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VMP824 Physiology/Microanatomy 2 > Lecture 18 2/16/24 > Flashcards

Lecture 18 2/16/24 Flashcards

1
Q

What is the single parent precursor of hormones in the ACTH family?

A

POMC

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2
Q

Which molecules are produced when POMC is split roughly in half?

A

-AACTH
-b-LPH

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3
Q

What must occur in order for AACTH and b-LPH to be secreted?

A

the two molecules must be separated via hydrolysis and co-secreted by pituitary cells

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4
Q

What can ACTH be hydrolyzed into?

A

-aMSH
-CLIP

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5
Q

What can b-LPH be hydrolyzed into?

A

-y-LPH
-b-endorphin

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6
Q

Which amino acids in ACTH are the most important and bioactive?

A

the first 24 AAs

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7
Q

Why is it important that ACTH is measured via an antibody recognition site in the tail?

A

-mutated ACTH with a normal bioactive region and abnormal tail can be active in the animal without being detected via assay
-mutated ACTH with a normal tail but abnormal bioactive region can lead to signs of ACTH deficiency while producing normal assay results

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8
Q

What are the potential roles of oxytocin?

A

-synthetic oxytocin used to reinforce contractions during birth process
-naturally produced oxytocin triggers milk ejection during breastfeeding

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9
Q

What is the primary source of both oxytocin and ADH?

A

hypothalamus

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10
Q

Which family is ADH classified into?

A

oxytocin family

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11
Q

What is a receptor?

A

molecule on the cell surface or within the cell that recognizes and binds with ligands to produce some effect in the cells

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12
Q

What are the characteristics that can vary between different receptors?

A

-specificity for hormone
-affinity
-saturability
-reversibility of binding
-specific response

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13
Q

What are the characteristics of receptor specificity?

A

-often HIGH specificity for the hormone/ligand
-can have some overlap with very similar hormones

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14
Q

What are the characteristics of the mineralocorticoid receptor (MR)?

A

-belongs to cytoplasmic/nuclear receptor family
-activated by mineralocorticoids and glucocorticoids
-protected from glucocorticoids via enzyme that converts cortisol into cortisone

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15
Q

What are the characteristics of receptor affinity?

A

-strength by which hormone is bound to its receptor
-high affinity receptor requires less hormone to reach 50% receptor saturation

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16
Q

How does affinity relate to concentration?

A

decreased concentration requires receptor to have increased affinity

17
Q

How does affinity relate to bioactivity?

A

increased affinity leads to increased bioactivity

18
Q

What are the characteristics of receptor saturability?

A

-number of receptors in a target cell can change by day, or even by minute
-receptor down-regulation leads to decreased target tissue responsiveness
-receptor up-regulation leads to increased target tissue responsiveness

19
Q

What can lead to receptor down-regulation?

A

-inactivation of receptor molecules
-inactivation of intracellular protein signaling molecules
-temporary sequestration of receptors
-destruction of receptors via lysosomes
-decreased receptor production

20
Q

What are the two types of hormone receptor models?

A

-plasma membrane receptors: bind hormones that cannot enter cell
-intracellular receptors: bind hormones that can freely enter cell

21
Q

What is signal transduction?

A

process involving the conversion of a signal from outside the cell to a functional change within the cell

22
Q

What is the pathway of signal transduction?

A

-first messenger + membrane receptor leads to series of reactions in cell membrane
-rxns release second messenger into cell
-second messenger leads to biological effect

23
Q

What are the 4 second messengers?

A

-cAMP
-IP3
-DAG
-Ca++

24
Q

What are the characteristics of intracellular hormone receptors?

A

-floating receptors
-called non-transformed when connected to molecular chaperones
-activated receptors move to DNA and bind
-binding leads to genomic effects
-no second messenger

25
Q

What are the characteristics of GABA?

A

-most important inhibitory molecule in brain
-synthesized starting from glutamic acid

26
Q

What is the role of vitamin B6 in GABA synthesis?

A

fundamental cofactor for synthesis and recycling back to glutamic acid

27
Q

What is the role of T4 in GABA synthesis?

A

-excess T4 binds and sequesters B6
-prevents GABA production due to lack of cofactor

28
Q

Which receptors recognize the catecholamines (epinephrine and norepinephrine)?

A

-alpha-1
-alpha-2
-beta-1
-beta-2

29
Q

Which response is associated with activation of the beta-1 receptor?

A

increased heart rate

30
Q

Which response is associated with activation of the beta-2 receptor?

A

increased glycogenolysis

VMP824 Physiology/Microanatomy 2 (50 decks)

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