Chapter 23 Adrenal glands Thyroid hormones Growth hormone

Chapter 23 § Adrenal glands § Thyroid hormones § Growth hormone § Tissue and bone growth § Calcium balance Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Review of Endocrine Principles § Hypothalamic-pituitary control system § Several hormones controlled by hypothalamic and anterior pituitary trophic hormones § Feedback patterns § Negative feedback: § Simple Pathway-Blood glucose level decreasing shuts off insulin secretion § Complex Pathway-use the hypothalamic-pituitary control system, where the feedback signal may be the hormone itself § Hormone receptors § May be on surface or inside the cell § Cellular responses § Target cells respond by altering existing proteins or making new proteins § Magnitude of target cell response § Depends on number of receptors and amount of active hormone § Endocrine pathologies § Excess hormone secretion § Inadequate hormone secretion § Abnormal target cell response to the hormone Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Adrenal Glands Structure and function of the adrenal gland Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -1 a

Adrenal Glucocorticoids Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -1 b

Adrenal Glands Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -1 c

Adrenal Cortex Secretes Steroid Hormones 1. Aldosterone (Mineralcorticoid) 2. Glucocorticoids § Cortisol 3. Sex Hormones Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Adrenal Glucocorticoids Synthesis pathways for steroid hormones Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -2

Cortisol The HPA pathway for the control of cortisol secretion Corticotropin Releasing Hormone Adrenocorticotropic Hormone Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -3

Circadian Rhythm of Cortisol Secretion Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -4

Cortisol Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Cortisol § Promotes gluconeogenesis § Causes breakdown of skeletal muscle proteins § Enhances lipolysis § Suppresses the immune system § Causes negative calcium balance § Influences brain function Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Cortisol: Therapeutic Drug § Suppresses the immune system § Inhibits the inflammatory response § Used to treat § Bee stings, poison ivy, and pollen allergies § Prevents rejection of transplanted organs Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Hypercortisolism: Excess cortisol in the body Cushings Syndrome: Hormonal disorder caused by prolonged exposure to excess cortisol (including iatrogenic). § Signs and Symptoms § Hyperglycemia § Muscle protein breakdown § Excess deposits of extra fat in trunk and face § Thin arms and legs § Thin skin and bruising Three causes of hypercortisolism: § Adrenal tumor that autonomously secretes cortisol (Primary Hypercortisolism) § Pituitary tumor that autonomously secretes ACTH (Secondary Hypercortisolism or Cushing’s Disease) § Iatrogenic hypercortisolism Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Hypercortisolism Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -5

Hypocortisolism § Less common than Cushing’s syndrome § Addison’s disease § Hyposecretion of all adrenal steroid hormones § Autoimmune destruction of adrenal cortex Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Thyroid: Structure Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -7 a

Thyroid: Structure Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -7 b

Thyroid hormones are made from iodine and tyrosine Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -8

Thyroid Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Hyperthyroidism § Increases oxygen consumption and metabolic heat production § Increase protein catabolism and may cause muscle weakness § Hyperexcitable reflexes and psychological disturbances § Influence -adrenergic receptors in the heart Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Hypothyroidism § Slow metabolic rate and oxygen consumption § Decreases protein synthesis § Slowed reflexes, slow speech and thought processes, and feelings of fatigue § Cretinism in infants § Bradycardia Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Pathway of Thyroid Hormone Control Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -12

Thyroid A man with goiter due to excessive TSH stimulation Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -13

Thyroid Goiter can occur in both hyperthyroidism and hypothyroidism Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -14 a

Thyroid Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -14 b

Normal Growth § Growth hormone and other hormones § An adequate diet § Absence of stress § Genetics Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Pathway of Growth Hormone Control Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -16

Growth Hormone Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Growth Hormone § Severe GH deficiency leads to dwarfism § Oversecretion of GH in children leads to giantism § Oversecretion of GH in adults leads to acromegaly Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Three Individuals with Acromegaly Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -17

Bone growth Linear growth of long bones takes place at the epiphyseal plates Epiphysis is the end of a long bone. Bone growth Epiphyseal plate is the site of bone growth. Dividing chondrocytes add length to bone. Chondrocytes produce cartilage. Old chondrocytes disintegrate. Diaphysis Compact bone Chondrocyte Cartilage Direction of growth Diaphysis is the shaft of a long bone. Osteoblasts lay down bone on top of cartilage. Newly calcified Osteoblast bone Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -19

