Cardio 2: Structure Of Blood Vessels

Front 1

Describe the structure/function of elastic vs muscular arteries.

Back 1

elastic - more elastic fibres, conducting, expand slightly with each heart beat
muscular - more smooth muscle fibres, distributing, branch into arterioles - regulate blood flow & BP (diameter controlled by autonomic nervous system)

Front 2

Describe 4 characteristics of capillary walls

Back 2

- 1 cell thick
- continuous or fenestrated (pores)
- pericytes - contractile cells
- specialised sinusoids (liver, spleen, BM) - special lining cells & incomplete basal lamina

Front 3

What vessels do capillaries merge into?

Back 3

venules

Front 4

List 4 differences between artery & vein structure, & how their flow is determined

Back 4

Arteries: thick media, thin adventitia, narrow lumen, vasoreactive elastic lamina, flow determined by systolic pressure

Veins: thin media, thick adventitia, wider lumen, semilunar valves, flow determined by 'muscle pump' & pressure factors

Front 5

name 3 structures of the body blood vessels do not reach.

Back 5

cartilage
epithelia
cornea

Front 6

name the 3 layers of vessel walls. What makes up the vasoreactive layer of arteries?

Back 6

tunica
- intima
- media
- adventitia

vasoreactive layer:
- internal elastic lamina
- tunica media
- external elastic lamina

Front 7

What vessel wall layer do atheromas start in?

Back 7

tunica intima. Destruction of the endothelium leads to thrombus formation.

Front 8

What changes occur when arteries become arterioles?

Back 8

constriction due to fewer smooth muscle cells in the tunica media

Front 9

Name 5 general factors that affect blood vessel diameter.

Back 9

- local metabolites (CO2)
- sympathetic nerve fibres
- vasoreactive hormones (alter BP)
- endothelium secretions (NO)
- mechanical factors (stretch)

Front 10

What are vasa vasorum & why do larger blood vessels have them?

Back 10

vasa vasorum = vessel network that supplies vessels themselves.
Larger vessels have walls that are too thick for the vessel to receive O2 & metabolites from their containing blood flow. More common in veins due to reduced O2 content of blood. Found in adventitia with branches into media & intima.

In body, cells generally within 50-100nm of nearest capillary.

Front 11

name 4 characteristics of smooth muscle in tunica media.

Back 11

- spindle-shaped cells with single, central nucleus
- 20-200um length
- not striated
- may have intrinsic activity, modified by e.g. ANS

Front 12

name 4 characteristics of cardiac muscle.

Back 12

- cylindrical, branched cells with single, central nucleus
- 50-100um
- striated
- intrinsic rhythmicity, modified by e.g. ANS

Front 13

name 4 characteristics of skeletal muscle.

Back 13

- cylindrical fibre cells, multiple peripheral nuclei
- 20cm
- striated
- require motor activation

Front 14

What is the microcirculation? What are its regulatory functions?

Back 14

microcirculation = delivery of fresh blood to the smallest blood vessels present within the vasculature embedded within organ tissues.
Regulates:
- blood flow, tissue perfusion
- BP
- tissue fluid (oedema)
- delivery of O2, nutrients, remove waste
- body temp
- role in inflammation

Front 15

What are pericytes? Name 4 functions.

Back 15

contractile mesenchymal cells surrounding capillaries.
- control blood flow, increase BP
- phagocytosis
- BBB permeability
- form fibroblasts for scar formation

Front 16

What is the precapillary sphincter? What happens when there is low blood flow?

Back 16

band of smooth muscle that adjusts blood flow.
Spasm when blood flow is low, so blood bypasses the capillary bed & flows through arteriovenous shunts e.g. in shock

Front 17

Name the 3 classes of capillaries.

Back 17

- continuous (uninterrupted endothelium, continuous basal lamina)
- fenestrated (pores, continuous basal lamina)
- discontinuous (open intercellular gaps)

Front 18

What are arteriovenous shunts? Where are they important? What controls them?

Back 18

vessels that provide a straight link from arteries to veins, bypassing capillaries.
Important in cutaneous circulation, direct blood into venous plexuses to enhance heat loss.
Under sympathetic control not metabolic.

Front 19

What are venae comitantes? What is their role in heat exchange?

Back 19

'companion veins' - deep veins that accompany arteries.
Collect blood from superficial veins via perforting veins which penetrate the deep fascia e.g. in leg, converge to form popliteal then femoral vein.
venous return aided by arterial pulsations

counter-flow of blood in arteries & vena comitantes permits heat exchange of blood going to/from peripheries.

Front 20

What structures in blood vessels help blood return to the heart?

Back 20

veins contain semilunar valves - essential given low pressure gradients & muscle pump actions generating blood flow.

Front 21

Explain varicose vein occurrence following thrombosis in a deep vein.

Back 21

Common in saphenous vein. Thrombosis causes distension, resulting in valve failure, so distension self-reinforcing. Superficial veins not helped by muscle pump. They drain through perforating veins into deep veins, so factors that impede deep flow e.g DVT may result in varicosities in superficial veins.

Front 22

What are end arteries? Give example. What will happen in the case of atherosclerosis?

Back 22

End arteries do not form anastomoses with each other, so only 1 pathway by which blood can reach a particular tissue region.
Lack of parallel blood flow in most parts of the heart - coronary arteries are end-arteries.
If artery blocked through atherosclerosis, supplied myocardium will become ischaemic & die.