Download Anatomy chapter 11 (Endocrine system)

Introduction
•The endocrine system is made up of the cells, tissues,
and organs that secrete hormones into body fluids.
•The body has two kinds of glands
•Exocrine - secretes products into ducts
•Endocrine - secrete products into body fluids to affect
target cells
•The endocrine system’s function is to communicate with
cells using chemicals called hormones.
•Endocrine glands and their hormones regulate a number
of metabolic processes within cells, and the whole body.
•Their actions are precise, they only affect specific
target cells.
•There are two main types of hormones:
•Steroidal Hormones – can pass through cell
membrane and affect the nucleus directly.
•Nonsteroidal Hormones – must first bind to
receptor in cell membrane and initiate a Signal
Transduction Pathway.
•Requires multiple chemical messengers inside
cell
Control of Hormonal Secretions
•Hormone levels are very precisely regulated.
•Negative Feedback Systems
•Commonly, negative feedback mechanisms control hormonal
releases.
•In a negative feedback system, a gland is sensitive to the
concentration of the substance it regulates or which
regulates it.
Major Endocrine Glands and Their Products
Pituitary Gland
• Releasing hormones from the hypothalamus control the
secretions of the anterior pituitary.
•A small gland located in the brain that is important for
puberty and sexual cycles.
•Growth hormone (GH) stimulates body cells to grow
and reproduce; it also speeds the rate at which cells use
carbohydrates and fats.
NFL
•Prolactin (PRL) promotes milk production following the
birth of an infant.
•Thyroid-stimulating hormone (TSH) controls the
secretion of hormones from the thyroid gland.
•Follicle-stimulating hormone (FSH) and
luteinizing hormone (LH) affect the male and female
gonads.
•Antidiuretic hormone (ADH) produces its effect by
causing the kidneys to conserve water.
•Oxytocin contracts muscles in the uterine wall and
forces milk into ducts from the milk glands.

Thyroid Gland
•
The thyroid gland is located
below the larynx and consists
of two broad lobes connected
by an isthmus.
Thyroid Gland
•The thyroid gland is located below the larynx and consists
of two broad lobes connected by an isthmus.
Thyroid


Consists of follicles that
are vesicles filled with
fluid called colloid
The follicles produce
hormones that are stored
in the colloid and
released into capillaries
Thyroid Gland
 Produces
two
iodine-containing
hormones:
 thyroxine

(T4)
triiodothyrine (T3)
•
These two hormones
together increase the
rate at which the
metabolism of a cell
runs.
•
Use of carbs, fats and
protein synthesis
Thyroid Gland
• calcitonin
•Inhibits osteoclasts from breaking down bone and
calcium emptying into blood.
•this lowers blood levels of calcium and phosphate ions
when they are too high.
Thyroid Gland Disorders

Hyperthyroidism
Too much thyroid hormone can cause the body’s
metabolism to speed up
 Most common form is known as Grave’s Disease


Symptoms

Muscle weakness, trembling hands, rapid heart rate,
fatigue, weight loss, diarrhea or frequent bowel
movements, vision problems, menstrual irregularities
Graves disease

Exophthalmos may occur with Graves
+
Thyroid Gland Disorders (cont.)

Hypothyroidism
Too little thyroid hormone can cause the body’s
metabolism to slow down
 Physical and mental functions become sluggish


Symptoms

Fatigue, mental depression, sluggishness, feeling
cold, weight gain, dry skin and hair, constipation,
menstrual irregularities
With hypothyroidism
Without hypothyroidism
Thyroid Gland Disorders (cont.)

Goiters
Enlargement of the thyroid gland itself
 Typically caused by lack of iodine in the diet or by a
disease that affects the thyroid glands ability to
produce thyroid hormone


