biochemistry makes sense

Question 1

what are the only 2 second messengers used by the autonomic nervous system?

Answer 1

1. cyclic AMP (cAMP)

2. inositol triphosphate (IP3)

Question 2

enumerate all the intracellular hormones

Answer 2

progesterone
estrogen
testosterone
cortisol
aldosterone
thyroid hormone

Question 3

characteristics of intracellular hormones

Answer 3

bind to receptors in the cell, whether in the cytoplasm or nucleus and modify gene transcription to exert its action

can pass through cell membrane as they are all steroid hormones, derived from cholesterol (except thyroid hormone which is fat soluble but not a steroid hormone)

needs to be bound to a protein (i.e. sex binding globulin (SBG), thyroid binding globulin (TBG), cortisol binding globulin (CBG)

Question 4

what is different about extracellular hormones

Answer 4

in order to drive effect, extracellular hormones bind to surface receptors.

this surface receptors can drive cellular change or second messengers are utilized

Question 5

surface receptors for extracellular hormones

Answer 5

1. tyrosine kinase

2. JAK/STAT

Question 6

what substances act on tyrosine kinase

Answer 6

insulin

growth factors: Insulin like GF, fibroblast GF, platelet derived GF, epidermal GF

Question 7

how do tyrosine kinases function to effect cellular change

Answer 7

taking into example insulin

when insulin binds to surface receptor where tyrosine molecules can be found

tyrosine kinase phosphorylates the receptor “autophosphorylation” ensues –> gene transcription

surface receptor gets the job done

Question 8

what is the JAK/STAT pathway

Answer 8

another signalling pathway for extracellular hormones
it can also cause tyrosine phosphorylation

cytokines (as example) bind to the surface receptor and activates JAK or janus kinases

janus kinases phosphorylate proteins called STAT (Signal Transducer and Activator of Transcription)

phosphorylation causes STAT to be activated

STAT enters the nucleus and effects gene transcription

Question 9

what substances use the JAK/STAT signaling pathway

Answer 9

many cytokines and precursor bone marrow cells

cytokines: interferon gamma, IL 2, IL 6
bone marrow: EPO, G-CSF, thrombopoeitin

also, prolactin & growth hormone

Question 10

what mutation is associated with myeloproliferative disorders

Answer 10

JAK 2 mutation

gene for cytoplasmic tyrosine kinase
mutation leads for increased tyrosine phosphorylation –> bone marrow cells hypersensitive to cytokines
=> more growth and more survival == myeloproliferative disorders

Question 11

which pituitary hormones act by cAMP

Answer 11

share the same alpha sub units:
FSH
LH
TSH
HCG

also ACTH

Question 12

identify which signaling pathway is used

is a lipid hormone

Answer 12

intracellular

Question 13

signaling pathway:

is not a lipid hormone

Answer 13

extracellular

Question 14

signaling pathway:

vasodilator (ANP/BNP/NO)

Answer 14

second messenger: cGMP

GTP—– guanylate cyclase —– cGMP

Question 15

signaling pathway:

cytokine/bone marrow precursors

Answer 15

JAK/STAT pathway

Question 16

signaling pathway:

prolactin
Growth hormone

Answer 16

JAK/STAT pathway

Question 17

signaling pathway:

not a lipid hormone
not a vasodilator (ANP/BNP/NO)
not a cytokine/bone marrow precursor
not insulin or growth factor
not prolactin nor growth hormone

Answer 17

cAMP or IP3

Question 18

signaling pathway:

insulin or a growth factor

Answer 18

tyrosine kinase

Question 19

what second messengers are used by hormones of the hypothalamus?

Answer 19

cAMP or IP3

Question 20

hormones of the hypothalamus that use cAMP

Answer 20

CRH corticotropin releasing hormone

GHRH growth hormone releasing hormone

Question 21

hypothalamic hormones that use IP3

and other substances that work through IP3

Answer 21

TRH thyrotropin releasing hormone
GRH gonadotropin releasing hormone

V1
H1
Gastrin
Angiotensin II

Question 22

what enzyme modifies PIP to IP3

Answer 22

phospholipase C

Question 23

where does protein kinase A come into the picture

Answer 23

in order for autonomic nervous system to cause effect, muscarinic/adrenergic receptors are used

binding of G protein coupled receptors activated second messengers

in the case of ANS 2 second messengers are used IP3 and cAMP

in the myocardial cells, when Gs is stimulated, adenyl cyclase is activated causing an increase in cAMP which then activated protein kinase A (PKA) to increase intracellular calcium levels = increase contractility