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Physiology and Pharmacology > Lecture 15 > Flashcards

Lecture 15 Flashcards

1
Q

What are three hormones needed for body fluid homeostasis?

A

Vasopressin (Anti-diuretic hormone ADH)
Aldosterone
Renin angiotensin

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2
Q

Which gland releases vasopressin?

A

neurosecretory gland

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3
Q

What fires action potentials after being stimulated?

A

Pituitary stalk

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4
Q

Which part of the kidney does vasopressin have an effect on?

A

Level of collecting duct

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5
Q

What does vasopressin do?

A

Regulates body fluid osmolality
- How concentrated a solution is
Conserves H2O
- Stimulates the kidney to retain more water
- In cardiovascular system: changes how concentrated the plasma is
- When body fluid osmolality increases, vasopressin increases (needs to be diluted by more water retention)
- When body fluid osmolality decreases, vasopressin decreases (more water secreted in urine)

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6
Q

What do Hypothalamic osmoreceptors look for?

A

Osmolality of plasma

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7
Q

The frequency of action potential is affected by…

A

Level of osmolality

- Detect changes of +/- 3 mosmol/kg H2O (sensitive)

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8
Q

What do hypothalamic osmoreceptors stimulate?

A

Supra-optic and paraventricular nuclei

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9
Q

What does stimulation of Supra-optic and paraventricular nuclei lead to?

A
  1. Release vasopressin from posterior pituitary

2. Feeling of thirst

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10
Q

What is being detected if vasopressin levels are high?

A

Solute ingestion or H2O deficiency (not drinking enough)

Stress and drugs

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11
Q

What is an example of a substance that increases vasopressin levels?

A 
Nicotine
 - Vasopressin levels for smokers will be higher than normal people
Ecstasy (3,4-Methylenedioxymethanphetamine)
 - If you drink large volumes of fluid..
 - can't excrete excess fluid
 - build up
 - end up with oedema in brain
 - death
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12
Q

What is being detected if vasopressin levels are low?

A

Excessive fluid ingestion

Drugs

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13
Q

What drugs can decrease vasopressin levels?

A

Alcohol

  • people have background release of vasopressin
  • vasopressin levels drop further
  • fluid that kidney would have retained would be lost
  • hangovers due to dehydration
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14
Q

How is vasopressin incorporated in the Principal cell model?

A

Vasopressin B2 on basolateral membrane stimulates Protein kinase A (PKA)

  • adds phosphate groups to proteins in vesicles which fuse to the apical membrane
  • moving aquaporin 2 channels to apical membrane
  • more water reabsorbed
  • So much aquaporin 3 and 4 on basolateral membrane but they are not affected by vasopressin but aquaporin 2 is regulated (Shuttle-link hypothesis)
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15
Q

What does vasopressin do in the Principal cell?

A

Increases water reabsorption

  • leads to fall in body fluid back to normal
  • fall in body fluid osmolality
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16
Q

How much urine would humans excrete if there was no vasopressin?

A

23l

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17
Q

What is Diabetes insipidus?

A

A condition in which too much urine is produced

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18
Q

What are the two types of Diabetes insipidus?

A

Acquired (due to damage to posterior pituitary etc)

Inherited

19
Q

What is central diabetes insipidus?

A

No release of vasopressin
Easy to treat
e.g. Nasal spray DDAVP (synthetic vasopressin)
Few impacts on day-to-day life

20
Q

What is nephrogenic diabetes insipidus?

A 
Kidney doesn't respond to vasopressin
Defective V2 receptor
Water channel defect
Doesn't activate PKA
No effective treatment
21
Q

What are the three main components of the adrenal gland from inward to outward?

A

Adrenal medulla
Adrenal cortex
Capsule

22
Q

What are the three zones of the adrenal cortex?

A

Zona reticularis
Zona fasciculata
Zona glomerulosa

23
Q

WHich zone of the adrenal cortex releases aldosterone?

A

Zona glomerulosa (released in circulation)

24
Q

What is a mineralcorticoid?

A

Hormone that regulates mineral content of body
Minerals: Na,K in plasma
Regulates Body fluid volume
Very sensitive
Controls total Na content but not concentration

25
Q

What are mineralcorticoids released in response to?

A

Increase in plasma K - 0.1mM
Decrease in plasma Na - minor concentration maintained by osmoregulation
Decrease in extracellular fluid volume - via renin angiotensin

26
Q

What do mineralcorticoids act on?

A

Late distal tubule, collecting duct

27
Q

What causes the release of aldosterone?

A

Increase in reabsorption of Na
Increase in reabsorption of water
Increase in secretion of K and H

28
Q

What is found inside the Principal cell?

A 
Aldosterone
Cytosolic receptor
Nucleus
RNA transcription
Protein synthesis
Na reabsorption
K secretion
H secretion
29
Q

What are main features of aldosterone?

A

Lipid-soluble: moves across membrane
Bids to mineralocorticoid receptor in the cell
Goes to nucleus
Makes more of transport proteins such as ENaC, ROMK and ATPase

30
Q

How fast is the genomic effect of aldosterone?

A

Slow (hours to days for response)

31
Q

What does aldosterone do in alpha intercalated cells?

A

Aldosterone inside cells
- production of H pump
- genomic action
Cell give plasma parameters back to normal

32
Q

What is the net effect in alpha-IC cells by aldosterone?

A

Increase in plasma Na
Decrease in plasma H
Decrease in plasma K
Increase in extracellular fluid volume

33
Q

Which system does aldosterone coordinate its response with?

A

Renin angiotensin system

34
Q

What are diseases related to aldosterone?

A

Liddle’s syndrome
- Disconnect between aldosterone and ENaC
-Leads to high Na reabsorption
- leads to low aldosterone
- leads to lots of reabsorption of water
- leads to hypertension
- increases number of Na channels in principal cell
Pseudohypoaldosteronism
- salt loss but high aldosterone
- loss of response to aldosterone
- mutations in mineralocorticoid receptor
- no action
- low blood pressure

35
Q

What does renin angiotensin regulate?

A

Body fluid volume

Concentration of plasma Na and K

36
Q

Where is renin released from?

A

Juxtaglomerular apparatus (JGA) from kidney

37
Q

What are features of juxtaglomerular apparatus?

A

Vesicles contain renin (looks like granules)

Cell’s (macula densa) flow rate in tubular fluid that acts on tubule

38
Q

The juxtaglomerular apparatus catalyzes conversion from angiotensiogen to angiotensin I. Where does this take place?

A

In cell capillaries

39
Q

Where are most of angiotensin II made and why?

A

Lungs; has the most capillaries

40
Q

What does Angiotensin II do?

A

Minimal role in diuretic effect
Active levels on arterioles to promote constriction
- increases blood pressure
If blood pressure drops…
- causes vasoconstriction (one-way)
- body can handle water handling side
Vasoconstriction helps maintain blood pressure

41
Q

What net effect does the renin angiotensin cascade have?

A

Increased plasma Na + extracellular fluid volume

Decreased blood pressure

42
Q

What do ACE (angiotensin converting enzyme) inhibitors do?

A

Prevent production of angiotensin II
Blood pressure is going to drop to a more normal level
Another way to treat hypotension

43
Q

When integrating volume and osmolality regulation, which takes priority?

A

Volume; vasopressin system is much faster than aldosterone

Must stop vasopressin system from working

Physiology and Pharmacology (27 decks)

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