Pathophysiology of Endocrine glands - PowerPoint Presentation

Slide1

Pathophysiology

of

Endocrine glandsSlide2

Control systems of the body

The

nervous system : working through nerve impulses, so it is a rapid control system.2) The hormonal, or endocrine system: working through hormones in blood, so it is a slow control system.

The functions of the body are regulated by two control systems:Slide3

Definitions

Hormone:

are special chemical messengers in the body that are secreted directly into the blood . These messengers control most major bodily functions.Hormones are secreted from the endocrine glands in the bodyEndocrine glands:

are ductless glands which secrete hormones directly to the blood.

They are:

1- Pituitary gland

2- Thyroid gland

3- Parathyroid gland

4- Supra renal gland

5- Pancreas

6- GonadsSlide4

Endocrine glands:

These organs secrete hormone in microscopic

amounts. Even a very slight excess of hormone secretion can lead to disease states, as can the slightest deficiency in a hormone.Slide5

The pituitary is an important gland in the body and it is often referred to as the 'master gland', because it controls several of the other hormone glands

Pituitary gland

(Hypophysis Cerebri)It is

found at the base of the brain, behind the bridge of

the nose

.

It is

very close to

hypothalamusSlide6

Pituitary gland

(

Hypophysis Cerebri)It is divided into 2 parts:Anterior pituitary: that secretes:1- Growth hormone

2- Prolactin

hormone

3-Trophic

Hormones

a-TSH

thyrotropin

that act on

Thyroid gland.

b- ACTH Adrenocorticotrophic hormone

that act on

Adrenal cortex.

c- GTH

Gonadotropin

hormone

(LH & FSH

) that act on

Gonads.

Posterior pituitary: that secretes:

1-Antidiuretic hormone (ADH).

2-Oxytocin hormone.Slide7

Pituitary glandSlide8

Growth hormone

Growth hormone is a protein hormone secreted by the anterior

pituitary into the bloodstream.Anterior pituitary

Growth hormone acts on many parts of the body to

promote growth in children

. 

In

adults, it does not cause growth but it helps to maintain normal body structure and metabolism, including helping to keep blood glucose levels within set levels.Slide9

Functions

:

I) Growth effects:

1-Stimulation of growth of bones in length

2-Stimulation of growth of soft tissues

e.g

, muscles and organs (liver, heart, kidney,….

etc

).

3-Formation of various body fluids,

e.g

, plasma and interstitial fluid.

4-Stimulation of erythropoiesis→ increased RBCs count.

5-Stimulation of protein synthesis (protein anabolic hormone)Slide10

Clinical Abnormalities in growth hormone Secretion:

Decreased GH secretion before puberty --->

Pituitary dwarfismIncreased GH secretion before union of epiphysis ---> GigantismIncreased growth hormone secretion, after union of epiphysis --->

acromegalySlide11
Slide12

Pituitary dwarfism

Occurs as a result of

decreased secretion of growth hormone before union of epiphyses.Causes: Genetic disorders but the causes of some disorders are unknown.Manifestations:

1) Symmetrical retardation of the growth of long

bones; the

pituitary dwarf is not more than 100-120 cm in height in adult age-

2) Symmetrical retardation of the growth of soft tissues.

3

)

Fascial

features are crowded in the middle of the face giving the characteristic doll face.

4) Mentality of the pituitary dwarf is

normal, but

emotionally unstable.Slide13

Pituitary dwarfismSlide14

Gigantism

*Results

from overproduction of growth hormone by the pituitary gland in the pre-adult life, i.e. before union of epiphyses.A pituitary gland tumor is almost always the cause of gigantism

*

Characteristic Features:

1) Delayed union of the epiphyses ---> over-growth of the skeleton and the giant height may reach 2

meters

.

2) Symmetrical over-growth of soft tissues:

3

)

HypogonadismSlide15

Acromegaly

*

Results, from over-production of GH during adult life, i.e. after union of epiphyses, usually caused by a benign tumour of the pituitary gland.

*Characteristic

Features

(1)It can

not

causes

further increase in height of the person, but it causes

disproportionate growth of thickness of long bones

as well as

continued growth of membranous bones

that have no epiphyses to unite

e,g

. jaws and

skull

.

a

)

Skull

:

Is

characterized

by:

Enlarged

nose which may be double the normal size.

Mandible: becomes broad ---> Teeth separation and

prognathism

.

b

) Hands and Feet

:

are thick and broad. (2) Hypogonadism.Slide16

Giantism

acromegalySlide17

Posterior pituitary: that secretes:

1-Antidiuretic hormone (ADH).

2-Oxytocin hormone.Slide18

Antidiuretic hormone(ADH)

or

vasopressinActions:Increases water

reabsorption

from the distal tubules and collecting ducts of the kidney→ increases the volume of body fluids and decreases the urine volume.Slide19

Diabetes

Insipidus

* Causes:1 Decreased ADH secretion .2 Failure of the kidney to respond to ADH .

