1. ENDOCRINE SYSTEM
• The endocrine system is made
up of glands that make
hormones. Hormones are the
body's chemical messengers.
They carry information and
instructions from one set of
cells to another. The endocrine
system influences almost every
cell, organ, and function of our
bodies.
2. FOUR PRINCIPAL AVENUES OF
COMMUNICATION FROM CELL TO CELL
• 1. GAP JUNCTIONS – join unitary smooth muscle, cardiac muscle, epithelial,
and other cells to each other.
• 2. NEUROTRANSMITTERS – are released by neurons, diffuse across a
narrow synaptic cleft, and bind to receptors on the surface of the next cell.
• 3. PARACRINES – are secreted by one cell, diffuse to nearby cells in the same
tissue, and stimulate their physiology.
• 4. HORMONES – are chemical messengers that are transported by the
bloodstream and stimulate physiological responses in cells of another, often
distant tissue or organ.
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8. ANTERIOR PITUITARY HORMONES
• FOLLICLE-STIMULATING HORMONE (FSH).
- FSH is secreted by gonadotropic cells. In the ovaries, it stimulates the secretion of ovarian sex
hormones and the development of the bubble-like follicles that contain the eggs. In the testes, it
stimulates sperm production.
• LUTEINIZING HORMONE (LH)
- LH is also secreted by the gonadotropic cells. In females, it stimulates ovulation, the release of
egg. It is name for the fact that after ovulation, the follicle becomes a yellowish body called the
corpus luteum.
• THYROID-STIMULATING HORMONE (TSH) or thyrotropin.
- Is secreted by cells called thyrotropic cells. It stimulates growth of the thyroid gland and the
secretion of thyroid hormone, which has widespread effects on metabolic rate, body temperature
and other functions.
9. • ADRENOCORTOCROPIC HORMONE (ACTH)
- Is secreted by cells called corticotropic cells. Its target organ and the basis for its name is the
adrenal cortex.
• PROLACTIN (PRL)
- Is secreted by pituitary cells called prolactin cells. The hormone and these cells are named for
the role of PRL in lactation. During pregnancy, the lactotropes increase greatly in size and
number, and PRL secretion rises proportionately, but it has no effect on the mammary glands
until after a women gives birth.
• GROWTH HORMONE (GH)
- Is secreted by somatotropic cells, the most numerous cells of the anterior pituitary. The
pituitary produces at least a thousand time as much GH as any other hormone. The general effect
of GH is to stimulate mitosis and cellular differentiation and thus to promote tissue growth
throughout the body.
10. POSTERIOR PITUITARY HORMONES
• 1. ANTIDIURETIC HORMONE (ADH)
• - ADH increases water retention by the kidneys, reduces urine volume, and helps prevent
dehydration.
• 2. OXYTOCIN (OT)
• - OT has a variety of reproductive functions in situations ranging from intercourse to breast-
feeding. It surges in both sexes during sexual arousal and orgasm, possibly aiding in the
propulsion of semen through the male reproductive tract and stimulating uterine contractions
that help transport sperm up the female tract.
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12. THE PINEAL GLAND
The pineal gland named for its pine cone
shape, is attached to the roof of the third
ventricle of the brain, beneath the posterior
end of the corpus callosum. The philosopher
René Descartes (1596–1650) thought it was
the seat of the human soul. If so, children
must have more soul than adults—a child’s
pineal gland is about 8 mm long and 5 mm
wide, but after age 7 it regresses rapidly and
is no more than a tiny shrunken mass of
fibrous tissue in the adult. Such shrinkage of
an organ is called involution.14 Pineal
secretion peaks between the ages of 1 and 5
years and declines 75% by the end of puberty.
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16. ADRENAL GLAND
The adrenal (suprarenal) glands sit like a cap on the
superior pole of each kidney .Like the kidneys, they are
retroperitoneal, lying outside the peritoneal cavity between
the peritoneum and posterior body wall. The adult adrenal
gland measures about 5 cm vertically, 3 cm wide, and 1 cm
from anterior to posterior. It weighs about 8 to 10g in the
newborn, but loses half of this weight by the age of 2 years,
mainly because of involution of its outer layer, the adrenal
cortex.
17. TWO LAYER OF ADRENAL GLAND
• ADRENA MEDULA
• Inner core, the adrenal medulla, is 10% to 20% of the gland. Depending on
blood flow, its color ranges from gray to dark red.
• ADRENAL CORTEX
• A much thicker adrenal cortex, constituting 80% to 90% of the gland and
having a yellowish color due to its high concentration of cholesterol and
other lipids.
18. THREE LAYERS OF TISSUE
• The zona glomerulosa (glo-MER-you-LO-suh) is a thin layer, less developed in humans than in
many other mammals, located just beneath the capsule at the gland surface. The name
glomerulosa (“full of little balls”) refers to the arrangement of its cells in round clusters. The zona
glomerulosa is the source of mineralocorticoids.
• The zona fasciculata (fah-SIC-you-LAH-ta) is a thick middle layer constituting about three-
quarters of the cortex. Here the cells are arranged in parallel cords (fascicles), separated by blood
capillaries, perpendicular to the gland surface. The cells are called spongiocytes because of a
foamy appearance imparted by an abundance of cytoplasmic lipid droplets. The zona fasciculata
secretes glucocorticoids and androgens.
• The zona reticularis (reh-TIC-you-LAR-iss) is the narrow, innermost layer, adjacent to the adrenal
medulla. Its cells form a branching network for which the layer is named. Like the preceding
layer, the zona reticularis also secretes glucocorticoids and androgens.
