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to accompany
Hole’s Human
Anatomy and Physiology
Eleventh Edition
Shier w Butler w Lewis
Chapter
13
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
Chapter 13
Endocrine System
• Endocrine glands
are ductless
• Exocrine glands
have ducts
2
Endocrine Glands
Paracrine secretions
Endocrine glands
• act locally
• release hormones
• affect only neighboring cells
• hormones travel
through blood to target
cells
Autocrine secretions
• affect only the secreting cell
3
Comparison of Nervous System
and Endocrine System
• Neurons release
neurotransmitters into
a synapse, affecting
postsynaptic cells
• Glands release
hormones into the
bloodstream
• Only target cells of
hormone responds
4
Comparison of Nervous System
and Endocrine System
5
Major Endocrine Glands
6
7
Chemistry of Hormones
Steroid or Steroid-Like
Hormones
• sex hormones
• adrenal cortex
hormones
Nonsteroid Hormones
• amines
• proteins
• peptides
• glycoproteins
• most hormones
8
Types of Hormones
9
Structural Formulas of
Hormones
10
Actions of Steroid Hormones
• hormone crosses membranes
• hormone combines with
receptor in nucleus
• synthesis of mRNA
activated
• mRNA enters cytoplasm to
direct synthesis of protein
11
12
Actions of
Nonsteroid Hormones
• hormone binds to receptor on cell
membrane
• adenylate cyclase activated
• ATP converted to cAMP
• cAMP promotes a series of
reactions leading to cellular
changes
13
14
Actions of
Nonsteroid Hormones
15
Prostaglandins
• paracrine substances
• act locally
• very potent in small amounts
• regulate cellular responses to hormones
• can activate or inhibit adenylate cyclase
• controls cAMP production
• alters cell’s response to hormones
• wide variety of functions
16
Control of Hormonal
Secretions
• primarily controlled by negative feedback mechanism
17
Negative Feedback
18
Major Endocrine Glands
19
Pituitary Gland
Two distinct portions
• anterior pituitary (adenohypophysis)
• posterior pituitary (neurohypophysis)
20
Pituitary Gland Control
• Hypothalamic releasing hormones stimulate cells of anterior pituitary
to release hormones
• Nerve impulses from hypothalamus stimulate nerve endings in the
posterior pituitary gland to release hormones
21
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
–
Hypothalamus
–
Releasing
hormone
(Hormone 1)
+
–
Anterior pituitary
Anterior pituitary
hormone
(Hormone 2)
+
Peripheral endocrine gland
(Hormone 3)
+
Target cells
Stimulation
Inhibition
22
Hypothalamic Hormones
23
Hormones of the Pituitary Gland
24
Thyroid Gland
25
26
Thyroid Gland Hormones
27
Disorders of the Thyroid Gland
28
29
Disorders of the Thyroid Gland
Graves Disease
• Hyperthyroidism
Cretinism
• Infantile hypothyroidism
30
Parathyroid Glands
31
Parathyroid Hormone
32
Parathyroid Hormone
Mechanism by which PTH promotes calcium absorption in
the intestine
33
Calcium Balance
34
Disorders of the Parathyroid
Glands
35
Adrenal Glands
36
37
Hormones of the Adrenal Medulla
38
Hormones of the Adrenal Cortex
39
Hormones of the Adrenal
Cortex
• Aldosterone – zona glomerulosa
(mineralocorticoid)
• Cortisol – zona fasciculata
(glucocorticoid)
• Sex hormones – zona reticularis
(adrenal androgens)
40
Hormones of the Adrenal Cortex
41
Hormones of the Adrenal Cortex
42
Pancreas
43
44
Cell Types in the Pancreatic Islets
•
•
•
•
Alpha cells (20%) produce glucagon
Beta cells (70%) produce insulin
Delta cells (5%) produce somatostatin
F cells produce pancreatic polypeptide
45
Hormones of the Pancreatic Islets
46
Insulin and Glucagon
Insulin and glucagon function together to stabilize blood
glucose concentrations
47
Other Endocrine Glands
Pineal Gland
• secretes melatonin
• regulates circadian rhythms
Thymus Gland
• secretes thymosins
• promotes development of certain lymphocytes
• important in role of immunity
48
Other Endocrine Glands
Reproductive
• ovaries produce estrogens and progesterone
• testes produce testosterone
• placenta produces estrogens, progesterone, and
gonadotropins
49
Hormonal Control of Male
Reproductive Functions
• hypothalamus controls
maturation of sperm cells
and development of male
secondary sex
characteristics
• negative feedback
among the hypothalamus,
the anterior lobe of the
pituitary gland, and the
testes controls the
concentration of
testosterone
50
Actions of Testosterone
• increased growth of body hair
• sometimes decreased growth of scalp hair
• enlargement of larynx and thickening of vocal cords
• thickening of skin
• increased muscular growth
• thickening and strengthening of the bones
51
Hormonal Control of Female
Reproductive Functions
• estrogens
inhibit LH and
FSH during
most of the
reproductive
cycle
52
Effects of Estrogens
• development of breasts and ductile system
of the mammary glands
• increased adipose tissue in breasts, thighs,
and buttocks
• increases vascularization of skin
53
Female Reproductive Cycle
54
Female Reproductive Cycle
55
Hormonal Control of Female
Secondary Sex Characteristics
56
Menopause
• usually occurs in late 40s or early 50s
• reproductive cycles stop
