ENDOCRINE SYSTEM CTLI Training: 12,13 July 2011 H.C.Adonis

HOMEOSTASIS LIVERSKIN PANCREAS LUNGS KIDNEYS glucose Amino acids Insulin & glucagon ureum Excess water, salts, ions oxygen carbondioxide ureum Excess water,salts,heat

HOMEOSTASIS: Main ideas Maintenance of constant internal environment in the body/keeping conditions in tissue fluid constant WHY? Cells dependant on tissue fluid to function optimally HOW? Various systems that help in maintaining tissue fluid/internal environment constant i.e. nervous system, excretory system, respiratory system, ENDOCRINE SYSTEM. Various systems need to be coordinated in order for body to function as a unit. HOW ARE THESE SYSTEMS COORDINATED?

CHEMICAL COORDINATION: Endocrine System Communication through the use of hormones: results in slower responses NERVOUS COORDINATION: Nervous system Communication takes place via neurons: results in quick responses

HOW DOES CHEMICAL COORDINATION TAKE PLACE? RECEPTORS: detect stimuli/change EFFECTORS (glands): react on stimuli HOMEOSTATIC CONTROL CENTRE: THE BRAIN (hypothalamus) Nerve impulses/Hormo nes in bloodstream Nerve impulses stimuliresponses Feedback

CHEMICAL vs NERVOUS COORDINATION CHEMICAL COORDINATION Co-ordinates different systems in the body to work together Involves hormones transported in the bloodstream in small quantities Has general and local effects on the body Is slower acting Has long-lasting effects NERVOUS COORDINATION Co-ordinates different parts of the body to work together Involves isensations that are transported via neurons in the form of impulses Has specific targets/effectors Is very fast acting Has more short-term effects

HUMAN ENDOCRINE SYSTEM Ductless glands Release hormones directly into bloodstream or lymph. Endocrine glands Release secretions in ducts to be carried to body cavity or outside of body i.e. saliva, tears etc. Exocrine glands

ENDOCRINE SYSTEM Endocrine system co-ordinates the body’s organs to help maintain homeostasis Based on the production of chemical messengers called HORMONES. Hormones control body processes that require several organs of the body to interact for a combined effect. Are chemical "messengers“, secreted by glands. Moves very slowly. Most hormones are proteins and some are steroids. Hormones have specific target organs Regulatory effect – stimulate OR inhibit Do not function in isolation – integrated with other hormones Functions controlled by hormones include: activities of entire organs growth and development reproduction sexual characteristics usage and storage of energy regulate water content (osmoregulation) ionic (salt) regulation regulation of blood glucose level

ENDOCRINE GLANDS: position + function IMPORTANT! POSITION OF GLANDS HORMONES SECRETED FUNCTION / EFFECT OF HORMONES

ENDOCRINE GLANDS: location Hypophysis / pituitary gland Thyroid gland Pancreas Adrenal glands Ovaries Testes

ENDOCRINE GLANDS: location & function Pituitary gland/hypophysis Located at base of brain, attached to hypothalamus Nerve fibres from hypothalamus runs into posterior lobe Known as “master gland” Consist of anterior (adenohypophysis) and posterior lobe (neurohypophysis) Anterior lobe releases: TSH (Thyroid-stimulating hormone) Growth hormone (STH) FSH (Follicle-stimulating hormone) LH (Luteinising hormone) Prolactin Posterior lobe releases: ADH (Anti-diuretic hormone) Oxytocin

HYPOPHYSIS / PITUITARY GLAND

HYPOPHYSIS HORMONES: Anterior lobe Stimulates the thyroid to secrete the hormone thyroxin TSH Promotes growth of skeleton and muscles by stimulating synthesis of proteins GROWTH HORMONE (STH) Stimulates development of primary follicles in ovaries into Graafian follicles FSH Stimulates ovulation LH Stimulates the mammary glands to produce milk after the birth of a baby PROLACTIN

HYPOPHYSIS HORMONES: Posterior lobe Controls re-absorption of water into blood from renal tubules ADH (Anti- diuretic hormone) Cause muscle contractions in uterus during birth Triggers milk release during breastfeeding OXITOCIN

ENDOCRINE GLANDS: location & function Thyroid: consist of two lobes on either side of trachea, just below larynx Produces and secretes hormone thyroxin The element iodine, essential for production of thyroxin Shortage could result in enlarged thyroid / goitre

