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 Steroid proteins –Synthesized from cholesterol –Lipid soluble –Carrier proteins –Inside target cell

nucleus target cell DNA mRNA protein blood protein carrier 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) cross cell membrane 1 steroid hormone mRNA read by ribosome 5 plasma membrane protein secreted 7 3

Action of protein hormones activates enzyme activates enzyme activates enzyme ATP produces an action P cytoplasm receptor protein response signal secondary messenger system signal-transduction pathway acts as 2° messenger target cell plasma membrane binds to receptor protein protein hormone ATP activates cytoplasmic signal cAMP GTP activates G-protein transduction

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 production 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

Peptide hormones –Prolactin –Growth hormone (GH) Stimulates cells to take in amino acids for protein synthesis Growth of bones and cartilage

Thyroid gland hypothalamus anterior pituitary gonadotropic hormones: follicle- stimulating hormone (FSH) & luteinizing hormone (LH) Mammary glands in mammals Muscles of uterus Kidney tubules posterior pituitary thyroid-stimulating hormone (TSH) antidiuretic hormone (ADH) Adrenal cortex Bone and muscle Testes Ovaries Melanocyte in amphibian adrenocorticotropic hormone (ACTH) melanocyte-stimulating hormone (MSH) oxytocin prolactin (PRL) growth hormone (GH) tropic hormones = target endocrine glands

Thyroxine Made by the 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 t 4 because it binds 4 iodine atoms Thyroid also makes T 3 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 ++ uptake in intestines high low Feedback Endocrine System Control  kidney reabsorption of Ca ++ bones release Ca ++  kidney reabsorption of Ca ++ Ca ++ deposited in 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 glands Sex steroids –Androgens Testosterone Estrogen and progesterone Two classes of cortisteroid hormones –Mineralocorticoids Influences salt and water balance of extracellular fluids –Glucocorticoids Increase blood glucose concentrations Cortisol and corticosterone

liver pancreas liver Regulation of Blood Sugar blood sugar level (90mg/100ml) insulin body cells take up sugar from blood liver stores glycogen reduces appetite glucagon pancreas liver releases glucose triggers hunger high low Feedback Endocrine System Control islets of Langerhans beta islet cells islets of Langerhans alpha islet cells