Download Endocrine system

The endocrine system
Overview
I. Pituitary
II. Adrenals
III. Pancreas
IV. Thyroid
V. Parathyroids
VI. Ovaries, testis
fenestrated capillaries
are general structures
http://www.ama-assn.org/ama/pub/category/7157.html
Major human endocrine glands and some
of their hormones
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Martini, Timmons – Anatomia Umana, IV Ed.
ACROMEGALY
CRETINISM
Addison’s disease
GOITER
Cushing's syndrome
Hyperthyroidism, excessive secretion of
thyroid hormones
– Can cause Graves’ disease in humans
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The pituitary gland, hypophysis
The master gland, a pea-sized body attached to the base of the
brain, It lies within the pituitary fossa of the sphenoid bone, where it
is covered superiorly by a circular diaphragma sellae of dura mater
Neurohypophysis, the median eminence, infundibular stem and
neural lobe or pars posterior
Adenohypophysis pars anterior (pars distalis) and the pars
intermedia. - Both include parts of the infundibulum-
The endocrine secretory activities
of the pituitary gland
the pituitary gland
(trichrome-stained).
A, The endocrine cells of the adenohypophysis
B, The neurohypophysis (right), with nerve fibres and pituicytes.
The pituitary gland development
neurohypophysis (post. lobe) develops as outgrowth of
diencephalon and forms:
1) pars nervosa (posterior lobe); 2) infundibulum
The pituitary gland development
adenohypophysis (ant. lobe) develops from Ratcke’s pouche
(oral ectoderm) and forms:
1) pars distalis (posterior lobe); 2) pars tuberalis and pars
intermedia
The pituitary gland
vascularization
Hypothalamo-hypophyseal
portal system
1. primary capillary plexus
(base of infundibulum/
hypothalamus)
2. veins to anterior lobe
3. secondary capillary plexus
Function: transports
neurohormones
a. releasing hormones
b. inhibiting hormones
The pituitary gland, adenohypophysis
pars anterior (pars distalis)
1. Chromophobes &
chromophils
2. Basophils
a. gonadotrophic cells
i) FSH, follicle-stimulating
hormone promotes the formation
of ova or sperm.
ii) LH, luteinizing hormone
stimulates ovulation in females
and the synthesis of androgen in
males.
b. thyrotropic cells
iii) TSH, thyroid-stimulating
hormone.
c. corticotrophic cells
iv) ACTH, adrenocorticotropic
hormone stimulating the adrenal
cortex
The pituitary gland, adenohypophysis
pars anterior (pars distalis)
3. Acidophils
d. somatotropic cells
v) GH, growth hormone
stimulates growth
e. mammotropic cells
vi) PRL
The pituitary gland, neurohypophysis
1. pituicytes
2. neurosecretory cells
3. ~100,000 unmyelinated
axons from hypothalamus
Neurohypophysis
Neurohypophysis
vii) vasopressin / ADH,
antidiuretic hormone
a. contraction of smooth
muscle in arteries
b. increase reabsorption
of H2O in collecting
tubules
viii) oxytocin
a. contraction in
pregnant uterus
b. stimulates the
ejection of milk into
the ducts of the
breasts.
Major calyces
renal pelvis
calyces
ureter
renal cortex
renal medulla
Renal medulla
GLOMERULUS
Adrenals (suprarenal glands)
ductless glands situated above the kidneys. Each consists of a core
region (adrenal medulla) secreting epinephrine and norepinephrine,
and an outer region ( adrenal cortex) secreting corticosteroids.
A. Overview
1. adrenal cortex
a. steroids
2. adrenal medulla
a. E & NE
3. stroma
a. capsule
b. trabeculae
c. reticular fibers
4. extensive capillary
plexuses
Adrenal cortex
zona glomerulosa
a. 15% of adrenal cortex
Adrenal cortex
zona glomerulosa
b.clusters of cells
c. mineralocorticoids (aldosterone)
Function: increase DCT (distal
convoluted tubule) absorption
of Na+
DCT is a portion of kidney nephron
between the loop of Henle and the
collecting duct system.
Adrenal cortex
zona fasciculata
a. 65% of adrenal cortex
b. cells in cords
c. many lipid droplets in cytoplasm
d. glucocorticoids (cortisol and
corticosterone)
Function: i) influence CHO
metabolism; ii) suppress immune
response
CHO= carbohydrate
Adrenal cortex
zona reticularis
a. 7% of adrenal cortex
b. irregular cords in network
c. lipofuscin granules
d. androgens
Function: little effect vs. testicular
hormones
Adrenal medulla
1. cells in cords
2. secrete epinephrine and
norepinephrine (E & NE)
3. innervated by preganglionic
sympathetic (myelinated) axons
Look for:
Preganglioni sympathetic fibers
Blood vessels
adult suprarenal gland (adrenal gland)
zona granulosa (ZG), zona fasciculata (ZF), zona
reticularis (ZR), and the highly vascular medulla (M).
adrenal gland
FC
L
F
G
R
C
M
V
adrenal gland
FC
1
G
F
C
2
R
M
4
3
V
zona granulosa (ZG)
1
FC
ZG
F
zona fasciculata (ZF) zona reticularis (ZR)
2
c
ZF
c
ZR
Zona Fascicolata (ZF)
S
A
B
Zona Reticularis (ZR)
3
sinusoid
Medulla (M)
4
*
*
*
*
*
Pancreatic endocrine tissue
Cluster of cells in cords
1. network of fenestrated capillaries
Islet of Langerhans
Pancreas islet vessels
V
*
*
V
*
V
Pancreas endocrine cells
Pancreatic endocrine tissue
Cluster of cells in cords
A cells: glucagon, incr. blood sugar
B cells: insulin, decr. blood sugar
D cells: somatostatin, produced
in pituitary too:
inhibits A & B cells
E cells: unknown function
[immunohistochemistry for glucagon cells]
[immunohistochemistry for insulin cells]
Thyroid
1. anterior to larynx
2. two lobes connected by isthmus
3. well vascularized
Follicle cells
1. squamous to columnar epithelium
a. squamous = inactive
b. columnar = active
2. colloid
a. thyroxine / T4
b. triiodothyronine / T3
Function: stimulates rate of
metabolism. Influenced by thyroidstimulating hormone (TSH)
Parafollicular cells
1. calcitonin
Function: decr. blood Ca++
human thyroid follicles (*)
*
*
*
*
reticular
connective tissue
human thyroid follicles
CT colloidal thyroglobulin
* calcitonin-secreting C cells
follicular epithelium
thyroid colloid (*)
*
*
*
Thyrocyte (T) and basal membrane (BM)
BM
T
calcitonin-secreting C cells
C1
C2
Parathyroid
The parathyroid glands are four or more
small glands, about the size of a grain of
rice, located on the posterior surface (back
side) of the thyroid gland
Parathyroid
Parathyroid gland
chief cells (or a "zymogenic
cell") release a precursor
enzyme.
Two types of chief cells:
-gastric chief cell (or "peptic
cell") is a cell in the stomach
that releases pepsinogen,
rennin and gastric lipase
enzymes, which help digest
triglycerides into free fatty
acids and di- and monoglycerides.
-the parathyroid chief cell of
the parathyroid gland. It
produces and secretes
parathyroid hormone.
oxyphil cells
Parathyroid glands
Parenchyma
1. oxyphil cells
a. larger, polygonal cells
unknown function
Parathyroid glands
Parenchyma
chief cells
a. pale, acidophilic cytoplasm
b. secretes parathyroid hormone
Funcion:
incr. blood Ca++ levels