19. TYPES OF ADRENAL GLANDS
• ALDOSTERONE
• Aldosterone stimulates the kidneys to retain sodium. Water is retained with
it by osmosis, so aldosterone helps to maintain blood volume and pressure
• CORTISOL
• Cortisol (also known clinically as hydrocortisone) is the most potent
glucocorticoid,This helps the body adapt to stress and repair damaged
tissues. Glucocorticoids also have an anti-inflammatory effect;
hydrocortisone is widely used in ointments to relieve swelling and other
signs of inflammation
20. ANDROGENS
Androgens are the primary adrenal sex steroids, but the adrenals
also produce small amounts of estrogen. ACTH regulates both
adrenal androgen and cortisol secretion. The sex steroids, too,
come from both the zona fasciculata and zona reticularis.
22. PANCREATIC ISLETS
• The pancreas is an elongated, spongy gland
located below and behind the stomach; most of
it is retroperitoneal it's aprimarily an
exocrine digestive gland.
23. TYPES OF FUNCTION
ALPHA (α) CELLS or GLUCAGON CELLS
is a secreted in response to rising amino acid levels in the blood after a high-
protein meal. It promotes amino acid absorption and thereby provides cells with
the raw material for gluconeogenesis
BETA CELL OR INSULIN CELL
Insulin is a hormone produced in the pancreas by special cells, called beta cells.
The pancreas is below and behind the stomach. Insulin is needed to move blood
sugar (glucose) into cells. Inside the cells, glucose is stored and later used for
energy
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25. ENDOCRINE FUNCTIONS OF OTHER
TISSUES AND ORGANS
• Ovaries
• Testes
• Liver.
• Kidney
• Heart
• Stomach and small
• intestine
• Adipose tissue
• Osseous tissue
• Placenta
26. THE GONADS
• Like the pancreas, the gonads (ovaries and
testes) function as both endocrine and
exocrine glands. Their exocrine products
are eggs and sperm, and their endocrine
products are the gonadal hormones, most
of which are steroids
28. THE HORMONE CHEMISTRY
• THREE CHEMICAL CLASSES
• 1. Steroid hormone
• are derived from cholesterol. They include sex steroids produced by the testes and ovaries
(such as estrogens, progesterone, and testosterone) and corticosteroids produced by the
adrenal gland (such as cortisol, aldosterone, and DHEA).
• 2. Monoamines (biogenic amines)
• The monoamine hormones include dopamine, epinephrine, norepinephrine, melatonin, and
thyroid hormone. The first three of these are also called catecholamines. Monoamines are
made from amino acids and retain an amino group, from which this hormone class gets its
name.
29. 3. PEPTIDE HORMONES
• are chains of 3 to 200 or more amino acids. The two posterior
pituitary hormones, oxytocin and antidiuretic hormone, are very
similar oligopeptides of just nine amino acids. Probably the best-
known large peptide (protein) hormone is insulin. Except for
dopamine, the releasing and inhibiting hormones produced by the
hypothalamus are polypeptides. Most hormones of the anterior
pituitary are polypeptides or glycoproteins—polypeptides conjugated
with short carbohydrate chains. Glycoprotein hormones usually have
an identical alpha chain of 92 amino acids and a variable beta chain
that distinguishes them from each other.
34. HORMONE SECRETION
• Hormones aren’t secreted at steady rates, nor do they
have constant levels in the bloodstream throughout
the day. Rather, they are secreted in some cases on a
daily (circadian) rhythm, in other cases on a monthly
rhythm (in a woman’s ovarian cycle), or under the
influence of stimuli that signify a need for them.
35. THREE KINDS OF STIMULI
• 1. Neural stimuli
• Nerve fibers supply some endocrine glands and elicit the release of their
hormones. For example, the sympathetic nervous system stimulates the
adrenal medulla to secrete epinephrine and norepinephrine in situations of
stress. In childbirth, nerve signals originate from stretch receptors in the
uterus, travel up the spinal cord and brainstem to the hypothalamus, and
stimulate the release of oxytocin.
• 2. Hormonal stimuli.
• Hormones from the hypothalamus regulate secretion by the anterior pituitary
gland, and pituitary hormones stimulate other endocrine glands to release
thyroid hormone, sex hormones, and cortisol
36. 3.HUMORAL STIMULI
• This refers to blood-borne stimuli. For example, rising
blood glucose concentration stimulates the release of
insulin, low blood osmolarity stimulates the secretion of
aldosterone, and a low blood calcium level stimulates the
secretion of parathyroid hormone.
42. HORMONE INTERACTIONS
• No hormone travels in the bloodstream alone,
and no cell is exposed to only one hormone.
Rather, there are many hormones in the
blood and tissue fluid at once. Cells ignore
the majority of them because they have no
receptors for them, but most cells are
sensitive to more than one
44. ANTAGONISTIC EFFECTS
• in which one hormone opposes the action of
another. For example, insulin lowers blood
glucose level and glucagon raises it. During
pregnancy, estrogen from the placenta inhibits
the mammary glands from responding to
prolactin; thus milk is not secreted until the
placenta is shed at birth.
45. ALARM REACTION
• The initial response to stress is the alarm reaction,
mediated mainly by norepinephrine from the
sympathetic nervous system and epinephrine from
the adrenal medulla. In extreme cases, as in wild
animals, these prepare the body to take action such
as fighting or escaping danger.
