Endocrine SystemUnit-P

The foundations of the endocrine system are the hormones (chemicals) that are secreted by the endocrine glands.

Objectives

• 1H16.01 Explain the structure of the endocrine system.

• 1H16.02 Analyze the functions of the endocrine system.

• 1H16.03 Discuss characteristics & treatment of common endocrine

disorders.

• Main Functions -To secrete hormones

• Body cells that react to a particular hormone are ct target cells.

• Cells that react to a particular hormones are called target organ cells.

• The 2 Types of Glands.

• ENDOCRINE• EXOCRINE

ENDOCRINE

• Secretes hormones directly into the blood stream.

• Ductless

Exocrine

Secrete substance

through a duct and

release secretions in

the skin or inside of the

mouth.

Sweat, salivary, lacrimal

& pancreas

Hormone Control

Negative feedback-dropin hormone level triggers a chain reaction.a. Blood levels of hormoneb. Brain gets message &

sends out hormone to stimulate.

c. Gland secretes more hormones

d. When blood level of hormone brain hormones stop.

Nervous Control

In some cases, sympathetic nervous system causes directrelease of hormone from gland(for example, when stress causes the adrenal medulla tosecrete adrenaline.

Adrenaline causes heart contraction, vasoconstriction, & increased heart rate.

Pineal Gland

• Melatonin is a hormone secreted by the pineal gland which seems to play an important role in regulating sleeping.

Pituitary Gland

Master GlandHas two Lobes-Anterior & Posterior

1. Tiny structure size of grape.

2. Located at base of the brain in the cranial cavity.

3. Connected to hypothalamus.

4. Divided into anterior and posterior lobes.

Anterior Pituitary LobeFunctionsA. Controls growth hormone

B. Prolactin-development of breast tissue, stimulates production of milk after childbirth.

C. Thyroid-stimulating hormone-TSH-stimulates (thyroid gland) thyroxine.

D. Adrenocorticotropic hormone-ACTH-stimulates adrenal cortex.

F. Follicle Stimulating Hormone-FSH-stimlutes growth of graafian follicle (in the ovaries) & production of estrogen in females, sperm in males. FSH/LH act on the ovaries & testes.

G. Luteinizing Hormone-LH-stimulats ovulation & formation of corpus luteum, which produces progestrone in females.

Pituitary Gland

Posterior Pituitary LobeA. Vasopressin-converts to

ADH (antidiurectic hormone) in the bloodstream acts on kidney to concentrate urine & preserve H2O in the body.

B. Oxytocin-released during childbirth causing contractions of the uterus.

Thyroid Gland

1. Butterfly-shaped mass of tissue.

2. On either side of larynx, in front of the trachea.

3. H-shaped.

Thyroid Function

1. Main hormone, thyroxine, is controlled by

secretion of TSH.

2. Thyroxine controls the rate of metabolism.

& stimulate cellar metabolism.

3. Calcitonin, another hormone that controls calcium ion concentration in the body, prevents hypocalcemia.

Thymus

1. Endocrine gland & lymphatic organ.

2. Located behind sternum, above and in front of heart. (thoracic cavity)

3. Begins to disappear at puberty.

Adrenal Glands

Located on top of eachkidney.

FunctionsAdrenal cortex secretesCorticoids (anti-inflammatoryhormones) & sex hormonesAndrogens-male sex hormones.

Adrenalin-hormone from adrenalmedulla, powerful cardiac stimulant, produced response to stress“fight or flight” hormone

Pancreas Located behind the stomach.Endocrine & exocrine functions.FUNCTIONS

Islets of Langerhans-Insulin production that utilization ofglucose (insulin blood sugar)(Endocrine function)

After meals is when thepancreas secretes the most insulin.

Located in Abdominal cavity.

Parathyroid Glands

1. Four glands, each the size of a grain of rice. Located in the neck.

2. Attached to posterior thyroid.

FUNCTION

Produce parathormone

which helps control blood

calcium, prevents hypocalcemia.

TetanyHypofunctioning of the parathyriod glands leads totetany. Decreased calcium levels affect functions of nerves.Symptoms – Convulsivetwitching develops, person dies of spasms in the respiratory musclesRx – Vitamin D, calcium & parathormone.

Gonads - located in pelvic cavity.1. Ovary in female.2. Testes in male.

Gonads Hormones

• Estrogen-development of female reproductive organs, secondary sex characteristics.

• Progesterone-plays a part in the menstrual cycle.

• Testosterone-male reproductive organs & secondary sex characteristics.

Prostaglandins

Tissue hormones, can

cause constriction of

blood vessels, muscle

contractions. Can be

used to induce labor.

Common Endocrine Disorders.

Dwarfism Hypofunction of pituitary in childhood. Defect ingrowth hormone.

Small size, but body proportions & intellect normal.

Rx – Early diagnosis, injection of growth hormone. one or more body parts being disproportionately large or small compared to the rest of the body.

A person with an adult height of less than 4 feet 10 inches .

Midget

An extremely short but normally proportioned person.

Gigantism

Hyperfunction of pituitary – Too muchgrowth hormone.In preadolescence – Overgrowth of long bones leads to excessive tallness.

Acromegaly is enlargement of the bones of the hands, feet & joints (protruding chin-common symptom)

Hyperthyroidism Overactive thyroid gland-Nervous irritability

Too much thyroxine leads to enlargement of gland.

Symptoms – Consuming large quantities of food but lose weight.

Goiter – Enlargement of gland low dietary intake of iodine ( cause of simple goiter.

Exophthalmos – Bulging of Eyeballs

Tx.Partial/total removal of gland, drugs to reduce include thyroxine radiation

Hypothyroidism

Not enough thyroxine

May be due to lack of

iodine (simple goiter)

Symptoms – Dry, itchy

skin; dry and brittle hair,

constipation, muscle

cramps at night.

Diabetes Mellitus

Cause – Decreased secretion

of insulin.

Symptoms – Polyuria,

Polyphagia (insatiable appetite),polydipsia, weight loss, blurred vision,

& possible diabetic coma.

If not treated, excess glucose in

blood (hyperglycemia) & secreted in

urine (glycosuria)

If too much insulin given, BS can get

too low (hypoglycemia) & person can

develop insulin shock.

Diabetes Mellitus

• A typical screening procedure for diabetes mellitus is?

Non insulin-dependent – Most common, usually familial, occurs later in life, usually treated with diet.

Test for diabetes – Blood sample at home, normal blood sugar is 80-100 mg.

Hyperglycemia (High Blood Glucose)

Causes: Too much food, too little insulin or diabetes medicine, illness or stress.

Onset: Gradual, may progress to diabetic coma.

Symptoms: Extreme thirst, frequent urination, dry skin, hunger, blurred vision, drowsiness, and nausea.

What can you do? Take blood glucose tests, and if over 250 mg/dL for several tests, call your doctor.

Hypoglycemia/Low Blood Glucose)

Causes: Too much insulin or diabetes medicine, or extra exercise.Onset: Sudden, may progress to insulin shock.Symptoms: Shaking, fast heartbeat, sweating, anxious, dizziness, hunger, impaired vision, weakness fatigue, headache, and irritability.

Hypoglycemia(Low Blood Glucose)

What can you do? Drink ½ glass of orange juice or skim milk, or eat several hard candies, test your blood glucose; if symptoms don’t stop call your doctor, within 30 minutes after symptoms go away, eat a light snack (a ½ peanut butter or meat sandwich and a ½ glass of milk.