Robert Wadlow 1918 1940 8 11 Hormones A

Robert Wadlow 1918 -1940 8' 11"

Hormones • A hormone is a chemical signal produced in one part of the body & used in another. Cause response in target cell. • Hormones are produced in endocrine glands which are ductless and secrete hormones directly into body fluids.

Regulation & Communication • Animals rely on 2 systems for regulation § endocrine system • system of ductless glands – – secrete chemical signals directly into blood chemical travels to target tissue target cells have receptor proteins slow, long-lasting response § nervous system • system of neurons – transmits “electrical” signal & release neurotransmitters to target tissue – fast, short-lasting response

Chain of Command • The CNS regulates the body’s hormones through a chain of command § the hypothalamus is the main switchboard of the neuroendocrine system. Hypothalamus Pituitary body gland § i. e. hypothalamus releases ‘releasing factors’ (RF’s) to pituitary gland. • RF’s cause the pituitary to release various hormones that target endocrine glands in the body

Pituitary hormones stimulate endocrine glands in body

Two Major Biological Molecules: Protein vs. Steroid Hormones •

Two Major Biological Molecules: Protein vs. Steroid Hormones • Proteins are hydrophobic • cannot pass through phospholipid cell membrane • Use ‘signal transduction’ after binding to cell receptor protein • 1 st messenger = hormone • 2 nd messenger = c. AMP which activities enzymes in cytoplasm Protein vs. Steriod ANIMATION Steroids are lipids • can pass through cell & nuclear membrane to directly impact transcription/translation

target cell Action of lipid (steroid) hormones steroid hormone S S cytoplasm 1 blood S protein carrier cross cell membrane 2 binds to receptor protein becomes transcription factor 5 S 3 m. RNA read by ribosome plasma membrane 4 DNA m. RNA nucleus 6 protein 7 protein secreted ex: secreted protein = growth factor (hair, bone, muscle, gametes)

Action of protein hormones i. e. epinephrine (adrenaline) adrenal gland signal 1 epinephrine activates G protein receptor protein in cell membrane activates GTP 3 activates adenylyl cyclase c. AMP GDP GTP 2 transduction 4 ATP activates 5 protein kinase-A activates phosphorylase kinase cytoplasm liver cell released to blood activates glycogen phosphorylase glycogen 6 glucose 7 response

Benefits of a 2° messenger system signal 1 Activated adenylyl cyclase receptor protein 2 Not yet activated amplification 4 3 GTP amplification c. AMP 5 G protein 6 Amplification! amplification protein kinase amplification enzyme Cascade multiplier! FAST response! 7 amplification product

Maintaining homeostasis hormone 1 lowers body condition gland high specific body condition low raises body condition gland hormone 2 Negative Feedback Model

Ex 1 Controlling Body Temperature nerve signals hypothalamus sweat dilates surface blood vessels high body temperature (37°C) low hypothalamus constricts surface shiver blood vessels nerve signals

Ex 2 Blood Sugar Regulation: The Pancreas • The pancreas has both exocrine and endocrine functions § it secretes digestive enzymes and hormones • the hormones, produced in the islets of Langerhans, are insulin and glucagon – Insulin: blood sugar DOWN (glucose into cells) – Glucagon: blood sugar UP (glycogen released from liver into blood)

Insulin and glucagon secreted by the pancreas regulate blood glucose levels

Diabetes Type I diabetes mellitus • insulin-dependent diabetes + autoimmune disorder - immune system mounts attack on pancreatic cells + require insulin injections Type II diabetes mellitus • non-insulin-dependent diabetes + adult diabetes (more common- 90% of diabetics) - deficiency of insulin or reduced response of target cells + managed by exercise and dietary control http: //kidshealth. org/misc/movie/cc/diabetes/index. html

Ex 3 Blood Calcium Regulation: The Thyroid & Parathyroid § Calcitonin: blood calcium DOWN (triggers calcium deposition into bones)

Parathyroid • The parathyroid glands are four small glands attached to the thyroid § these glands produce parathytoid hormone (PTH). § PTH brings blood calcium UP (triggers release of calcium from bones) § Calcium is necessary for muscle contractions

Blood Calcium Regulation via Thyroid & Parathyroid Hormones

Goiter The thyroid also produces throxine increases metabolic rate and promotes growth thyroxine contains iodine and if the amount of iodine in the diet is too low, the thyroid cannot make enough thyroxine… Low thyroxin TSH from hypothalamus goes up thyroid grows bigger in attempt to increase thyroxin levels

Ex. 4: ADH (vasopressin) Antidiuretic Hormone Alcohol inhibits ADH secretion (along w/ normal hydration)

What about positive feedback? Childbirth, breastmilk, blood clotting:

Are lemmings an example of positive or negative feedback?

Adrenal Glands – Stress Hormones • The adrenal glands are located just above the kidney and release “stress hormones”: § Epinephrine/adrenalin and norepinephrine/noradrenalin –FIGHT OR FLIGHT hormones (short term) § Cortisol - long term stress molecule

You Must Know… • Two ways hormones target organs. • An illustration of positive and negative feedback in the regulation of homeostasis by hormones. • Antagonistic action of hormones regulating blood Ca 2+ & blood sugar • Osmoregulation via ADH