Endocrine System-I
Upcoming SlideShare
Loading in...5
×
 

Endocrine System-I

on

  • 2,258 views

 

Statistics

Views

Total Views
2,258
Views on SlideShare
2,256
Embed Views
2

Actions

Likes
3
Downloads
184
Comments
1

1 Embed 2

http://www.slideshare.net 2

Accessibility

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Endocrine System-I Endocrine System-I Presentation Transcript

  • ENDOCRINE SYSTEM 1 R. Kalliecharan
  • Hormonal Effects Hormones regulate : 1) Homeostasis– chemical comp and volume 2) Metabolic Activities 3) Growth and Development 4) Reproduction 5) Immune System 6) Smooth and Cardiac Muscles
  • Location of Glands • 1) Specific Hormones affect Specfic TARGET Cells by binding to ` Specific RECEPTORS • For e.g. TSH binds to receptors on surface of Thyroid Follicular cells but not to Adrenals • Receptors are constantly synthesized and broken down
  • Hormone Transport Circulating Hormones ( Endocrine secretion) - hormones in blood act on distant target cell e.g. LH or ACTH Paracrine secretion – act within short distance e.g. Gastrin H of G-cells in pylorus act on parietal cells of fundic glands Juxtacrine secretion-- act at very short distance e.g. somatostatin inhibits insulin Autocrine secretion-act on themselves e.g. interleukin-2
  • Mechanism of Hormone Action • 1) Steroid and Thyroid Hormones— activation of intracellular receptor • 2) Protein Hormones—activation of plasma membrane –1st messenger – adenyl cyclase activation followed by 2 nd messenger (c AMP )
  • Pituitary Gland (Hypophysis) • Location: Sella Turcica of Sphenoid bone • Gland is attached to Hypothalamus by infundibulum • Lobes:1) Adenohypophysis- oral ectoderm and (2) Neurohypophysis-neural ectoderm • 1)Adeno—consists of pars distalis (Ant pit) , pars tuberalis and pars intermedia • 2)Neuro—consists of pars nervosa (Post pit) , infundibular stem and median eminence
  • Pars nervosa
  • Hypophyseal Portal System • 1) Hypothalamus secretes releasing and inhibiting hormones into primary capillary plexus (pcp) at Med Eminence • 2) Int Carotid A—superior hypophyseal artery---PCP---hypophyseal portal veins --- secondary CP in pars distalis— hormones go out via Ant hypophyseal veins
  • Ant Pit (pars distalis) • 1) Cells are ÷ into chromophils and chromophobes • Chromophils are ÷ into acidophils and basophils • 2) Acidophils and secretions : a) somatotrophs → GH (somatotropin) b) mammotrophs → prolactin
  • • 3) Basophils and secretions a) thyrotrophs → TSH b) corticotrophs → ACTH, LPH, MSH, endorphins and enkephalins c) gonadotrophs → LH and FSH 4) Chromophobes → no cytoplasmic staining
  • Hypothalamic Regulation of Pars Distalis • Hypothalamus secretes Releasing and Inhibiting Hormones • TRH--- ↑ TSH --- ↑ T 4 + T 3 • CRH--- ↑ ACTH--- ↑ glucocorticoids (Adrenals) • GnRH--- ↑ FSH--- ovary (↑ estrogens) , -- Sertoli cells (↑ABP and inhibin) • --↑ LH maturation,ovulation, and corpus luteum • --Leydig cells (↑ testosterone )
  • Hypothalamic Regulation of Pars Distalis GRH(SRH)---↑GH--- ↑Somatomedin C • • Somatostatin---↓ GH PRH--- ↑ Prolactin--- ↑ milk secretion • PIH (dopamine)--- ↓ Prolactin •
  • Cont. • Pars Tuberalis--- some cells secrete FSH and LH • Pars Intermedia---Area is rudimentary in Humans
  • Negative Feedback System • Hypothalamus(CRH)->AntPit(↑ACTH) ↑ ↓ • • ¦ Adrenal cortex(↑cortisol) ↓ • ¦ ---------------------------------- ↓ •
  • ++ Target Target Tissue Tissue TSH T3& T4
  • Neurohypophysis • Pars nervosa (post pit)---has no secretory cells. It has pituicytes and unmyelinated axons of neurosecretory neurons. • Herring bodies contain hormones. These are Oxytocin from paraventricular N.- uterine m • And ADH (vasopressin )from supraoptic N • -- increases water permeability of kidneys