Endocrine System Notes

BY: - PRAMOD KUMAR M.SC. NURSING 1 ST YEAR ENDOCRINE SYSTEM GLANDS: An organ which secretes particular chemical substances for use in the body or for discharge into the surroundings .  There are three types of glands in our body:  Endocrine glands  Exocrine glands  Hetero...

BY: - PRAMOD KUMAR M.SC. NURSING 1 ST YEAR ENDOCRINE SYSTEM GLANDS: An organ which secretes particular chemical substances for use in the body or for discharge into the surroundings .  There are three types of glands in our body:  Endocrine glands  Exocrine glands  Heterocrine glands EXOCRINE GLANDS Exocrine glands are glands that secrete their products into ducts EXAMPLE:  S weat glands  S alivary glands  M ammary glands  Stomach  L iver ENDOCRINE GLANDS G lands that secrete their product (hormones) directly into the blood rather than through a duct EXAMPLE:  Pituitary gland  Pancreas  T hyroid gland  Adrenal glands HETEROCRINE GLANDS These are glands that perform both exocrine and endocrine functions. For example pancreas ENDOCRINE SYSTEM  Consists of glands and Group of capillaries which Facilitates diffusion of hormones to Bloodstream  They are commonly referred as the ductless glands, because the hormones secreted directly into bloodstream Endocrine system continue…  It consists of a number of glands: Pituitary gland Thyroid gland Parathyroid gland Adrenal gland Pancreases Thymus gland PITUITARY GLAND: pituitary gland continue…  The pituitary gland consists of: 1. Adenohyphophysis: - Anterior lobe. It is influenced by hormones which come from the hypothalamus. 2. Neurohypophysis: - Posterior lobe. It is influenced by neurons which convey hormones directly from hypothalamic nuclei for storage of posterior lobe HORMONES: Anterior lobe:  Growth hormone (GH )  Prolactin  Thyroid stimulating hormone (TSH )  Adrenocorticotrophic hormone (ACTH )  Follicle stimulating hormone (FSH )  Luteinizing hormone (LH ) Intermediate lobe:  A and B melanocyte stimulating hormone Posterior lobe: 1. Vasopressin (ADH) 2. oxytocin ANTERIOR PITUITARY GROWTH HORMONE (GH): Action of growth hormone 1. Stimulating of growth of bones, cartilage and connective tissue :  Somatomedins are synthesized in the liver, in response to stimulation by the GH  The effects of GH on skeletal growth are mediated by somatomedins action of GH continue… 2. Effect on Protein and Mineral Metabolism:  On protein metabolism : GH is protein anabolic hormone.  On mineral metabolism :  Increase calcium absorption from GIT  Decrease sodium, potassium, calcium and phosphorous excretion from kidney action of GH continue… 3. Effect on carbohydrate and fat metabolism:  On carbohydrate - GH is diabetogenic, because it produce hyperglycemia  On fat metabolism - GH has catabolic effect i.e . Increases mobilization of fats from adipose tissues CONTROL OF GROWTH HORMONE The release of GH is primary under the control of two hypothalamic hormones :  GH releasing hormone  GH inhibiting hormone Stimuli increases GH Secretions by stimulating GHRH release . E .g . during exercise and stress Stimuli decrease GH secretion by release of GHIH also called Somatostatin DISEASES RELATED TO GROWTH HORMONE 1. Gigantism : It is due to overproduction of GH during adolescence. It is characterized:  Tall stature  Bilateral gynaecomastia.  Large hand and feet. diseases continue…  Acromegaly : It is due excessive secretion of GH during adulthood It is characterized by :  Broad, thick nose  Thickening of the skin  Prominent brow  Pronathism : elongation and widening of the mandible diseases continue… 3. Dwarfism : Deficiency of GH secretion.  Shortness of stature  Small genitalia  Delicate extremities. Hormones of anterior pituitary continue… 2. Prolactin : Actions of prolactin :  Prolactin plays an important role in the development of the mammary gland and in milk synthesis . prolactin continue… Control of prolactin secretion : A . Stimulating factors : They act via stimulating Prolactin releasing factor . e .g . Exercise, emotional stress, pregnancy and breast feeding . continue… B . Inhibitory factors : which is released by the hypothalamus inhibits prolactin secretion from the anterior pituitary Dopamine may be the main prolactin inhibiting factor . Hormones of anterior pituitary continue… 3. Thyroid -stimulating hormone(TSH) : It stimulates the thyroid gland to produce:  T hyroxin (T 4 ), and  T riiodothyronine (T 3 ) Hormones of anterior pituitary continue… 4. ADRENOCORTICOTROPHIC HORMONE(ACTH) :  It is secreted by the anterior pituitary gland .  It is often produced in response to biological stress.  Its principal effects are increased production and release of corticosteroids . Hormones of anterior pituitary continue… 5. FOLLICLE STIMULATING HORMONE(FSH ):  It is synthesized and secreted by anterior pituitary gland  FSH regulates the development, growth, pubertal maturation and reproductive processes of the body Hormones of anterior pituitary continue… 6. LUTEINIZING HORMONE(LH) :  It is a hormone produced by the anterior pituitary gland .  