ENDOCRINE
SYSTEM
What is its main function in
the body?
ENDOCRINE SYSTEM
Exocrine glands release their secretions into
ducts, or tubes
Liver Bile released into the gallbladder, then
through a duct into the small intestine
Pancreas releases pancreatic juice into the small
intestine via a duct
Endocrine Glands are called ductless glands
Release hormones directly into the bloodstream
Blood transports hormones throughout the body
Each hormone acts on only a certain kind of tissue
called its target tissue
ENDOCRINE SYSTEM
The endocrine system includes the
endocrine glands and their hormones
The function of the endocrine system is
to secrete hormones into the
bloodstream.
Hormone: A Chemical messenger which
targets a specific group of cells, in order
to cause that group of cells do some
activity or stop doing an activity.
HORMONES
Chemical substance secreted by the
glands that controls various body
processes.
This Chemical acts as messenger which
targets a specific group of cells, in
order to cause that group of cells do
some activity or stop doing an activity.
FUNCTIONS OF HORMONES:
1. Regulate and balance the functioning
of the organs, tissues, and cells.
2. Influence growth, appearance,
emotions, and reproductive functions.
3. They play important role in the
occurrence of sickness and disorders.
ENDOCRINE SYSTEM
Each hormone acts on a certain kind of tissue called its
target tissue
HUMAN ENDOCRINE GLANDS
Hypothalamus
The hypothalamus is a part of the brain that
has a vital role in controlling many bodily
functions including the release of hormones
from the pituitary gland.
The hypothalamus releases:
- Thyrotropin RH
- Corticotropin RH
- GrowthHormone-
- Prolactin Rh
- Gonadotropin RH
Pituitary gland is a round organ about
the size of a pea (~1 cm in diameter),
located behind the bridge of the nose at
the base of the brain
Secretes 9 different hormones, which
affect many different areas of the body,
including:
•Growth
•Blood pressure
•Regulation of Pregnancy
PITUITARY •Breast milk production
•Sex organ functions in both men
and women
•Thyroid gland function
•Metabolism
•Water regulation in the body
(kidneys)
•Temperature regulation
Pituitary gland has two parts:
Thyroxin(T4)
- Part of the endocrine system that secretes
the hormone, melatonin.
- Help control the circadian cycle of sleep and
wakefulness to human and some animals.
COMMON
DISORDERS
GROWTH HORMONE
Oversecretion of growth hormone:
Giantism in childhood and acromegaly in adults
(bones of face, hands and feet enlarge)
Undersecretion of growth hormone:
Dwarfism in childhood
Hailing from Nagpur,
Maharashtra, India
Born on December
16, 1993.
Stands 2 ft and 0.72
in.
Located in the neck
Releases hormone thyroxin
Function is to regulate rates of metabolism in the body
Essential for normal physical and mental development
Oversecretion of thyroxin:
Results in nervousness and weight loss
Undersecretion of thyroxin:
Results in cretinism (mental retardation, small size) in
children
GOITER
Iodine deficiency in your diet
results in goiter (enlargement
of thyroid gland)
Function is to control metabolism of
calcium
Necessary for normal nerve and muscle
function, blood clotting, healthy bones
and teeth
Located in back of thyroid gland (in neck)
PARATHYROID
Hormone released is parathormone
Undersecretion of parathormone results in
nerve disorders, brittle bones and clotting
problems
ADRENAL GLANDS (KIDNEY
HATS)
Located at the top of each kidney
Hormones released are cortisone and
adrenaline
Function of cortisone is to regulate
carbohydrate, protein and fat metabolism
promotes conversion of fats and proteins
to glucose
Function of adrenaline is to raise blood
sugar levels and increases heartbeat and
breathing rates
Undersecretion of adrenaline
results in the inability to deal
with stress
ISLET OF LANGERHANS
Located on the pancreas
Hormones secreted are insulin and glucagon
Insulin stimulates glucose uptake by cells
Glucagon promotes conversion of glycogen (animal-
based carbohydrate) to glucose
BLOOD SUGAR REGULATION
Oversecretion of insulin results in low blood
sugar
Undersecretion of insulin results in high blood
sugar
This can lead to a condition known as diabetes
DIABETES-TYPE 1
Type 1- Usually found in children and young
adults; the body doesn’t make enough insulin
Symptoms:
Frequent urination
Unusual thirst
Extreme hunger
Unusual weight loss
Extreme fatigue and Irritability
DIABETES- TYPE 2
Type 2- Either the body doesn’t produce
enough insulin, or the cells ignore it.
If you consume too much sugar over a long
period of time, your body has to release
large amounts of insulin. This can result in
your cells building up a tolerance for
insulin, which means they won’t be
affected by it.
Symptoms:
Any of the type 1 symptoms
Frequent infections
Blurred vision
Cuts/bruises that are slow to heal
Tingling/numbness in the hands/feet
Recurring skin, gum, or bladder
infections
ENDOCRINE SYSTEM
CONTROL
Regulated by feedback mechanisms
2 types of feedback mechanisms
1. positive feedback
2. negative feedback
FEEDBACK MECHANISMS
Negative Feedback mechanisms:
- antagonistic effect between 2
substances.
Example: Body sugar increases after a
meal, so the pancreas secretes insulin,
which tells the body’s cells to take in
glucose. Once blood sugar levels reach
normal, the pancreas stops making
insulin. This is used to maintain
homeostasis
NEGATIVE FEEDBACK
Homeostasis is often maintained by two
hormones who have antagonistic effects
Each hormone does the opposite of the
other.
For example, if the blood pressure drops
too low, the pituitary releases ADH, which
causes the kidneys to reabsorb more
water. If the blood pressure increases too
much, then the heart will release ANH,
(Atrial Natireutic) which will cause the
kidneys to reabsorb less water.
POSITIVE FEEDBACK
MECHANISMS
Positive Feedback mechanisms control events
that can be out of control and do not require
continuous adjustment
Rarely used to maintain homeostasis
Example of positive feedback found in childbirth
Oxytocin stimulates and enhances labor
contractions
As labor continues, more oxytocin is produced
Intensifies contractions until the baby is
outside birth canal
Oxytocin production stops and labor
contractions stop
WHAT ABOUT THE
OVARIES AND THE
TESTES?
Don’t worry, we’re
saving them for our unit
on Reproduction
