Endocrine System PDF

ENDOCRINE SYSTEM 1 INTRODUCTION ❑Consists of glands and tissues that secretes hormones. ❑Hormones – are chemical signals that affect the activity of other glands or tissues ❑Importance of hormone functions Reproduction Growth and development Immune system response...

ENDOCRINE SYSTEM 1 INTRODUCTION ❑Consists of glands and tissues that secretes hormones. ❑Hormones – are chemical signals that affect the activity of other glands or tissues ❑Importance of hormone functions Reproduction Growth and development Immune system response Homeostasis 2 ENDOCRINE SYSTEM 3 4 5 6 Hormone Exocrine glands Secrete nonhormonal chemicals into ducts Which transport chemicals to a specific location Include sudoriferous (sweat), sebaceous (oil), mucous, and digestive glands, Salivary gland Endocrine glands Ductless glands located throughout the body Secrete hormones into the bloodstream 7 FUNCTIONS OF HORMONES 1. Help regulate: Chemical composition and volume of internal environment (interstitial fluid). Metabolism and energy balance. Contraction of smooth and cardiac muscle fibers. Glandular secretions. Some immune system activities. 2. Control growth and development. 3. Regulate operation of reproductive systems. 4. Help establish circadian rhythms. 8 9  Classes of hormone A. Lipid-Soluble Hormones 1. Steroid hormones 2. Two thyroid hormones (T3 and T4) 3. The gas nitric oxide (NO) B. Water-Soluble Hormones 1. Amine hormones 2. Peptide hormones and protein hormones 3. Eicosanoid hormones 10 11 12 13  Hypothalamus Regulates the internal environment through the autonomic system Ie heart beat, body temperature and water balance Located beneath the thalamus in the brain Considered master switchboard for the endocrine system Controls the glandular secretions of the pituitary gland 14 Hypothalamus 15  The Pituitary Gland A small gland about 1 cm in diameter is connected to the hypothalamus by a stalk-like structure Pituitary has 2 portions: anterior and posterior pituitary Posterior pituitary stores 2 hormones Vasopressin (or ADH) Cause kidney to form concentrated urine and conserve water Oxytocin Stimulates uterus contraction during labor and causes the release of milk 16  Anterior Pituitary Gland Controls by the hypothalamus through hypothalamic releasing hormone and inhibiting hormone 6 types of hormones released by the anterior pituitary TSH (thyroid stimulating hormone) ACTH (Adrenocorticotropic Hormone) Gonadotrophic hormone (FSH & LH) PRL (Prolactin) MSH (Melanocyte stimulating hormone) GH (Growth Hormone) 17  ASSIGNMENT 1 WHOLE SHEET OF YELLOW PAPER INDIVIDUAL HAND WRITTEN DEADLINE : NEXT MEETING Make a table and differentiate the different HORMONES secreted by the anterior pituitary according to the ff: 1. Description 2. Secreted by 3. Hypothalamic-releasing Hormone 4. Hypothalamic-inhibiting Hormone 5. Target tissues 6. Principal action 18 Posterior Pituitary 19  Posterior Pituitary ANTIDIURETIC HORMONE (ADH) OXYTOCIN 20 21  FEEDBACK MECHANISM Hypothalamus Releasing hormone (hormone 1) Feedback inhibits Anterior pituitary release of hormone 1 Stimulating hormone (hormone 2) feed back inhibit release of hormone 2 Target gland Target gland horm (hormone 3) 22 Thyroid gland Located in the neck just below the larynx Produces Triiodothyronine (T3) Thyroxine (T4) Calcitonin T3 and T4 – stimulates and maintains metabolic rate , normal heart rate, blood pressure and body temperature. More glucose breakdown over fat usage for energy requires iodin for hormonal production Iodin defficient – simple Goiter Thyroid fails to develop – creatinism Oversecretion of thyroid hormone – Graves disease Creatinism Graves disease  Thyroid gland Calcium plays important role nervous conduction, muscle contraction and blood clotting Calcitonin maintains calcium level in blood and inhibits calcium release from bone It does this by temporarily reducing the activity and number of osteoclast Blood Ca lowers, calcitonin inhibited Low Ca level stimulates parathyroid hormone (PTH) 25  Thyroid gland ACTION OF THYROID HORMONE Increase basal metabolic rate Regulate