Download Chapter 16 Endocrine part 1

Chapter 16 Endocrine part 1
control systems
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endocrine
nervous system
3 steps of endocrine communication
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3 steps of cell communication :
signal sender
endocrine gland
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signal transporter
blood
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signal receiver
target cell
• receptors
• transduction
• cell response
specific for hormone
hormones as chemicals
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steroids
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amines
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polypeptides longer chains than amines
made from cholesterol
• estrogen, progesterone, testosterone
• cortisol , aldosterone
made from tyrosine
• epinephrine, norepinephrine
• thyroid hormone
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insulin, growth hormone
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glycoproteins
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cheap !
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FSH , LH , TSH
Mechanisms of hormone action
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affect nucleus - gene activation
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• turns on/off specific gene
steroid family
non-steroid family
thyroid hormone
Vitamin D
second-messenger systems
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• affects chemical in cytoplasm = second messenger
• response = turns on/off specific enzymes
amines
steroid
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hormone passes into cytoplasm or nucleus
binds to and activates receptor – chaperonin
hormone-receptor moves to nucleus
binds to nuclear receptor (on DNA)
turns on/off specific gene - acts as transcription factor
protein synthesis of:
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enzymes
structural protein
secretory protein
non-steroid family
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Thyroxine:
T4 transported by TBG (thyroxine binding globulin)
T4 changed to T3 in cytoplasm
T3 binds to receptor on DNA
activation of genes
also: Vitamin D
Vitamin A derivative
9-cis retinoic acid
2 messenger systems - general
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problem?
hormone can’t get through cell membrane
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hormone
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2 messenger =
chemical in cytoplasm
transduction
1st messenger activates 2nd messenger
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chemicals of transduction
1 messenger =
transducer
nd
2 messenger activates enzymes in cytoplasm
enzymes produce cell’s response
note: hormone effect based on enzymes present in cell
cAMP as 2nd messenger
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hormone binds receptor
hormone = 1 st messenger
receptor activates G-protein
=
transducer
G protein activates Adenylate cyclase
ATP  cAMP
cyclic AMP = 2nd messenger
cAMP activates protein kinase
protein kinase turns on/off enzymes in cell
inactivation
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cAMP inactivated by phosphodiesterase
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drugs that inhibit phophodiesterase :
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theophylline
bronchodilation
caffeine
viagra
other 2nd messengers
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1 messenger
hormone
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membrane enzyme
Phospholipase C
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2nd messenger
IP3
DAG
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(via Ca++)
(diacylglycerol)
Ca as 2nd messenger
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calcium effects:
calcium – calmodulin
Ca
++
activates protein kinase
exocytosis / secretions
muscle contraction
insulin
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receptor = tyrosine kinase
activation stimulates cell’s responses
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increase glucose carrier proteins GLUT4
increase glycogen production
steroid vs 2 messenger
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speed
2 messenger faster
enzymes already present
long term
steroid hormones effects last longer
amplification
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2 messenger
1 hormone stim 1000’s of enzymes
steroid
1 hormone stim 1 gene transcription
multiple outcomes of 2 messenger system
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can affect several diff enzymes in cell
>1 cell function may be turned on by one hormone
endocrine system and homeostasis
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maintainance of optimum function
stimulus = not optimum conditions
receptor
endocrine gland
integration
endocrine gland
efferent signal
hormone
effector
organ , tissue response
negative feedback
response opposite to stimulus
negative inhibition
response  hormone production
action of enzyme  enzyme
end product inhibition
hormone affect on target cell
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change plasma membrane permeability
activate / deactivate genes
protein synthesis
activate / deactivate enzymes
stim secretion
mitosis
target cell response
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amount of response depends on:
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blood levels of hormone
specificity of receptors
affinity for hormone
long-term effects:
up-regulation
hormone increases effect
 # receptors
down-regulation
hormone decreases effect
 # receptors
stimulus of hormones
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humoral changes
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hormonal changes
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neural changes
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A cell’s gene is controlling the functions in a distant cell
chemical levels in blood
• Glucose , Ca++ , NaCl , O2
other hormones
• produced by other endocrine glands
neurotransmitters
• neuron stimulates endocrine gland
• Adrenal medulla
another look at genetics
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cytoplasm of a distant cell
distant cell’s genes and protein synthesis
its cell membrane