endocrine system

endocrine system

secretes chemicals within the body to control tissues remote from where they are secreted

what do the hormone glands and cells do

• secrete hormones

• blood transports

• intended target has receptors

• intake into the cell targeted-signal/response occurs

organs in endocrine system

• pituitary gland

• thyroid gland

• parathyroid glands

• adrenal glands

• pancreas

• ovaries

• testes

• thymus

• pineal body 

• placenta

hormones

• Produced and secreted by the endocrine glands.

• Frequently called “chemical messengers”.

• Transported throughout the body by the bloodstream and perform many functions.

hormone functions

• Stimulate exocrine glands (glands with ducts or tubes) to produce secretions.

• Stimulate other endocrine glands

• Regulate growth and development 

• Regulate metabolism

• Maintain fluid and chemical balance

• Control various sex processes

pituitary gland

MASTER GLAND

• Often called the “master gland” of the body because it produces many hormones that affect other glands.

• It is located at the base of the brain in the sella turcica- a small bony depression of the sphenoid bone

• Divided into 2 sections/lobes; anterior and posterior

• Each lobe secretes certain hormones.

anterior pituitary gland (adenohypophysis) releases

• growth hormone (GH)

• thyroid stimulating hormone (TSH)

• adrenocorticotrophic hormone (ACTH)

• luteinizing hormone (LH)

• follicle stimulating hormone (FSH)

• prolactin (PRL

• melanocyte stimulating hormone (MSH)

another name for anterior pituitary gland

adenohypophysis

FSH follicle stimulating hormone:

stimulates growth and hormone production in the ovarian follicles of female, production of sperm in males

LH- luteinizing hormone (female):

 causes ovulation and secretion of progesterone in females

ICSH- interstitial cell-stimulating (male):

stimulates testes to secrete testosterone

GH somatotropin

• Stimulates growth of most cells

• Regulates metabolism

TSH thyrotropin

• stimulates growth

• stimulates thyroxine  from thyroid

ACTH adrenocorticotropic

• Stimulates growth

• Increases in time of stress and increases cortisol (adrenal secretion)

PRL prolactin or LTH lactogenic

• Stimulates milk production in breast tissue (mammary glands)

MSH melanin stimulating hormone

• Increases synthesis of melanin into skin pigments

posterior pituitary gland hormones released

• antidiuretic hormone (ADH)

• Ocytocin (OT)

ADH antidiuretic hormone (vasopressin)

• promotes reabsorption of water in kidneys, constricts blood vessels.

Controls the amount of urine output.

OT Oxytocin (pitocin)

• Increases contractions of uterus during childbirth

• stimulates milk flow from the breasts.

another name for posterior pituitary gland

neurohypophysis

acromegaly

• Etiology:  over secretion of somatotropin (growth hormone) in an adult- usually caused by a tumor of the pituitary. 

• Symptoms: Bones of the hands, feet and face enlarge and create a misshapen appearance. The skin and tongue thicken, and slurred speech develops. 

• Treatment:  removal and/or radiation of the tumor is the usual treatment.

gigantism

• Etiology: Over secretion of somatotropin before puberty. 

• Symptoms: Causes excessive growth of long bones, extreme tallness, decreased sexual development and possibly, retarded mental development. 

• Treatment: If a tumor is involved, surgical removal or radiation is the treatment

diabetes insipidus

• Etiology: a decreased secretion of vasopressin or antidiuretic hormone (ADH). 

• A low level of ADH prevents water from being reabsorbed in the kidneys. 

• Symptoms: polyuria (excessive urination), polydipsia (excessive thirst), dehydration, weakness, constipation and dry skin. 

• Treatment: give ADH

dwarfism

• Etiology:  under-secretion of somatotropin and can be caused by a tumor, infection, genetic factors or injury. 

• Symptoms: Characterized by small body size, short extremities and lack of sexual development. Mental development is normal.

• Treatment: If diagnosed early, can be treated with injections of somatotropic hormone for 5 or more years until long bone growth is complete.

thyroid gland

• secretes thyroxine and triiodothyronine

  • increase metabolic rate

  • stimulate physical and mental growth, regulate metabolism of carb, fats, and proteins

• secretes thyrocalcitonin or calcitonin

  • accelerates absorption of calcium by the bones and lowers blood calcium level

• synthesize hormones that regulate the body’s metabolism and control the level of calcium in the blood

• located anterior at the superior part of the trachea in the neck

• has 2 lobes, one on either side of the larynx. connected by the isthmus- a small piece of tissue

• requires iodine to produce its hormones. iodine is obtained form certain foods and iodized salt

goiter

• enlargement of thyroid gland.