Bone growth Epiphysis is the end of a long bone. Diaphysis is the shaft of a long bone. Epiphyseal plate is the site of bone growth. Diaphysis Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -19 (1 of 5)

Bone growth Epiphysis is the end of a long bone. Diaphysis is the shaft of a long bone. Epiphyseal plate is the site of bone growth. Dividing chondrocytes add length to bone. Compact bone Chondrocyte Diaphysis Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -19 (2 of 5)

Bone growth Epiphysis is the end of a long bone. Diaphysis is the shaft of a long bone. Epiphyseal plate is the site of bone growth. Dividing chondrocytes add length to bone. Chondrocytes produce cartilage. Compact bone Chondrocyte Cartilage Diaphysis Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -19 (3 of 5)

Bone growth Epiphysis is the end of a long bone. Diaphysis is the shaft of a long bone. Epiphyseal plate is the site of bone growth. Dividing chondrocytes add length to bone. Chondrocytes produce cartilage. Old chondrocytes disintegrate. Compact bone Chondrocyte Cartilage Diaphysis Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -19 (4 of 5)

Bone growth Epiphysis is the end of a long bone. Bone growth Epiphyseal plate is the site of bone growth. Dividing chondrocytes add length to bone. Chondrocytes produce cartilage. Old chondrocytes disintegrate. Diaphysis Compact bone Chondrocyte Cartilage Direction of growth Diaphysis is the shaft of a long bone. Osteoblasts lay down bone on top of cartilage. Newly calcified Osteoblast bone Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -19 (5 of 5)

Calcium Balance Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Calcium § Important signal molecule § Part of intercellular cement that holds cells together at tight junction § Cofactor in the coagulation cascade § Affects the excitability of neurons Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Calcium Balance in the Body Small intestine Dietary calcium Calcitrol (PTH, prolactin) Some calcium is secreted into the small intestine. ECF Bone Ca 2+ Calcium in feces Ca 2+ Kidney Calcitonin [Ca 2+] PTH Calcitriol Cortisol 2. 5 m. M Electrochemical gradient Passive filtration PTH Calcitonin Ca 2+ in kidney tubules Active transport Cells [free Ca 2+] 0. 001 m. M KEY Ca 2+ in urine Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings PTH = parathyroid hormone Figure 23 -20

Calcium Balance in the Body ECF [Ca 2+] 2. 5 m. M KEY PTH = parathyroid hormone Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -20 (1 of 5)

Calcium Balance in the Body ECF [Ca 2+] 2. 5 m. M Electrochemical gradient Active transport Cells [free Ca 2+] 0. 001 m. M KEY PTH = parathyroid hormone Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -20 (2 of 5)

Calcium Balance in the Body ECF Bone Ca 2+ Calcitonin [Ca 2+] PTH Calcitriol Cortisol 2. 5 m. M Electrochemical gradient Active transport Cells [free Ca 2+] 0. 001 m. M KEY PTH = parathyroid hormone Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -20 (3 of 5)

Calcium Balance in the Body Small intestine Dietary calcium Ca 2+ Calcitrol (PTH, prolactin) ECF Bone Ca 2+ Calcitonin [Ca 2+] PTH Calcitriol Cortisol 2. 5 m. M Electrochemical gradient Active transport Cells [free Ca 2+] 0. 001 m. M KEY PTH = parathyroid hormone Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -20 (4 of 5)

Calcium Balance in the Body Small intestine Dietary calcium Calcitrol (PTH, prolactin) Some calcium is secreted into the small intestine. ECF Bone Ca 2+ Calcium in feces Ca 2+ Kidney Calcitonin [Ca 2+] PTH Vitamin D Cortisol 2. 5 m. M Electrochemical gradient Passive filtration PTH Calcitonin Ca 2+ in kidney tubules Active transport Cells [free Ca 2+] 0. 001 m. M KEY Ca 2+ in urine PTH = parathyroid hormone Total body calcium = intake output Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -20 (5 of 5)

Calcium Balance Osteoclasts are responsible for bone resorption Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -21

Calcium Balance § Parathyroid hormone § Mobilizes calcium from bone § Enhances renal reabsorption § Indirectly increases intestinal absorption § Vitamin D (Calcitriol) § Calcitonin (from Thyroid) Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Calcium Balance: Parathyroid Glands Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -22

Calcium Balance Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Endocrine Control of Calcium Balance Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -23

Calcitonin Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Osteoporosis Normal bone (left) and bone loss in osteoporosis (right) Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 23 -24