blood pressure

Question 1

what’s blood pressure like in the heart

Answer 1

-under high pressure arteries receive blood directly from the heart
-high pressure
-compared to veins, arteries have a lower compliance/ capacitance which is the ability of blood vessels to expand and hold a larger volume of blood without a significant increase in blood pressure

Question 2

what does tonically active mean

Answer 2

always a bit contracted due to vascular smooth muscle

Question 3

what’s the blood pressure like in arterioles

Answer 3

-tonically active
-highest resistance to blood flow, changed in response to:
1) sympathetic nerves (fight or flight)
=alpha1 adrenergic recs such as skin/ mucous membranes/ splanchnic arterioles leads to contraction and constriction of vascular smooth muscle leading to a decrease in diameter of arteriole and an increase in resistance to blood flow (same amount of blood flow through a smaller hole
=beta2 adrenergic recs- skeletal muscle and heart muscle leading to dilate/ relax- more O2 needed to skeletal muscles during fight or flight
-balance of a1 and b2 receptor activation plays a crucial role in regulating blood flow through different organs and tissues in changing conditions
2) circulating catecholamines (hormones) e.g. adrenaline
3)other vasoactive substances which activate vascular bed such as NO

Question 4

what is the blood pressure in capillaries like

Answer 4

-low pressure
-slow flow
-sit of exchange, but not all perfused with blood (not all full of blood at the same time)
-controlled by dilation/constriction of arterioles

Question 5

what’s blood pressure like in venues and veins

Answer 5

-low pressure
-walls contain much less elastic tissue than arteries
-large capacitance so can increase their volume
-contain large percentage of blood in CVS ‘unstressed volume”
-smooth muscle in walks innervated by sympathetic nerve fibres
-increased activity via alpha1 adrenergic receptors- contraction to reduce capacitance- decrease in ;unstressed volume’

Question 6

what’s the equation for velocity of blood flow

Answer 6

-v=Q/A
where v= velocity of blood in cm/s
Q =flow mL/s
A= cross-sectional cm2

Question 7

what’s the relationship between velocity and cross-sectional area

Answer 7

-in identical flow, there is an inverse relationship

Question 8

what’s the equation for blood flow

Answer 8

-Q=change in P/R
-where Q= blood volume per unit of time mL/s
change in P= pressure difference mmHg
-R= resistance mmHg/mL per min

Question 9

what’s the relationship between blood flow, resistance and pressure

Answer 9

-in blood pressure regulation, vasoconstriction leads to an increase in resistance causing the BP to increase (alongside blood loss and stress) vice versa for vasodilation
-blood flow distribution is adjusted due to need
-disease states

Question 10

what does TPR mean

Answer 10

-total peripheral resistance
-resistance of entire systemic vasculature

Question 11

how can resistance of a single organ be calculated

Answer 11

by substitution flow

Question 12

what’s the equation for the poiseuilles law

Answer 12

R=8nl/pie r4 *weird n
where R= resistance
n=viscosity of blood
l-length of blood vessel

Question 13

what are the factors involved in blood vessels and their resistance

Answer 13

-blood vessel diameter
-vessel length
-series/parallel arrangement (side by side)
-blood viscosity

Question 14

what are the different types of vessel arrangements

Answer 14

-series resistances
-parallel resistance

Question 15

what’s series resistance in vessel arrangement

Answer 15

–within an organ
-total resistance= sum of individual resistances
-pressure decreases though each sequential component
-largest decrease in pressure in arterioles because of the largest resistance
-change in P= R*Q

Question 16

what’s parallel resistance in vessel arrangement

Answer 16

-less than any of the individual resistances
-result= no loss in pressure e.g. aorta

Question 17

what’s the pressure in the cardiovascular system like

Answer 17

-varies throughout system
-pressure decreases with blood flow and energy is lost overcoming frictional resistance
-aorta- P high and late CO and low compliance
-arteries- P remains high with elastic recoil
-arterioles- huge decrease in P due to high resistance
-capillaries- frictional resistance to flow and filtration
-veins and venues- high capacitance and low pressure

