Endocrine Gland |
Hormone(s) Secreted |
Function(s) of Hormones |
| |
|
|
(1) Hypothalamus |
Part
of the Brain: The Control and Relay Centre
of the Endocrine System. |
(2) Pituitary |
Known
as the "Master Gland", this part of
the brain consists of three lobes called "anterior",
"interior" and "posterior". |
Posterior |
|
 |
Stimulates
utrine contraction and brest contraction
for milk release.
|
|
Posterior |
|
Anti-Diuretic
Hormone (ADH), also known as 'vasopressin'. -
more info
|
|
|
Stimulates
re-absorption of water from kidney tubules.
|
|
Hypo- causes Diabetes
Insipidus (large amounts of
urine produced).
|
|
Anterior |
|
|
Production
of breast milk (works in men too).
|
|
Anterior |
|
|
Growth |
|
Hypo- Dwarfism |
|
Hyper- Gigantism
|
|
|
|
Thyroid
Stimulating Hormone (THS) -
more info
|
|
|
Stimulates
the thyroid to release thyroxin.
|
|
Anterior |
|
Adrenocorticotrophic
Hormone (ACTH) -
more info
|
|
|
Stimulates
the adrenal cortex to produce:
|
| |
Corticosteroids |
-
mineral corticoids |
|
-
glucocorticoids |
|
-
cortisol (natural anti-inflammatory) |
|
-
androgens, e.g. acdosterone. |
|
|
Anterior |
|
|
Brings
about ovulation and maintains the corpus
luteum.
|
|
Anterior |
|
Follicle
Stimulating Hormone (FSH) -
more info
|
|
|
Stimulates
growth/development of Graafin follicles
(= a mature follicle in the ovary prior
to ovulation, containing a large fluid-filled
cavity that distends the surface of the
ovary) on approx. 28 day cycle.
|
|
|
|
Melanin
Stimulating Hormone (MSH)
|
|
|
|
|
|
Secondary
sexual characteristics.
|
|
Anterior |
|
Interstitial
Cell Stimulating Hormone (ICSH) -
more info
|
|
|
Works
on the seminiferous tubules in the testes – to
produce sperm – which take 21
days to mature.
(If not ejaculated within
21 days, the sperm are re-absorbed back
into the body.)
|
|
Intermediate |
|
|
Control
of melanocyte production.
|
|
(2) Pineal |
A pea-sized mass of nerve tissue
attached by a stalk to the posterior wall of
the third ventricle of the brain, deep between
the cerebral hemispheres at the back of the skull.
(It functions as a gland, secreting the hormone
melatonin - which regulates the pituitary
gland and is associated with the biological
clock.)
|
|
|
|
A
hormone produced by the pineal gland in
darkness but not in bright light.
|
|
Melatonin
receptors in the brain react to this hormone
and synchronize the body to the 24 hour
day/night rhythm, thus informing the brain
when it is day and when it is night.
|
|
Melatonin
is derived from seratonin, with which it
works to regulate the sleep cycle.
|
|
(3a) Thyroid Gland |
Part
of the Thyroid/Parathyroid Gland, which is
in the neck. |
|
|
|
Concerned
with the Basal Metabolic Rate (BMR), which
is the amount of energy the body uses,
just to ‘tick over’.
|
Hyper-Thyroidism
= ‘over-active thyroid’ = Thyrotoxicosis
Symptoms:
increase in BMR; increase in heart-rate;
loss of weight; hyper-activity; insomniac;
develops bulging eyes due to accumulation
of fluid behind the eye; may develop Goitre;
possible link with Attention Deficit Disorder.
|
Hypo-Thyroidism
Symptoms;
decrease in BMR; weight gain; lethargy;
skin becomes dry and puffy; hair becomes
thin and brittle.
Causes: Derbyshire
Neck (originally due to insufficient iodine
in the soil in Derbyshire), Graves
Disease,
and Cretinism (= metal and sexual development
imapaired, if occurs in children).
|
|
|
|
|
Uptake
of calcium to bone.
|
|
(3b) Parathyroid Gland |
Part
of the Thyroid/Parathyroid Gland, which is
in the neck. |
|
|
|
Associated
with the growth of muscle and bone.
|
|
Distribution
of calcium and phosphate in the body.
|
Hyper- Causes
transfer of calcium from the bones to the
blood; bones become fragile & easily
broken; osteoporosis.
(Parathormone activity
is inhibited by oestrogen.)
|
Hypo- Lowers
blood calcium levels, causing tetany (which
may be treated by injections of the hormone);
low calcium levels in skeletal muscle (which
may cause cramps).
|
|
(4) Thymus |
The
thymus gland is located straddled across
the trachea & bronchi
in the upper thorax (a bi-lobed organ in the
root of the neck, above and in front of the
heart).
