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General Functions of Hormones
Figure 11.2 page 278
A.
Help regulate:
1.
2.
3.
4.
extracellular fluid
metabolism
biological clock
contraction of cardiac &
smooth muscle
5. glandular secretion
6. some immune functions
B.
C.
Growth & development
Reproduction
1
Types of Endocrine Glands
A.
Exocrine glands
1. secrete products into ducts which empty into body
cavities or body surface
a)
B.
sweat, oil, mucous, & digestive glands
Endocrine glands
1. secrete products (hormones) into bloodstream
a)
pituitary, thyroid, parathyroid, adrenal, pineal
2. other organs secrete hormones as a 2nd function
a)
hypothalamus, thymus, pancreas,ovaries,testes, kidneys,
stomach, liver, small intestine, skin, heart & placenta
2
Hormone Receptors
A.
Hormones only affect target cells with specific
membrane proteins called receptors
3
Steroid Hormones
A.
Steroids
1. lipids derived from
cholesterol
2. different functional
groups attached to core
of structure provide
uniqueness
3. Lipid-soluble
4
Nonsteroid Hormones
A.
Amine, peptide and
protein hormones
1.
2.
B.
modified amino acids or
amino acids put together
e.g. serotonin, melatonin,
histamine, epinephrine and
some glycoproteins
Eicosanoids
1.
2.
derived from arachidonic
acid (fatty acid)
prostaglandins or
leukotrienes
5
Action of Steroid Hormones
Figure 11.3; page 279
1.
2.
3.
4.
Hormone diffuses
through phospholipid
bilayer into cell
Binds to receptor, w/in
nucleus, turning on/off
specific genes
New mRNA is formed
& directs synthesis of
new proteins
New protein alters
cell’s activity
6
Action of Nonsteroid Hormones
Figure 11.4; page 280
1.
2.
Can not diffuse through
plasma membrane
Hormone receptors are
integral membrane proteins
a) act as first messenger
3.
4.
Receptor protein activates
G-protein in membrane
G-protein activates adenylate
cyclase to convert ATP to
cAMP in the cytosol
7
Water-soluble Hormones (2)
5.
6.
7.
8.
Cyclic AMP is the 2nd
messenger
Activates kinases in the
cytosol to speed up/slow
down physiological
responses
Phosphodiesterase
inactivates cAMP
quickly
Cell response is turned
off unless new hormone
molecules arrive 8
Cholera Toxin and G Proteins
1.
2.
3.
4.
Toxin is deadly because it produces massive
watery diarrhea and person dies from
dehydration
Toxin of cholera bacteria causes G-protein to
lock in activated state in intestinal epithelium
Cyclic AMP causes intestinal cells to actively
transport chloride (Na+ and water follow) into
the lumen
Person dies unless ions and fluids are replaced
& receive antibiotic treatment
9
Control of Hormone Secretion
Regulated by signals from nervous
system, chemical changes in the blood or
by other hormones
Negative feedback control (most
common)
A.
B.
1.
Positive feedback control
C.
1.
D.
decrease/increase in blood level is reversed
the change produced by the hormone causes
more hormone to be released
Disorders involve either hyposecretion or
hypersecretion of a hormone
10
Gland Overview and Experts
Gallery Tour
Overview: male and female posters
 Gallery Tour: expert brochures and
presentations

11
Overview Guidelines

Male/ Female posters need...
– Correct anatomical drawings and locations of
the endocrine glands
– Listing of hormones produced by each gland
12
Experts Gallery Tour


Each group will be assigned a particular gland
A brochure must be produced that is visually
appealing and provides the following
information…
– Anatomy details of the gland
– Key hormones produced and the physiology of how
they function
– Control mechanism(s) for the hormone
– Medical conditions associated with the hormone
13
Negative Feedback Systems
1.
2.
3.
4.
Decrease in blood
levels
Receptors in
hypothalamus &
thyroid
Cells activated to
secrete more TSH or
more T3 & T4
Blood levels increase
14
Positive Feedback
1.
2.
Oxytocin stimulates
uterine contractions
Uterine contractions
stimulate oxytocin
release
15
Pituitary Gland (Figure 11.7; page 298)
A.
B.
C.
Two parts: anterior and posterior
Anterior lobe controlled by hypothalamic hormones
Posterior lobe controlled by nerve endings from the
16
hypothalamus
Human Growth Hormone
1.
Within target cells increases synthesis of insulinlike growth factors that act locally or enter
bloodstream
a) common target cells are liver, skeletal muscle,
cartilage and bone
b) increases cell growth & cell division by increasing
their uptake of amino acids & synthesis of proteins
c) retard use of glucose for ATP production so blood
glucose levels remain high enough to supply brain
d) Know dwarfism vs gigantism
17
Regulation of hGH
Low blood sugar stimulates
release of GHRH from
hypothalamus
a)

