3a - Arteries, veins, and capillaries

Question 1

Types of arteries:

Answer 1

-large (elastic)
-small (muscular)
-resistance (arterioles)
*distribution and resistance

Question 2

Capillaries:

Answer 2

-small
-organ-dependent features
*exchange

Question 3

Types of veins:

Answer 3

-venules
-veins
-vena cava
*capacitance

Question 4

Tissue layers in arteries and veins:

Answer 4

-tunica intima
-tunica media
-tunica externa (adventitia)

Question 5

Tunica intima:

Answer 5

-inner layer
-endothelium
-internal elastic membrane

Question 6

Tunica media:

Answer 6

-middle layer
-smooth muscles
-also some elastic tissue

Question 7

Tunica externa (adventitia):

Answer 7

-outside layer
-collagen/elastic fibers
-perivascular nerves

Question 8

Elastics arteries: close to heart

Answer 8

-come off heart
-buffer or absorb large pressures generated by heart

Question 9

Muscular arteries: further from heart

Answer 9

-branch off the aorta
-supply to organs
-buffer or absorb pressures generated by the heart

Question 10

Arterioles: furthest from heart

Answer 10

-dilate and constrict to distribute blood flow within organs
-respond to intrinsic and extrinsic stimuli
-primary determinants of systemic vascular resistance
*vascular tone

Question 11

Vascular tone:

Answer 11

-degree of constriction experienced by a blood vessel relative to its max dilated state

Question 12

What is the formula for MAP?

Answer 12

MAP=CO x SVR (systemic vascular resistance)

Question 13

Pressure in arteries, capillaries, and veins:

Answer 13

-arteries: leaves aorta at 120/80mmHg
-decreases as it approaches capillaries
-continues to decrease and reaches near 0 at vena cava
*high to low pressure

Question 14

Blood velocity and total cross-sectional area: arteries, capillaries and veins

Answer 14

-velocity: decreases until capillaries then increases again in venous system
-cross-sectional area: greatest in the capillaries=important for gas/nutrient exchange

Question 15

What are capillaries?

Answer 15

-small exchange vessels
-large vascular volume

Question 16

What do capillaries consist of?

Answer 16

-endothelial cell and basement membrane
>no smooth muscle

Question 17

Types of capillaries (3):

Answer 17

-continuous
-fenestrated
-discontinuous

Question 18

Continuous capillaries:

Answer 18

*tight
-skin
-muscle
-lung
-CNS

Question 19

Fenestrated capillaries:

Answer 19

*perforations to increase permeability
-exocrine glands
-renal glomeruli
-intestinal mucosa

Question 20

Discontinuous capillaries:

Answer 20

*leaky (very large gaps)
-liver
-spleen
-bone marrow

Question 21

What are the different routes that substances can take through capillaries into the tissues:

Answer 21

-diffusion (continuous)
-vesicular or active transport (continuous)
-fused vesicular pores (continuous)
-intercellular clefts (all three)

Question 22

Calveolae in capillaries:

Answer 22

-membrane bound vesicles
-involved in endocytosis and transcytosis of larger macromolecules from blood to interstitial space

Question 23

Exercise and capillaries:

Answer 23

-capillary number increases in muscle and brain

Question 24

Capillary refill time (CRT):

Answer 24

-normal: pink mucous membrane
-measuring the time it takes for colour to return to normal
*1.5-2s or less
-slow or fast

Question 25

When does slow CRT happen?

Answer 25

-discoloured (grey/white)
-indicator of poor circulation
-common with heart problems

Question 26

What is seen in some patients that have a slow CRT?

Answer 26

-hypovolemia
-low BP
-dehydration
-shock
-low or high pulse rate (arrhythmia)
-anemia
-capillary rarefaction

Question 27

When does a fast CRT happen?

Answer 27

-discoloured (red)
-uncommon
-indicator of over perfusion

Question 28

What is seen in some patients that have a fast CRT?

Answer 28

-high BP
-high pulse rate
-local inflammation

Question 29

Venules: furthest from the heart

Answer 29

-receive blood from capillaries
-thin walled and prone to rupture
-low pressure

Question 30

Veins: close to heart

Answer 30

-capacitance vessels
-one-way valves to prevent backflow
-low pressure

Question 31

Vena cava: closest to heart

Answer 31

-returns blood to R atrium
-pressure here=central venous pressure

Question 32

Central venous pressure:

Answer 32

-primary determinant of right ventricular filling or preload

Question 33

When does jugular vein distension (JVD) occur?:

Answer 33

-when central venous pressure is above normal healthy value
>blood can back up into the veins causing them to bulge (and to pulse)

Question 34

What are some different things that cause JVD?

Answer 34

-cardiac tamponade or pericarditis: restricted filling
-vena cava obstruction
-tricuspid valve stenosis
-R. sided heart failure or pulmonary hypertension

Question 35

Vena cava obstruction:

Answer 35

-tumor in chest prevents blood from entering the atria

Question 36

Tricuspid valve stenosis:

Answer 36

-valve can become stiff and entry of blood from the atria to the ventricle is impeded

Question 37

R. sided heart failure or pulmonary hypertension:

Answer 37

-right ventricle does not empty during systole (increased afterload)
>R. ventricle backs up, leads to R. atrium backing up

Question 38

Histology of arteries:

Answer 38

-3 distinct layers
-more smooth muscle
-large tunica media
-hold shape

Question 39

Histology of capillaries:

Answer 39

-small
-no smooth muscle
-sometimes contain RBC

Question 40

Histology of veins:

Answer 40

-thin walls
-wide lumen
-often do NOT hold shape