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Ch 30 hormones
Ap Biology Lecture
Endocrine System
• Includes cells that produce and release chemical signals (hormones) –Endocrine cells secrete hormones –Endocine glands are the oragns • Testes, thyroid
*Remember that hormones are long distance endocrine signals that travel via the blood stream*
Regulation by chemical messengers
axon
endocrine gland
receptor proteins
target cell
• Neurotransmitters released by neurons• Hormones release by endocrine glands
receptor proteins
hormone carried by blood
neurotransmitter
Hormone groups
• peptide and protein hormones –Large, water soluble –Need external target cell –Via blood
Action of protein hormones
activatesenzyme
activatesenzyme
activates enzyme
ATP
produces an action
P1
2
3
cytoplasm
receptor protein
response
signal
secondarymessengersystem
signal-transduction pathway
acts as 2° messenger
target cell
plasma membrane
binds to receptor protein
proteinhormone
ATPactivatescytoplasmicsignal
cAMP
GTP
activatesG-protein
transduction
• Steroid proteins–Synthesized from cholesterol –Lipid soluble–Carrier proteins–Inside target cell
nucleus
target cell
DNA mRN
A protein
blood
proteincarrier
S
S
S
S
Action of lipid (steroid) hormones
binds to receptor protein
cytoplasm
becomes transcription factor
ex: secreted protein = growth factor (hair, bone, muscle, gametes)
2
4
6
cross cell membrane
1
steroid hormone
mRNA read by ribosome
5
plasma membrane
protein secreted
7
3
• Amine hormones –Synthesized from amino acids–Polar or nonpolar
*Recall hormones bind to a receptor*
*actions of hormones depend on the target cell or receptor*
Example flight or fight response caused by epinepherine
Pituitary gland
• Attached to hypothalamus • Attaches Nervous and endocrine
system • Nervous – Communicates via neurotransmitters in
the nerve cell – rapid
• Endocrine – Communicates via signals in the blood– Long term
Parts of pituitary glands
• Posterior • Anterior
Posterior
• Antidiuretic hormone (ADH) produced in hypothalamus then sent to posterior – Increase water retention in kidney –When high, kidney produces small volumes of
concentrated urine–When low, kidney produces large volumes of
diluted water
• Oxytocin produced in hypothalamus then sent to posterior– Stimulates uterine contractions and the flow of
milk
anterior
• Hormone release communicated by hypothalamus
• 4 tropic hormones that control the activities of the other endocrine glands– Thyroid stimulating hormone (TSH) :
stimulate thyroid to release thyroxine – Luteinizing hormone (LH) – Follicle stimulating hormone (FSH) – Adrenocorticotropic hormone (ACTH)
• Peptide hormones – Prolactin – Growth hormone (GH) • Stimulates cells to take in amino acids for
protein synthesis • Growth of bones and cartilage
Thyroid gland
hypothalamus
anteriorpituitary
gonadotropic hormones:follicle-stimulatinghormone (FSH) & luteinizing hormone (LH)
Mammaryglandsin mammals
Musclesof uterus
Kidneytubules
posteriorpituitary
thyroid-stimulating hormone(TSH)
antidiuretic hormone(ADH)
Adrenalcortex
Boneand muscle
Testes Ovaries
Melanocytein amphibian
adrenocorticotropic
hormone (ACTH)melanocyte-stimulating hormone(MSH)
oxytocin
prolactin (PRL)
grow
th ho
rmon
e (GH)
tropic hormones = target endocrine glands
Thyroid gland
• Thyroids wraps around the windpipe like a bowtie
• One side – thyroxine• One side- calcitonin• Thyroid also has parathyroid gland
• Thyroxine is an amine hormone made from tyrosine
• Also know as t4 because it binds 4 iodine atoms
• Thyroid also makes T3 which controls most hormonal activity
• Thyroxine : – Lipid soluble – Raises metabolic rate – Insufficient amounts Can cause
cretinism
• So…Anterior releases TSH because it was
stimulated by thyrotropin releasing hormone (TRH)
TSH then stimulates the thyroid to produce and release thyroxine
Negative feedback
• Goiter is an enlarges thyroid gland
• Hypothyroidism – deficient – Low metabolism, intolerance of cold,
sluggish– Caused by lack of iodine
• Hyperthyroidism – excess– Fat behind eyeballs cause them to bulge – Caused by autoimmune over production
Regulation of calcium concentrations
• Calcium used by neuron to release neurotransmitters and by muscle to trigger contraction
• Too low cause muscle spasms and seizure • Too high muscle to weaken and stop• adjust levels : controlled by calcitonin,
calcitriol and parathyroid hormone (PTH) – Deposits or absorption of bone– Excretion or retention in kidney – Absorption from digestive tract
calcitonin
• Released by thyroid gland • Reduces concentration of calcium in
the blood • Bone turnover
Vitamin D and calcitriol
• Vitamin D from sunlight • In liver turns into calcitriol• Calcitriol stimulates digestive tract to
absorb calcium from ingested food
Parathyroid hormone
• Most important • Triggered when calcium levels too
low • Increase calcium concentration by: – Stimulating bone turnover– Stimulating kidney to reabsorb – Activating more calcitriol from vitamin D
Regulation of Blood Calcium
blood calcium level(10 mg/100mL)
calcitonin
parathyroid hormone (PTH)
Ca++ uptakein intestines
high
low
FeedbackEndocrine System Control
kidney reabsorption of Ca++
bones release Ca++
kidney reabsorption of Ca++
Ca++ depositedin bones
activated Vitamin D
thyroid
parathyroid
Adrenal glands
• Sit right above the kidney • Core is the adrenal medulla– Produce epinephrine and
norepinephrine, stress
• Around adrenal medulla is the adrenal cortex– Controlled by hypothalamus and
anterior pituitary
Adrenal cortex
• Two classes of cortisteroid hormones –Mineralocorticoids• Influences salt and water balance of
extracellular fluids
– Glucocorticoids• Increase blood glucose concentrations • Cortisol and corticosterone
Adrenal cortex
• Sex steroids – Androgens • Testosterone
– Estrogen and progesterone
liver
pancreas
liver
Regulation of Blood Sugar
blood sugar level(90mg/100ml)
insulin
body cells takeup sugar from blood
liver storesglycogen
reducesappetite
glucagon
pancreas
liver releasesglucose
triggershunger
high
low
FeedbackEndocrine System Control
islets of Langerhans beta islet cells
islets of Langerhansalpha islet cells