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