Unit 12- Endocrine System

Organs of endocrine system

Hypothalamus, Pituitary Gland, Pineal Gland, Thyroid Gland, Parathyroid Glands, Thymus Gland, Adrenal Glands, Pancreas, Ovaries, Testes.

Cells in upper GI tract

Secrete: gastrin

stimulates gastric secretions

cells in the kidney

secrete: erythropoietin

stimulates RBC production in bone marrow

fat cells

secrete: leptin

help suppress appetite. lack of can lead to overeating and obesity

body cells

secrete: prostaglandins

act locally; dilate BVs, relax airways, stimulate uterine contractions in menstrual cramps or labor, and lower acid secretion in stomach

in tissue injury, promote an inflammatory response

Hypothalamus

connects brain to endocrine system

6 local hormones (regulate production of hormones by anterior pituitary gland). 2 (oxytocin and antidiuretic horomone— ADH) are through posterior pituitary gland (stored until they are needed elsewhere)

Pineal Gland

serotonin during day

melatonin at night

sleep cycles

maximum size in childhood

Pituitary Gland

large anterior lobe, small posterior lobe

Follicle-stimulating hormone (FSH)

target cells in ovaries to develop eggs and sperm production in testes. Gonadotropin-releasing hormone (GnRH) of hypothalamus

Luteinizing hormone (LH)

ovulation/formation of corpus luteum in ovary to secrete estrogen and progesterone. In male, stimulates testosterone. Gonadotropin-releasing hormone (GnRH) of hypothalamus

Thyroid-stimulating hormone (TSH)/ thyrotropin

stimulates growth of thyroid gland and production of thyroxine. Thyrotropin-releasing hormone (TRH) of hypothalamus

Adrenocorticotropic hormone (ACTH)/ corticotropin

stimulates adrenal glands to produces corticosteroids like hydrocortisone (cortisol) and cortisone. Cortico-releasing hormone (CRH) of the hypothalamus regulates its secretion.

Prolactin (PRL)

milk production after pregnancy.

in males sensitizes testes to LH, increasing testosterone production.

Thyrotropin-releasing hormone (TRH) of hypothalamus

Growth hormone/ somatotropin

stimulates cells to grow and divide.

Most common hormone

Growth hormone-releasing hormone (GhRH) of hypothalamus

Tropic hormones

hormones that stimulate other endocrine glands to release their hormones.

Examples: FSH and LH

Oxytocin (OT)

stimulates uterine contractions and lactation

increases in social and sexual interactions, creates feelings of satisfaction and emotional bonding

Antidiuretic hormone (ADH)/ vasopressin

reduces volume of urine produced by kidneys

Thyroid Gland

secrete: T3 and T4 (thyroxine)

T3/T4: thyroid hormone

Thyroid Hormone

stimulates most tissues in the body to produce proteins

increases amount of oxygen used by cells

controls speed of body’s chemical functions (Metabolic rate)

produces calcitonin

Parathyroid glands

4 glands (posterior portion of thyroid)

secrete: Parathyroid hormone (PTH)

Parathyroid hormone (PTH)

stimulates bone resorption— brings calcium back into blood

calcitonin— takes calcium from blood to stimulate bone deposition

Thymus Gland

secretes hormones to stimulate production of T lymphocytes

Adrenal Glands

produces more than 25 steroid hormones (adrenocortical hornomes/ corticosteroids)

1. Glucocorticoids

2. Mineralcorticoids

3. Sex steroids

Glucocorticoids

mainly hydrocortisone (cortisol)

help regulate blood glucose levels

anti-inflammatory effect

found in dermatologic lotions and ointments

Mineralocorticoids

mainly aldosterone

promotes sodium retention and potassium excretion by kidneys

Sex steroids

weak androgen to be converted to testosterone

Adrenal medulla

inner layer of adrenal gland

secretes catecholamines (epinephrine and norepinephrine)

Pacnreas

contains exocrine and endocrine glands

Alpha cells

secrete: glucagon (in repsonse to low blood glucose)

a. in liver: stimulates gluoneogenesis, glycogenolysis, and release of glucose into bloodstream

b. in adipose tissue: stimulate fat catabolism and release of free fatty acids

Beta cells

secrete: insulin (in response to high blood glucose)

a. in muscle/fat cells: enable to absorb glucose and store glycogen and fat

b. in liver: stimulate conversion of glucose to glycogen

Delta cells

secrete: somatostatin

prevents secretion of glucagon and insulin within the pancreas

Pituitary adenoma

benign tumor

caused by overproduction of growth hormones stimulating excessive growth of bones and muscles

Gigantism

in children

excessive production before growth plates of long bones have closed

Acromegaly

in adults

excessive growth hormones

enlarged hands/feet, protruding jaw, coarse hair, and sweating

Prolactinoma

benign prolactin-secreting tumor in pituitary gland

can lead to breast milk production and scanty menstrual periods (F)

breast milk and impotence (M)

Hypopituitarism

uncommon

can be caused by pituitary tumor

can cause decrease in production of hormones (panhypopituitarism)

Pituitary Dwarfism

underproduction of growth hormoneduring childhood, leading to short stature and normal body proportions.