In females, an acute rise of LH triggers ovulation and development of the corpus luteum  In males, it stimulates the production of testosterone INTERMEDIATE LOBE intermediate lobe continue… HORMONES OF INTERMEDIATE LOBE: It secretes:  α melanocyte stimulating hormone  β melanocyte stimulating hormone Function:  They stimulate the production of melanin by melanocytes in skin and hair  MSH signals to the brain have effects on appetite and sexual arousal . POSTERIOR PITUITARY: HORMONES OF POSTERIOR PITUITARY: A. Anti -diuretic hormone (ADH) /vasopressin :  It is a hypothalamic hormone synthesized in the cells of the supra optic nucleus  ADH is stored in the posterior pituitary ADH continue… Functions of ADH : Its two primary functions -  To retain water in the body  To constrict blood vessel. DISEASES RELATED TO ADH:  Diabetes Insipidus : It is a condition characterized by -  Excessive thirst  Excretion of large amounts of severely diluted urine diseases continue…  Polyuria: It is the excessive or abnormally large production of urine (at least 2.5 or 3L /in adults) Hormones of posterior pituitary continue… B. OXYTOCIN : -  Oxytocin is synthesized in the hypothalamus  Stored in the posterior lobe of pituitary gland oxytocin continue… Action of oxytocin :  Oxytocin stimulates contraction of mammary gland to produce milk.  Stimulate contraction of the smooth muscles of the uterus THYROID GLAND Thyroid gland continue… ANATOMY OF THE THYROID GLAND : -  The thyroid gland is situated in the neck in front of the larynx and trachea  It weighs about 25g  It looks like butterfly in shape  Consisting of two lobes  The lobes are joined by a narrow isthmus THYROID HORMONES  Triiodothyronine (T 3): It affects almost every physiological process in the body:  G rowth and development ,  M etabolism ,  B ody temperature , and  H eart rate  Thyroxin (T 4):  Controls development and maturation  Excess thyroxin results rapid development  Deficiency of thyroxin results in delayed development hormones continue…  Calcitonin: It is a hormone secreted by the C cells of the thyroid gland Its main actions are :  to increase bone calcium  to decrease blood calcium levels Calcitonin opposes the effects of parathyroid hormone, which acts to increase the blood level of calcium. Thyroid gland continue… Thyroid is not absolutely essential for life, but its removal in adults leads to :  P oor resistance to cold  M ental and physical slowing. and in children’s :  M ental retardation  D warfism REGULATION OF THYROID SECRETION Thyroid stimulating hormone (TSH ) controls the regulation of thyroid hormones.  The release of TSH by the anterior lobe of the pituitary, is regulated by the hypothalamus via negative feedback mechanism . It is a reaction that causes a decrease in function. It occurs in response to some kind of stimulus. DISEASES RELATED TO THYROID GLAND 1. GOITER : - Any enlargement of the thyroid gland is called goiter Caused by iodine deficiency . Characteristic features: -  Swelling in the neck  Breathing difficulties  Cough  Hoarseness  Swallowing difficulties diseases continue… 2. HYPOTHYROIDISM : - It is the condition resulting from reduced circulating levels of T 3 and T 4. Characteristic features: -  Goiter  Puffiness of face with  Periorbital swelling  Loss of scalp hairs  Ptosis, i.e., drooping of upper eyelid.  Dry, thickened, rough and yellow skin diseases continue… 3. HYPERTHYROIDISM/GRAVES DISEASE : - It is the condition resulting from increased circulating level of T 3 and T 4 Characteristic features: -  Moderate enlargement of thyroid gland  Exophthalmos(Lid retraction) PARATHYROID GLANDS  In humans there are 4 parathyroid glands  Parathyroid glands are essential for life, as their removal can cause death from asphyxia FUNCTION OF PARATHYROID HORMONE  Parathyroid glands contains chief cells which secrete parathyroid hormone .  The main function of parathyroid hormone is to increase the blood calcium level DISEASES RELATED TO PARATHYROID GLAND 1. RICKETS :  It is a disease characterized mainly by bone deformities in young children’s  The disease of children sets in about 6 th month of life Characteristic features: -  Deformed bones  Thick wrist and ankles  Retarded growth diseases continue… 2. OSTEOMALACIA : -  This is due to inadequate absorption of calcium due to deficiency of Vitamin D and Calcium in the diet  The disease is limited to females, usually appears after multiple pregnancies and lactation. diseases continue… 3. HYPOPARATHYROIDISM: It is an abnormally low level of calcium in the blood  Characteristic features: -  Psychiatric disturbance  Par aesthesia  Development of cataract diseases continue… 4. HYPERPARATHYROIDISM : - Excessive secretion of parathyroid hormone. Characteristic features: -  Formation of renal calculi  Polyuria  Polydipsia  Anorexia  Muscle weakness  General fatigue  Calcification of soft tissue PANCREASE