*

Characters:

1-

Polyuria

: due to failure of H

2

O

reabsorption

. Urine volume increases up to 20 liters/day with low specific

gravity.

2- Loss of H

2

O soluble vitamins --->

hypovitaminosis

.

3-

Polydepsia

: means increased fluid intake caused by thirst sensation which is secondary to

polyuria

.Slide20

Thyroid Gland

Structure

:An endocrine gland present in front of the lower part of the neck just below the larynx.Thyroid gland contains:1) Follicular A cells: secretes thyroxin (T4) and tri-

iodothyronine

(T3).

2)

Parafollicular

C cells :

secretes calcitonin (calcium lowering hormone).Slide21

Parafollicular

C cells

1)Follicular A cells

Thyroid GlandSlide22

Thyroid hormone (T3&T4)

Functions:

1-Physiological doses of thyroid hormones stimulate protein synthesis (protein anabolic).2-Stimulation of all aspects of glucose metabolism: absorption from GIT, uptake by the tissues and production by the liver.

3-Thyroid

hormones are essential for mental and skeletal growth in infants and growing

childrenSlide23

Clinical Abnormalities in thyroid hormone Secretion

Hypothyroidism:

- In infants and young children ---> Cretinism - In older children and adults ---> Myxedema

Hyperthyroidism

at any age

--->

thyrotoxicosis or toxic goiterSlide24

Cretinism

*

Causes:1- Congenital absence of thyroid gland. 2- Failure of thyroid gland to produce active thyroid hormones.3- Iodine lack in the diet (endemic cretinism

).

*

Manifestations

:

-

Start to appear few months after birth .

Delayed

physical

growth:

a-

Delayed eruption of teeth.

c-

Delayed sitting and

walking

2) Failure of mental development:

So the cretin:

-Is idiot,- Is incontinent to urine and stools

, and has

defective speech.

Treatment:

With thyroid hormone returns of physical growth. But unless the cretin is treated in the first few months after birth, permanent retardation of mental growth will take place.

 Slide25
Slide26

MYXEDEMA

Caused by

decreased secretion of thyroid hormones in older children and adults.

Hypothyroidism may be due to a number of factors,

including:

Autoimmune

disease

Treatment for hyperthyroidism.

Thyroid

surgery.

Radiation

therapy.

Medications

.

Pituitary disorder. A relatively rare cause of hypothyroidism

Iodine deficiencySlide27

MYXEDEMA

Manifestations:

Metabolic:Decreased BMR; patient cannot tolerate cold weather Dry and yellow skinIncreased body

weight

Increased blood cholesterol

Basal metabolic rate (BMR) refers to the minimum amount of energy -- in the form of calories -- that your body requires to complete its normal functions

II) Systemic:

1-CNS:

-

Poor

memory ,Slow thinking and speech., Hypersomnia .

Eyes

are

swollen eye lid

, night

blindness ,loss of outer third of eye browSlide28

THYROTOXICOSIS

Caused by

increased secretion of thyroid hormones at any ageManifestations:Metabolic:Increased BMR; patient cannot tolerate hot weather Moist and

flushy

skin

Decreased

body

weight

Decreased blood cholesterol

II) Systemic:

Increased excitability and irritability

,

Fine tremors, Insomnia. Increased appetite,

Exophthalmos in 30% of

patients,

Increased heart rate and cardiac output

Slide29

Toxic

goitre

MyxedemaSlide30

Thyroid Function Tests

I.

Nonspecific testsl. BMR 2. Serum cholesterol 

II. Specific tests

Protein

bound iodine (PBI)

Radioactive iodine uptake by thyroid gland

Radioimmunoassay of plasma T4 , T3 (free and total) and TSH

 Slide31

Thyroid Gland

Thyroid gland contains:

1) Follicular A cells: secretes thyroxin (T4) and tri-iodothyronine (T3).

2)

Parafollicular

C cells :

Secretes calcitonin (calcium lowering hormone).Slide32

Hormones of calcium homeostasis

Functions of calcium:

1) Bone and teeth mineralization.2) Blood coagulation .3) In neuromuscular system : calcium is important for : * Normal excitability of nerves * Neuromuscular transmission.

* Muscle contraction.

4) In endocrine glands, calcium mediates the secretion and action of hormones.

5) Calcium is important for ATP formation in the mitochondria and ATP utilization in the cell.

6) Calcium is essential for normal cell membrane permeability and cell proliferation.Slide33

Hormones of calcium homeostasis

Hormonal Control of Calcium Homeostasis:

The blood level of ionisable calcium is kept constant mainly by 3 hormones:I. Parathormone

:

Ca

++

raising hormone

II.

Calcitonin

:

Ca

++ lowering hormone

Ill.

1, 25

dihydroxy

cholecalciferol

which is vitamin D3 metabolite : Ca

++

raising hormoneSlide34

Tetany

Definition:

a state of increased neuromuscular excitability resulting from decreased blood level of ionized calcium.Causes of decreased Ca++ concentration in blood:

1-

Hypoparathyroidism

.

