Vascular Anatomy

Question 1

briefly explain the structure of a blood vessel

Answer 1

tunica intima - endothelial lining
tunica media - smooth muscle
tunica adventitia - CT and vasa vasorum
(its own blood supply)

Question 2

name the layers of the vascular structure from deep to superficial

Answer 2

tunica intima
internal lamina
tunica media
external lamina
tunica adventitia
adventitial fibroblasts
nerve
perivascular adipose tissue

Question 3

what are the functions of the tunica intima?

Answer 3

barrier between vessels and blood
alters blood flow
regulates capillary exchange

Question 4

what is the structure and function of the internal and external lamina?

Answer 4

composed of collagenous fibres

provides strength/flexibility and binds endothelium to CT

Question 5

what is the function of the tunica media?

Answer 5

contracts/relaxes to control vessel diameter
(vasoconstriction/vasodilation)

Question 6

what is the structure and function of the tunica adventitia?

Answer 6

composed of collagenous and elastic fibres, some smooth muscle

holds vessel in place

Question 7

what are the general functions of vascular smooth muscle in vessels?

Answer 7

determines vessel radius by contracting/relaxing
secretes ECM giving vessels elasticity

Question 8

what is the function of elastic arteries and how are they specialised to carry out their function?

Answer 8

conduct high pressure blood flow out of heart

numerous elastic fibres (lamina) in tunica media enabling walls to resist pressure and recoil (maintains arterial pressure during diastole)

Question 9

what is the function of muscular arteries and how are they specialised to carry out their function?

Answer 9

distribute blood to small arteries/organs

thick tunica media (smooth muscle contracting) to maintain BP far from heart

Question 10

what structural differences are seen in veins compared to arteries?

Answer 10

less defined tunica layers
less organised smooth muscle
thinner media than adventitia
valves present

Question 11

what is the purpose of arterial elasticity?

Answer 11

controls compliance of the vessel (expands/contracts as needed)
prevents pressure dropping as blood leaves arteries

Question 12

explain capillary function

Answer 12

exchanges nutrients/waste product from target tissues
one cell thick to allow rapid exchange

Question 13

what occurs in capillaries to favour fluid moving outwards?

Answer 13

blood in capillaries exerts pressure on capillary wall (hydrostatic pressure)

Question 14

what occurs in capillaries to favour fluid moving inwards?

Answer 14

plasma has intrinsic osmotic pressure due to plasma proteins (colloid pressure)

Question 15

what is the function of the arterioles?

Answer 15

a variable resistance system distributing blood
dissipates most of the pressure

Question 16

how can the venule/venous system be described?

Answer 16

a low pressure collecting and resevior system containing most of the blood

Question 17

how is built up tissue fluid returned to blood?

Answer 17

using lymph capillaries/vessels which contract to aid fluid movement

Question 18

what happens to resistance and flow as branching increases down the arterial tree?

Answer 18

resistance increases
flow reduced

Question 19

how is flow maintained in veins?

Answer 19

valves direct blood to heart
skeletal muscle pumps blood
respiratory movement aids venous return
in sympathetic nerves - noradrenaline constricts veins (increases venous return)

Question 20

how can vessels locally control BP?

Answer 20

a system modulating local BP/flow overrides central control systems
modified by local changes in TPR