vascular control

Question 1

why is the circulatory system called the closed system?

Answer 1

blood remains within the vessels

Question 2

diagram of the circulatory system?

Answer 2

slide 4
lecture 9 Vascular control

Question 3

what is the inner lumen for arterial, capillary and venous systems for?

Answer 3

to regulate movement of blood in/out of the circulation

Question 4

what is the structure of capillaries?

Answer 4

single layer endothelial cells
lack smooth muscle cells
basement membrane of collagen and pericytes
fenestrations in some for movement of larger moelcules

Question 5

what is the purpose of capillaries?

Answer 5

deliver oxygen to tissues and bring about metabolic exchnage

Question 6

what arteries and veins change structure when blood is carried?

Answer 6

muscular arteries
elastic arteries
arterioles
valves
position of veins around arteries and skeletal muscles to push blood

Question 7

how are arteries and venules connected?

Answer 7

capillaries

Question 8

what happens at the arteriole end?

Answer 8

muscle constricts to regulate blood flow

Question 9

what are anastomoses?

Answer 9

direct link between arteriole and venule

Question 10

how does oncotic and hydrostatic pressure differences in capillary bed effect molecule movement?

Answer 10

regulates movement of molecules in circulation system

Question 11

what are the systolic and diastolic ventricular wall stresses influenced by?

Answer 11

systemic arteriolar and venous tone

Question 12

what do arteriole tones control?

Answer 12

vascular resistance and therefore blood pressure

Question 13

what are arteries and small muscular arteries known as?

Answer 13

resistant vessels

Question 14

what are baroreceptors and chemoreceptors for?

Answer 14

regulate mean arteriole pressure

Question 15

where are baroreceptors and chemoreceptors located?

Answer 15

carotid arteries and aorta

Question 16

what effects blood flow and blood pressure?

Answer 16

cardiac output- blood flow from the heart
compliance- ability to expand if increases in content
volume of blood- increases blood pressure
viscosity of blood-number of blood cells
blood vessel length and diameter- effects tone

Question 17

what is afterload?

Answer 17

systolic ventricular wall stress include vascular resistance/ arteiolar tone

Question 18

what is preload?

Answer 18

end-diastolic ventricular wall stress includes venous tone which regulates blood returning to the heart

Question 19

how is tissue perfusion ensured?

Answer 19

balanced O2 delivery to the heart

Question 20

when does coronary perfusion occur?

Answer 20

during diastole

Question 21

when does Myocardial ischemia occur?

Answer 21

when O2 supply and demand isn’t balanced

Question 22

what are the roles of endothelium?

Answer 22

transport of blood
haemostasis for clotting
vascular tone to control constriction
haemodynamic controls flow, viscosity and wall tension
Host defence
Angiogenesis for tissue repair
growth factors

Question 23

what is the structure of endothelium cells?

Answer 23

very flat
central nucleus
long axes parallel to direction of blood flow
stress fibres
gap junctions

Question 24

what is the structure and characteristics of smooth muscle cells?

Answer 24

lack sarcomeres
actin-myosin filaments arranged indirectly
action potentials are varied
anchor points for actin
interact with neighbouring cells
slower contraction time
sustained for longer periods

Question 25

draw diagram of vascular smooth muscle?

Answer 25

slide14
lecture 9 vascular control

Question 26

how does contraction occur in vascular smooth muscles?

Answer 26

dependant on Ca2+
uses calmodulin instead of troponin
Ca2+ binds to calmodulin and activates myosin light chain kinase (MLCK)
myosin heads are phosphorylated and increase myosin ATPase activity
Depolarization / hyperpolarization is dependant on Ca2+ and K+

Question 27

what are the mechanics of smooth muscle contraction?

Answer 27

contraction is slow and sustained
dense bodies are analogous to Z liens in cardiac muscle
myosin head are in side polar arrangements
dense bodies pulled closer by contraction

Question 28

difference between cardiac muscle and smooth muscle?

Answer 28

smooth muscle aren’t arranged parallel
they cause a twisting contraction

Question 29

what is vascular tone regulated by?

Answer 29

NO and Ca2+ stimulate contraction and relaxation

Question 30

what is nitric oxide for?

Answer 30

a gas released by endothelial cells for vasodilation/relaxation

Question 31

what does nitric oxide do in blood?

Answer 31

inhibits platelet adhesion

Question 32

what is endothelin?

Answer 32

vasoconstrictor peptide and is the mirror image of NO
produced by endothelial cells

Question 33

what are the three different isoforms of endothelin?

Answer 33

ET-1, ET-2, and ET-3

Question 34

what are endothelin subtypes?

Answer 34

ETA and ETB

Question 35

what does ETA do?

Answer 35

mediates vasoconstricition

Question 36

what does ETB do?

Answer 36

mediate vasodilation

Question 37

what is the renin-angiotensin-aldosterone system involved in?

Answer 37

regulated blood volume and fluid metabolism

Question 38

what is the role of the enzyme renin?

Answer 38

converts circulating angiotensinogen into angiotensin I
then converted to angiotensin ll by angiotensin converting enzyme (ACE)

Question 39

what is angiotensin ll?

Answer 39

potent vasoconstrictor peptide by releasing Ca2+

Question 40

what molecules stimulate vasoconstriction?

Answer 40

epinephrine
EPO
Antidiuretic hormone
Activation of α1-adrenergic receptors

Question 41

how vascular smooth muscle relaxed?

Answer 41

Atrial natriuretic peptide increasing intracellular cGMP causing dephosphorylation of MLCK and causing vasorelaxation

Question 42

how does autonomic nervous system influence vascular tone?

Answer 42

because vascular beds have sympathetic innervation and no parasympathetic innervation

Question 43

how does Ca2+ blockers effect the cardiovascular system?

Answer 43

Ca2+ regulates constriction of myocardium