Download Lecture 8 - Endocrine

Endocrine
Endocrine
Function
• Influences growth, metabolism, and homeostasis over prolonged periods
• Secretes hormone products into interstitial spaces which are then
absorbed into the blood and transported throughout the body
• Hormonal control is much slower than nervous control, but the effects of
the endocrine system are much longer lasting
Key Features of Endocrine Glands
• A rich capillary blood supply is necessary for secretion and reception of
hormones
• Endocrine glands are, by definition, ductless
• Organelles required to synthesize specific hormones are in great supply
Hormone Classifications
Amino Acid Derivatives
• Hormones derived from the amino acid tyrosine
• Epinephrine, norepinephrine, and thyroxine
Polypeptide Hormones
• Hormones with a peptide structure
• Insulin, prolactin, NGF, EGF, GH, PTH, TSH, enkephalin, TRH, ADH
Steroids
• Hormones derived from cholesterol
• Testosterone, cortisol, aldosterone, progesterone, estradiol
Pituitary Gland
•
Controlled by hypothalamus
•
Infundibulum serves as a communication
channel between the hypothalamus and
pituitary
•
The hypothalamohypophyseal neural
tract is the passageway for two
hypothalamic hormones to the posterior
pituitary
•
The hypothalamohypophyseal portal
system carries hypothalamic hormones
that regulate secretion from the
anterior pituitary
•
The anterior pituitary secretes
hormones that regulate lactation,
metabolism, growth, stress response,
and reproduction
Pituitary Gland
A: Adenohypophysis (anterior
pituitary):
1. Pars distalis.
2. Pars intermedia
3. Pars tuberalis
B: Neurohypophysis (posterior
pituitary):
1. Infundibulum
2. Pars nervosa
A
B
A
E
B
D
C
Practice
Adenohypophysis
A: Chromophobes
B: Basophilic chromophils
Gonadotrophs– FSH and LH
Corticotrophs– ACTH
Thyrotrophs– TSH
C: Acidophilic chromophils
Somatotrophs– GH
Mammotrophs– Prolactin
B
C
A
Practice
Neurohypophysis
A: Pituicytes
H: Herring Bodies
A
Review
Fill in the missing hormones secreted from the pituitary or list
their respective functions
Hormone
Function
FSH
Follicle maturation and spermatogenesis
LH
Causes follicle maturation and
testosterone production in leydig cells
ACTH
Stimulates adrenal cortex
TSH
Stimulates T3 and T4 secretion from
thyroid
GH
Controls growth
Prolactin
Stimulates mammary glands
ADH
Stimulates water resorption
Oxytocin
Smooth muscle contraction and milk
letdown
Thyroid
4
B
A: Follicular cells
B: Parafollicular cells
A
Parathyroid
A: Adipose tissue.
C: Capillaries
P: Principal or chief cells
O: Oxyphil cells
B
A
Practice
A
B
Pancreas
A: Islets of Langerhans contain
four different cells:
1. α-cells
2. β-cells
3. δ-cells.
4. PP– cells
A
Stomach
Gastrin or G-cells
A: Parietal cell.
B: Chief cell.
A
B
Adrenal Gland
A
A: Zona glomerulosa
B: Zona fasciculata
C: Zona reticularis
D: Medulla
B
C
D
Practice
Clinical Connections
Pheochromocytoma
• Neuroendocrine tumor of the adrenal medulla
• Results in excessive secretion of catecholamines
• Diagnosed by measuring plasma or urine levels of catecholamines
Source: http://en.wikipedia.org/wiki/Pheochromocytoma
Enteroendocrine Cell
A: Argentaffin cells
A
B: Central Lacteal
B
Practice
Review
Know the following hormones, where they are secreted, their function, and
target organ.
Anterior Pituitary
FSH
LH
ACTH
TSH
GH
Prolactin
Posterior Pituitary
ADH
Oxytocin
Thyroid
T3 and T4
Calcitonin
Parathyroid
PTH
Pancreas
Glucagon
Insulin
Somatostatin
Pancreatic Peptide
Stomach
Gastrin
Adrenal
Aldosterone
Cortisol
DHEA
Argentaffin Cell
CCK
Secretin
Serotonin