 Chapter 45: Endocrine System

Learning Targets 1. I can idnetify and explain the role that hormones have in homeostatic pathways.  I can diagram how hormones bind to tarfet receptors and trigger specific pathways.  I can explain one hormone that displays positive feedback and one that displays negative feedback. 2. I can explain how steriod and peptide hormones differ as ligands in signal transduction pathways. 3. I can explain the significance of having antagonistic hormones to maintain homeostasis.

Steroid vs. water soluble hormones

 Figure Spinal cord (cross section) (a) (b)Long-term stress response and the adrenal cortex Short-term stress response and the adrenal medulla Stress Nerve signals Nerve cell Releasing hormone Hypothalamus Anterior pituitary Blood vessel Nerve cell ACTH Adrenal medulla secretes epinephrine and norepinephrine. Adrenal gland Kidney Adrenal cortex secretes mineralo- corticoids and glucocorticoids. Effects of epinephrine and norepinephrine: Effects of mineralocorticoids: Effects of glucocorticoids: Glycogen broken down to glucose; increased blood glucose Increased blood pressure Increased breathing rate Increased metabolic rate Change in blood flow patterns, leading to increased alertness and decreased digestive, excretory, and reproductive system activity Retention of sodium ions and water by kidneys Increased blood volume and blood pressure Proteins and fats broken down and converted to glucose, leading to increased blood glucose Partial suppression of immune system

Figure Epinephrine G protein Adenylyl cyclase G protein-coupled receptor GTP ATP cAMP Second messenger Inhibition of glycogen synthesis Promotion of glycogen breakdown Protein kinase A

 Figure 45.9 Different receptors Same receptors but different intracellular proteins (not shown) Different cellular responses Epinephrine  receptor  receptor  receptor Glycogen deposits Vessel dilates. Vessel constricts. Glycogen breaks down and glucose is released from cell. (a) Liver cell (b) Skeletal muscle blood vessel Intestinal blood vessel (c)

Figure Pathway Example  Stimulus Low pH in duodenum Endocrine cell S cells of duodenum secrete the hormone secretin ( ). Hormone Blood vessel Target cells Pancreas Response Bicarbonate release Negative feedback

Figure Pathway  Example Stimulus Suckling Sensory neuron Positive feedback Hypothalamus/ posterior pituitary Neurosecretory cell Neurohormone Blood vessel Target cells Response Posterior pituitary secretes the neurohormone oxytocin ( ). Smooth muscle in breasts Milk release

 Figure Tropic effects only: FSH LH TSH ACTH Nontropic effects only: Prolactin MSH Nontropic and tropic effects: GH Hypothalamic releasing and inhibiting hormones Posterior pituitary Neurosecretory cells of the hypothalamus Portal vessels Endocrine cells of the anterior pituitary Pituitary hormones HORMONE FSH and LH TSH ACTH Prolactin MSH GH TARGET Thyroid Melanocytes Testes or ovaries Adrenal cortex Mammary glands Liver, bones, other tissues

Figure 45.UN04