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HUMAN ANATOMY AND PHYSIOLOGY -  IV
 Endocrine system & immune system
 This unit covers two most important systems in human body. They are endocrine system and immune system.
 
 Important Points to Remember:
 *    Endocrine glands are ductless glands which secrete hormones.
 *    Hormones are non-nutrient chemicals. They act as intercellular messengers.
 *    Secretin is the first hormone to be detected.
 *    Most of the hormones are target specific.e.g.,TSH,ACTH.
 *    But thyroxine and STH act on all somatic cells.
 *    Hormones belong to three classes like amine hormones, peptide and protein hormones and steroid hormones.
 *    Endocrine glands in human body are pituitary, pineal, thyroid, parathyroid, adrenal, pancreas, thymus and gonads.
 *    Hypothalamus is the master control centre of the endocrine system as its secretions directly control the pituitary gland which is considered as master gland of the endocrine system.
 *    Hypothalamus controls the secretion of growth hormone(somatotropin) from pituitary gland in the following  method... by releasing them through hypophyseal portal system
 a)    Growth hormone releasing hormone (Somatocrinin)  stimulates the synthesis of release.
 b)    Growth hormone inhibiting hormone (somatostatin)  .. inhibits the release .
 *    Pituitary gland/hypophysis has anterior  and posterior pituitary with pars intermedia between them.
 *    Hormones of anterior pituitary or adenohypophysis are
 a)    growth hormone/somatotropin
 b)    prolactin or lactogenic or luteotropic hormone.
 c)    thyroid stimulating hormone
 d)    Adrenocorticotropic hormone/corticotrophin
 e)    follicle stimulating hormone
 e)    Lutenizing hormone
 *    Hormone of Pars intermedia is melanocyte stimulating hormone (MSH).
 *    posterior pituitary/neurohypophysis  stores and releases oxytocin and vasopressin/ADH of hypothalamus
 *    Pineal gland or epiphysis cerebri secretes melatonin. It regulates circadian rhythms within 24 hrs in our body. It maintains sleep-wake cycle.
 *    Thyroid gland is the largest endocrine gland which secretes thryroxine and calcitonin.
 *    Thyroid hormones maintain basal metabolic rate (BMR).
 *    Calcitonin is hypoglycaemic hormone while parathormone is hyperglycaemic hormone.
 *    Thymus gland is present below the breast bone. It secretes thymosins which play a major role in differentiation of T-lymphocytes for cell-mediated immunity and provide humoral immunity also by producing antibodies.
 *    Adrenal glands/supra renal glands contain cortex and medulla.
 *    Adrenal cortex has three zones like zona glomerulosa, zona fasciculata and zona reticularius.
 *    Adrenal cortex secretes mineralo corticoids like aldosterone, glucocoricoticoids like cortisol and androgens.
 *    Adrenal medulla secretes two catecholamine  hormones known as adrenaline/epinephrine and noradrenaline or *orepinephrine. These are emergency chormones or hormones of fight or flight.
 *    Pancreas is mixed gland with exocrine and endocrine in function. Exocrine part consists acini which secrete pancreatic juice.
 *    Endocrine part of pancreas consists Islets of Langerhans with a - cells and b - cells.
 *     a - cells secrete glucagon which is hyperglycaemic hormone and b - cells secrete insulin which is hypoglycaemic hormone.
 *    Testes are male gonadal glands. Leydig cells produce androgens like testosterone. Male sex hormones are required for the development, maturation and functioning of male accessory sex organs like epididymis, vas deferens, seminal vesicles, prostate gland, urethra.
 *    Ovaries are female gonadal organs which produce ova. Ovaries secrete female hormones like estrogen and progesterone.
 *    Estrogen helps in the development and activity of female secondary sex organs.
 *    Progesterone prepares uterus for the implantation of blastocyst.
 *    Atrial myocytes of heart secrete atrial natriuretic factor or peptide which dilates blood vessels and decreases blood pressure.
 *    Erythropoietin is the hormone secreted by kidney which stimulates erythropoiesis.
 *    Gastrin,secretin, cholecystokinin(CCK), gastric inhibitory peptide are the hormones secreted by mucosa of gastrointestinal tract.
 *    Hormones show their effects on hormone receptors present in target tissues.
 *    Hormone receptors are membrane bound and intracellular receptors.
 *    Water soluble hormones cannot enter the cell.  They interact with membrane bound receptors and generate second messengers like cyclic AMP.
 *    Lipid soluble hormones can interact with intracellular receptors and enter the nucleus to regulate gene expression.
 
 
 IPE Weightage:
 *    10 marks weightage is given for this unit in the form of 3 VSAQ type and One SAQ type que-stion.
 Important VSAQ:
 *    Acromegaly?
 *    which hormone is antidiuretic hormone? Which gland secretes it?
 *    distinguish between diabetes insipidus and diabetes mellitus?
 
*    which hormone is commonly known as fight and flight hormone?
 *    what is erythropoietin? Mention its function?
 *    writes the names of any 4 mononuclear phagocytes?
 *    differentiate between perforins and granzymes?
 *    How can the graft rejections be avoided in patients?
 Important SAQ:
 *    Write short notes on immunoglobulins?
 *    Explain the mechanism of humoral immunity?
 *    Explain the mechanism by which HIV multiplies and leads to AIDS?
 *    Describe the role of hypothalamus as a neroendocrine gland?
 *    Given an account of secretions of pituitary gland?
 *    Write a note on Addison's disease and Cushing's syndrome?
 *    Write  a note on the mechanism of action of hormones?