The thymus (a gland associated with the immune system), is enclosed in a capsule
and
divided internally by cross-walls into many lobules
(full of T-lymphocytes). In relation to body size the
thymus is largest at birth. It doubles in size
by puberty, after which it gradually shrinks,
its functional tissue being replaced by fatty
tissue. In infancy the thymus controls the
development of lymphoid tissue and the immune response to
microbes and foreign proteins (accounting for
allergic response, antoimmunity, and the rejection
of organ transplants). T-lymphocytes migrate
from the bone marrow to the thymus, where they
mature and differentiate until activated by
antigen.
|
|
|
|
Activates
the immune system by activating the T-Cells
(T-Killer Cells; T-Helper Cells; T-Memory
Cells).
|
|
|
|
T-Lymphocytes
|
|
|
The
thymus consists of lobules full of T-lymphocytes
(white blood cells associated with antibody
production).
|
|
T-lymphocytes
migrate from the bone marrow to the thymus,
where they mature and differentiate until
activated by antigens.
|
|
(5) Pancreas |
The
pancreas lies behind the stomach.
It is both exocrine (ducted) and endocrine
(ductless). |
As
an exocrine gland it secrets enzymes
(organic catalysts) into the small intestine. |
The enzymes are: |
|
Pancreatic
amylase (which breaks down polysaccharides,
i.e. starch into sugar) |
|
Lipase
(which breaks down fats into fatty
acids and glycerol) |
|
Proteases
(which breaks down protein (polypeptide)
into di-peptides). |
|
The
islets of Langerhans are within the pancreas. |
|
Islets of Langerhans |
Located
within the pancreas. Contains groups of both
Alpha- and Beta- cells. |
Beta Cells |
|
|
Conversion
of glucose to glycogen.
|
|
Cellular
up-take of Glucose. |
|
Conversion
of excess glucose to fat.
|
Hyper- |
Hypo- causes Diabetes
Mellitus: |
Symptoms:
Blood glucose levels rise (hyperglycaemia).
Glucose is excreted into the urine (glycosuria)
- which increases levels of urination,
causing dehydration.
As glucose levels in the blood increase,
fa and protein are broken-down for energy.
Coma and death may follow if the symptoms
are not treated. |
|
Alpha Cells |
|
|
Conversion
of glycogen to glucose.
|
|
(6) Adrenal Glands |
|
|
Adrenal Medulla |
|
Prepares
the body for "fright, fight or flight"
and has many effects: |
|
Action
of heart increased.
|
|
Rate
and depth of breathing increased.
|
|
Metabolic
rate increased.
|
|
Force
of muscular contraction improves.
|
|
Onset
of muscular fatigue delayed.
|
|
Blood
supply to the bladder and intestines
reduced, their muscular walls relax,
the sphincters contract.
|
|
|
|
Similar
effects to adrenalin: |
|
Constriction
of small blood vessels leading to increase
in blood pressure.
|
|
Increased
blood flow through the coronary arteries
and slowing of heart rate.
|
|
Increase
in rate and depth of breathing.
|
|
Relaxation
of the smooth muscle in the intestinal
walls.
|
|
Adrenal Cortex |
|
Glucocorticoids (e.g. cortisol, cortisone, corticosterone) |
|
Utilization
of carbohydrate, fat and protein by the
body.
|
|
Normal
response to stress.
|
|
Anti-inflammatory
effects.
|
|
Hypersecretion
of cortisol results in Cushings Syndrome.
|
| Mineralocorticoids (e.g.
aldosterone) |
|
Regulation
of salt and water balance.
|
|
Hypersecretion
of Alderosterone decreases the potassium
in the body (affecting nerve impulse
transmission and leading to muscular
paralysis).
|
|
(7) Ovaries |
Produce
mature ova. Theoretical potential for 400-450
viable ova.
(Therefore the more and the longer pregnancies
a woman has, the later her menopause
because there is no ovulation during pregnancy.) |
|
|
|
Break-down
of the utrine wall.
|
|
|
|
Progesterone -
more info
|
|
|
Builds
up and maintains the uterus wall for
embedding of fertilized egg.
|
|
Associated
with secondary sexual characteristics,
e.g. body hair, breast enlargement,
changes in physical body.
|
|
(8) Testes |
Located
outside the pelvic cavity. |
|
|
|
Development
and function of male sex organs. |
|
Secondary
sexual characteristics. e.g. body hair,
muscle development, voice change. |
|
