Sphincters (2)

Answer 14

 Smooth Muscle

 Control entrance to capillaries

Question 15

Arteriovenous Anastomosis (2)

Answer 15

 Direct connection between arteriole and Vein

 No Exchange

Question 16

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

Answer 16

tissue’s metabolic activity

Question 17

Capillary Network

Regulation (4)

Answer 17

 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

Question 18

Velocity is slowest in

Answer 18

capillary
beds because they have a
greater cross-sectional area

Question 19

Diffusion Across the Capillary Wall: Exchange of (2)

Answer 19

Nutrients and Metabolic End Products

Question 20

Bulk Flow (2)

Answer 20

 Water distribution between plasma and interstitial fluid

 Movement of protein free fluid between plasma and interstitial fluid

Question 21

bulk flow occurs through

Answer 21

water filled channels

Question 22

bulk flow function

Answer 22

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

Question 23

Two Directions Fluid Movement (2)

Answer 23

1. Filtration

2. Absorption

Question 24

**Magnitude and Direction of fluid movement determined by

Answer 24

ΔP

Question 25

1. Hydrostatic Pressure of Capillary (PC)

Answer 25

Force exerted by the fluid pressing against a capillary wall (Capillary Blood Pressure)
Filtration Force (30 mmHg arterial end; 10mmHg venous end)

Question 26

2. Colloid Osmotic Pressure in Capillary (ΠC) (2)

Answer 26

Osmotic force created by impermeable plasma proteins
Absorptive Force (28 mmHg)

Question 27

3. Hydrostatic Pressure of Interstitial Fluid (PIF) (2)

Answer 27

Force exerted by the fluid in the interstitial space

Absorptive Force; (-3mmHg)

Question 28

4. Colloid Osmotic Pressure of Interstitial Fluid (ΠIF) (2)

Answer 28

Force exerted by the impermeable proteins in the interstitial space
Filtration Force; (8 mmHg)

Question 29

Net Filtration Pressure =

Answer 29

PFiltration – PAbsorption

Pc + πif) – (πc + Pif

Question 30

The Starling Equation also accounts for the

Answer 30

water permeability of the capillary (Kf)

Net Filtration Pressure = Kf [(Pc + πif) – (πc + Pif)]
+ value = net filtration
- Value = net absorption

Question 31

Filtered fluid returned

to CV system by

Answer 31

lymphatic system

Question 32

Overall Net Filtration Pressure (2)

Answer 32

 Varies based on status of arterioles feeding capillary bed

 Arteriolar dilation and constriction alter PC and overall net filtration pressure

Question 33

Lymphatic System

Functions: (3)

Answer 33

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)

Question 34

1. • Return filtered fluid and proteins to circulation (5)

Answer 34

a. Normally produce ≈ 3L filtrate/day
b. Escaped Proteins
Normally small amount filtered
Injury
Hormones and Paracrines (ex. Histamine, Bradykinin)

Question 35

Mechanism of Lymph Flow (3)

Answer 35

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

Question 36

Edema

Answer 36

Fluid accumulation in interstitial space

Question 37

Edema causes loss of (2)

Answer 37

1. Loss of normal lymph drainage

2. Loss of normal balance between PC and ΠC

Question 38

1. Loss of normal lymph drainage (2)

Answer 38

 Blocked by parasites (ex. Bancroftian Filariasis (Elephantiasis))
 Removal/Damage during surgery

Question 39

2. Loss of normal balance between PC and ΠC (3)

Answer 39

A. increase PC
B. decrease ΠC
C. increase Πif

Question 40

Causes & Examples of Edema Formation (4)

Answer 40

Increased Pc
Decreased πc
Increased capillary permeability
Impaired lymphatic drainage

Question 41

Cause: Increased Pc
Ex: (5)

Answer 41

Arteriolar Dilation
Venous Constriction
Increased Venous pressure
Heart failure
NOT increased MAP

Question 42

Cause: Decreased πc
Ex: (4)

Answer 42

Decreased plasma protein concentration
Severe liver failure (lack of plasma protein)
Protein malnutrition
Nephrotic syndrome

Question 43

Cause: Increased capillary permeability
Ex: (2)

Answer 43

Burn

Inflammation

Question 44

Cause: Impaired lymphatic drainage
Ex: (3)

Answer 44

Standing
Removal of lymph nodes
Infection of lymph nodes

Question 45

Edema Treatment (3)

Answer 45

1. Ice
2. Elevation
3. Compression