development and growth of nervous tissue and bones Enhance some actions of catecholamines Stimulate lipolysis Stimulate protein synthesis Increase body temperature (calorigenic effect) Stimulate synthesis of Na+ /K+ ATPase Increase the use of glucose and fatty acids for ATP production 26  Parathyroid hormone Attached to or embedded in the backsurface of thyroid gland, 2 in each lobe Produces PTH to regulate Ca level in blood By increasing reabsorption Ca in the kidneys and increasing Ca uptake from the digestive system Important in promoting proper nerve and muscle function and maintaining bone structure Loss of PTH results in violent muscular spasms known as tetany 27 Action of Parathyroid Hormone 1. Slows the rate at which Ca2 and Mg2 are lost from blood into the urine. 2. Increases the loss of HPO4 2 from blood into the urine. 3. Formation of the hormone calcitriol. 1,25- dihydroxyvitamin D3 1,25- dihydroxyvitamin D3 Adrenal glands Two adrenal glands sit atop the kidneys Each adrenal gland consists of Outer – adrenal cortex Inner – adrenal medulla Controlled by hypothalamus Where it stimulates anterior pituitary to release ACTH ACTH reacts at adrenal cortex 30 Adrenal cortex Outer portion, makes up 80% of the mass of the gland Produces hormones Glucocorticoid ( cortisol ) Affects CHO, protein and fat metabolism and helps to cope stress Minerelocorticoid ( Aldosterone ) Regulates sodium reabsorption and potassium excretion by the kidneys Affects water and salt balance Androgens (sex drive) Secrets dehydroepiandrosterone (DHEA) Testosterone in males Estrogens in Females Decrease activity of adrenal cortex – addison’s disease Increase adrenal cortex activity – Cushing’s syndrome 32 Adrenal medulla Inner portion specialized part of sympathetic nervous system Secretes 2 a.a hormones – adrenaline and noradrenalin “Fight or flight” hormones – nerve impulses from sympathetic system causes hormone secretion Epinephrine (Adrenaline) Increase heart rate, BP, Glycogen to glucose, increase metabolic rate Norepinephrine (Noradrenaline) Stimulates heart muscle by increasing the rate and strength of heartbeat 33 Addison’s disease Cushing’s syndrome Reproductive glands Gonads – produces gamette and a group of sex hormone Sex hormone regulate body changes that begin with puberty FSH and LH stimulate secretion of sex hormone from gonads Ovaries produces – estrogen and progesterone Testes produces testosterone 36 Pancreas Is both exocrine (duct) and endocrine gland Hormone producing cells – islets of langerhans Islets of langerhans Alpha cells – secretes glucagon Beta cells – secretes insulin Delta cells – secretes somatostatin F cells – secretes pancreatic polypepide. Both insulin and glucagon regulates blood glucose Insulin – stimulates target cells to take up glucose, “use or store”, reduce bld glucose Glucagon –breakdown the stored glycogen, increase glucose level 39 Maintenance of blood glucose 40 Pancreas Type I or juvenile onset – before 25, little or no insulin, requires a strict diet and daily insulin injection Type II or adult onset – after 40, producing normal or reduced amounts of insulin, or cells are unable to respond due lack of insulin receptors 41 Pancreas Hypoglycemia Caused by excess insulin or low blood sugar Causes release of glucagon and epinephrine (adrenaline) Symptoms : lethargy, dizziness, nervousness, overactivity and unconsciousness and death Hyperglycemia Caused by low insulin or high blood sugar Cause nausea, rapid breathing, oxygen deficiency, circulatory and nervous failure, diabetic coma or death 42 43 Thymus gland Thymus gland is located beneath the sternum (breastbone) and between the lungs The thymus consists of mostly T-cells Important role in immune system Thymus gland secretes thymosin (a.a hormone) Stimulates formation of T cells and help defend body from pathogen 44 Pineal gland Located near the base of the brain Secretes the hormone melatonin Melatonin concentration increase at night Regulates our daily sleep-wake cycle Circadian rhythms are controlled biological clock located in the hypothalamus 45 The end 46