Prepared by Mickelder Kercy, MD - Instructor

Definition : System of glands. A gland is a group of

cells that produces and secretes, or gives off chemicals

directly into the bloodstream. These chemicals called

hormones can be transported to other parts of the body

where they influence cells, organs, and functions of our

bodies

Hypothalamus

Pituitary Gland

Pineal Gland

Thymus

Thyroid Gland

Parathyroid Gland

Pancreas

Adrenal Glands

Ovaries

Testes

Placenta

Gastrointestinal Mucosa

Secretes: - Thyrotropin-releasing hormone (TRH) that causes the

anterior pituitary to secrete TSH

- Prolactin-releasing hormone (PRH ) that causes the

anterior pituitary to secrete PRL

- Dopamine (Prolactin-inhibiting hormone) to inhibit

prolactin release from the anterior pituitary gland

- Growth hormone-releasing hormone (GHRH) that

causes the anterior pituitary to secrete GH

- Somatostatin/Growth hormone-inhibiting hormone

(GHIH) that inhibits GH and thyroid-stimulating hormone (TSH)

release from the anterior pituitary gland

- Gonadotropin-releasing hormone GnRH or

LHRH that causes the anterior pituitary to secrete LH

- Gonadotropin-releasing hormone GnRH or

FSHRH that causes the anterior pituitary to secrete FSH

- Corticotropin-releasing hormone CRH that

causes the adrenal cortex to secrete glucocorticoids

- Controls body temperature, hunger, moods,

sex drive, sleep and thirst

Produces the serotonin derivative melatonin, a

hormone that affects the modulation of wake/sleep

patterns and seasonal functions

Anterior Lobe : - GH (causes bones and muscular growth)

- ACTH (stimulates the adrenal cortex to

secrete the glucocorticoids hormones)

- TSH (stimulates the thyroid to secrete the

hormones thyroxine/T4, Triiodothyronine/ T3)

- FSH (stimulates spermatogenesis and

oogenesis)

- LH (Causes ovulation and the production of

testosterone)

- PRL (stimulates the mammary glands to

produce milk)

- MSH (stimulates the production of melanin)

Posterior Lobe : - ADH/Vasopressin (Stimulates the

reabsorption of water by the kidneys)

- Oxytocin (stimulates the uterus to

contract during labor and childbirth as well as the

release of milk from the mammary glands)

Located anterior to the trachea

Secretes Thyroxine/T4 that regulates the BMR and

affects growth and development, body temperature,

and heart rate

Transforms T4 into Tri-iodothyronine/T3 that has

more effect on the body than T4

Secretes Calcitonin that reduces the level of calcium

in the blood

They are 4 glands located around the dorsal and lower

sides of the thyroid gland

Secrete Parathyroid hormone/PTH that increases the

level of calcium in the blood to reach normal range

when the calcium level in the blood goes down

Located behind the stomach across the back of the abdomen with the head connected to the duodenum through the pancreatic duct

Islets of Langerhans divided into the alpha(α), beta(β) and delta (∆) cells

The alpha cells secrete glucagon that increase the glucose level in the blood

The beta cells secrete insulin that decreases the glucose level in the blood so that the normal fasting blood glucose level is 70-100mg/dl

The delta cells secrete somatostatin that inhibit the secretion of insulin, glucagon and many other hormones

Adrenal Cortex secretes : - Cortisol (increases blood sugar level and reduces inflammation)

- Corticosterone (increases blood

sugar level)

- Aldosterone (regulates

electrolytes and water balance by reabsorbing sodium and

chloride and excreting potassium)

- Androgens (Testosterone,

Dehydroepiandrosterone (DHEA), Androstenedione (Andro),

Androstenediol, Androsterone, Dihydrotestosterone (DHT)

Adrenal Medulla secretes : - Dopamine

- Epinephrine (also known

as adrenaline is responsible for the fight or flight

syndrome. Regulated by the sympathetic nervous

system)

- Norepinephrine (increases

the heart rate, cardiac output and level of glucose in the

blood)

Secretes Progesterone : - Prepares the uterus for pregnancy

Secretes Estrogen : - Causes the repair of the endometrium after the menses

- Causes the following secondary sexual

characteristics → Enlargement of breasts and erection of

nipples

→ Growth of body hair especially underarm

and pubic areas

→ Fat deposits mainly around the buttocks, thighs

and hips

→ Smaller waist, hands and feet than men

→ Widening of hips and greater development of

thigh muscles behind the femur

Secretes testosterone: - Necessary for the maturation of sperm to occur

- That causes the following secondary

sexual characteristics → Growth of facial hair and body hair

(chest, underarm, abdominal and pubic areas)

→ Enlargement of larynx (Adam's apple)

and deepening of voice

→Increased muscle mass and strength

and secretions of oil and sweat glands often causing acne

and body odor

→ Enlargement of the penis

→ Broadening of shoulders (wider than

hips) and chest

→ Coarsening or rigidity of skin texture

due to less subcutaneous fat

→ Larger hands and feet than women

→ Greater mass of thigh muscles in

front of the femur

→ Smaller and wider waist than females

→ On average heavier skull and bone

and taller than adult females

Secretes Human Chorionic Gonadotrophin hormone

(HCG), estrogen and progesterone that help during

pregnancy

Mucosae of the stomach, pancreas and duodenum secrete

gastrin : - Stimulates Gastric acid secretion in the

stomach

Mucosa of the duodenum secretes Secretin :- Stimulates

the pancreas to release pancreatic juice to reduce the

acidity of the gastric juice in the small intestine

Mucosa of the duodenum secretes Pancreozymin-

cholecystokinin : - Stimulates the contraction of the

gallbladder and the secretion of pancreatic juice

Addison’s Disease : Decreased production of the

adrenocortical hormones caused by autoimmune

disease or infections or cancer or hemorrhage in the

adrenal glands. Causes weakness, lethargy,

hypoglycemia, vomiting, diarrhea, increased

pigmentation of the skin etc…

Acromegaly : Overproduction of GH

Cushing’s disease : Hypersecretion of cortisol

Diabetes Mellitus : - Pancreas does not produce enough

insulin causing high blood sugar level (Type 1

diabetes)

- Insulin is unable to help the

glucose get into the cells in the body (type 2 diabetes).

Type 2 diabetes happens in adults and pregnant women

Dwarfism : Hyposecretion of GH

Gigantism : Hypersecretion of GH during childhood before the closure of the bone growth plates

Robert Wadlow, the tallest man known to have lived

(8 ft 11 in) with his father, Harold Wadlow (5 ft 11 1/2 in)

Hyperthyroidism : Hypersecretion of thyroid

hormone. Most common form is Graves’ Disease

Hypothyroidism : Hyposecretion of thyroid hormones

Examples are Hashimoto’s thyroiditis and Myxedema