The endocrine system regulates homeostasis through hormones that target cells and organs throughout the body. Key endocrine glands include the pituitary gland, which regulates other glands; the thyroid gland, which produces hormones regulating metabolism; and the adrenal glands, which produce cortisol and other hormones critical for stress response. Hormones act through feedback loops between the hypothalamus and pituitary to maintain hormone levels within target ranges.

1. Endocrine System
SHAHINA BANO
Objectives
•Define Endocrine system
•Identify Endocrine glands and Endocrine tissues present in the body
•Discuss types of Hormones, target cells, target organ
•Briefly discuss Mechanism of Action of Hormone (protein and
•steroids)
•Discuss the location and structure of pituitary gland.
• Discuss the role of hypothalamic hormones in the regulation of pituitary gland secretions.
•Discuss the function of the hormones secreted by anterior and posterior pituitary gland.
•Briefly discuss the structure, function & hormones of the following glands
•Thyroid
•Para Thyroid
•Pineal
•Adrenal
•Pancreas
Endocrine System

2. Endocrine System
•Circulating or local hormones of the endocrine system contribute to homeostasis by regulating the activity and growth of
target cells in your body.
•Hormones also regulate your metabolism.
Endocrine System

3. Hypothalamus
•The hypothalamus is part of the brain.
•It receives messages from all over the body and keeps the body balanced by sending out messages to the Nervous System
via the brain.
• It also sends out hormone messages to the pituitary gland and helps to regulate the control of thirst and hunger.
Hypothalamus
•The hypothalamus is the link between the endocrine and nervous systems.
•The hypothalamus produces releasing and inhibiting hormones, which stop and start the production of other hormones
throughout the body.
Pituitary Gland

4. Pituitary Gland
•Pituitary gland or hypophysis
•It is also known as master endocrine gland
•Pea shaped structure
•It secrete several hormones that control other endocrine glands
•Pituitary gland it self has a master the hypothalamus
•It lies in pituary fossa of sella tunica of the sphenoid bone
•It attached with stalk
•It has two lobes
Anterior lobe Adnophypophyses
Five hormones released
1. Somatotrophs Human growth (hGh)
2. Throtrophs Thyroid stimulating hormone(TSH )
3. Gonadotrophs Follicle stimulating hormone (FSH)
Luteinizing hormone (LH)
4. Lactotrophs Prolactin (PRL)
5. Corticortrophs Adrenocorticotropic hormone (ACTH)
Human growth hormone and insulin like growth factor
•Somatotropin secrete human growth hormone
•Human growth hormone in turn stimulates several tissue to secrete insulin like growth and regulate aspect of metabolism
•hGH is most plentiful hormone
•IGFs cause cells to grow and multiply by accelerating protein synthesis

5. •IGF also decrease the break down of protein
Thyroid stimulating Hormone
•Thyrotrophs secrete thyroid stimulating hormone TSH
•TSH control the secretions and other activities of the thyroid gland
Follicle stimulating hormone FSH
•Gonadotrophs secrete two hormones FSH and LH
•Both act on the gonads
•They stimulate secretion of estrogen and progesterone and the maturation of oocytes in the ovaries
•They stimulate sperm production and secretion of testesrone in the testes
Lactotrophs
•Secrete prolactin (PRL) which initiate milk production in the mammary glands.
Adrenocorticotropic Hormone
•Corticotrophs secrete adrenocorticotropic hormone which is stimulates the adrenal cortex to secrete glucocorticoids such
as cortisol
•Some corticotrophs remnants of the pars intermedia also secrete melanocytes stimulating hormones (MSH)
Posterior lobe Neurohyphophses
•Two parts
•Pars nervosa large tubular portion
•Infundibulum
•10,000 terminal is called pituictyes

6. •Two hormones released
1.Antidiuretic hormone ADH
2.Oxytocin
Antidiuretic hormone ADH
•Anti = Against
•Diuretic = Increased urine production
•Also called vasopressin
•Vaso = Blood
•Pressure = Press
Oxytocin
Ok, se TO-sin; okytoc
•Oxytocin = Quick after birth

7. Mechanism of Action of Hormone (protein and steroids)
Thyroid gland
•Butterfly shape
•Located just inferior to larynx
•Two lobes
•Right lobe
•Left lobe
•Connected by isthmus
•Normal mass 30g
•It receive 80-120ml of blood/ minute

8. Thyroid gland
Thyroid gland
•Follicular cells produce
•T4 or thyroxin Tetraiodothyronine
•T3 Triiodothryronine
•Parafolicular cells (C cells)

9. •Produces calcitonin
•Calcitonin regulate calcium homeostasis
•Regulating the rate at which your body uses calories (energy)
•Slowing down or speeding up your heart rate
•Raising or lowering your body temperature
•Influencing the speed at which food moves through your digestive tract
Parathyroid glands
•Embedded in posterior surface of the lateral lobes of the thyroid gland.
•Para means beside.
•Weight 40g.
•Chief cells are more numerous cells.
•Chief cells produce parathyroid hormone PTH
•Parathyroid hormone is also called parathorme
•Function major regulate of levels of calcium magnesium and phosphate
•Oxyphil cells unknown function
•Release of calcium by bones into the bloodstream
•Absorption of calcium from food by the intestines
•Conservation of calcium by the kidneys
•Stimulates cells in the kidney to transforms weaker forms of vitamin D into the form that is strongest at absorbing calcium
from the intestines

10. Adrenal gland
•Supra renal gland
•2 gland located on top of kidney superior to each kidneys
•3.5-5cm height
•Two parts
•Adrenal medulla
•Adrenal cortex

11. Adrenal Cortex
•Comprising 80-90% of adrenal gland
•Produced steroid hormones
•Layers of adrenal cortex
•Zona Glomerulosa = Aldosterone
•Zona Fasciculata = Cortisol Glucocorticoids
•Zona Reticulata = Androgens
Adrenal Medulla
•Inner potion
•Chromaffin cells secrete hormones
•Two hormones
•Epinephrine adrenaline
•Nor epinephrine noradrenaline

12. Thymus gland
•Located behind sternum between lungs
•Major role in immunity
•Hormones produces
•Thymosin
•Thymic lumoral factor THF
•Thymic factor TF
•Thymopoietin
•Function promote maturation of T cells
Thymus Gland

13. Pinal gland
•Pinecone shape
•Small endocrine gland
•Attached to roof of 3rd ventricle of brain at midline
•0.1-0.2g weight
•Gland consist of pinealocytes cells
•Physiological role is still unclear
•Produces melatonin
•Melatonin is thought to contribute to setting the body biological clock
•During sleep plasma level of melatonin increase and then decline plasma level before awakening
References
•Tortora J.G, Derkison, B. principle of Anatomy and physiology (11th Ed) USA john Willey & Sons, inc