Diabetes Insipdus (DI)

decreased production of ADH causing excessive thirst and urination.

Hyperthyroidism

increased body metabolism

tachycardia, hypertension, hyperpyrexia, sweating, shakiness, anxiety, weight loss despite increased appetite, and diarrhea

weight loss can cause emaciation

Graves disease

autoimmune

antibody stimulates thyroid to produce/secrete lots of thyroid hormone into blood

Exophthalmos— bluging of the eyes

goiter

non-pitting, waxy edema of lower leg

Hypothyroidism

decreases body’s metabolism

10% of older women

gradually develops

hair loss, dry and scaly skin, puffy face and eyes, slow hoarse speech, weight gain, constipation, and high sensitivity to cold temps

Myxedema

severe hypothyroidism

lack of iodine in diet

Thyroiditis

inflammation of thyroid gland

most commonly in Hashimoto disease— autoimmune with lymphocytic infiltration of the gland

needing thyroid hormone replacement therapy

Cretinism

congenital

thyroid deficiency

retards mental and physical growth

Thyroid Cancer

symptomless nodule in thyroid gland

can metastasize to cervical and mediastinal lymph nodes, liver, lungs, and bones

Hypoparathyroidism

deficiency of PTH

lowers blood calcium levels (hypocalcemia)

most symptoms are nueromuscular— tingling in fingers, muscle cramps, painful muscle spasms (tetany)

Hyperparathyroidism

excess PTH/ more common

caused by one of the four glands enlarging and working out of pituitary control

leads to calcium depletion in bones, high blood calcium, and kidney stones

Adrenocortical hypofunction/ Addison disease

wasting away of adrenal cortex

weakness, fatigue, increased susceptibility to infection, and diminished resistance to stress

treated with hormone replacement therapy

Adrenocortical hyperfunction/ Cushing syndrome

excess production of steroid hormones

“moon” facies, muscle wasting and weakness, kidney stones, and reduced resistance to infection

most caused by pituitary secreting too much ACTH, leading to adrenal glands releasing too much steroids

Adrenal virilism/ adrenogenital sydrome

Hypersecretion of androgens

(W) hirsutism, baldness, acne, deepened voice, decreased breast size, and other signs of masculinization

Diabetes Mellitus

hyperglycemia

impairment in insulin secretion and/or insulin action

T1/T2

Type 1 diabetes/ Insulin-dependent diabetes mellitus (IDDM)

10-15% all cases of DM

mostly found in patients under 30

90% of pancreatic insulin-producing cells have already been destroyed by antibodies

Type 2 diabetes/ non-insulin-dependent diabetes mellitus (NIDDM)

95% of all DM cases

1/10 people diagnosed

impairment of insulin response and decreased glucose uptake by tissues (insulin resistance)

leads to: hypertension, hyperlipidemia, and coronary artery disease

Latent autoimmune diabetes in adults (LADA/ type 1.5)

10% people with diabetes

same antibodies as T1, but no need for insulin treatment in first 6 months

slower progressing version of T1

Gestational diabetes

during pregnancy

5% of all

30% chance of developing T2 within 10 years of pregnancy

Mature-onset diabetes of the young (MODY)

genetically linked form of diabetes

usually in thin people under 55

will repsond to small doses of insulin or sulfonylurea drugs

Hypoglycemia

blood glucose below 70 mg/dL

brain impacted first

can lead to insulin shock

Hyperglycemia

excessive urination, excessive thirst, and excessive hunger with unexplained weight loss

T1 unsymptomatic/T2 symptomatic

damages capillary endothelial cells in retina, renal glomerulus, and neurons in peripheral nerves

85% develop diabetic retinopathy

30% develop diabetic nephropathy

Diabetic ketoacidosis (DKA)

state of hypergylcemia with dehydration, metabolic acidosis, and ketone formation

most seen in T1