Lecture 7: Blood Vessels - Structure and Function Flashcards Preview

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Flashcards in Lecture 7: Blood Vessels - Structure and Function Deck (41):
1

what is the basic arterial vessel wall structure

tunica intima - endothelial cell layer, basement memb, sub endothelial CT layer, internal elastic lamina
tunica media - smooth muscle cells & elastic fibres in concentric layers, external elastic lamina
tunica adventitia - CT blends with surrounding tissue, contain smaller blood vessels in larger arteries = vasa vasorum

2

what is the function of the tunica intima

barrier
prevents plasma membranes escaping
secretes vasoactive mediators

3

what is the function of the tunica media

mechanical strength
contractile power

4

what is the function of the tunica adventitia

tethers vessel to surrounding tissue

5

what is the functional significance of the smooth continuous endothelium

low frictional resistance

6

what is the functional significance of the elastic lamina and elastic fibres?

elasticity during pulsate pressure changes

7

what is the functional significance of the smooth muscle cells

regulate internal calibre of vessel lumen

8

what is the functional significance of the collagen fibres

protection against stresses

9

what are the five functional groups of blood vessels?

1. conducting arteries
2. distributing arteries
3. resistance vessels
4. exchange vessels
5. capacitance vessels

10

list three features of conducting arteries

1. large and thick walled
2. very distendable - lots of elastic
3. most compliant ARTERIES - can stretch and recoil important for the changing blood pressure

11

what are some examples of conducting arteries?

aorta
pulmonary
brachiocephalic
subclavian
common carotid

12

what is compliance ?

the degree of volume change when distending pressure increases.
C = Delta V/ Delta P
veins are more compliant than arteries

13

why is arterial compliance important?

important in converting pulsative flow from the heart
elastic arteries act as a pressure reservoir, continues driving blood forward during diastole

14

what are two features of distributing arteries

1. muscular - tunica media has more smooth muscle (relative to lumen) than conducing arteries
2. rich sympathetic innervation

15

what is the primary role of the distributing arteries?

conduct flow to the smaller arteries

16

what are some examples of distributing arteries?

femoral artery, internal carotid artery

17

where does the most major fall in blood pressure occur?

over the resistance vessels

18

what are examples of resistance vessels?

arterioles and metarterioles

19

what is the role of the arterioles?

regulate total peripheral resistance, control blood flow to the capillary beds with metarterioles

20

what is the wall structure of the arterioles

tunica intima - fenestrated endothelium
tunica media - 1-2 layers of smooth muscle
tunica adventitia - loose CT

21

what is the role of the metarterioles?

regulate total peripheral resistance, co-op with arterioles to control blood flow to capillary beds

22

what is the wall structure of the metarterioles?

tunica intima - fenestrated endo
tunica media - single intermittent layer of smooth muscle or no smooth muscle
tunica adventitia - not recognised

23

what is resistance?

the opposite of flow
= difference in mean pressure needed to drive one unit of flow.
the largest blood pressure decrease is found in the arterioles vessels, pulsative flow also disappears here -- this is where the largest resistance is.

24

describe the rate of blood flow (L/min)

remains the same across all vascular beds
in individual capillary speeds is very slow but same volume is maintained

25

what is TPR?

resistance to flow through the entire systemic circulation
TPR = (mean aortic pressure - Vena cava pressure/ CO)

26

what is CO?

CO = HR x TPR

27

what are some determinants of TPR?

MAP = CO x TPR
MAP = diastolic pressure e+ 1/3rd pulse pressure

28

what are two features of exchange vessels?

low resistance
high cross sectional area

29

what is the function of exchange vessels?

metabolic exchange takes place across the walls of exchange vessels, CO2, O2 and Metabolites

30

how are capillaries classified

1. position in vascular bed
2. nature of endothelial lining

31

what is the x2 essential components of capillary wall structure

1. thin endothelial layer
2 basement membrame

32

how can the endothelial lining differ

- continuous with thick or thin endothelium = lipid soluble
- fenestrated
- discontinuous = proteins can come through

33

what are sinusoids

exchange vessels
discontinuous endothelial layer and basement membrane
= allow easy interchange of macromolecules and fluid
characteristic of liver and haemopoietic tissue

34

what are post capillary venules

exchange vessels
drain several capillaries
continuous endothelial layer and basement membrane, surrounded by persecutes, no or few SMC
promote migration of WBC due to leaky joins b/w cells

35

what are capacitance vessels?

large volume and low pressure
return blood to heart
includes all muscular venules and veins

36

what is the wall structure of the capacitance vessels?

tunica intima - same as arteries but no internal elastic lamina
tunica media - relatively small amounts of SMC and elastic fibres
usually abundant collagen fibres
no external elastic lamina
tunica adventitia - many large collagen fibres in the CT
often the thickest layer

37

what factors influence venous return?

smooth muscle contraction- induce vasoconstriction
skeletal muscle pump effect
one way valves
thoracic and cardiac pressure: incl pressure gradient between veins and heart

38

valves in the lumen of veins

composed of two cusps
valves present in medium size veins.
opening of pocket directed towards the heart
standing animal, weight bearing limbs extend well below heart, would lead to pooling and excessive filtration bt the valves convert the column of the vein into short segments reducing hydrostatic pressure
--> even blood vol in each segment
valves make sure theres an equal amount of blood in each segment

increase VR prevent back flow and pooling

39

skeletal muscle pump

contraction of the muscles in the limb applies pressures to the veins. promotes movement of blood towards the heart since the valves prevent the movement away from the heart

40

respiratory activity and cardiac suction

mechanism work by increasing pressure gradient between the veins and the heart

41

sympathetically induced vasoconstriction

sympathetically induced vasoconstriction