Lecture 2: Blood Pressure

Question 1

what do portal systems allow

Answer 1

transport of chemicals from one tissue to another without being diluted by mixing with blood at the heart

Question 2

what is a portal system

Answer 2

2 capillary beds in series

Question 3

what is a healthy blood pressure

Answer 3

120 / 75

Question 4

what is the reciprocal of heart rate

Answer 4

RR interval, 60 / heart rate

Question 5

what is stroke volume and average value for an adult

Answer 5

• volume of blood pumped out of a ventricle during one beat of the heart
• 70ml

Question 6

what is cardiac output and average value for an adult

Answer 6

• volume of blood pumped out of a ventricle per minute

- 4.9 L/min

Question 7

what is end diastolic volume and average value

Answer 7

• volume of blood in ventricle at the end of diastole

- 120ml

Question 8

what is end systolic volume and average value

Answer 8

• volume of blood remaining in ventricle at the end of systole
• 50ml

Question 9

what is ejection fraction (Ef) and average value

Answer 9

• percentage of filled ventricular volume pumped out during a heart beat
• 55-70%

Question 10

how does vasoconstriction affect resistance and flow rate

Answer 10

• higher resistance

- lower flow rate

Question 11

by what power does flow increase as radius increases

Answer 11

power of 4

Question 12

what causes vasoconstriction and dilation

Answer 12

• CNS autonomic and endocrine systems
• local regulation of pressure
• immune system
• haemostasis

Question 13

where does exercise cause vasodilation and vasoconstriction

Answer 13

• vasodilation in muscle and skin

- vasoconstriction in splanchnic (digestive) circulation

Question 14

how is heart rate, systolic pressure and diastolic pressure affected when standing up

Answer 14

• heart rate increases
• systolic unchanged
• diastolic increases

Question 15

how is systemic blood pressure controlled

Answer 15

• endothelial cells make NO, causing relaxation of muscle tissue
• symapthetic system releases noradrenaline
• hormones released by renal pituitary and adrenal systems

Question 16

where are baroreceptors located

Answer 16

• transverse aortic arch

- left and right internal carotid arteries

Question 17

what do chemoreceptors detect and where are they located

Answer 17

• detect when O2 levels are low and feed back to the brain

- aortic and carotid bodies

Question 18

what is venous return

Answer 18

rate of blood flowing back to heart through the veins

Question 19

what is preload

Answer 19

• initial stretching of cardiac myocytes during diastole, before contraction
• ventricular filling

Question 20

what is volume overload

Answer 20

pathological state when preload is too large for the heart to pump out

Question 21

how does heart rate affect preload

Answer 21

decreased heart rate increases preload, as there is more time for the ventricles to fill

Question 22

what is afterload

Answer 22

resistance during systole

Question 23

what factors increase afterload

Answer 23

• increased back pressure from aorta or pulmonary arteries

- if the exit valve fails to open completely

Question 24

what results from elevated afterload

Answer 24

pressure overload

Question 25

features of the pulmonary circulation

Answer 25

• high capillary density
• low vascular resistance
• act as blood reservoir and filter
• endocrine control of blood pressure by ACE

Question 26

how does low O2 affect pulmonary circulation

Answer 26

• constriction of arterioles

- minimises amount of blood that is poorly oxygenated

Question 27

what is hypertension caused by

Answer 27

• mismatch between blood volume and circulatory capacity
• mostly idiopathic, hormones or brain medulla
• secondary to kidney diseases

Question 28

what can chronic hypertension lead to

Answer 28

• aneurysm or stroke
• myocardial infarct
• kidney failure
• heart failure
• cardiac hypertrophy

Question 29

what is orthostatic hypotension and what is it caused by

Answer 29

• low blood pressure on standing

- drugs, hypovolaemia and age

Question 30

signs and symptoms of cardiogenic shock

Answer 30

• tachycardia and tachypnoea are compensatory mechanisms
• low urine output
• hypotension
• confusion
• syncope
• acidosis