• ovaries no longer produce as much estrogens and
progesterone
• some female secondary sex characteristics may
disappear
• may produce hot flashes and fatigue
• hormone therapy may prevent effects on bone tissue
57
Mammary Glands
• located in the subcutaneous
tissue of the anterior thorax
within the breasts
• composed of lobes
• estrogens stimulate breast
development in females
58
Pineal Gland
•
•
•
•
Small gland attached to 3rd ventricle of brain
Consists of pinealocytes & neuroglia
Melatonin responsible for setting of biological clock
Jet lag & SAD treatment is bright light
59
Effect of Light on Pineal Gland
• Melatonin secretion producing sleepiness occurs during
darkness due to lack of stimulation from sympathetic ganglion
60
Stress
Types of Stress
• physical stress
• psychological stress
61
Responses to Stress
62
Life-Span Changes
• endocrine glands decrease in size
• muscular strength decreases as GH levels decrease
• ADH levels increase due to slower break down in liver and kidneys
• calcitonin levels decrease; increase risk of osteoporosis
• PTH level changes contribute to risk of osteoporosis
• insulin resistance may develop
• changes in melatonin secretion affect the body clock
• thymosin production declines increasing risk of infections
63
Clinical Application
Growth Hormone Ups and Downs
• Gigantism - hypersecretion of GH in children
• Acromegaly – hypersecretion of GH in adults
• Dwarfism – hyposecretion of GH in children
Figure shows oversecretion of GH in adulthood as changes occur in the
same person at ages (a) nine, (b) sixteen, (c) thirty-three, and (4) fifty-two
64
Adrenal Cortex - Review
• Mineralocorticoids
– Mineralocorticoids (e.g., aldosterone) increase sodium and water
reabsorption and decrease potassium reabsorption, helping to
regulate sodium and potassium levels in the body.
– Secretion is controlled by the renin-angiotensin pathway (Figure
18.16) and the blood level of potassium.
• Glucocorticoids
– Glucocorticoids (e.g., cortisol) promote breakdown of proteins,
formation of glucose, lipolysis, resistance to stress, anti-inflammatory
effects, and depression of the immune response.
– Secretion is controlled by CRH (corticotropin releasing hormone) and
ACTH (adrenocorticotropic hormone) from the anterior pituitary
(Figure 18.17).
• Androgens
– Androgens secreted by the adrenal cortex usually have minimal
effects.
65
Adrenal Medulla - Review
• The adrenal medulla consists of hormone-producing cells,
called chromaffin cells, which surround large blood-filled
sinuses.
• Medullary secretions are epinephrine and norepinephrine
(NE), which produce effects similar to sympathetic
responses.
• They are released under stress by direct innervation from
the autonomic nervous system. Like the glucocorticoids of
the adrenal cortex, these hormones help the body resist
stress. However, unlike the cortical hormones, the medullary
hormones are not essential for life.
• Table 18.8 summarizes the hormones produced by the
adrenal glands, the principal actions, and control of
secretion.
66
Review: Cell Types in the Pancreatic Islets
• Alpha cells secrete the hormone glucagon which increases
blood glucose levels.
• Beta cells secrete the hormone insulin which decreases
blood glucose levels.
• Delta cells secrete growth hormone inhibiting hormone or
somatostatin, which acts as a paracrine to inhibit the
secretion of insulin and glucagon.
• F-cells secrete pancreatic polypeptide, which regulates
release of pancreatic digestive enzymes.
67
OVARIES AND TESTES - Review
• Ovaries are located in the pelvic cavity and produce sex
hormones (estrogens and progesterone) related to
development and maintenance of female sexual
characteristics, reproductive cycle, pregnancy, lactation, and
normal reproductive functions. The ovaries also produce
inhibin and relaxin.
• Testes lie inside the scrotum and produce sex hormones
(primarily testosterone) related to the development and
maintenance of male sexual characteristics and normal
reproductive functions. The testes also produce inhibin.
68
PINEAL GLAND - Review
• The pineal gland (epiphysis cerebri) is attached to the roof
of the third ventricle, inside the brain (Figure 18.1).
• Histologically, it consists of secretory parenchymal cells
called pinealocytes, neuroglia cells, and scattered
postganglionic sympathetic fibers. The pineal secrets
melatonin in a diurnal rhythm linked to the dark-light cycle.
• Seasonal affective disorder (SAD), a type of depression that
arises during the winter months when day length is short, is
thought to be due, in part, to over-production of melatonin.
Bright light therapy, repeated doses of several hours
exposure to artificial light as bright as sunlight, may provide
relief for this disorder and for jet lag.
69
THYMUS GLAND
• The thymus gland secretes several hormones related to
immunity .
• Thymosin, thymic humoral-factor, thymic factor, and
thymopoietin promote the proliferation and maturation of T
cells, a type of white blood cell involved in immunity.
70