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DEMS IV > hormones and receptors > Flashcards

Flashcards in hormones and receptors Deck (21):
1

Three categories of hormones

1) derivatives of tyrosine, 2) derivatives of cholesterol (steroids), and 3) peptides and proteins

2

list Tyrosine derived hormones

epinephrine, norepinephrine, dopamine and thyroxine

3

List steroid hormones

testosterone, cortisol, estrogen, aldosterone, Vitamin D, progesterone

4

list peptide hormones

oxytocin, vasopressin, angiotensin, thyrotropin releasing hormone, GnRH

5

List protein hormones

insulin, glucagon, growth hormone, ACTH, prolactin, TSH

6

synthesis/secretion of peptide and protein hormones

pro-hormone synthesized on ribosomes > targeted to ER > presequence is cleaved > prohormone transported to golgi >processed and packaged in secretory vesicles > secretion via vesicular exocytosis (Ca dependent)

7

synthesis/secretion of catecholamines

pro-hormone synthesized on ribosomes > targeted to ER > presequence is cleaved > prohormone transported to golgi >processed and packaged in secretory vesicles > secretion via vesicular exocytosis (Ca dependent)

8

Why is the half life of peptide/protein hormones limited

The blood contains many proteases

9

Which peptide/protein hormones are NOT transported in blood as free hormones

growth hormone, prolactin and Insulin-like growth factor

10

precursor for all steroid hormones

cholesterol

11

How do steroid hormones differ from peptide hormones

1. They are lipophilic and membrane permeant, so they are not secreted via vesicular exocytosis. 2. Steroids are not stored in the cell which synthesizes them, so they are immediately released into blood stream. 3. steroids Must be carried by carrier proteins in blood. 4. Steroids have much longer half lives (hours to days) so they linger in blood stream for long time

12

What proportion of steroid hormone exist in free forms

1-5% The rest is bound to carrier proteins.

13

Which form of steroid hormones is active

free form only

14

describe two ways of measuring hormone levels

1. bioassays: hormone function is measured by using an exogenous system e.g. cell lines, to measure hormone activity. 2. immunoassays: Radio-immunoassays (RIA) and enzyme linked immunosorbent assays (ELISA) measure antibody binding to a specific region of the hormone

15

epinephrine/NE action at target organ

Bind to G-protein receptors > changes intracellular second messengers (cAMP, DAG, IP3, etc)

16

Which hormones bind to JAK/STAT receptors

growth hormone and prolactin

17

Function of JAK/STAT receptors

Binding to these receptors results in coupling and activation of a tyrosine kinase (Janus kinase or JAK), which then causes the phosphorylation of a group of proteins called signal transducers and activators of transcription (STATs).

18

which hormones bind to tyrosine kinase receptors

insulin and IGF-1

19

List steps in steroid receptor activation

steroid hormone enters cell and binds to receptor in cytosol or nucleus. The receptor-hormone complexes then bind to specific hormone responsive elements (HRE) and activate transcription of specific genes

20

How is hormone secretion regulated

Via feedback loops which keep levels regulated around a specific set point.

21

give example of a positive feedback loop

oxytocin release during labor