ENDOCRINE SYSTEM

presented by THARANNI

Learning objectivesDefine hormoneDraw and label the location of anterior and

posterior pituitary lobe, thyroid gland, parathyroid gland, pancreatic islets, adrenal gland, pineal gland, thymus gland, testes and ovary

List the major hormones secreted by anterior pituitary gland, posterior pituitary gland, thyroid gland, pancreatic islets, adrenal gland, pineal gland, thymus gland, testes, ovary including their functions.

• Controls many body functions– exerts control by

releasing special chemical messenger/mediator into the blood called hormones

• Derives its name from the fact that various glands release hormones directly into the blood, which in turn transports the hormones to target tissues via ducts.

The Endocrine System

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

• Pituitary gland: a small gland located on a stalk hanging from the base of the brain

• “The Master Gland” – Primary function is to

control other glands.– Produces many

hormones.– Secretion is controlled by

the hypothalamus in the base of the brain.

The Endocrine System

• The Pituitary Gland is divided into 2 areas, which differ– structurally and

functionally – each area has

separate types of hormone production.

• The two segments are:– Posterior Pituitary:

• oxytocin and antidiuretic hormone (ADH)

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

• Posterior Pituitary– Oxytocin (the natural

form of pitocin)• stimulates gravid

uterus• causes “let down” of

milk from the breast.

– ADH (vasopressin) causes the kidney to retain water

• Anterior Pituitary– Primarily regulates

other endocrine glands– rarely a factor in

endocrinological emergencies

– TSH stimulates the thyroid gland to release

• T3,T4• thus metabolic rate

– Growth hormone (GH) glucose usage consumption of fats

as an energy source

– ACTH stimulates the adrenal cortex to release

• aldosterone• Cortisol• androgen– FSH & LH stimulates

maturation & release of eggs from ovary.

• The Thyroid Gland– lies in the anterior neck

just below the larynyx.• Thyroid hormones:

– thyroxine (T4)– triiodothyronine (T3)

• When stimulated (by TSH or by cold), these are released into the circulatory system and the metabolic rate.

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

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

• Parathyroid Glands– small, 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.

• Pancreas– a key gland located in

the folds of the duodenum

• Islets of Langerhans– specialized tissues in

which the endocrine functions of the pancreas occurs

– include 2 types of cells:

• alpha ( )• beta ()

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

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

• The surge of glucagon stimulates the liver to release glucose stores (from glycogen and additional storage sites).

• Glucagon also stimulates the liver to manufacture glucose

• Glycogenolysis

• 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.

• Insulin is rapidly broken down by the liver and must be secreted constantly.

• Gluconeogenesis.

• Adrenal Glands– 2 small glands that sit

at top both kidneys.

• the Adrenal Medulla secretes the catecholamine hormones norepinephrine and epinephrine (stimulated by sympathetic nerve & ACTH).

• The Adrenal Cortex secretes 3 classes of hormones, all steroid hormones:– mineralocorticoids– gluticocorticoids – androgen

Gluticocorticoids:(CORTISOL)– accounts for 95% of

adrenal cortex hormone production

the level of glucose in the blood

– Released in response to stress, injury, or serious infection - like the hormones from the adrenal medulla.

• Mineralocorticoids:• (aldosterone)

– work to regulate the concentration of potassium and sodium in the body.

• Prolonged in adrenal cortex hormone results in Cushing’s Disease.

• Signs & Symptoms of Cushing’s Disease: in blood sugar

levels– unusual body fat

distribution– rapid mood swings

• And - if there is an in mineralocorticoids as well– A serious electolyte

imbalance will occur due to the potassium excretion by the kidney, which results in hypokalemia.

• Sodium can also be retained by the kidney, resulting in hyponatremia.– Causes:

• dysrhythmias• coma• death

Androgen :• Stimulates the

development and maintenance of male and female 2ndry characteristcs

• Gonads and Ovaries:– the endocrine glands

associated with human reproduction.

– Female ovaries produce eggs

– Male gonads produce sperm

• both have endocrine functions.

• Ovaries:– located in the

abdominal cavity adjacent to the uterus.

– Under the control of LH and FSH from the anterior pituitary they manufacture

• estrogen• protesterone

• Estrogen - estrous cycle &

development of 2ndry sex charcteristics.

Male..maturation of sperm

• Progesterone preparation of the uterus for implantation of the egg.

• Testes:– located in the scrotum– produce sperm for

reproduction– manufacture testosterone –

have anabolic and androgenic effect

• promotes male growth and masculinization

– Controlled by anterior pituitary hormones FSH and LH.

Thymus Gland

• Thymosin hormone• Stimulates the

maturation of T-lymphocyte

Pineal gland

• Melatonin• It’s release is stimulated by darkkness• Effects – synchronizer of the circadian rhythm Helps control the timing and release of female

reproductive hormones

• RECALL BACK TIME

REFRENCES

• Anatomy and physiology Tortora eight edition

• Youtube• Wikipidea• Notes