Special Circulations

Question 1

the 2 circuation systems of the heart and what leads them?

Answer 1

• pulmonary = supply driven
• systemic = demand led

Question 2

what side of the heart determines cardiac output

Answer 2

left side

Question 3

describe the b supply associated with the lungs

Answer 3

• pulmonary artery are superior to the pulmonary veins
• lungs get their own b supply for metabolic needs via the bronchial circulation

Question 4

what affects special circulations

Answer 4

-special tasks -adaptations -clinical problems

Question 5

pressure of the RV and LV (systole and diastole)

Answer 5

RV= 15-30 systole

RA 0-8mmHg

LV=100-140mmHg systole

LA=1-10mmHg

Question 6

why not same systolic pressure in ventricles and atria

Answer 6

b ventricles contract more than the atria (90% gravity)

Question 7

pressure of Aorta and PA (systole and distale)

Answer 7

A= 100-140mmHg systole A = 60-90 mmHg diastole PA =15-30mmHg systole PA=4-12 mmHg diastole

Question 8

why is the diastolic pressure the way it is in the aorta

Answer 8

because of the elastic recoil of the , aorta/arteries maintains the bp we have higher diastolic pressure in the aorta compared to the sudden drop in the ventricle

Question 9

PA-

Answer 9

elastic recoil of the PA maintains that blood pressure

Question 10

features of the Pcirculation

Answer 10

-lower resistance therefore shorter distance -lots of capillaries - arterioles have relatively little smooth muscle this helps keep lumen one and v resistance so b flow is more readily transported

Question 11

adap

Answer 11

-very high densities of capillaries in the alveolar wall so large capillary surface area - short diffusion distance i.e capillaries close to alveoli 0.3microm so overall large SA and short distance

Question 12

what must you match

Answer 12

ventilation and perfusion ratio

Question 13

wats the V/Q rtion

Answer 13

• matching ventilation of alveoli with its perfusion -0.8

Question 14

how do you maintain that V/Q ratio

Answer 14

by diverting blood from the alveoli which aren’t ventilated

Question 15

how does this happen

Answer 15

-response to hypoxia;

Question 16

hy

Answer 16

-hypoxic pulmonary vasoconstriction - constrict and lumen the of vessel of hypoxia present this optimises -differecne in csytemic sicruclation is vasodialtion

Question 17

dis

Answer 17

-works well with mucus block -but chronic hypoxia can cause Right ventrciular failure - so if someones living in low altitude, then gt hypoxia wc c vasoconstriction wc increases resistance b RS failed b pressure ^ to try and pump b around the lung

Question 18

emphysema

Answer 18

• ^ resistance of vessels in lungs so harder for RS to pump c RS ventricular failure

Question 19

what are the vessels influenced by? what happens in the upright position? how does this work at different levels to the lungs?

Answer 19

-gravity -at upright position there’s greater hydrostatic pressure on vessels in the lower part of the lung -bv above the lung collapse due to the the lower hydrostatic pressure (wc is created by gravity) - below the lungs the vessels distend due to increased hydrostatic pressure (this pressure is due to the effect o gravity)

Question 20

effect of exercise on pulmonary flow

Answer 20

• ^ exercise = ^ arterial bp so pulmonary arterial bp so the bv above the lungs (apical) are open instead of collapsing and this improves the V/Q ratio -also b flows better through the capillaries w/o impairing gas exchange (goes from 1 second for RBC to flow and undergo gas exchange to 0.3, without resulting in less gas exchange to occur, this is possible d to short diffusion distance and ^ capillaries)

Question 21

formation of tissue fluid systemic

Answer 21

• Starling’s LAW ; it determines fluid formation , hydrostatic pressure (out) +oncotic pressure (plasma P draws fluid into capillaries) - fluid taken up by lymphatic

Question 22

what is hydrostatic pressure affected more by?

Answer 22

-venous pressure (5x greater( than arterial pressure changes)

Question 23

if venous pressure ^

Answer 23

^ hydrostatic pressure

Question 24

peripheral oedema is seen with what pressure change

Answer 24

venous d more fluid moving out d^ hydrostatic pressure and lymphatic cant take it in

Question 25

whats the hydrostatic pressure of lungs? and why less likely to form ins

Answer 25

lower hydrostatic pressure / oncotic same / higher intersitial oncotic pressure -but fluid does move out, just less than the systemic , so filtration and resabosprtion in

Question 26

^ hydrostatic pressure in lungs

Answer 26

• more fluid moves out so get pulmonary oedema -^venous pressure and ^ arterial pressure (this isn’t a thing in the systemic circulation because arterioles don’t contribute much to hydrostatic pressure d lower resistance(?)