THYROID GLAND

Functions of thyroxine Increases basal metabolic rate ( amount of energy the body needs to function when body is at rest) Increases breathing rate and heart rate Development and functioning of nervous system Normal growth and development of important organs

Thyroid Disorders Increased metabolic rate Weight loss Increased heart rate, respiration rate and blood pressure Increased irritability Over secretion: Hyperthyroidism m Causes very low metabolism In children: cretinism In adults: myxoedema Under secretion : Hypothyroidism Abnormal growth Mental retardation Do not reach sexual maturity Cretinism Mental decline, physical lethargy Thickening of skin, increase in body mass Myxoedema

THYROID DISORDERS HYPERTHYROIDISMHYPOTHYROIDISM

HOMEOSTATIC CONTROL THYROID HYPOPHYSIS More TSH less TSH Less thyroxin More thyroxin NEGATIVE FEEDBACK SYSTEM

GROWTH DISORDERS HYPOSECRETIONHYPERSECRETION Gigantism & Acromegaly Dwarfism

ENDOCRINE GLANDS: location & function Pancreas Two types of cells: Pancreatic cells Islets of Langerhans (small groups of cells) Pancreatic cells have exocrine function and secrete pancreatic juice into pancreatic duct which leads to duodenum Islets of Langerhans have endocrine function and secretes 2 hormones directly into bloodstream i.e. glucagon and insulin Alpha cells secrete glucagon and beta cells produce insulin Insulin and glucagon responsible for homeostatic control of blood glucose levels through negative feedback system

PANCREAS

PANCREAS

INSULIN & GLUCAGON: Homeostatic control Stimulates absorption of glucose to body cells Stimulates conversion of glucose to glycogen in liver and muscles Inhibits conversion of glycogen to glucose INSULIN: Beta cells Stimulates conversion of glycogen to glucose in the liver Inhibits conversion of glucose to glycogen GLUCAGON: Alpha cells

LOW BLOOD GLUCOSE glucagon Blood glucose levels return to normal, feedback to hypothalamus Low blood glucose(stimulus) 3. 4.

HIGH BLOOD GLUCOSE High blood glucose(stimulus) insulin Blood glucose returns to normal, feedback to hypothalamus

HOMEOSTATIC CONTROL: BLOOD GLUCOSE

DIABETES mellitus: Type 1 Dysfunction of beta cells, little or no insulin is produced - can cause elevation of glucose level in blood. The excess glucose is now removed from the body through urine. Excess glucose is also removed through sweating. SYMPTOMS: Frequent urination Increased hunger Inexplicable weight loss Repeated infections Impaired vision Exhaustion and dizziness Wounds that heal slowly

Treatment and management Daily insulin injection A specially adapted diet Regular testing of blood sugar levels

Type 2 diabetes Characterised by insulin resistance Life style disease CAUSES: Overweight and obesity Inactivity Age TREATMENT AND MANAGEMENT Maintain normal body mass through balanced diet Regular exercise Oral medication or insulin

ENDOCRINE GLANDS: location & function Adrenal glands Located at top of each kidney ; consist of outer cortex and inner medulla Adrenal cortex produces hormone aldosterone. Adrenal medulla produces adrenalin.

ADRENAL GLANDS

Effects of Adrenalin & Aldosterone: ADRENALIN: Known as “fight or flight” hormone Increases heart rate - more blood with oxygen and glucose to muscles Increases blood pressure due to vasoconstriction of vessels in skin- more blood to muscles,heart and brain Increases conversion of glycogen to glucose – increase glucose levels in blood which releases energy Increase rate and depth of respiration – more oxygen absorbed in blood Increase muscle tone – muscles can react faster Pupils dilate – allow more light into eye for improved vision Increase sweat production – cool body during activity ALDOSTERONE: Steroid hormone that regulates ionic balance of tissue fluid

ENDOCRINE GLANDS: location & function Gonades: testes and ovaries Testes located outside body in scrotum Interstitial cells (Leydig cells) produces hormone testosterone Ovaries located in abdominal cavity, on either side of uterus Graafian follicles produce hormone oestrogen Corpus luteum produces hormone progesterone

GONADS: Testes & ovaries TESTOSTERONE Secondary male sex characteristics Role in development of male sex organ during puberty Neccesary for maturation and quality of sperm cells OESTROGEN Secondary female sex characteristics Role in development of female sex organs during puberty Responsible for thickening of endometrium and preparation for implantation PROGESTERONE Responsible for further thickening of endometrium and maintenance therof during pregnancy Suppresses release of FSH and LH

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