anterior pituitary releases more
hGH, more glycogen broken
down into glucose by liver cells
High blood sugar stimulates
release of GHIH from
hypothalamus
b)

less hGH from anterior pituitary,
glycogen does not breakdown
into glucose
18
Thyroid Stimulating Hormone (TSH)
1.
2.
3.
4.
Hypothalamus regulates thyrotroph cells
Thyrotroph cells produce TSH
TSH stimulates the synthesis & secretion of
T3 and T4
Metabolic rate stimulated
19
Follicle Stimulating Hormone (FSH)
1.
FSH functions
a) initiates the formation of follicles within the ovary
b) stimulates follicle cells to secrete estrogen
c) stimulates sperm production in testes
20
Luteinizing Hormone (LH)
1.
In females, LH stimulates
a)
b)
c)
d)
2.
secretion of estrogen
ovulation of 2nd oocyte from ovary
formation of corpus luteum
secretion of progesterone
In males, stimulates
interstitial cells to secrete
testosterone
21
Prolactin (PRL)
1.
2.
3.
Under right conditions, prolactin causes
milk production
Suckling reduces levels of hypothalamic
inhibition and prolactin levels rise along
with milk production
Nursing ceases & milk
production slows
22
Adrenocorticotrophic Hormone
1.
2.
3.
ACTH stimulates cells
of the adrenal cortex that
produce glucocorticoids
Regulated by
Corticotropin releasing
hormone.
Stress causes the
increase release of CRH
23
Melanocyte-Stimulating Hormone
1.
2.
3.
During fetal development in a spot between
anterior and posterior pituitary (intermediate
lobe).
Function is to increase melanin production.
Intermediate lobe atrophies as you get older.
24
Posterior Pituitary Gland (Neurohypophysis)
A.
B.
Consists of axon
terminals of
hypothalamic neurons
Neurons release two
hormones that enter
blood stream
1. antidiuretic hormone
(ADH)
2. Oxytocin (OT)
25
Oxytocin
1.
2.
Two target tissues both involved in neuroendocrine
reflexes
During delivery
a) baby’s head stretches cervix
b) hormone release enhances
uterine muscle contraction
c) baby & placenta are delivered
3.
After delivery
a) suckling & hearing baby’s cry stimulates milk ejection
b) hormone causes muscle contraction & milk ejection
26
Antidiuretic Hormone (ADH)
1.
2.
Known as vasopressin
Functions
a) decrease urine
production
b) decrease sweating
c) increase BP
27
Thyroid Gland (Figure 11.9a; page 301)
A.
B.
On each side of trachea is lobe of thyroid
Weighs 1 oz & has rich blood supply
28
Histology of Thyroid Gland
A.
Follicle = sac of stored
hormone (colloid)
surrounded by follicle
cells that produced it
1. T3 & T4
B.
C.
Inactive cells are short
In between cells called
parafollicular cells
1.
produce calcitonin
29
Photomicrograph of Thyroid Gland
30
Actions of Thyroid
Hormones
1.
2.
T3 & T4 = thyroid hormones
responsible for our metabolic
rate, synthesis of protein,
breakdown of fats, use of
glucose for ATP production
Calcitonin = responsible for
building of bone & stops
reabsorption of bone (lower
blood levels of Calcium)
31
Control of T3 & T4
Secretion
1.
2.
3.
4.
Negative feedback
system
Low blood levels of
hormones stimulate
hypothalamus
It stimulates pituitary
to release TSH
TSH stimulates gland
32
to raise blood levels
Parathyroid Glands
A.
4 pea-sized glands found on back of thyroid gland
33
Histology of Parathyroid Gland
1.
2.
Principal cells
produce
parathyroid
hormone (PTH)
Oxyphil cell’s
function is
unknown
34
Parathyroid Hormone
1.
Raise blood calcium levels
a)
b)
c)
d)
2.
increase activity of osteoclasts
increases reabsorption of Ca+2 by kidney
inhibits reabsorption of phosphate (HPO4) -2
promote formation of calcitriol (vitamin D3)
by kidney which increases absorption of Ca+2
and Mg+2 by intestinal tract
Opposite function of calcitonin
35
Adrenal Glands
A.
General Info:
1. One on top of each kidney
2. 3 x 3 x 1 cm in size and weighs 5 grams
3. Cortex produces 3 different types of hormones from 3 zones
of cortex
4. Medulla produces epinephrine & norepinephrine
36
Structure of Adrenal Gland
Figure 11.12(a); page 305
37
Adrenal Cortex:
Mineralocorticoids
1.
2.
95% of hormonal activity due to aldosterone
Functions
a) increase reabsorption of Na+ with Cl- , bicarbonate and water
following it
b) promotes excretion of K+ and H+
3.
Hypersecretion = tumor producing aldosteronism
a) high blood pressure caused by retention of Na+ and water in
blood
38
Adrenal Cortex: Glucocorticoids
1.
2.
95% of hormonal activity is due to cortisol
Functions = help regulate metabolism
a) increase rate of protein catabolism & lipolysis
b) conversion of amino & fatty acids to glucose
c) provide resistance to stress by making
nutrients available for ATP production
d) raise BP by vasoconstriction
e) anti-inflammatory effects reduced (skin
cream)
•
•
•
reduce release of histamine from mast cells
decrease capillary permeability
depress phagocytosis
39
Adrenal Sex Hormones
1.
Small amount of male hormone
(androgen) produced.
a) may stimulate increase of sex hormones by
gonads.
b) may contribute to sex drive in females.
c) is converted to estrogen in postmenopausal
females.
40
Adrenal Medulla
A.
B.
Produce epinephrine & norepinephrine
Hormones are sympathomimetic
1. effects mimic those of sympathetic NS
2. cause fight-flight behavior
C.
Acetylcholine increase hormone
secretion by adrenal medulla
41
Anatomy of Pancreas:
Figure 11.14; page 308
A.
B.
Cells (99%) in acini produce digestive enzymes
Endocrine cells in pancreatic islets produce hormones
42
Cell Organization in Pancreas


