Endocrine Control Chapter 32

An Orchestra of Hormones Hormones influence the growth, development, and reproductive cycles of nearly all animals They influence behavior, physical appearance, and well-being

Hormones Secreted by endocrine glands, endocrine cells, and certain neurons Animal hormones travel through the bloodstream to nonadjacent target cells

Other Signaling Molecules Neurotransmitters Local signaling molecules Pheromones

Endocrine System Main Sources Pituitary gland Adrenal glands Thyroid gland Parathyroid glands Pineal gland Thymus gland

HYPOTHALAMUS PINEAL GLAND PITUITARY GLAND THYROID GLAND PARATHYROID GLANDS THYMUS GLAND ADRENAL GLANDS PANCREATIC ISLETS OVARIES Fig. 32.2b, p. 523 TESTES

Responses to Hormones Vary Different hormones activate different responses in the same target cell Not all types of cells respond to a particular hormone

Two Main Hormone Types Steroid hormones Peptide hormones Derived from cholesterol Estrogens, progestins, androgens (such as testosterone), cortisol, aldosterone Peptide hormones Peptides, proteins, or glycoproteins Glucagon, ADH, oxytocin, TRH, insulin, somatotropin, prolactin, FSH, LH, TSH

Steroid Hormone Action Most diffuse across the plasma membrane and bind to a receptor Hormone-receptor complex acts in nucleus to inhibit or enhance transcription (protein synthesis)

hormone-receptor complex Steroid Hormones hormone Most diffuse across the plasma membrane and bind to a receptor Hormone-receptor complex acts in nucleus to inhibit or enhance transcription receptor hormone-receptor complex gene product

Protein Hormone Hormone binds to a receptor at cell surface glucagon Hormone binds to a receptor at cell surface Binding triggers a change in activity of enzymes inside the cell glucagon receptor cyclic AMP + Pi ATP cAMP activates protein kinase A Protein kinase A converts phosphorylase kinase to active form and inhibits an enzyme required for glucagon synthesis.

The Hypothalamus Region in the brain Contains hormone-secreting cells Interacts with pituitary pituitary gland

HYPOTHALAMUS PITUITARY GLAND bone at base of cranial cavity anterior lobe posterior lobe Fig. 32.2a, p. 522

Pituitary Gland Two lobes Posterior lobe (neurohypophysis) stores and secretes hormones that were synthesized in the hypothalamus Anterior lobe (adenohypophysis) produces and secretes its own hormones

Posterior Lobe Antidiuretic hormone (ADH ) Oxytocin (OCT) cell body in hypothalmus Antidiuretic hormone (ADH ) Oxytocin (OCT) axons to the general circulation

cell body in hypothalmus POSTERIOR LOBE OF PITUITARY oxytocin ADH axons kidney tubules mammary glands smooth muscle in wall of the uterus to the general circulation Fig. 32.5, p. 527

Anterior Pituitary ACTH TSH FSH LH PRL STH

Cell bodies secrete releasing and inhibiting hormones growth-promoting effects on most cells ANTERIOR LOBE OF PITUITARY STH (GH) ACTH PRL Capillary bed at base of hypothalmus TSH FSH LH both act on: adrenal cortex thyroid gonads mammary glands Capillary bed in anterior pituitary Fig. 32.6, p. 527

Feedback Mechanisms Negative feedback Positive feedback An increase in concentration of a hormone triggers activities that inhibit further secretion Positive feedback An increase in concentration of a hormone triggers activities that stimulate further secretion

Control of Cortisol Secretion (1) Hypothalamus senses decline in glucose and secretes a releasing hormone (CRH) CRH stimulates anterior pituitary to secrete ACTH ACTH acts on the adrenal cortex to stimulate cortisol secretion

Control of Cortisol Secretion (2) Inhibits blood glucose uptake by muscle and other tissues Causes breakdown of proteins to amino acids and conversion to glucose Causes degradation of adipose tissue to fatty acids for use as energy source

Control of Cortisol Secretion (3) Decrease in glucose uptake and release of glucose from protein breakdown causes blood glucose level to rise Hypothalamus and anterior pituitary detect the increase and decrease secretion of CRH and ACTH Adrenal cortex decreases cortisol secretion

Thyroid Gland Disorders Goiter Hyperthyroidism Hypothyroidism

Feedback Control of Ovaries Pituitary produces hormones (LH, FSH) that stimulate egg maturation and ovulation in the ovary They also stimulate ovary to produce progesterone and estrogen After ovulation, rising levels of these hormones inhibit further secretion of LH and FSH

Control of Glucose Metabolism insulin Glucose uptake Glucose to glycogen Glucose falls Glucose is absorbed Cells use glucose Glucose rises Glycogen to glucose glucagon

Diabetes Mellitis Disease in which excess glucose accumulates in blood, then urine Effects include Excessive urination Constant thirst Weight loss Ketone formation and acid-base imbalances

Two Types of Diabetes Type 1 Type 2 Auto-immune disease Usually appears in childhood Treated with insulin injections Type 2 Target cells don’t respond Usually appears in adults Treated with diet, drugs