Animal form and function: endocrine

Controls

Animals have 2 systems of control

Nervous: rapid response

Endocrine: slower response. Longer lasting Reception: hormone binds receptor protein on target cell

(or in) Change receptor protien: initiates transduction Hormones (steroid): bind protein in cytosol: enter

nucleus as transcription factors and turn genes off or on.

Signal transduction: binding triggers events within the cell Response: change in cells behavior

Types of signals

Endocrine: long distance stim. Carried through blood stream

Paracrine: local. Stim neighboring cells Neurotransmitters Growth factors prostoglandins

Endocrine example: epinephrine

Epinephrine is secreted from the adrenal medulla in response to stress. Receives Neural stimulus from hypothalmus

Epinephrine stimulates the breakdown of glycogen to glucose in the muscle and liver

Sutherland found: in test tube epinephrine + glycogen phosphorylase + glycogen = no

work Need intact cells and cell membrane Epinephrine uses G protein-linked receptors: binds on

outside of cell: stims change in G protein in cytosol. Makes it active

FYI: epinephrine stimulates:

Dilation of capillaries in the lungs

Increased heart rate and cardiac output

Smooth muscles of some blood vessels contract, others dilate

Remember cell signaling

Hormones that act inside the cell (steroids) transcription factors

G-protein linked receptors: on cell membrane: act on protein in the cytosol (change out the guanine) making it active

Tyrosine kinase: catalyze the transfer of a phosphate group from ATP to tyrosine

Ion gated channels: affected by the level of certain ions in the extracellular fluid (Na)

Glands of endocrine

Hypothalamus

Pineal

Pituitary

Thyroid

Thymus

Adrenals

Pancreas

Ovaries/ testes

Hypothalamus

Hypothalamus makes hormones and stores them in:

Posterior pituitary: oxytocin: uterine contraction ADH: anti diuretic hormone (decrease urination)

Anterior pituitary: Secretes trophic hormones: control other glands: regulated by hypothalmus ACTH: adrenal control FSH/LH: gonad regulation Growth hormone: growth regulation Prolactin: milk production TSH: thyroid stim

Hypothalamus

Hypothalamus: TSH releasing hormone

Stims Anterior Pituitary to release: TSH

Stims Thyroid: release T3 and T4

Negative feedback: T3 and T4 negative feedback to hypothal.

A signal transduction pathway with cAMP as 2nd messenger

Thyroid

Thyroid Thyroxine: metabolic rate Calcitonin: decreases blood calcium

Parathyroid PTH: when Ca++ is low, PTH stim osteoclasts to

breakdown bone and kidneys to retain Ca++ so, raises Blood calcium

Pancreas

Exocrine: digestive enzymes: through DUCT to small intestine

Endocrine: Islets of Langerhan: Alpha cells: glucagon Beta cells: insulin

Glucagon: stim breakdown of glycogen Insulin: increases cells ability to take up glucose.

And stim. the storage of glucose as glycogen in liver and muscles

Adrenal glands

Adrenal Medulla Stim by acetylcholine from sympathetic nerve

system Epinepherine norepinepherine

Adrenal Cortex Glucocorticoids: aldosterone

Blood Pressure

Blood volume low: Kidneys secrete renin Stims angiotensin from liver:

constricts blood vessels Stims aldosterone from adrenal cortex

Kidney tubules increase reabsorbtion of water

Antiduiretic hormone works in same situation

Ovaries & testes

Ovaries Estrogen progesterone

Testes Testosterone

Pineal gland

Melatonin: involved in light/dark cycles