Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Endocrine System Lecture PPT
ENDOCRINE SYSTEM
INTRODUCTION
? Endocrine tissue is made
up of cells that produce
secretions which are
poured directly into blood.
? Endocrine cells lie in close
apposition
to
blood
capillaries or sinusoids.
? Secretions of endocrine
cells are called hormones.
? Hormones travel through
blood to target cells and
influence their function.
Endocrine Glands (Ductless gland)
? Pituitary (hypophysis)
? Anterior pituitary
? Posterior pituitary
? Adrenal gland (suprarenal)
? Adrenal cortex
? Adrenal medulla
? Thyroid gland
? Follicles
? Parafollicular cells
? Parathyroid gland
Pituitary Gland ( Hypophysis Cerebri)
a
Pituitary Gland (hypophysis)
? "Master endocrine gland".
? Parts-->
? Adenohypophysis (Ant. Pituitary):
? Pars distalis,
? Pars intermedia
? Pars tuberalis.
? Neurohypophysis (Post. Pituitary):
? Pars nervosa,
? Infundibular stalk
? Median eminence.
Adenohypophysis (Anterior pituitary)
Pars Distalis:
? Consists of 2 major group of cells:
? Chromophils ( secretory granules)
Acidophils (alpha cells) & Basophils ( beta cells)
? Chromophobes ( few or no granules )
Pars Intermedia:
? Consists mainly of basophils.
? Some cells produce melanocyte stimulating hormone (MSH).
Pars Tuberalis:
? Consists of chromophilic (mostly basophilic) & chromophobic cells
? Harmone secreted by chromophils
? Acidophils--Growth hormone & Prolactin
? Basophils-- TSH
FSH, LH
ACTH
Neurohypophysis (Posterior pituitary)
Consists of:
? Numerous non-myelinated nerve
fibres
? Supporting cells (pituicytes)
Produce 2 hormones:
? Oxytocin [paraventricular nucleus]
? Vasopressin (ADH)[supraoptic nuc.]
Herring bodies:
Collection of secretory granules at
the terminal portion of axonal
processing.
Pituitary gland
THYROID GLAND
Microscopic structure
? The gland is surrounded by a thin
fibrous capsule.
? Septa from the capsule extend into
the gland & divide it into lobules.
? Lobules are made up of spherical
masses called follicles.
? Follicle has a cavity filled with
homogenous material called
colloid.
? Follicular cells-- cuboidal
? Secrete 2 hormones:
? Tri-iodothyronine (T3)
? Tetra-iodothyronine (T4) or
thyroxine.
Parafollicular cells (C-
cells):
? Embedded within a
follicle or lie between
follicles.
? Singly or in groups.
? Cells are polyhedral with
oval eccentric nucleus
and cytoplasm contains
secretory granules.
? Light staining cells.
? Secrete hormone
calcitonin.
Parathyroid Gland
? Small ovoid bodies (4 in no.)
embedded in the connective
tissue capsule on the posterior
surface of thyroid gland.
? Consists of 2 types of cells:
? Chief cells (principal cells):
more numerous, polygonal,
round
centrally
located
nucleus.
? Secrete parathyroid hormone
(PTH).
? Oxyphil cells: larger in shape,
inactive phase of chief cells.
Parathyroid Gland
Adrenal Gland
(Suprarenal Gland)
Microscopic structure
? The gland is
capsule
covered
by
connective tissue
capsule.
cortex
? Capsule sends
septa inside the
gland.
? 2 parts
medulla
? Cortex
? Medulla
Microscopic structure
Zona glomerulosa
Mineralocorticoid
(aldosterone)
Cortex
Glucocorticoids
Zona fasciculata
(cortisol)
Androgen
(dehydroepiandrosterone)
Zona reticularis
& Estrogen
Catecholamines
Medulla
(epinephrine &
norepinephrine)
Adrenal Cortex
3 layers:
? Zona Glomerulosa: cells are
arranged as rounded clusters Cells
are columnar with dark staining
nuclei.
? Zona Fasciculata: thick zone,
large pale staining polyhedral cells
arranged into parallel columns.
? Zona Reticularis: small rounded
deep staining cells arranged in
branching & anastomosing cords.
Adrenal Medulla
? Consists of chromaffin cells
? Cells are large, epitheloid &
Capsule
arranged in groups.
? Cells are closely related to
sinusoidal capillaries.
Cortex
? Cytoplasm is light basophilic.
? Chromaffin reaction--
? Tissue
fixation
with
potassium
dichromate
shows fine brown granules
Medulla
in the cells of medulla
SELF-ASSESSMENT
(URINARY SYSTEM)
1. Transitional epithelium is present in:
a. Renal pelvis
b. Loop of Henle
c. Terminal part of urethra
d. PCT
2. Urothelium does not line:
a. Collecting ducts
b. Minor calyx
c. Ureter
d. Urinary bladder
3. Which cell type comprises the visceral layer of
Bowman capsule?
a. Endothelial cells
b. Juxtaglomerular cells
c. Mesangial cells
d. Podocytes
4. Which type of epithelium lines the thick
ascending limb of the loop of Henle?
a. Pseudostratified columnar
b. Simple columnar
c. Simple cuboidal
d. Simple squamous
5.Which cell is a modified smooth muscle cell in
the wall of afferent arteriole ?
a. Macula densa cells
b. Mesangial cells
c. Podocytes
d. Juxtaglomerular cells
6. Cortex of the kidney contains the following
structures except
(a) Proximal convoluted tubule (PCT)
(b) Distal convoluted tubule (DCT)
(c) Renal corpuscle
(d) Thin segment of loop of Henle
7. Macula densa is present in
(a) PCT
(b) DCT
(c) afferent arteriole
(d) efferent arteriole
8.Components of the Juxtaglomerular apparatus
are all EXCEPT
(a)Macula densa
(b)Extra mesangial cells
(c)Epithelium of PCT
(d) Juxtaglomerular cells
1.(a). Renal pelvis
2.(a). Collecting ducts
3.(d). Podocytes
4.(c). Simple cuboidal
5.(d). Juxtaglomerular cells
6.(d). Thin segment of loop of Henle
7.(b). DCT
8.(c). Epithelium of PCT
This post was last modified on 30 November 2021