Controls many body functions

- exerts control by releasing special chemical substances into the blood called hormones

- Hormones affect other endocrine glands or body systems

Consists of several glands located in various parts of the body.

1.Pituitary gland

The Pituitary Gland is divided into 2 areas

Posterior Pituitary:oxytocin antidiuretic hormone (ADH)

Anterior Pituitary: thyroid-stimulating hormone (TSH)growth hormone (GH)adrenocorticotropin (ACTH) follicle-stimulating hormone (FSH) luteinizing hormone (LH)prolactin

2. Thyroid Gland- lies in the anterior neck just below the larynyx.

- Two lobes, located on either side of the trachea, connected by a narrow band of tissue called the isthmus.

- Sacs inside the gland contain colloid

thyroxine (T4)triiodothyronine (T3)

“C” cells within the thyroid produce the hormone calcitonin.

Calcitonin, when released, lowers the amount of calcium in the blood.

hypothyroidism, or Myxedema.

hyperthyroidism, commonly called Graves’ disease.

Long term hyperthyroidism:Exopthalmos

bulging of the eyeballs In severe cases - a medical emergency called

thyrotoxicosis can result.

3. Parathyroid Glandssmall, pea-shaped glands, located in the neck near the thyroid

usually 4 - number can vary

regulate the level of calcium in the body

produce parathyroid hormone - level of calcium in blood

Hypocalcemia can result if parathyroids are removed or destroyed.

4. Pancreas

Islets of Langerhansspecialized tissues in which the endocrine functions of

the pancreas occursinclude 3 types of cells:

alpha ( )beta ()delta ()

each secretes an important hormone.

Alpha () cells release glucagon, essential for controlling blood glucose levels.

When blood glucose levels fall, cells the amount of glucagon in the blood.

Beta Cells () release insulin (antagonistic to glucagon). Insulin the rate at which various body cells take up glucose.

Thus, insulin lowers the blood glucose level.

Delta Cells () produce somatostatin,

which inhibits both glucagon and insulin.

5. Adrenal Glands2 small glands that sit atop both kidneys.

Each has 2 divisions, each with different functions.

Adrenal Medulla catecholamine

hormones norepinephrine

epinephrine

Adrenal Cortex steroid hormonesglucocorticoids mineralocorticoidsandrogenic hormones

6. Gonads and Ovariesthe endocrine glands associated with human reproduction.

Ovaries:located in the

abdominal cavity adjacent to the uterus.

Manufactureestrogenprotesterone

Testes:located in the scrotum

produce sperm for reproduction

Manufacture

Testosterone

Hypothalamic Hormones/Factors

Corticotropin releasing hormone (CRH)- ACTH

Thyrotropin releasing hormone (TRH)- TSH

Gonadotropin releasing Hormone (GnRH)- FSH,LH

Prolactin release inhibiting hormone (PRIH)- Prolactin

Prolactin releasing factor (PRF)- Prolactin

Growth hormone releasing hormone (GHRH)- GH

Growth hormone releasing inhibiting Factor (GHRIF)- GH

Malinocyte-stimulating hormone releasing factor (MSH-RF)-

α,β &ᵞ-MSH

MSH release inhibiting factor (MSH-RIF)- α,β &ᵞ-MSH

At cell membrane receptorsa) Through alteration of intracellular cAMP concentration

b) Through IP3/DAG pathway

c) Tyrosin kinase pathway

AdrenalinGlucagonTSH,FSH,LH,PTHACTHCalcitoninVesopressin(V2)

Vasopressin(V1)Oxytocin

InsulinGrowth hormoneProlactin

Steroidal hormonesGlucocorticoidsMineralocorticoidsAndrogensEstrogensProgestins

At nuclear receptor Thyroid hormones

Stimuli which cause growth hormone releaseFastingHypoglycaemiaExerciseStress

Gh secretion is ↓ by ↑ in plasma free fatty acidsHigh dose of glucocorticoidsβ adrenergic agonist

Gh secretion is ↑ by 5HT agonist α adrenergic agonist

Growth hormone inhibitorsSomatostatin14 amino acidInhibit secretion of- GH TSH Prolactin Insulin Glucagon G.I secretions

By pitutary

By Pancreas

Synthetic octapeptide of somatostatin40 times more potentLong acting

Use AcromegalySecretory diarrhoeas associated with carcinoids, AIDS, cancer chemotherapy