Question 27

what prevents odemea

Answer 27

Low capillary pressure - ^ arterial pressure

Question 28

pulmonary oedema effecdt

Answer 28

• impair gas exchange -affected by posture, upright okay but speed they get fluid build up d gravity pulling fluid at the base of lungs when upright , so more spread of the fluid during the -also lie down, congenital heart failure, lower p o reabsorption c increasing b volume returning in the heart ^ pressure in the lung c ^ p o

Question 29

pO tratmetn

Answer 29

-diuretic to v b volume -treat underlying cause

Question 30

cerebral circulation demand of the brain? and why?

Answer 30

• brain wants 20% of (15% of cardiac output d neurones continuously active) - bra

Question 31

how does the

Answer 31

• ^ capillary density (^SA - v cerebral diffusion (10microm) - ^basal floor - high 02 extraction (more than 35% of the whole body, good diffusion gradient)

Question 32

why is this 02 demand important in the brain?

Answer 32

• neurones are sensitive to hypoxia - drop of perfusion, loose consciousness and innrevesibel damage to neurones in 4 mins

Question 33

how is b supply ensured in brain?

Answer 33

-sturctural; anatomies between basilar(from vertebral) and carotid arteries , ‘circle of wills?’ - functionally; myogenic auto regulation maintains perfusion during hypotension / metabolic factors / brainstem regulates flow (of other circulation)

Question 34

myogenic auto regulation

Answer 34

• the cerebral resistance vessels in the brain have a myogenic response to changes in transmural pressure - ^ bp across body (systemic) = increases b flow to the brain, but don’t want too much, so vessels vasoconstriction to maintain relative b f - b flow v = vasodilation ot ^ b flow to the brain

Question 35

image

Answer 35

-myogenic response by ^ resistance / v restiane by contracting and dilating to maintain a b f

Question 36

myogenic response were else found?

Answer 36

-renal, skeletal muscle

Question 37

metabolic regualtions ?

Answer 37

• hypercapnia ^Co2 vasodilation to remove that - hypercapnia v co2

Question 38

how does ventilation c syncope?

Answer 38

• v co2 so hypocapnic state, detected by myogenic cerebral vessels wc c vasoconstriction and v bf to therein

Question 39

what shows regional activity bf differences? more neuronal acitivy what metallic factors released?

Answer 39

• fMRI - ^ pco2,k+,adenosine (vasodilator ),v p02

Question 40

Cushing’s reflex

Answer 40

-skull doesnt allow expansionists , so ^ cranial pressure (e.g tumour/haemorrhage) c ^ pressure int he brain c vasoconsitricon and implore cerebral b flow - push brain down towards the foramen magnum c bushings reflex ; vasomotor control centre in brain stem, push onto them c ^ SYMP vasomotor action so ^ SYMp to peripheral so activate a-.. c vasoconstriction c ^ arterial bp wc maintains cerebral bp B also detected by baroreceptors os ^ vagus acitivy of heart so you see bradycardia with ^ bp , -it also affects respiratory c irregular breaths

Question 41

coronary ciruclation rate?

Answer 41

• R L coronary armies come off L R aortic sinuses - at rest 70pbm, but can ^ 5 folds if excercise (so this demand must be met ) - LCA gets flow during diastole

Question 42

cardiac vs skeletal muscles perfusion

Answer 42

• fibre diameter is smaller in cardiac, continuous patent d NO. released by endothelial,=this maintains ^ basal flow rate , so ^ capillary density -some vessels in seltela are closed and not perfused at rest c v capillary density + also their bv have ^ fibre diametre -endo

Question 43

metabolic hyperaemia

Answer 43

-metabolic factors acting as vasodilators - adenosine, k+ ^ and vpH c VASODILATION

Question 44

what are coronary arteriesprone to

Answer 44

angina d few arterio-arterial anatomies

Question 45

hw does angina occur and what part of life cycle? what else can c angina?

Answer 45

• diastole shortened therefore more b flow reduced -cold and stress

Question 46

skeletal muscle

Answer 46

^ supply of 02 to meet demands , also regulates arterial b pressure, -resistance vessels have rich innervations by SYM vasoconstriction part of the baroreceptor reflex maintains b p

Question 47

skeletal muscle

Answer 47

^ supply of 02 to meet demands , also regulates arterial b pressure, -resistance vessels have rich innervations by SYM vasoconstriction part of the baroreceptor reflex maintains b p - capillary density depends on the muscle type , postural ones wc are used 24/7 have more capillary

Question 48

why does high capillary tone matter in skeletal muscle

Answer 48

• bg increase in flowx20 fad, or great increase in vasodilation

Question 49

what c increased flow

Answer 49

metabolic hyperaemia ; ^ k, ^ osmolarity, inorganic phosphates, adenosine, ^H -adrenaline wc acts on beta 2 and noradrenaline a1

Question 50

cutaneous circulation how is body temp regulated?

Answer 50

temp regulation , d vasoconstriction of bv in hehe skins (capillary bed) bradykinin and arterio-venous anatomies -arterio-venous anatomies wc are under vasoconsitricon from sympathetic control, turning it off c vasodilation so lose heat a lot b lose heat through a-venous anastomies and capillary bed -also bradykinin released c vasodilation c loss of heat