• Causes can include: hyperactive thyroid, iodine deficiency, over secretion of thyroid stimulating hormone on the part of the pituitary gland, or a tumor

• Symptoms include thyroid enlargement, dysphagia (difficult swallowing), a cough, and a choking sensation. 

• Treatment- eliminate cause. Iodine given if deficient. Surgery if goiter very large.

hyperthyroidism

• Etiology: Overactivity of the thyroid gland

• causes increased production of thyroid hormones and increased basal metabolic rate (BMR) 

• Symptoms: extreme nervousness, tremors, irritability, rapid pulse, weight loss, goiter formation, hypertension

• Treatment: radiation to destroy part of the thyroid or thyroidectomy. 

graves’ disease

• Etiology: Severe form of hyperthyroidism 

• More common in women than men

• Symptoms: strained and tense facial expression, exophthalmia (protruding eyeballs), goiter, nervous irritability, emotional instability, tachycardia, a tremendous appetite accompanied by weight loss and diarrhea

• Treatment: medication to inhibit synthesis of thyroxine, radioactive iodine to destroy thyroid tissue and/or thyroidectomy.

hypothyroidism

• Etiology - Underactivity of the thyroid gland and a deficiency of thyroid hormones

• 2 main forms:

 

Cretinism

& 

Myxedema

cretinism

• develops in infancy or early childhood and results in a lack of mental and physical  growth, leading to mental retardation and an abnormal, dwarfed stature

• diagnosed early, oral thyroid hormone can be given to minimize mental and physical damage.

myxedema

• occurs in later childhood or adulthood

• Symptoms: coarse, dry skin; slow mental function, fatigue, weakness, intolerance of cold, weight gain, edema, puffy eyes, slow pulse.

• Treatment: administer oral thyroid hormone to restore normal metabolism

parathyroid glands

• Four small glands located behind and attached to the thyroid gland

• Their hormone regulates the amount of calcium in the blood

• Stimulates bone cells to break down bone tissue and release calcium and phosphates into the blood which causes the kidneys to conserve and reabsorb calcium and activates intestinal cells to absorb calcium from digested foods. 

importance of parathyroid gland

• Most of the body’s calcium is located in the bones, but the calcium circulating in the blood is very important for blood clotting, the tone of heart muscle and muscle contraction. 

• Because there is a constant exchange of calcium and phosphate between the bones and the blood the Parathyroid hormone plays an important function in maintaining the proper level of circulating calcium

parathyroid hormones

• PTH - parathyroid hormone 

  • Regulates amount of calcium and phosphate in the blood. Increases reabsorption of calcium and phosphates from the bones

HYPERPARATHYROIDISM

• An over-activity of the parathyroid gland resulting in hypercalcemia (increased calcium in the blood), which leads to renal calculi formation, lethargy, GI disturbances, and calcium deposits on the walls of blood vessels and organs. 

• Because calcium is drawn from the bones, they become weak, deformed and likely to fracture.

• Often caused by and adenoma (glandular tumor). Removal of the tumor usually results in normal parathyroid function.

hypoparathyroidism

• Underactivity of parathyroid gland

• Causes a low level of calcium in the blood

• Symptoms include tetany (sustained muscular contraction), hyperirritability of the nervous system, convulsive twitching.

• Death can occur if the larynx and respiratory muscles are involved.

• Easily treated with calcium, vitamin D (increases the absorption of Ca from the digestive tract) and parathyroid hormone.

adrenal gland

• Cortex- outer part

• Secretes steroid hormones: mineralocorticoid,glucocorticoids and gonadocorticoids.

• Medulla- inner part

• Secretes epinephrine and norepinephrine.

• These hormones are sympathomimetic (mimic sympathetic nervous system =flight or fight response)

another name for adrenal gland

suprarenal

ADRENAL HORMONES CORTEX

• Mineralocorticoids

 (aldosterone) 

• regulate the reabsorption of sodium in the kidney and the elimination of potassium.