ANATOMY OF PANCREASES There are approximately 0.5 to 1.5 million Islets of Langerhans T here are four types of cells:  70 -80% beta - cells secrete Insulin  15 -20%, alpha – cells secrete Glucagon  1 -8% delta - cells secrete Somatostatin and gastrin  1 -2% f- cells. These cells secrete pancreatic polypeptide which decreases the absorption of food from the GIT PANCREATIC HORMONES 1. INSULIN: Actions:  On carbohydrate metabolism:  Insulin increases the glucose entry into most of body cells  Insulin produce hypoglycemia  On protein metabolism:  Insulin promotes amino -acid uptake  It decrease protein breakdown  It promotes protein synthesis especially in muscles DISEASES RELATED TO INSULIN: - DIABETES MELLITUS  It is a group of metabolic diseases in which there are high blood sugar over a prolonged period.  This high blood sugar produces the symptoms of  frequent urination ,  increased thirst , and  increased hunger . hormones continue… 2. GLUCAGON: - Glucagon act mostly on the liver and adipose tissues where it antagonizes the actions of insulin  Stimulate glycogenolysis  Promotes gluconeogenesis hormones continue… 3. SOMATOSTATIN: A hormone that is widely distributed throughout the body, especially in the hypothalamus and pancreas Action:  It regulates the endocrine and Nervous system functions ADRENAL GLANDS  There are two adrenal glands ,  A bout 4 cm long and 3 cm thick  It has two parts:  outer part is cortex and  the inner part is medulla. adrenal glands continue… 1. ADRENAL CORTEX: -  It produces three hormones:  Glucocorticoids  Mineralocorticoids  Sex hormones (androgens ) These are collectively called as adrenocorticoids adrenal cortex continue… A. Glucocorticoids: -  Cortisol, corticosterone and cortisone are the main Glucocorticoids  They are essential for life, regulating metabolism and stress  They are high in between 4 to 8 am  Lowest between midnight and 3 am glucocorticoids continue… Effects:  Gluconeogenesis (formation of new sugar )  Lipolysis (breakdown of triglycerides into fatty acids and glycerol for energy production ). In pathology and pharmacology:  H ave an anti -inflammatory action.  S uppress the immune response.  S uppress the response of tissue to injury.  D elay wound healing. adrenal glands continue… B. Mineralocorticoids (aldosterone): -  Aldosterone is the main mineralocorticoids  It maintains Water and electrolyte balance adrenal glands continue… C. Sex hormones: -  Androgens are the main sex hormones  They contribute to the onset of puberty DISORDERS OF ADRENAL CORTEX 1. Cushing’s syndrome : - It is caused due to hyper secretion of glucocorticoids Characteristic features:  Pain in face, neck and abdomen  Pathological fractures  Diminished protein synthesis  Suppression of growth  Hypertension  Menstrual disturbance  Peptic ulcers disorders of adrenal cortex 2. Conn’s syndrome : -  This is due to excessive secretion of mineralocorticoids.  It is usually caused by tumor affecting only one adrenal gland disorders of adrenal cortex 3. Addison’s disease :  It is due to hypo secretion of glucocorticoids and mineralocorticoids  Caused by autoimmune disease Effects:  Muscle weakness.  Vomiting and diarrhea.  Tiredness.  Mental confusion.  Low blood volume.  Hypotension.  Loss of body hairs in women. adrenal glands continue… 2. ADRENAL MEDULLA: -  It is surrounded by the cortex  It produces two hormones  adrenaline and  noradrenaline . adrenal medulla continue… Adrenaline and noradrenaline:  Noradrenaline and adrenaline are released into the blood  They are structurally very similar and have similar effects  Together they potentiate by:  Increasing heart rate  Increasing blood pressure  Increasing metabolic rate  Dilating the pupils DISORDERS OF ADRENAL MEDULLA: - The effects of excess adrenaline and noradrenaline are: -  Hypertension  Hyperglycemia  Raised metabolic rate  Nervousness  Headache THYMUS GLAND Thymus is located in the anterior part of the upper mediastinum  At birth it weighs 10 -12 gms  D uring childhood and adolescence 20 -30 gms  D uring old age it weighs 3 -6 gms thymus gland continue… Functions: -  It initiates and maintain T - lymphocytes HORMONE : - Thymosin: -  It is required for the development of T -lymphocytes for cell mediated immunity CONCLUSION In endocrine system we use to study and get knowledge about:  v arious glands of our body  H ormones secreted by them  Their various functions So it is very necessary to study for :  Implementing the gained knowledge clinical area  F or the better and quality nursing care SUMMARY So we discussed about the endocrine system and why it is important to us In which we also studied about various gland:  Pituitary gland  Thyroid gland  Parathyroid  Adrenal glands  Pancreas  Thymus gland Their location, function and disorders RECAPTUALISATION  Define glands and their types?  Enlist the hormones secreted by anterior pituitary?  What is negative feedback mechanism?  Define gynacomastia?  What is gycogenolysis?