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Physiology Exam 2 Endocrine (Shelby) > Adrenal Medulla > Flashcards

Flashcards in Adrenal Medulla Deck (42)
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1
Q

dopamine enters _______ and is converted to norepinephrine by _______

A

the granules

dopamine B-hydroxylase

2
Q

Catecholamine effect on pupils?

A

dilation

3
Q

Catecholamine effect on alertness?

A

increased

4
Q

What is the rate limiting step of catecholamine synthesis

A

tyrosine hydroxylase converting tyrosine to DOPA

5
Q

Catecholamine effect on GI activity?

A

decreased

6
Q

synthesis of catecholamines occurs in the ____ cells

A

chormaffin

7
Q

What are the two main enzymes of catecholamine degradation?

A
  1. monoamine oxidase (MAO)

2. Catechol-O-methyltransferase (COMT)

8
Q

What is the only cause of HYPERfunction of adrenomedullary catecholamine synthesis

A

pheochromocytoma

9
Q

monoamine oxidase (MAO) converts norepinephrine into __________ and is then excreted in the urine as __________

A

MHPG - 3-methoxy-4-hydroxyphenylglycol

VMA - 3-methoxy-4-hydroxymandelic acid

10
Q

Pheochromocytoma produces catecholamines ___x more than normal

A

20

11
Q

tyrosine hydroxylase converts ______ to _______

which part of the cell?

A

tyrosine to DOPA

cytosol

12
Q

Which enzyme predominantly degrades epinephrine?

A

Catechol-O-methyltransferase (COMT)

13
Q

Chronic stress activates which enzyme in the pathway of catecholamine synthesis

HOW

A

tyrosine hydroxylase

increased expression and concentration

(acute stress = activity of TH)

14
Q

Catechol-O-methyltransferase (COMT) degrades which catecholamine?

A

epinephrine

15
Q

Catecholamine effect on bronchioles?

A

dilation

16
Q

phenylethanolamine-N-methyltransferase “PNMT” is regulated by:

A

cortisol

17
Q

storage of catecholamines:

\_\_\_% = norepinephrine 
\_\_\_% = epinephrine
A

15% epinephrine

85% norepinephrine

18
Q

half life of catecholamine

A

~2 min

19
Q

What converts DOPA to dopamine?

A

amino acid decarboxylase

20
Q

monoamine oxidase (MAO) degrades which catecholamine?

A

norepinephrine

21
Q

Which enzyme predominantly degrades norepinephrine?

A

monoamine oxidase (MAO)

22
Q

clinical manifestations of pheochromocytoma

What age is it usually found/diagnosed?

A
  1. hypertension
  2. rapid pulse
  3. chest pain
  4. sweating
  5. headache
  6. hyperglycemia***
  7. fatigue

40’s/50’s

23
Q

What can be measured in the urine that serves as an index of SNS activity or pathology

A

VMA - 3-methoxy-4-hydroxymandelic acid

24
Q

MOST of the norepinephrine made in the granules is ______________

SOME of the norepinephrine made in the granules is ______________

A

MOST = converted to epinephrine in the cytosol

SOME = stored in granules

25
Q

phenylethanolamine-N-methyltransferase “PNMT” converts _________ to ________

which part of the cell?

A

norepinephrine to epinephrine

cytosol

26
Q

Where do you find Catechol-O-methyltransferase (COMT)

A

heart, liver, kidney

27
Q

Acute stress activates which enzyme in the pathway of catecholamine synthesis

HOW

A

tyrosine hydroxylase

ACTIVITY

(chronic stress = increased expression and concentration of TH)

28
Q

What enzyme converts tyrosine to DOPA

A

tyrosine hydroxylase

29
Q

Catechol-O-methyltransferase (COMT) converts epinephrine into __________ and is then excreted in the urine as __________

A

MHPG - 3-methoxy-4-hydroxyphenylglycol

VMA - 3-methoxy-4-hydroxymandelic acid

30
Q

catecholamine effects on the cardiovascular system

A
  1. increased cardiac contractility
  2. increased heart rate
  3. increased conduction
  4. increased blood pressure
  5. increased arteriolar vasoconstriction in the renal, splanchnic and cutaneous bed
31
Q

amino acid decarboxylase converts _____ to _____

which part of the cell?

A

DOPA to dopamine

cytosol of the cell

32
Q

What is the only cause of HYPOfunction of adrenomedullary catecholamine synthesis

A

post-adrenalectomy surgery

33
Q

dopamine B-hydroxylase converts _____ to _____

which part of the cell?

A

dopamine to norepinephrine

granules

34
Q

epinephrine mobilizes fuels of stress by:

A
  1. increased glycogenolysis
  2. inhibition of glycogen synthesis
  3. increased gluconeogenesis
  4. inhibition of insulin secretion
  5. increased glucagon secretion
  6. increased lipolysis
35
Q

What is pheochromocytoma?

How can it be detected?

A

catecholamine-secreting tumor

VMA (3-methoxy-4-hydroxymandelic acid) in the urine

36
Q

what enzyme converts norepinephrine to epinephrine

A

phenylethanolamine-N-methyltransferase

“PNMT”

37
Q

Secretion of catecholamines occurs during which events (5)

A
  1. fight-or-flight
  2. hypotension
  3. shock
  4. heart failure
  5. hypoglycemia
38
Q

What is the precursor molecule for all catecholamines

A

tyrosine

39
Q

catecholamine effects:

fast/slow ?
short-acting/ long lasting?

A

fast

short-lived

40
Q

Why does epinephrine mobilize fuels in times of stress?

A

to sustain glucose production for use by the CNS

41
Q

cortisol regulates which enzyme in catecholamine synthesis?

A

phenylethanolamine-N-methyltransferase

“PNMT”

42
Q

Where do you find monoamine oxidase (MAO)

A

neuronal cytoplasm