MMR
Endocrine emergency
Lecture 1
Dr. Miada Mahmoud Rady
Topics
1 •Introduction. •Overview of the whole endocrine system.
2 •Mechanism of hormone regulation.•Hormonal control of the endocrine system.
3 •Function of hormones.•Individual body glands.
MMR
Introduction
Endocrine system is the body second great
controlling system.
The endocrine system influences almost every
cell, organ, and function of the body.
That is why patients with an endocrine disorder
often have a broad range of signs and symptoms.
MMR
Overview of the whole endocrine system
System of ductless glands that produces and secrete
hormones.
Ductless i.e. without a duct i.e. it releases hormones
directly into the blood stream.
Function : it acts in conjugation with the nervous system
to control several body function by secretion of hormones .
MMR
• Main Glands Of The
Endocrine System:
1. Pituitary gland.
2. Pineal gland.
3. Thyroid gland.
4. Parathyroid gland.
5. Suprarenal gland.
6. Pancreas .
7. Gonads .
MMR
Hormones
1. Messenger molecules.
2. Circulate in the blood to act on distant target cells.
3. Target cells respond to the hormones for which they have
receptors.
4. The effects are dependent on the programmed response of the
target cells , it could be either agonist or antagonist effect.
5. Some hormones acts only on single organ cells while others
act on multiple.
MMR
Mechanisms of hormone regulation
1. Humoral: in response to changing levels of ions or nutrients
in the blood.
2. Neural: stimulation by nerves.
3. Hormonal: stimulation received from other hormones.
Hormones operate within positive or negative feedback
systems to maintain an optimal operating environment in the
body.
MMR
MMR
Hormonal control of endocrine glands secretion
Endocrine regulation maintains hormone secretion
through Negative Feedback.
Drop in the level of a hormone triggers a chain reaction
of responses to increase the level hormones in the blood.
Disease occurs System Stops Providing Negative
Feedback to regulate function i.e. Positive Feedback Is
Given.
MMR
Function of hormones
1. Increase or decrease rate of cellular metabolism
2. Transfer information between cells to coordinate
body functions such as Growth and Development ,
Metabolism, Hemostasis , Reproduction , Response
to Stress And Sexual Development And Function
MMR
Individual Components Of The Endocrine System
MMR
Hypothalamus
Located in the brain .
Produces two categories of hormones :
1. Several releasing and inhibiting factors that stimulate such as
(TRH , CRH , GHRH ,PRF and GnRH) or inhibit (GH
inhibiting hormone , PIF) anterior pituitary’s secretion of
hormones.
2. Hormones that are stored in and released from posterior
pituitary( Oxytocin and ADH).
Hormone Name function
GHRH Growth hormone releasing hormone Stimulate GH release
GnRH Gonadotropin releasing hormone Stimulate LH & FSH release
TRH thyroid releasing hormone Stimulate TSH release
CRH corticotropin releasing hormone Stimulate ACTH release
PRF Prolactin releasing factor Stimulate prolactin release
GHIH growth hormone inhibiting hormone Inhibit GH release
PIF Prolactin inhibiting factor Inhibit prolactin release
ADH Antidiuretic hormone Stimulate water reabsorption
Oxytocin Oxytocin Uterine contraction and milk ejection.
Hormones released by hypothalamus
MMR
Pituitary gland
Located at the Base Of The Brain .
Connected to the hypothalamus by Hypothalamo-pituitary
Stalk.
Also known as Master Gland because its main function is to
control secretions of the other glands.
Secretion of pituitary gland is controlled by releasing and
release inhibiting factors of the hypothalamus.
hypothalamus
Pituitary gland Hypothalamo-pituitary axis
Anatomy and physiology of the hypothalamo-pituitary
axis
MMR
Pituitary Gland
It is divided into two parts :
1. Anterior pituitary : it synthesize and secretes seven
hormones which controls secretion of other body
hormones.
2. Posterior pituitary : it only holds and secretes
(ADH and Oxytocin) , which are produced in the
hypothalamus.
A. TSH : stimulates the thyroid gland to produce thyroid
hormone
B. ACTH : stimulates the adrenal cortex to produce
corticosteroids.
C. FSH : stimulates follicle growth , estrogen production and also
sperm production.
D. LH : play major rule ovulation and the growth of the corpus
luteum.
So what do the anterior pituitary hormones do?