2-

Vitamin D deficiency → decreased Ca

++

absorption from the intestine e.g. rickets and

osteomalacia

.

3- Excessive administration of oxalates or citrates.

4- Renal failure .

Types: Two types:

I. Manifest

tetany

.

II. Latent

tetany

.Slide35

Carpopedal

spasmSlide36

The adrenal

glands =Suprarenal gland

In the body, there are two suprarenal glands, each lies at the superior pole of the corresponding kidney.Each gland consists of 2 distinctive parts: *Suprarenal medulla (central):

secretes

catecholamines

(epinephrine and

norepinephrine

) and

*

Suprarenal cortex(peripheral):

secretes corticosteroids.Slide37

Suprarenal glandSlide38

SUPRARENAL CORTEX

Consists of 3 zones which secrete 3 groups of hormones. All are steroid in nature:

1) Zona

Glomerulosa

Secretes

mineralocorticoids

. mainly

aldosterone

which:

a- Regulate Na

+

, K

+

and H2O metabolism.

b- Have weak glucocorticoid-like activity

2)

Zona

Fasciculata

:

Secretes glucocorticoids, mainly

cortisol

which:

a- Regulate CHO, protein and fat metabolism

b- Have weak mineralocorticoid-like activity.

3) Zona

Reticularis

Secretes sex hormones mainly

androgen (

dehydroepiandrosterone

DHEA) and little estrogen

N.B,:

Cortisol

and

aldosterone

are essential to life.Slide39

SUPRARENAL CORTEXSlide40

Cortisol

hormone (

contin)II. Cortisol has the following actions (pharmacological actions):Antistress effect of

cortisol

:

2) Anti-inflammatory effect of

cortisol

:

3)

Antiallergic

effect of

cortisol

:

4) Effect on blood cells and immunity:

Cortisol

increases the number of RBCs →

polycythemia

Cortisol

decreases the number of

esinophils

and lymphocytes → decreased level of immunity for all foreign invaders. Slide41

Cushing's Syndrome

•

Cause: Increased cortisol secretion from the suprarenal cortex .• Characteristics:1) Metabolic Effects:A-Fat Metabolism: mobilization of fats from the lower part of the body with its deposition in the: head region →moon face and thorax & upper abdomen →buffalo torso.

b

) CHO

Metabolism:

hyperglycemia

c) Protein

Metabolism:

1- Decreased protein content of skin

→ damages and delayed wound healing

2- muscle weakness.

3-Decreased

protein content of

bones (Osteoporosis)

2) Excess androgenic activity

→ acne and hirsutismSlide42

Cushing syndrome Slide43

adrenal cortex Secretion

Increased secretion of :

Aldosterone hormone → Conn’s syndrome Cortisol

hormone → Cushing syndrome

Decreased secretion of adrenal cortex

→

Addison’s diseaseSlide44

Addison's Disease

Cause:

Decreased secretion of adrenal cortex1) Atrophy of adrenal cortex by autoimmune disease.2) Destruction of adrenal cortex by tuberculosis or cancer.

Characteristics:

1

)

Decreased mineralocorticoids

→

•

hypotension

and

shock.

• Hyperkalemia and acidosis

.

2

) Decreased glucocorticoids

→

hypoglycemia.

Treatment

:

Small quantities of mineralocorticoids and glucocorticoids are administered

dailySlide45

Pancreatic hormones

- Pancreas consists of 2 types of tissues:

Acini (exocrine part): which secrete digestive juices into the duodenum.2) Islets of Langerhans

(endocrine Part): which secrete hormones directly into the blood. These islets contain 4 types of cells (Fig.):

1- B or beta cells (60%)→secrete insulin hormone

2- A or alpha cells (25%) → secrete glucagon hormone

3- D or delta cells (10%) → secrete somatostatin hormone

4- PP cells (5%) →pancreatic polypeptide.Slide46

Endocrine and exocrine pancreasSlide47

Insulin hormone

Is a protein hormone secreted by the beta cells of islets of

Langerhans.Functions:- On CHO Metabolism: insulin is a hypoglycemic Hormone

- On Protein Metabolism:

insulin is a protein anabolic hormone

- On Fat Metabolism:

insulin is a

lipogenic

hormone

- On K

+

Metabolism:

insulin causes K

+

to enter the cellsSlide48

Diabetes Mellitus

It is due to

decreased secretion of insulin by B cells of islets of Langerhans.If it begins in early life  juvenile diabetes mellitus If it begins in later life



maturity onset diabetes mellitus

.

Pathophysiology Of Diabetes Mellitus

A) Decreased glucose uptake and utilization

by body cells leading to hyperglycemia .

1 Dehydration of the cells.

2-

Glucosuria



osmotic diuresis, polyuria, and polydipsia

B) Increased protein catabolism

→ muscle weakening

C) Increased

lipolysis



increased free fatty acids in the blood that pass to the liver

 fatty liver

D) Metabolic Acidosis :

caused by: aminoacidemia and

lactiacidosis

Slide49

Glucose tolerance testSlide50

Thank you