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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.

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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.

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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 .

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• 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 .

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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.

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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.

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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.

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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

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Individual Components Of The Endocrine System

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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

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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

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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

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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.

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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

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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.

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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

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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

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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

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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

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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 .

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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

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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

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Thank you