Question 18

what’s arterial pressure (Pa) like in systemic circulation

Answer 18

-Pa oscillations reflect pulsatile heart activity
-diastolic pressure is lowest at Pa during ventricular relaxation
-systolic pressure is highest Pa following
-variation of different pressure in arterial pressure than pulmonary pressure

Question 19

what’s venous pressure (Pv) like in systemic circulation

Answer 19

-venules and veins, pressure less than 10mmHg
-result of decreased resistance at each level of vasculature

Question 20

is pulmonary pressure lower of high than systemic pressure

Answer 20

-lower due to much lower resistance

Question 21

how to work out pulse pressure

Answer 21

-systolic pressure- diastolic pressure
-reflects blood volume ejected from left ventricle (stroke volume)

Question 22

how to work out mean arterial pressure

Answer 22

• diastolic pressure +1/3 pulse pressure
  -shows the average pressure in a complete cardiac cycle

Question 23

why does pressure change throughout the day

Answer 23

-BP and CO (volume of blood pushed out the heart) change throughout the day
-normally higher in the day than at night
-regulated to meet body needs and activity levels

Question 24

how does rapid regulation of blood pressure work

Answer 24

-baroreceptors (for pressure) in carotid band aortic sinuses
-increase in Pa leads to an increased stretch therefore an increase in afferent nerve firing- vice versa
-solitary nucleus receive input
-solitary nucleus and SNS and PNS changes via medullar CV centres

Question 25

how does parasympathetic control ave a negative effect on HR and BP

Answer 25

-PNS outflow via vagus nerve to SAN leads to decrease in HR and BP

Question 26

how does the sympathetic nervous system have a positive effect on HR and BP

Answer 26

-SNS control to regulate BP:
1. SAN increases HR
2. increase in cardiac muscle contractility so an increase in stroke volume
3. arteriole vasoconstriction leads to an increase in tar
4. veins vasoconstriction leads to a decrease in unstressed volume

Question 27

is the para(sympathetic) control of BP long term or short term

Answer 27

-short term

Question 28

what’s the long term control of BP

Answer 28

-hormonal system: renin- angiotensin-aldosterone system (RAAS) regulated blood volume, electrolyte balance and systemic vascular resistance
-in kidneys:
=Pa renal perfusion pressure detected by kidney afferent arteriole mechanoreceptors, prorenin released into blood
=angiotensinogen-> angiotensin I-> angiotensin II

Question 29

what are the angiotensin II effects

Answer 29

-increase in aldosterone leading to Na+ reabsorption increase in ECF
-stimulates an increase in Na+ reabsorption in ECF
-hypothallamus causes an increase for thirst and ADH secretion so more water is reabsorbed in collecting ducts
-vasoconstriction of arterioles causes an increase in TPR

Question 30

how do chemoreceptors regulate BP homeostasis

Answer 30

-in carotid and aortic sinuses bodies detected a low O2 level which leads to arteriole vasoconstriction
-within brain detects CO2 leading also to arteriole vasoconstriction

Question 31

how does chronic hypertension work

Answer 31

-desensitises baroreceptors
-prolonged exposure to high BP reduces stretch sensitivity
-decrease in sensitivity of NTS to baroreceptor input
-blunted response of CNS
-reduced sympathetic inhibition- therefore hypertension maintained/ not corrected

Question 32

why is hypertension bad

Answer 32

-people with high blood pressure don’t often experience the night time dip in BP
-small increase in BP causes an increase I risk or morbidity and mortality
-if the BP is too high then there is extra strain on blood vessels and other organs
-persistent high BP causes an increase risk of heart disease, heart attacks, strokes, heart failure, aortic aneurysms, peripheral arterial disease, kidney disease and vascular dementia

Question 33

how can we treat hypertension

Answer 33

-low slat intake
-more exercise
-less alcohol and stress
-more weight management
-several drug treatments
-diuretic
-angiotensin- converting enzyme (ACE) inhibitors
-angiotensin II receptor blockers (ARBs)
-renin inhibitors
-Ca2+ channel blockers- contractility and increased vessel relaxation
-beta blockers -HR and contractility