Blood Flow and Blood Pressure

Question 1

Relationship Between Blood Pressure and Perfusion

Answer 1

Pressure is driving force of perfusion. Low pressure = low flow (organ failure). High pressure = high proliferation (damaged cells)

Question 2

Relationship between pressure, tissue stretching, baroreceptor signalling and heart rate

Answer 2

Increased pressure = increased stretching = more barorecptor signalling = activated parasymplathetic (negative chronotopes) (increased ressistance)= slowed heart rate

Question 3

Sensory Afferents Function

Answer 3

Baroreceptors activates sympathetic/parasympathetic nervous system

Question 4

Central Relays Outline

Answer 4

Cardiovascular centres in brain stem and medulla oblongata

Question 5

Effector efferents Outline

Answer 5

Innervates heart and blood vessels

Question 6

Realtionship between Cardiac Output, total peripheral ressistance and Mean Arterial Blood Pressure

Answer 6

Increase CO + Increase TPR = Increase MABP

Question 7

How baroreceptors can lead to chronic hypertension over time

Answer 7

Baroreceptor resets every few days. If blood pressure is high at all times receptor may accept high value as new standard

Question 8

Hypertension Outline

Answer 8

Independently asymptomatic. Risk factor for cardiovascular and renal disease. Measured over span of 24 hrs

Question 9

Vascular Tone Def.

Answer 9

Force holding blood vessel shape when not fully constricted or dialated. Changing radius shape effects ressistance and changes perfusion. This helps control where blood flows to. Effected by constant dialtion and condtriction messages

Question 10

Vascular Tone Regulation Outline

Answer 10

Both intrinsic and extrinsic factors. Tissues have different responses

Question 11

2 Intrinsic Levels

Answer 11

meachanical stimuli (stretch and shear) and endothelail metabolites and autocoids

Question 12

Extrinsic level

Answer 12

systemic regulation (nerves and hormones)

Question 13

Vascular Endothelium Outline

Answer 13

Intrinsic via release of paracrine factors. Can be dialators (eg NO) or vasoconstrictors (eg thromboxane)

Question 14

NO case stisy

Answer 14

Free radiacal, vasodilator, stimulted by shear stress and histamine. Relaxes vascular smooth muscle. anti-thrombogenic and anti-atherogenic

Question 15

Shear def.

Answer 15

Blood passing through artery causing pooling at endothelium

Question 16

endothelial Dysfunction consequences

Answer 16

Aggregation of blood. Impedement of substances corolling tone

Question 17

Metabolites Def

Answer 17

Vasoactive waste products of metabolism. Tend to act locally. Increased metabolites = increased relaxation

Question 18

Vasodilating Metabolites

Answer 18

CO2, K+, H+ and adenosine

Question 19

Sympathetic nervous system effects on circulatory

Answer 19

Maintains tone

Question 20

Sympathetic Fibre Innervation Results

Answer 20

Noradrenaline acts at alpha1-adrenoreceptors. Increased sympathetic activity = increased vasoconstriction

Question 21

Beta-adrenoreceptors innervation results

Answer 21

Activated by adrenaline. Leads to vasodialation

Question 22

Coronary Circulation (Heart Blood Supply) Outline

Answer 22

Left and Right coronary arteries supply myocardium and drain to right atrium. Most are end arteries (blood has 1 pathway) leading to increased risk of ischemia

Question 23

Heart O2 Consumption

Answer 23

5% cardiac ouyput. O2 extraction by perfusion is 65% at rest, increasing activity increases perfusion. Perfusion occurs in diastole (arteries are compressed at systole)

Question 24

Relationship between heart rate and amount of blood perfused

Answer 24

Increasing heart rate = decreased time for blood perfusion

Question 25

Coronary Adaptation

Answer 25

More capillaries then myocytes = decreased distances, mainly intrinsic control and the extrinsic efefct via the sympathetic nervous system

Question 26

Cerebral Circulation

Answer 26

35% O2 extraction. Irreversible damage occurs at >4 mins of ischema. Basal grey matter has more blood flow then most of body

Question 27

Cerebral Autoregulation

Answer 27

Primarily via myogenic activity and local mediators. Cerebral arteries contract when stretched (limiting blood flow). O2 Avtivity linked to K+, adenosine and NO

Question 28

pulmonary system

Answer 28

low pressure. Right ventricle is smaller then left. Lower pressure = lower ressistance

Question 29

Pulmonary Adaptations

Answer 29

Recieves same volume of blood, low extrinsic influence, pulmonary arteries act differently from systemic (eg hypoxia constricts arteries)

Question 30

Gravity and Pulmonary Circulation

Answer 30

Difference in circulation at base and top of lung. Apex of lung has compressed capillaries. Apex = no flow, middle = intermediate flow and base = continuos flow