Lecture 16 Endocrine 1 Flashcards Preview

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Flashcards in Lecture 16 Endocrine 1 Deck (16)
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1

Endocrine Glands

secrete hormones; no ducts

2

Hormone

chemical messenger, carried in blood
affect target cells
(ie. cells that have receptors for the hormone)

3

Receptor

binds to hormone, required for response to the hormone

4

Nervous System

fast response, short duration, secretes neurotransmitters, specific localized effects

5

Endocrine System

slow response, longer duration, secretes hormones, widespread effects

6

Neurotransmitters

affect a specific cell (the postsynaptic cell) at a synapse

7

Hormones

affect target cells throughout the body

8

neurohormones

hormones secreted by neurons

9

paracrine substances

e.g. prostaglandins
exert local effects on neighboring cells

10

lipophilic

lipid soluble
steroid hormones, thyroid hormones, eicosanoids
cross the plasma membrane
bind to intracellular (cytoplasmic) receptors

11

lipophobic

water soluble
epinephrine (amino acid derivatives), insulin, antidiuretic hormone (peptides and proteins)
do not cross plasma membrane
bind to receptors on the PM

12

Lipophilic hormones

hormone binds to cytoplasmic receptor
diffuses through membrane
intracellular hormone-receptor complex -> binds to DNA, acts as transcription factor
->regulates transcription of specific genes->mRNA->protein synthesis ->metabolic and developmental effects

alters production of proteins, activates or represses 1 or more genes

13

Lipophobic hormones

hormone binds to membrane receptor
hormone receptor binding activates a signal transduction pathway
activates enzymes within the cell
mostly metabolic effects

14

Cyclic AMP second messenger system 1-3

e.g. epinephrine :B-adrenergic receptors
1. Hormone Binds to receptor
2.G protein associated with receptor is activated
3. activated G protein activates adenylyl cyclase in the plasma membrane

15

Cyclic AMP second messenger system 4-6

4. adenylyl cyclase converts ATP to cyclic AMP (cAMP)
5.Cyclic AMP acts as secondary messenger, activated protein kinase enzyme in the cell
6. Protein kinase activates other enzymes via phosphorylation
->amplification of cellular response

16

Phospholipase-C (DAG-IP3) Second messenger system

(norepinephrine: a-adrenergic receptors)
G protein coupled receptor
activation of G protein activates phospholipase C enzyme in the cell membrane
phospholipase C cleaves a membrane phospholipid
forms 2 second messengers: diacylglycerol (DAG)
and inositol triphosphate (IP3)