• Glucocorticoids (cortisol-hydrocortisone, cortisone)

  • aid in metabolism of proteins, fats, and carbohydrates; increase amount of glucose in blood; provide resistance to stress; depress immune responses (anti-inflammatory) 

• Gonadocorticoids 

  • (estrogens, androgens)

  • act as sex hormones

    • Estrogens

      • stimulate female sexual characteristics 

    • Androgens

      • stimulate male sexual characteristics

adrenal hormones medulla

• Epinephrine

  • activates sympathetic nervous system, acts in stress

• Norepinephrine

  • activates body in stress situations 

addison’s disease

• Etiology - decreased secretion of aldosterone on the part of the adrenal cortex

• Interferes with the reabsorption of sodium and water and causes an increased level of potassium in the blood

• Symptoms - dehydration, hypotension, mental lethargy, weight loss, muscle weakness, excessive pigmentation leading to a “bronzing” of the skin, hypoglycemia, edema

• Treatment - steroid hormones, controlled intake of sodium, fluid regulation to combat dehydration.

cushing’s syndrome

• Etiology - Over secretion of glucocorticoids on the part of the adrenal cortex

• Caused by either a tumor of the adrenal cortex or excess production of ACTH on the part of the pituitary gland

• Symptoms - hyperglycemia, hypertension, muscle weakness, poor wound healing, tendency to bruise easily, “moon” face, obesity

• Treatment - removal of tumor (if the cause). Must have hormone replacement for missing hormones.

pancreas

• Fish-shaped organ located behind the stomach.

• Both an exocrine and endocrine gland

pancreas as exocrine gland

• Secretes pancreatic juices which are carried to the small intestine by the pancreatic duct to aid in the digestion of food

ENDOCRINE PANCREATIC HORMONES

• Glucagon

  • maintains blood level of glucose

  • Alpha (A) cells- produce glucagon, which increases the glucose level in blood

• Insulin

  • used  in metabolism of glucose (sugar) by promoting entry of glucose into cells

  • needed for the cells to absorb sugar from the blood

  • Beta (B) Cells- located throughout the pancreas in patches of tissue called Islets of Langerhans- produces hormone insulin

Diabetes Mellitus

• Chronic disease caused by decreased secretion of insulin

• Affects the metabolism of carbohydrates, proteins and fats

• Two types according to the age of onset and need for insulin

INSULIN-DEPENDENT DIABETES MELLITUS(IDDM) or TYPE 1

• Usually occurs early in life

• More severe type

• Requires insulin medication

NON-INSULIN DEPENDENT DIABETES MELLITUS (NIDDM) or TYPE 2

• Mature onset

• Frequently occur in obese adults

• Controlled with diet and/or oral hypoglycemic (lower blood sugar) medications

• Symptoms: hyperglycemia, polyuria, glycosuria, weight loss/gain, fatigue, slow healing of skin infections, vision changes. If not treated, diabetic coma and death may occur.

Treatment: carefully regulated diet to control the blood sugar level, regulated exercise and oral hypoglycemic drugs or insulin injections

ovaries

• Gonads, or sex glands, of the female

• Located in the pelvic cavity

• One on each side of the uterus

• Secrete hormones that regulate menstruation and secondary sexual characteristics

Hormones

• Estrogen

  • promotes growth and development of sex organs in female

• Progesterone

  • maintains lining of uterus

testes

• Gonads of the male

• Located in the scrotal sac and are suspended outside the body

• Produce hormones that regulate sexual characteristics of the male

Hormones

• Testosterone

  • stimulates growth and development of sex organs in the male

thymus

• Mass of tissue located in the upper part of the chest and under the sternum.

• Contains lymphoid tissue .

• Active in early life, activating cells in the immune system, but atrophies during puberty and becomes a small mass of connective tissue and fat.

Hormone

• Thymosin

  • stimulates production of antibodies early in life

pineal body

• Small structure attached to the roof of the third ventricle in the brain

hormones

• Melatonin

  • may delay puberty by inhibiting gonadotropic (sex) hormones. May regulate sleep/wake cycles

• Adrenoglomerulotropin

  • may stimulate adrenal cortex to secrete aldosterone

• Serotonin

  • may prevent vasoconstriction of blood vessels in the brain

placenta

• Temporary endocrine gland produced during pregnancy

• Acts as a link between mother and infant

• Provides nutrition for the developing infant

• Promotes lactation

• Expelled after the birth of the child (called afterbirth)

HORMONES OF PLACENTA

• Estrogen

  • stimulates growth of reproductive organs

• Chorionic gonadotropin

  • causes corpus luteum of ovary to continue secretions

• Progesterone

  • maintains lining of uterus to provide fetal nutrition.