hypotension

Question 1

what happens to baroreceptors when there is hypotension

Answer 1

the blood vessel walls are not stretching, meaning the sodium channels on the nerve endings are not opened leading to no action potentials
therefore there is inhibition of the baroreceptors

Question 2

what are the three centres in the medulla oblongata

Answer 2

cardiac acceletory
vasomotor
cardiac inhibitory

Question 3

which centres of the medulla oblongata are sympathetic

Answer 3

cardiac acceletory and vasomotor

Question 4

which regions of the medulla oblongata are parasympathetic

Answer 4

the cardiac inhibitory centre becuase it has the dorsal nucleus of the vagus nerve

Question 5

which two factors will affect blood pressure

Answer 5

total peripheral resistance and cardiac output

Question 6

what is total peripheral resistance

Answer 6

the constriction of the blood vessels that impacts the speed or force that blood is being pumped

Question 7

which centres are activated when there is low blood pressure

Answer 7

the vasomotor A1 centre and the cardiac acceletory centre

Question 8

what are the main pathways the activation of the cardiac accelatory centre

Answer 8

• sinoatrial node stimulation
• atrioventricular node stimulation
• increase contractility through the myocardium

Question 9

how does the cardiac acceletory system increase heart rate through the nodes of the heart

Answer 9

• preganglionic fibres in the lateral grey horn of the thoracolumbar region of the spinal cord come out
• release noradrenaline and bind to beta one adrenergic receptors on the nodes
• g stimulatory proteins activated
• GDP to GTP
• GTP works with adenyl cyclase to convert ATP to cAMP
• cAMP activates the protein kinase A
• phosphorylates calcium channels
• influx of calcium
• more action potentials
• increased heart rate
• increased cardiac output
• increased blood pressure

Question 10

how does the cardiac acceletory centre act on the myocardium to increase blood pressure

Answer 10

• same mechanism as the nodes
• noradrenaline binding to stimulate influx of calcium ions into the contractile units of the heart
• more cross bridge formation
• more powerful contractions
• increased stroke volume
• increased cardiac output
• increased blood pressure

Question 11

how does the vasomotor centre increase blood pressure

Answer 11

post ganglionic nerve fibres from thoracolumbar region that goes to blood vessels tunica media
- release noradrenaline to bind to alpha one adrenergic receptors
- more calcium enters the cell
- vasoconstriction
- decreased radius
- increased total peripheral resistance
- increased blood pressure

Question 12

how does the adrenal medulla act to increase blood pressure

Answer 12

sympathetic fibres activate production of adrenaline and noadrenaline from the chromaffin cells of the medulla.
adrenaline causes vasoconstriction of blood vessels and contractility in the myocardium

Question 13

what proportion of hormones from the adrenal medulla is adrenaline

Answer 13

80%

Question 14

what proportion of hormones produced by the adrenal medulla are noradrenaline

Answer 14

20%

Question 15

how do kidneys increase blood pressure

Answer 15

• detect low blood delivery
• release renin from its JG cells
• adrenaline also acts on beta one adrenergic receptors in the kidney to increase renin production
• renin in the bloodstream
• comes across angiotensinogen and activates it
• angiotensin follows circulation to the lungs
• ACE converts it to angiotensin 2

Question 16

what produces angiotensinogen

Answer 16

liver

Question 17

how does angiotensin 2 increase blood pressure

Answer 17

• adrenal cortex zona glomerulosa: stimulates aldosterone release
• stimulates action potentials in hypothalamus: release ADH into bloodstream
• increases thirst levels: greater fluid absorption in the small intestine, greater blood volume
• increase sodium water and chloride absorption in the proximal convoluted tubule to increase blood volume
• act on tunica media for vasoconstriction

Question 18

what does ADH do

Answer 18

goes to kidney to act on receptors to activate g stimulatory proteins - same pathway for protein kinase A to phosphorylate the aquaporins to increase water absorption into the blood to increase plasma volume and therefore blood volume.

Question 19

what does aldosterone do

Answer 19

increases sodium levels

Question 20

what happens to urination during hypotension and why

Answer 20

oliguria, decreased urine flow, occurs due to an increase in absorption of fluids into the body to try and maintain the blood volume and pressure.