Exocrine acinar cells surround a small duct
Endocrine cells secrete near a capillary
43
Cell Types in the Pancreatic Islets
1.
Alpha cells (20%) produce glucagon
a) What are the effects?
b) How are secretions controlled?
2.
Beta cells (70%) produce insulin
a) What are the effects?
b) How are secretions controlled?
44
Regulation of Glucagon & Insulin Secretion
1.
2.
Low blood glucose
stimulates release of
glucagon
High blood glucose
stimulates secretion
of insulin
45
Ovaries and Testes
A.
Ovaries
1. estrogen, progesterone, relaxin & inhibin
2. regulate reproductive cycle, maintain pregnancy &
prepare mammary glands for lactation
B.
Testes
1. produce testosterone
2. regulate sperm production & 2nd sexual
characteristics
46
Pineal Gland
A.
B.
Small gland attached to 3rd
ventricle of brain
Produces melatonin
1. Melatonin responsible for setting
of biological clock
2. Jet lag & SAD treatment is bright
light
47
Effect of Light on Pineal Gland
1.
Melatonin secretion producing sleepiness occurs
during darkness due to lack of stimulation from
48
sympathetic ganglion
Thymus Gland
A.
B.
Important role in maturation of T cells
Hormones produced by gland promote the
proliferation & maturation of T cells
1.
2.
3.
4.
thymosin
thymic humoral factor
thymic factor
thymopoietin
49
Miscellaneous Hormones
Eicosanoids
A.
Local hormones released by all body cells
1. Leukotrienes influence WBCs & inflammation
2. Prostaglandins alter
a) smooth muscle contraction (uterus & intestines),
smooth muscle relaxation (lungs and blood vessels),
glandular secretion, blood flow, platelet function, nerve
transmission, metabolism etc.
b) Ibuprofen & other nonsteroidal anti-inflammatory
drugs treat pain, fever & inflammation by inhibiting
prostaglandin synthesis
3. Erythropoietin (kidney) stimulate RBC production
50
Pituitary Gland Disorders
A.
B.
Hyposecretion during childhood = pituitary
dwarfism (proportional, childlike body)
Hypersecretion during childhood = giantism
1. very tall, normal proportions
C.
Hypersecretion as adult = acromegaly
1. growth of hands, feet, facial features & thickening
of skin
51
Thyroid Gland Disorders
A.
B.
C.
Hyposecretion during infancy results in
dwarfism & retardation called cretinism
Hypothyroidism in adult produces
sensitivity to cold, low body temp. weight
gain & mental dullness
Hyperthyroidism (Grave’s disease)
1. weight loss, nervousness, tremor &
exophthalmos (edema behind eyes)
D.
Goiter = enlarged thyroid (dietary)
52
Goiter
53
Cushing’s Syndrome
A.
B.
C.
Hypersecretion of glucocorticoids
Redistribution of fat, spindly arms &
legs due to muscle loss
Wound healing is poor, bruise easily
54
Addison’s disease
A.
Hypersecretion of glucocorticoids
1. hypoglycemia, muscle weakness, low
BP, dehydration due to decreased Na+ in
blood
2. mimics skin darkening effects of MSH
3. potential cardiac arrest
55
Diabetes Mellitus & Hyperinsulinism
A.
Diabetes mellitus marked by hyperglycemia
1. excessive urine production (polyuria)
2. excessive thirst (polydipsia)
3. excessive eating (polyphagia)
B.
C.
Type I----deficiency of insulin (under 20)
Type II---adult onset
1. drug stimulates secretion of insulin by beta cells
2. cells may be less sensitive to hormone
56