1. II
Anatomy and Physiology
Endocrine System

3. Endocrine system
• The endocrine system regulates body activities
by releasing hormones (chemical messengers)
into the bloodstream, where they are carried
throughout the entire body.
• Hormonal responses may be almost
instantaneous (Sudden), or may occur days later.
There is a wide variety of hormonal effects.

4. 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.
• They are commonly referred as the ductless
glands, because the hormones secreted
directly into bloodstream

5. Glands
• An organ which secretes particular chemical
substances for use in the body or for discharge
into the surroundings.
• There are three types of glands in our body:
- Endocrine glands
- Exocrine glands
- Heterocrine glands

6. Exocrine glands
• Are glands that secrete their products into
ducts
• EXAMPLE:
- Sweat glands
- Salivary glands
- Mammary glands
- Stomach
- Liver

7. Endocrine glands
• Endocrine Glands are called ductless glands
• Glands that secrete their product (hormones)
directly into the blood rather than through a duct
• Each hormone acts on only a certain kind of
tissue called its target tissue
• Example:
-Pituitary gland
-Pancreas
-Thyroid gland
-Adrenal glands

9. Heterocrine glands
• These are glands that perform both exocrine
and endocrine functions.
• For example pancreas

10. Endocrine system
• It consists of a number of glands:
- Pituitary gland
- Thyroid gland
- Parathyroid gland
- Adrenal gland
- Pancreases
- Thymus gland
- Testes and Ovaries

12. Pineal gland
• It is an important endocrine gland in higher
vertebrates. The name is derived from its
pinecone like structure.
• It is also known as ‘third eye’ as this gland
receives its stimuli through vision.
• It was first discovered by Herophilus about
2000 years ago.

13. Pineal gland
Function
• The pineal gland is involved in several
functions of the body including:
– Secretion of the Hormone Melatonin
– Regulation of Endocrine Functions
– Conversion of Nervous System Signals to
Endocrine Signals
– Causes Feeling of Sleepiness
– Influences Sexual Development

14. Pituitary gland and hypothalamus
• The pituitary gland or hypophysis is attached
to the hypothalamus at the base of the brain.
• The hypothalamus is the major integrating link
between the nervous and endocrine systems.
• Together, the hypothalamus and pituitary
gland regulate virtually all aspects of growth,
development, metabolism, and homeostasis.

15. Pituitary gland
• The pituitary gland is called the 'master gland' as
the hormones it produces control so many different
processes in the body. It senses the body's needs and
sends signals to different organs and glands
throughout the body to regulate their function and
maintain an appropriate environment.
• 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

17. Pituitary gland
• Secretes more than 9 hormones, which affect many
different areas of the body, including:
• Growth
• Blood pressure
• Regulation of Pregnancy
• Breast milk production
• Sex organ functions in both men and women
• Thyroid gland function
• Metabolism
• Water regulation in the body (kidneys)

18. Pituitary gland parts
There are two parts :
• Neurohypophysis
-Small posterior lobe
- Stores hormones
- Oxytocin
- Anti Diuretic hormone (ADH)

19. Pituitary gland parts
• Adenohypophysis
-Large anterior lobe
-Releases hormones
-Growth hormone (GH)
-Thyroid Stimulating hormone (TSH)
-Adenocorticotropic hormone (ACTH)
-Lutenizing hormone (LH)
-Follicle stimulating hormone (FSH)
-Melanocyte stimulating hormone (MSH)
-Prolactin (PRL)

20. Pituitary gland hormones
Function
Target(s)
Hormone
Stimulates the adrenal gland to produce
a hormone called cortisol. ACTH is also
known as corticotrophin
Adrenals
(ACTH)
Stimulates the thyroid gland to secrete
its own hormone, which is called
thyroxine. TSH is also known as
thyrotrophin
Thyroid
TSH
Stimulates the breasts to produce milk.
This hormone is secreted in large
amounts during pregnancy and breast
feeding, but is present at all times in
both men and women
Breasts
PRL

21. Pituitary gland hormones
Function
Target(s)
Hormone
Stimulates growth and repair. Research is
currently being carried out to identify the
functions of GH in adult life.
All cells in the
body
Growth Hormone
(GH)
Exact role in humans is unknown.
MSH
Stimulates the production of estrogen
and testosterone
Ovaries
Testes
Luteinizing
Hormone (LH

22. Pituitary gland hormones
Function
Target(s)
Hormone
Controls the blood fluid
and mineral levels in the
body by affecting water
retention by the kidneys.
This hormone is also
known vasopressin or
argenine vasopressin
(AVP).
Kidneys
ADH
Affects uterine
contractions in pregnancy
and birth and subsequent
release of breast milk
Uterus
Breasts
Oxytocin

24. Growth Hormone
• Over-secretion of growth hormone:
– Giantism in childhood and acromegaly in adults
(bones of face, hands and feet enlarge)
• Under-secretion of growth hormone:
– Dwarfism in childhood

26. Thyroid
• Located in the neck
• Releases hormone thyroxin
• Function is to regulate rates of metabolism in the
body
– Essential for normal physical and mental development
• Over-secretion of thyroxin:
– Results in nervousness and weight loss
• Undersecretion of thyroxin:
–
Results in cretinism (mental retardation, small size) in
children

28. • Iodine deficiency in your diet results in goiter
(enlargement of thyroid gland)

29. Parathyroid glands
Small rounded mass
• Attached to posterior surface of thyroid gland
• Produces Parathyroid hormone (PTH)

30. Parathyroid glands
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)
• Hormone released is parathormone
• Undersecretion of parathormone results in
nerve disorders, brittle bones and clotting
problems

31. Thymus gland
• Primary lymphatic organ in the body.
• Position:- it is located over the heart and/or in
the neck area, anterior to the ascending aorta
and posterior to the sternum.
• The thymus consists of two lobes enclosed in
a capsule and is further divided internally
• Weight:- 10-15 gm at birth & grows until
puberty

32. Thymus gland
• Function :
– Secretion of thymosin

34. Adrenal Glands
• Located at the superior 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

35. Adrenal Glands
• Divided into:
(i) Outer cortex
(ii) Inner medulla
Undersecretion of
adrenaline
results in the inability
to deal with stress

36. 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

39. Pancreas
• Flattened organ
• Lies retroperitoneally & transversly across posterior
abdominal wall
• Posterior to stomach, between doudenum on right & spleen
on left
• Classified as exocrine & endocrine
Hormones:
• Islets of Langerhans secrete: Glucagon, α cells : ↑ blood
glucose
Insulin, β cells: ↓ blood glucose
• Growth harmone inhibiting hormone (GHIH), δ cells :
inhibits glucagon & insulin

40. Islet of Langerhans

42. Blood Sugar Regulation
• Over-secretion of insulin results in low blood
sugar
• Undersecretion of insulin results in high blood
sugar
– This can lead to a condition known as diabetes

43. 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

44. 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