Endocrine System Endocrine and Exocrine u Endocrine functions

Endocrine System

Endocrine and Exocrine u Endocrine functions: communication and control, via hormones u Exocrine functions: secrete products into ducts that empty on a surface or into a cavity – Example sweat and saliva glands

Endocrine u Secretes HORMONES into the blood u Endocrine Organs are located throughout the body: head, neck, chest, abdomen, pelvis. u Endocrine secretions (hormones)bind to specific cells ( target organ cell) that have receptors for that specific hormone.

How hormones work u Bind to receptors on target cells u Steroid hormones- powerful because they bind to sites inside the cell

Protein Hormones u Protein (non-steroid) hormones serve as “first messengers”- they send message to a specific target organ for functions to take place. Then a number of chemical reactions occur. These reactions activate molecules inside the cell…”second messengers” u Second messengers provide communication within a hormones target cells.

Steroid Hormones u Pass directly through cell membrane u Enters the nucleus of the cell u Forms hormone receptor complex that acts on the DNA u New protein is formed in the cytoplasm that causes a specific effect in the target cell

Endocrine Control u HOMEOSTASIS u Negative Feedback: reverses the direction of change in a physiological system. Ex: Pancreatic Insulin to lower blood sugar u Positive Feedback: increases physiological changes. Ex: Oxytocin release during labor to advance birth

Sources of Control of Hormone Levels u Neural Control – Nervous system u Hormonal Control – Other hormones u Humoral Control – Body fluids, such as blood

Hypothalamus u Important link between nervous and endocrine systems – Controls hunger, thirst, fluid balance, body temperature and more u Controls the pituitary gland

Pituitary Gland u The Master Gland because it controls many other glands – Rarely acts on its own u No larger than a grape located in the base of the brain u A two part gland

Posterior Pituitary Gland u Extension of the hypothalamus u Antidiuretic hormone (ADH) – Absorbs water, decreases urine – Released when blood volume is decreased or dehydration happens u Oxytocin – Increases uterine contractions

Anterior Pituitary Hormones u Also controlled by hypothalamus u Thyroid-stimulating hormone (TSH) u Adrenocorticotropic hormone (ACTH u Follicle-stimulating hormone (FSH) u Luteinizing hormone (LH) u Growth hormone (GH) u Prolactin

Cushing Syndrome u Over secretion of cortisol – Upper body obesity – Round face – Easy bruising – Osteoporosis – Fatigue – Depression – Hypertension – hyperglycemia

Stature Disorders u Dwarfism u Giantism Caused by growth hormone issues Acromegaly- excess growth in body tissues

Thyroid Gland Lies in the neck, just on either side of the larynx, butterfly shaped u Unlike most glands it stores hormones once produced u Thyroxine (T 4) u Triodothyronine (T 3) u u Both increase energy release from foods u Both secreted when ordered by pituitary u Calcitonin – Decreases calcium concentration in blood

Hypothyroidism u When too little thyroid hormone is produced – fatigue – Feeling cold – Dry, itchy skin – Brittle, thinning hair – Constipation – Leg cramps – Muscle pain – Forgetfulness – Depression – Sexual dysfunction

Hashimoto’s thyroiditis u Most common cause of hypothyroidism u Caused by autoimmune attack on thyroid gland

Hyperthyroidism u Overproduction of thyroid hormones u Dramatically increases metabolism u S&S: losing weight, increase appetite, nervous irritability, restless, jumpy, prominent protruding eyes

Graves’ disease u Most common cause of hyperthyroidism u Also an autoimmune disorder u Treated with medicine or removal of thyroid gland

Goiter u Enlargement of the thyroid gland due to hyper or hypo thyroidism u May effect swallowing or breathing u Can be caused by lack of dietary intake of iodine

u Parathyroid glands- small glands embedded in the posterior surface of the thyroid – Produce parathyroid hormone (PTH) – Tetany-Muscle cramps, twitching, spasms, or seizures u can be caused by low blood calcium is PTH is low

Thymus u Located behind the sternum u Also has immune system functions u Thymosin- hormone that helps mature WBCs during childhood and begins to disappear at puberty

Pineal Gland u u Tiny gland found in brain; full function remains unknown Melatonin – Regulates the onset of puberty – Responds to sensory information from optic nerves- may serve as our internal clock u Seasonal Affective Disorder u Sleep cycle

Pancreas u Accessory organ of the digestive system, located behind the stomach u Produces hormones that regulate blood sugar: insulin and glucagon – Insulin- removes glucose from the blood u If missing or ineffective diabetes mellitus occurs – Glucagon- puts glucose in the bloodstream

January 17, 2017 *Terminology will be tomorrow* u What is the main function of the endocrine system?

Adrenal Glands u Curves over kidneys u 2 regions – Adrenal cortex u Outer layer – adrenal medulla u Inner layer

Adrenal Medulla Epinephrine Norepinephrine – Adrenaline – “fight or flight” – Reaction to the body being in stress

Adrenal Cortex u Adrenocorticosteroids – Mineralocorticoids (MCs) u Regulate electrolyte, salt, and fluid balance – Glucocorticoids (GCs) u Regulate blood sugar

Addison disease Insufficient production of adrenal hormones u Muscular weakness, low blood pressure, excessive skin pigment, low blood sugar, nausea, loss of appetite, weight loss u Most cases are autoimmune but can be caused by infection or cancer u John F. Kennedy had u

Side effects of therapeutic steroids u Prednisone – Used for immune disorders, inflammation, organ transplant rejection – Bone density loss, weight gain, hair growth, fat deposits, delayed wound healing

Steroid abuse u Anabolic steroids – Increase muscle mass – Side effects u Men- change in sperm production, enlarged breasts, shrinking of testicles u Women- deepening of voice, decreased breast size, excessive body hair growth u Suppress immune function, leads to cardiovascular disease – Banned by all athletic organizations

u Caused Diabetes Mellitus by decreased secretion of insulin or the body’s insensitivity to insulin u Type 1 - Insulin dependent – Typically Juvenile onset – Patients do not produce enough insulin u Type 2 - Non. Insulin Dependent – Often occur in obese patients – Treat first with diet and exercise – Some also become insulin dependent

DM, cont. u Diagnosed by blood test and urinalysis u Kidney damage if not controlled due to excretion of excess sugar u S&S: Decreased wound healing, weight loss, excess urination, extreme thirst – Type 2 symptoms are usually more subtle than type 1

Gonads Chief function is to produce and store reproductive cells u Ovariesu – estrogen-development of reproductive organs and secondary sex traits – Progestrone- helps regulate menstral cycle u Testes– Testosterone- development of reproductive organs and secondary sex traits

PROSTOGLANDINS – Molecules that act like hormones u Produced in tissue –diffuse short distance u Influence: respiration , BP, GI secretions, inflammation, reproduction.

Placenta u Temporary endocrine gland u During pregnancy it produces chorionic gonadotropins – Secreted in the urine in the first few weeks of pregnancy leading to the development of early pregnancy tests u Also produces estrogen and progesterone

Other endocrine structures u Cells in the stomach wall – Ghrelin u Boosts appetite u Slows metabolism u Reduces fat burning u May be involved in the development of obesity u Cells in the upper chambers of the heart – Atrial natriuretic hormone (ANH) u Regulator of fluid and electrolyte homeostatsis

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