Symptoms

Swelling of neck (range from small nodule to
massive lump), feeling of tightness in throat area,
difficulty breathing and swallowing, hoarseness,
dizziness when hands raised above head
Parathyroid Glands
•The four, tiny parathyroids are located on the
posterior of the thyroid.
•Parathyroid hormone (PTH) increases blood
calcium ion concentration.
Adrenal Glands
•The adrenal glands sit atop the kidneys enclosed in a layer of fat.
Epinephrine and Norepinephrine
•They are used in times of stress and trigger the “Fight or Flight”
response.
Aldosterone
•Causes the kidneys to conserve water.
•Secreted in response to decreasing blood volume and blood
pressure.
Cortisol
•Influences the metabolism of glucose, protein, and fat in response
to stress.
•High concentrations cause increase in use of fatty acids for
energy.
•Stress triggers cortisol release.
Pancreas
•The pancreas is both an endocrine gland and a digestive
gland located superior to your belly button, medial to the
kidneys.
•Glucagon increases the blood levels of glucose by
stimulating the breakdown of glycogen.
•Insulin decreases the blood levels of glucose by
shuttling glucose into cells and stimulating the liver to
form glycogen.
•These two hormones operate to keep the blood
glucose levels relatively constant.
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Hormonal Control of Female Reproductive
Functions
A.
Hormones secreted by the hypothalamus, the anterior
pituitary, and the ovaries control female reproduction and
development of secondary sexual characteristics.
44
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B.
Female Sex Hormones
1.
At about 10 years of age, the hypothalamus
begins to secrete more GnRH (Gonadotropin-releasing
hormone), which in turn stimulates the anterior pituitary
to produce LH and FSH.
45
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2.
At puberty, the ovaries synthesize estrogens in
response to FSH.
a. Estrogens are responsible for the female secondary
sexual characteristics, such as breast development,
increased adipose tissue deposition, and increased
vascularization of the skin.
b. Ovaries also secrete progesterone, which triggers
uterine changes during the menstrual cycle.
46
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C. Female Reproductive Cycle
1. Menarche is characterized by monthly changes in
the uterine lining that lead to menstrual flow as the
endometrium is shed.
2. A menstrual cycle is started by FSH, which
stimulates the maturation of a follicle in the ovary.
47
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3. Follicular cells surrounding the developing oocyte
secrete estrogen, which is responsible for maintaining
secondary sexual characteristics as well as the thickening
of the uterine lining.
4. Ovulation is triggered by a mid- cycle surge in LH.
5. Following ovulation, follicular cells turn into a
glandular corpus luteum that secretes increasing
amounts of estrogen and progesterone.
48
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6. If pregnancy does not occur, the corpus luteum
degenerates, hormone levels decline, and the uterine
lining disintegrates and is shed, the remnant is called the
corpus albicans.
7. During the cycle, estrogen and progesterone inhibit
the increased release of FSH and LH; when estrogen
and progesterone levels fall, the secretion of FSH and
LH increases.
49
Fig19.13
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Plasma hormonal
concentration
Ovarian activity
LH
FSH
Ovarian events
FSH
Developing
follicle
Mature
follicle
Follicular phase
Days
1
Early
corpus luteum
LH
Regressive
corpus luteum
Ovulation
7
Corpus
albicans
Luteal phase
14
21
28
Plasma hormonal
concentration
Uterine activity
Estrogens
Progesterone
Thickness of endometrium
Progesterone
Days
Estrogens
1
3
Menstruation
5
7
9
11
13
15
Proliferative phase
17
19
21
23
Secretory phase
50
25
27
1
3
Menstruation
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D.
Menopause
1. Menstrual cycles continue throughout middle age until
menopause, when the cycles cease.
2. The cause of menopause is the aging of the ovaries
when follicles no longer mature and estrogen levels
decline.
51
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Birth Control
A.
Birth control refers to the voluntary regulation
of the number of offspring produced, requiring
the use of contraception. The following slide lists the
different methods.
52
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1.
2.
3.
4.
5.
6.
7.
8
9.
Coitus Interruptus
Rhythm Method
Mechanical Barriers
Chemical Barriers
Oral Contraceptives
Injectable Contraception
Contraceptive Implants
Intrauterine Devices
Surgical Methods
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Regulation of Menstrual Cycle
Fig19.15
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©The McGraw-Hill Companies, Inc./Jill Braaten, photographer
©The McGraw-Hill Companies, Inc./Jill Braaten, photographer
(a)
(b)
©PhotoLink/Getty Images
(c)
©The McGraw-Hill Companies, Inc./Jill Braaten, photographer
©Don Farrall/Getty Images
(d)
(e)
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Fig19.16
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Cut and ligated
ductus (vas) deferens
Scrotum
(a)
Cut and ligated
uterine tubes
Path of sperm
Path of egg
Ovary
Uterus
Cervix
Vagina
(b)
57
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Hormonal Control of Male Reproductive
Functions
A. Hormones secreted by the hypothalamus, the anterior
pituitary, and the testes control male reproduction and
development of secondary sexual characteristics.
58
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B.
Hypothalamic and Pituitary Hormones
1. At the time of puberty, the hypothalamus controls the
many changes that lead to the development of a
reproductively functional adult.
2. The hypothalamus releases (GnRH), which triggers the
production of the gonadotropins luteinizing
hormone (LH), and follicle-stimulating hormone (FSH)
from the anterior pituitary.
59
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a. LH promotes the development of interstitial cells
of the testes and they, in turn, secrete male hormones
(testosterone).
b. FSH stimulates the supporting cells of the
seminiferous tubules where spermatozoa are created.
c. FSH and testosterone stimulate spermatogenesis.
60
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C. Male Sex Hormones
1. The male sex hormones are called androgens, of
which testosterone is the most abundant.
2. Testosterone is secreted in a fetus until birth, and
then not again until puberty, after which it is
continuously secreted.
61
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3. Actions of Testosterone
a. Testosterone stimulates the development of the
male reproductive organs and causes the testes to
descend.
b. Testosterone is also responsible for male secondary
sexual characteristics (deep voice, body hair, thickening
of the skin, and so forth).
62
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4. Regulation of Male Sex Hormones
a. A negative feedback system involving the
hypothalamus regulates the quantity of testosterone.
b. As the concentration of blood testosterone increases,
the hypothalamus becomes inhibited, and its stimulation
of the anterior pituitary declines.
c. As the amount of LH drops in response, the amount
of testosterone is reduced.
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