Download MBBS Endocrine System Lecture PPT

ENDOCRINE SYSTEM


INTRODUCTION

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? Endocrine tissue is made

up of cells that produce

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secretions which are

poured directly into blood.

? Endocrine cells lie in close

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apposition

to

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blood

capillaries or sinusoids.

? Secretions of endocrine

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cells are called hormones.

? Hormones travel through

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blood to target cells and

influence their function.
Endocrine Glands (Ductless gland)

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? Pituitary (hypophysis)

? Anterior pituitary
? Posterior pituitary

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? Adrenal gland (suprarenal)

? Adrenal cortex
? Adrenal medulla

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? Thyroid gland

? Follicles
? Parafollicular cells

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? Parathyroid gland


Pituitary Gland ( Hypophysis Cerebri)

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a

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Pituitary Gland (hypophysis)

? "Master endocrine gland".
? Parts-->
? Adenohypophysis (Ant. Pituitary):

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? Pars distalis,
? Pars intermedia
? Pars tuberalis.
? Neurohypophysis (Post. Pituitary):
? Pars nervosa,

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? Infundibular stalk
? Median eminence.
Adenohypophysis (Anterior pituitary)

Pars Distalis:

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? Consists of 2 major group of cells:
? Chromophils ( secretory granules)

Acidophils (alpha cells) & Basophils ( beta cells)

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? Chromophobes ( few or no granules )

Pars Intermedia:

? Consists mainly of basophils.

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? Some cells produce melanocyte stimulating hormone (MSH).

Pars Tuberalis:

? Consists of chromophilic (mostly basophilic) & chromophobic cells

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? Harmone secreted by chromophils
? Acidophils--Growth hormone & Prolactin
? Basophils-- TSH

FSH, LH

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ACTH

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Neurohypophysis (Posterior pituitary)

Consists of:
? Numerous non-myelinated nerve

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fibres

? Supporting cells (pituicytes)
Produce 2 hormones:
? Oxytocin [paraventricular nucleus]

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? Vasopressin (ADH)[supraoptic nuc.]
Herring bodies:
Collection of secretory granules at

the terminal portion of axonal

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processing.


Pituitary gland

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THYROID GLAND

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Microscopic structure

? The gland is surrounded by a thin

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fibrous capsule.

? Septa from the capsule extend into

the gland & divide it into lobules.

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? Lobules are made up of spherical

masses called follicles.

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? Follicle has a cavity filled with

homogenous material called

colloid.

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? Follicular cells-- cuboidal
? Secrete 2 hormones:
? Tri-iodothyronine (T3)
? Tetra-iodothyronine (T4) or

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thyroxine.


Parafollicular cells (C-

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cells):

? Embedded within a

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follicle or lie between

follicles.

? Singly or in groups.

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? Cells are polyhedral with

oval eccentric nucleus

and cytoplasm contains

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secretory granules.

? Light staining cells.
? Secrete hormone

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calcitonin.


Parathyroid Gland

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? Small ovoid bodies (4 in no.)

embedded in the connective

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tissue capsule on the posterior

surface of thyroid gland.

? Consists of 2 types of cells:

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? Chief cells (principal cells):

more numerous, polygonal,

round

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centrally

located

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nucleus.

? Secrete parathyroid hormone

(PTH).

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? Oxyphil cells: larger in shape,

inactive phase of chief cells.

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Parathyroid Gland

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Adrenal Gland

(Suprarenal Gland)

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Microscopic structure

? The gland is

capsule

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covered

by

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connective tissue

capsule.

cortex

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? Capsule sends

septa inside the

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gland.

? 2 parts

medulla

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? Cortex
? Medulla

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Microscopic structure

Zona glomerulosa

Mineralocorticoid

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(aldosterone)

Cortex

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Glucocorticoids

Zona fasciculata

(cortisol)

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Androgen

(dehydroepiandrosterone)

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Zona reticularis

& Estrogen

Catecholamines

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Medulla

(epinephrine &

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norepinephrine)


Adrenal Cortex

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3 layers:
? Zona Glomerulosa: cells are

arranged as rounded clusters Cells

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are columnar with dark staining

nuclei.

? Zona Fasciculata: thick zone,

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large pale staining polyhedral cells

arranged into parallel columns.

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? Zona Reticularis: small rounded

deep staining cells arranged in

branching & anastomosing cords.

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Adrenal Medulla

? Consists of chromaffin cells

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? Cells are large, epitheloid &

Capsule

arranged in groups.

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? Cells are closely related to

sinusoidal capillaries.

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Cortex

? Cytoplasm is light basophilic.
? Chromaffin reaction--
? Tissue

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fixation

with

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potassium

dichromate

shows fine brown granules

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Medulla

in the cells of medulla

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SELF-ASSESSMENT

(URINARY SYSTEM)
1. Transitional epithelium is present in:
a. Renal pelvis

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b. Loop of Henle
c. Terminal part of urethra
d. PCT
2. Urothelium does not line:
a. Collecting ducts

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b. Minor calyx
c. Ureter
d. Urinary bladder
3. Which cell type comprises the visceral layer of

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Bowman capsule?

a. Endothelial cells
b. Juxtaglomerular cells
c. Mesangial cells

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d. Podocytes
4. Which type of epithelium lines the thick

ascending limb of the loop of Henle?

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a. Pseudostratified columnar
b. Simple columnar
c. Simple cuboidal
d. Simple squamous
5.Which cell is a modified smooth muscle cell in

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the wall of afferent arteriole ?

a. Macula densa cells
b. Mesangial cells

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c. Podocytes
d. Juxtaglomerular cells
6. Cortex of the kidney contains the following

structures except

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(a) Proximal convoluted tubule (PCT)
(b) Distal convoluted tubule (DCT)
(c) Renal corpuscle
(d) Thin segment of loop of Henle

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7. Macula densa is present in
(a) PCT
(b) DCT
(c) afferent arteriole
(d) efferent arteriole

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8.Components of the Juxtaglomerular apparatus

are all EXCEPT

(a)Macula densa

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(b)Extra mesangial cells
(c)Epithelium of PCT
(d) Juxtaglomerular cells
1.(a). Renal pelvis
2.(a). Collecting ducts

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3.(d). Podocytes
4.(c). Simple cuboidal
5.(d). Juxtaglomerular cells
6.(d). Thin segment of loop of Henle
7.(b). DCT

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8.(c). Epithelium of PCT