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Anatomy and Physiology, Sixth Edition

Rod R. SeeleyIdaho State UniversityTrent D. StephensIdaho State UniversityPhilip TatePhoenix College

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

*See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.

Chapter 18Chapter 18

Lecture OutlineLecture Outline**

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Chapter 18

Endocrine Glands

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Endocrine System Functions

• Metabolism and tissue maturation• Ion regulation• Water balance• Immune system regulation• Heart rate and blood pressure regulation• Control of blood glucose and other nutrients• Control of reproductive functions• Uterine contractions and milk release

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Pituitary Gland and Hypothalamus

• Where nervous and endocrine systems interact

• Pituitary gland/hypophysis– Secretes 9 major hormones

• Hypothalamus– Regulates secretory activity

of pituitary gland through neurohormones and action potentials

– Posterior pituitary is an extension of

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Pituitary Gland Structure

• Posterior or neurohypophysis– Continuous with the brain– Secretes neurohormones

• Anterior or adenohypophysis– Consists of three areas

with indistinct boundaries: pars distalis, pars intermedia, pars tuberalis

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Relationship of Pituitary to Brain

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Hypothalamus, Anterior Pituitary and Target Tissues

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Pituitary Gland Hormones

• Posterior– Antidiuretic hormone

(ADH)

– Oxytocin

• Anterior– Growth hormone (GH) or

somatotropin– Thyroid-stimulating

hormone (TSH)– Adrenocorticotropic

hormone (ACTH)– Melanocyte-stimulating

hormone (MSH)– Luteinizing hormone (LH)– Follicle-stimulating

hormone (FSH)– Prolactin

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Antidiuretic Hormone

• Also called vasopressin• Promotes water retention by kidneys• Secretion rate changes in response to alterations in blood

osmolality and blood volume• Lack of ADH secretion is a cause of diabetes insipidus

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Oxytocin

• Promotes uterine contractions during delivery

• Causes milk ejection in lactating women

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Growth Hormone (GH)

• Stimulates uptake of amino acids and conversion into proteins

• Stimulates breakdown of fats and glycogen

• Promotes bone and cartilage growth

• Increased secretion in response to increase amino acids, low blood glucose, or stress

• Regulated by GHRH and GHIH or somatostatin

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TSH, ACTH, MSH

• TSH or thyrotropin– Causes release of

thyroid hormones from thyroid gland

• ACTH– Stimulates cortisol

secretion from adrenal cortex

• MSH– Increases skin

pigmentation

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LH, FSH, Prolactin

• LH and FSH– Both hormones regulate

production of gametes and reproductive hormones

• Testosterone in males

• Estrogen and progesterone in females

– GnRH from hypothalamus stimulates LH and FSH secretion

• Prolactin– Stimulates milk

production in lactating females

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Thyroid Gland

• One of largest endocrine glands

• Highly vascular

• Histology– Composed of follicles

– Parafollicular cells• Secrete calcitonin which

reduces calcium concentration in body fluids when levels elevated

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Biosynthesis of Thyroid Hormones

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Thyroid Hormones

• Include– Triiodothryronine or T3

– Tetraiodothyronine or T4 or thyroxine

• Transported in blood• Bind with intracellular receptor molecules and

initiate new protein synthesis• Increase rate of glucose, fat, protein metabolism in

many tissues thus increasing body temperature• Normal growth of many tissues dependent on

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Regulation of T3 and T4 Secretion

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Thyroid Hormone Hyposecretion and

Hypersecretion• Hypothyroidism

– Decreased metabolic rate

– Weight gain, reduced appetite

– Dry and cold skin

– Weak, flabby skeletal muscles, sluggish

– Myxedema

– Apathetic, somnolent

– Coarse hair, rough dry skin

– Decreased iodide uptake

– Possible goiter

• Hyperthyroidism– Increased metabolic rate

– Weight loss, increased appetite

– Warm flushed skin

– Weak muscles that exhibit tremors

– Exophthalmos

– Hyperactivity, insomnia

– Soft smooth hair and skin

– Increased iodide uptake

– Almost always develops goiter

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Parathyroid Glands

• Embedded in thyroid • Secrete PTH

– Increases blood calcium levels

– Stimulates osteoclasts

– Promotes calcium reabsorption by kidneys

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Regulation of PTH Secretion

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Adrenal Glands

• Functions as part of sympathetic nervous system• Composed of medulla and cortex (3 layers)• Hormones

– Medulla secretes epinephrine and norepinephrine– Cortex secretes mineralocorticoids, glucocorticoids, androgens

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Hormones of Adrenal Cortex• Mineralocorticoids

– Zona glomerulosa– Aldosterone produced in greatest amounts

• Increases rate of sodium reabsorption by kidneys increasing sodium blood levels

• Glucocorticoids– Zona fasciculata– Cortisol is major hormone

• Increases fat and protein breakdown, increases glucose synthesis, decreases inflammatory response

• Androgens– Zona reticularis– Converted to androgen and testosterone

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Pancreas

• Located along small intestine and stomach

• Exocrine gland– Produces pancreatic digestive

juices

• Endocrine gland– Consists of pancreatic islets– Composed of

• Alpha cells secrete glucagon• Beta cells secrete insulin• Delta cells secrete

somatostatin

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Insulin and Glucagon

Insulin• Target tissues: liver,

adipose tissue, muscle, and satiety center of hypothalamus

• Increases uptake of glucose and amino acids by cells

Glucagon• Target tissue is liver• Causes breakdown of

glycogen and fats for energy

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Regulation of Insulin Secretion

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Regulation of Blood Nutrient Levels After a Meal

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Regulation of Blood Nutrient Levels During Exercise

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Hormones of the Reproductive System

Male: Testes

• Testosterone– Regulates production of

sperm cells and development and maintenance of male reproductive organs and secondary sex characteristics

• Inhibin– Inhibits FSH secretion

Female: Ovaries• Estrogen and Progesterone

– Uterine and mammary gland development and function, external genitalia structure, secondary sex characteristics, menstrual cycle

• Inhibin– Inhibits FSH secretion

• Relaxin– Increases flexibility of

symphysis pubis

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Pineal Body

• In epithalamus• Produces

– Melatonin• Enhances sleep

– Arginine vasotocin• Regulates function of

reproductive system in some animals

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Effects of Aging on Endocrine System

• Gradual decrease in secretory activity of some glands– GH as people age– Melatonin– Thyroid hormones– Kidneys secrete less renin

• Familial tendency to develop type II diabetes

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Diabetes Mellitus

• Results from inadequate secretion of insulin or inability of tissues to respond to insulin

• Types– Type I or IDDM (Insulin-dependent)

• Develops in young people

– Type II or NIDDM (Non-insulin dependent)• Develops in people older than 40-45

• More common