Download Chapter 18

Anatomy and Physiology, Sixth Edition
Rod R. Seeley
Idaho State University
Trent D. Stephens
Idaho State University
Philip Tate
Phoenix College
Chapter 18
Lecture Outline*
*See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.
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Chapter 18
Endocrine Glands
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Endocrine System Functions
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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
• ACTH
• TSH or thyrotropin
– Causes release of
thyroid hormones from
thyroid gland
– 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
• Prolactin
– Stimulates milk
production in lactating
females
– GnRH from hypothalamus
stimulates LH and FSH
secretion
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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
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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
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