A. GH : stimulates growth of the bones by closure of
epiphyseal plates.
B. PRL : stimulates mammary glands in breast to make
milk.
C. MSH : stimulates melanocytes and may increase
mental alertness.
So what do the anterior pituitary hormones do?
1. ADH (antidiuretic hormone i.e. vasopressin) : stimulates the
kidneys to reclaim more water from the urine, raises blood
pressure
2. Oxytocin : prompts contraction of smooth muscle in reproductive
tracts, initiation of labor and ejection of milk from breasts
What about the posterior pituitary hormones?
Remember posterior pituitary only secretes
hormones
Small posterior lobe Large anterior lobe
Stores hormones Releases hormones
Oxytocin Growth hormone (GH)
Anti Diuretic hormone (ADH) Thyroid Stimulating hormone (TSH)
Adenocorticotropic hormone (ACTH)
Luteinizing hormone
Follicule stimulating hormone
Melanocyte stimulating hormone
Prolactin Pituitary
hormones
MMR
Thyroid gland
Located in the front of the neck .
Divided into two lateral lobes connected by an
isthmus .
Thyroid gland secretes 3 hormones :
A. Thyroid hormones : T3 and T4 , both secreted from
Follicular Cells .
B. Calcitonin : secreted from parafollicular cells.
MMR
A. Increases the Basal Metabolic Rate : it is rate at which the
body uses oxygen to transform nutrients into energy.
B. Affects many processes and cells throughout the body as :
1. Protein synthesis
2. Bone growth
3. Neuronal maturation
4. Cell differentiation
Effects of Thyroid Hormone
MMR
The Effects of Calcitonin
Secreted when blood Calcium Levels are High.
Calcitonin Lowers Ca level by :
1. Slowing activity of osteoclasts in bone.
2. Increasing calcium secretion by the kidney.
3. Decrease intestinal absorption of ca.
MMR
The Parathyroid Gland
Located on the posterior surface of the thyroid gland ,
sometimes embedded .
Secretes parathyroid hormone (PTH):
PTH increases ca level by :
1. Increase of Ca2+ release from bone by osteoclasts.
2. Increases intestinal absorption .
3. Increase renal reabsorption of calcium.
Opposite of Calcitonin
MMR
Paired , triangular shaped gland .
Located at the upper pole of the kidney.
Divided into two parts :
1. Cortex : the outer part , secrets 3 types of hormones
( Glucocorticoids , Mineralocorticoids And Androgens).
2. Medulla : inner part , secretes Catecholamines.
The Supra Renal Glands
Anatomy of
the thyroid gland
MMR
1. Help the body deals with stressful condition whether physical
e.g. trauma or surgery , psychological e.g. depression and
physiological e.g. fasting .
A. Supporting and regulating several metabolic ,
cardiovascular , immunologic and haemostatic function.
B. Hyperglycemia i.e. increasing blood glucose level to
support brain.
That’s Why Corticosteroids Are Essential For Life.
Corticosteroids
MMR
Corticosteroids
2. Catabolic effects e.g. increase protein break down.
3. In large doses it suppresses the immune system.
That’s why steroids
are given in
autoimmune diseases
MMR
Mineralocorticoids
Increase Sodium and Water Reabsorption from the
kidney leading to increase in blood volume and
increase in the blood pressure .
Main mineralocorticoid is Aldosterone , it is secreted
in response to Hypotension or Hypovolemia .
MMR
Catecholamines
Secreted by the adrenal medulla , which is considered
as part of Autonomic Nervous System.
It includes adrenaline and noradrenaline
Prolong and intensify the sympathetic nervous system
response during stress ( Fight Or Flight Response ) .
Effect of adrenal medulla hormones
MMR
Flattened intra-abdominal organs .
Consists of both endocrine and exocrine cells (mixed
gland).
Endocrine cells is called islets of Langerhans.
There are 3 types of islet cells ; alpha , beta and
delta , each secrete different hormone.
The Pancreas
Hormones of the pancreas
CELLS HARMONE EFFECT
Alpha () cells Glucagon Glucose synthesis & glycogen breakdown in liver Blood glucose concentration
Beta () cells Insulin Stimulation of lipids & glycogen storage & formation Blood glucose concentration
Delta () cells Somatostatin Inhibits secretion of insulin & glucagon
MMR
Thank you