23_lect

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Dee Unglaub Silverthorn, Ph.D.

HUMAN PHYSIOLOGYHUMAN PHYSIOLOGY

PowerPoint® Lecture Slide Presentation byDr. Howard D. Booth, Professor of Biology, Eastern Michigan University

AN INTEGRATED APPROACH

T H I R D E D I T I O N

Chapter 23Endocrine Control of Growth

and Metabolism


About this ChapterAbout this Chapter

• How several key hormone pathways influence metabolism

• How cortisol is produced & regulated; how it impacts many tissues

• How thyroid hormones are regulated and their effect on targets

• The role of growth hormone in growth & development

• Calcium metabolism and its role in bones and cell regulations


Endocrine Control in ReviewEndocrine Control in Review

• Hypothalamic – pituitary: feedback loop & trophic control

• Hormones can have receptors on many diverse tissues

• Usually initiating protein change or synthesis in target cells

• Problems come from too much or too little hormone


• Aldosterone, sex hormones, cortisol

• Synthesized from cholesterol–steroid ring

Adrenal Cortex: Steroid Hormone ProductionAdrenal Cortex: Steroid Hormone Production


Adrenal Cortex: Steroid Hormone ProductionAdrenal Cortex: Steroid Hormone Production

Figure 23-2: Synthesis pathways of steroid hormones


Cortisol Effects: Body Responses to StressCortisol Effects: Body Responses to Stress

• Permissive effect on glucagon

• Memory, learning & mood

• Gluconeogenesis

• Skeletal muscle breakdown

• Lipolysis, calcium balance

• Immune depression

• Circadian rhythms


Cortisol Effects: Body Responses to StressCortisol Effects: Body Responses to Stress

Figure 23-4: Circadian rhythm of cortisol secretion


Control of Cortisol Secretion: Feedback LoopsControl of Cortisol Secretion: Feedback Loops

Figure 23-3: The control pathway for cortisol

• External stimuli

• Hypothalamic

• Anterior Pituitary

• Adrenal cortex

• Tissues


Cortiso: Role in Diseases and MedicationCortiso: Role in Diseases and Medication

• Use as immunosuppressant

• Hyperimmune reactions (bee stings)

• Serious side effects

• Hypercortisolism (Cushing's syndrome)

• Tumors (pituitary or adrenal)

• Iatrogenic (physician caused)

• Hypocortisolism (Addison's disease)


Thyroid Gland: Hormones and Iodine MetabolismThyroid Gland: Hormones and Iodine Metabolism

• C-cells – calcitonin (covered later)

• Follicule cells

• Amine hormones:

• thyroxine, T1, T2 & T3

• growth

• metabolism

• Thermogenic


Thyroid Gland: Hormones and Iodine MetabolismThyroid Gland: Hormones and Iodine Metabolism

Figure 23-7b: The thyroid gland


Thyroxine and its precursors: Structure & SynthesisThyroxine and its precursors: Structure & Synthesis

Figure 23-8: Thyroid hormones are made from tyrosine and iodine


Thyroxine and its precursors: Structure & SynthesisThyroxine and its precursors: Structure & Synthesis

Figure 23-9: Thyroid hormone synthesis


T3 & T4 Control Pathways & Diseases from MalfunctionT3 & T4 Control Pathways & Diseases from Malfunction

• Hypothalamus

• Anterior Pituitary

• Thyroid

• Hypothyroidism

• Goiter (TSH )• Grave's disease


T3 & T4 Control Pathways & Diseases from MalfunctionT3 & T4 Control Pathways & Diseases from Malfunction

Figure 23-12: Thyroid hormone pathway


Growth Hormone (GH): Functions & MalfunctionsGrowth Hormone (GH): Functions & Malfunctions

• Polypeptide H from hypothalamus/anterior pituitary

• growth (with T4, sex Hs, paracrines)

• metabolism

• protein & bone synthesis

• Regulation – hypothalamus

• Dwarfism

• Acromegaly


Growth Hormone (GH): Functions & MalfunctionsGrowth Hormone (GH): Functions & Malfunctions

Figure 23-16: Growth hormone pathway


• Epiphyseal plate – new bone growth site

• Chondrocytes, osteoblasts & calcification build bone

Bone Growth and Calcium MetabolismBone Growth and Calcium Metabolism


Bone Growth and Calcium MetabolismBone Growth and Calcium Metabolism

Figure 23-19: Bone growth at the epiphyseal plate


• Maintain [plasma]: from diet, from bone "storage", recycled

• Key roles: muscle contraction, bone support, cell signaling

Calcium Metabolism:Calcium Metabolism:

PLAY Animation: Fluids & Electrolytes: Electrolyte Homeostasis


Calcium Metabolism:Calcium Metabolism:

Figure 23-20: Calcium balance in the body


Control of Calcium Balance & MetabolismControl of Calcium Balance & Metabolism

Figure 23-23: Endocrine control of calcium balance

• Parathyroid H

• Calcitrol

• Vitamin D

• Sun/diet

• Calcitonin

• Thyroid

• C-cells

• (Phosphate balance)


Osteoporosis: Disease of Bone Growth & Calcium MetabolismOsteoporosis: Disease of Bone Growth & Calcium Metabolism

Figure 23-21: Osteoclasts are responsible for bone resorption

• Bone reabsorption exceeds deposition

• Osteoclasts mobilize Ca++ to plasma

• Factors: inadequate Ca++ intake, genes, hormones, smoking


SummarySummary• In addition to insulin and glucagon,

metabolism is influenced by hormones from adrenal, thyroid, parathyroid and hypothalamus

• Cortisol catabolic activities responding to stress

• Growth H anabolic activities to promote growth

• PTH, cacitrol, & calcitonin balance plasma [Ca++] for bone synthesis, muscle contraction, & cell signaling

• Endocrine diseases result from pathway or glandular hypo or hyper secretion

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