The document provides an overview of the endocrine system and the functions of various glands, including the pituitary, thyroid, parathyroid, adrenal glands, and the pancreas. It outlines key hormones produced by these glands, their functions, and abnormalities related to hormone secretion such as gigantism, acromegaly, dwarfism, and diabetes mellitus. Additionally, it covers mechanistic aspects of how hormonal regulation occurs and the physiological effects of various endocrine disorders.

1. ENDOCRINE SYSTEM
(Endocrinology)
•The endocrinology is the study of
the glands of internal secretion.
•The secretion of endocrine
glands are called hormones.

2. The main endocrine
glands are:
1- The pituitary gland beneath the brain.
2- The thyroid, in the lower part of the
neck.
3- The parathyroid adjacent to the
thyroid gland.

3. 4- The adrenals, above the kidney.
5- The endocrine part of the
pancreas (islets of Langerhans).
6- The ovaries in the pelvis (female).
7- The testis in the scrotal sac (male).

4. The Pituitary
Gland
• lies in a bony cavity beneath
the base of the brain.
• It is divided into: anterior
pituitary and posterior
pituitary.

5. Site of the pituitary gland

6. I. Anterior Pituitary gland
Anterior pituitary hormones:
1- Growth hormone.
2-Thyrotropin (T.S.H.). .
3-Corticotropin (A.C.T.H.) .
4-Prolactin.

7. 5-Follicle - Stimulating hormone
(F.S.H.).
6-Luteinizing hormone (L.H.).
(All the A.P hormones except growth
H. exert their effect by stimulating
target gland directly).

9. 1- Growth hormone
It is secreted by Ant. Pit.
throughout life.
Functions of growth hormone:
1- growth of all tissues, bone &soft
tissues.

10. 2- growth H. has a metabolic
effects:
a.on proteins it increases protein synthesis
and amino acid transport through the cell
membrane.
b.on CHO it decreases glucose utilization
by the tissues and increases blood glucose
level.
c.mobilization of fats from adipose
tissue.

11. 3-Stimulation of cartilage and bone
growth:
• growth H. acts indirectly on cartilage and
bone by causing the liver to form
somatomedins.
• somatomedins act on cartilage and bone
to promote their growth.

12. • after union of the epiphysis bone continue
to increase in thickness not in length .
• excess growth H. after adolescence cause
increase of the thickness of the long bone
and continued growth of membranous
bone.

14. Abnormalities of growth hormone
secretion (dysfunction)
Hyper function:
1- Gigantism: characterized by,
• the overproduction of growth H. before puberty.
• overgrowth of the long bone, skeleton, muscles
and viscera.
• the height may exceed 2 meters.
• hypogonadism .
• hyperglycemia.

15. Gigantism

17. 2- Acromegaly: characterized by
• overproduction of growth H. after
puberty.
• membranous bone of hands, feet
and lower jaw show over growth.
• over growth of viscera and
muscles.
• atrophy of gonads.
• hyperglycemia.

18. Acromegaly

20. Hypofunction: Dwarfism:
deficiency of growth H. in young
age.
• the rate of physical growth is
decreased, the child who has
reached the age of 10 years have
the body of 4 years.

21. • the dwarf is short but
proportionate (nice looking).
• mentally normal.
• sexually normal.

22. Dwarfism

24. Other anterior pituitary hormone
•Thyrotrophic H. (TSH):
it increases the rate of production of thyroid H.
•Corticotrophin H. (ACTH):
it increases the release of adrenocortical H.

25. •Prolactin H.:
- is secreted during the last few days of
pregnancy and during lactation.
- prepares the mammary gland for
lactation and increases the formation
of milk.

26. •The gonadotrophic HS.
(G.T.H.):
a- Follicle stimulating H. (FSH):
- In the female: growth of the follicles in the
ovaries and secretion of estrogen.
- In the male, it stimulates growth of testis
and generation of sperms.

27. b- Luteinizing H. (LH):
- In the female it causes ovulation and
secretion of estrogen and progesterone
from the ovaries.
- In the male it stimulates the testes to
secrete testosterone hormone.

28. II - The posterior pituitary
• stores 2 hormones, which are primarily
secreted in the hypothalamus:
1-Antidiuretic hormone A.D.H
(vasopressin).
2-Oxytocin hormone.

29. 1-Antidiuretic hormone (ADH):
It has the following functions:
• keeping water balance in the body; it
increases water absorption from the
collecting tubules of the kidney.
• vasoconstrictor effect, A.Bl.P.

30. • deficiency of A.D.H. leads to
diabetes insipidus,
characterized by :
polyuria excessive secretion of diluted
urine with low specific gravity and
polydipsia.

31. • it stimulates the uterus to
contract to facilitate delivery
• it also causes evacuation of
milk from the breast.
2- Oxytocin hormone:

32. Thank you

33. Thyroid Gland
• It is the largest endocrine gland.
• lies in front of the neck.
• formed of two lobs connected by an
isthmus which crosses the trachea.

34. The thyroid gland secretes the
following hormones:
1-Thyroxin Hs. (tetraiodothyronine) T4,
and ( triiodothyronine) T3, both
hormones are iodine containing amino
acid it mainly control the cell
metabolism.
2-Calcitonin H.: it is a calcium lowering
hormone. Secreted from parafollicular
cells of thyroid gland. It lowers the
plasma calcium level.

35. Actions of thyroxin hormones:
1- Increase the metabolic rate all over
the body.
2- Increase protein synthesis in muscles
and liver.
3- Increases the rate of glucose
absorption by the by the G.I.T.,
Glycogenolysis and gluconeogenesis
are enhanced (diabitogenic).

36. 4- Increase the mobilizations of fat from its
stores, a lipolytic effect .
5- On cardiovascular system: accelerate the
heart rate and force of contraction.
6- On blood cells: has erythropoietic effect.
7- On G.I.T.: It increases appetite, the
motility and secretions .
8- On C.N.S ;- are important for normal
development and maturation of the C.N.S.

37. • the hypothalamus secretes thyrotropin releasing
factor, which stimulates TSH secretion.
• TSH of A.P. increases synthesis and secretion of
thyroid hormones.
• an increase in the level of T4 and T3 inhibits
TSH secretion from antir.pit. (feedback
mechanism)
• cold weather stimulates the release of thyroxin
hormones
Control of thyroid secretion:

38. Dysfunction of thyroid gland
I- Hyperthyroidism, (Grave’s disease), It is
characterized by:
1 - exophthalmoses: protrusion of the eye
balls due to excessive growth of tissues
behind the eye.
2 - goiter: enlargement of the thyroid gland.
3 - warm sweating skin.
4 - rapid pulse.

39. 5- loss of weight in spite of increasing
appetite.
6- fine tremors in the hands, with
nervousness.
7-intolerance to heat, the BMR
increases up to 100%.
8- demineralization of bones with loss
of its calcium and phosphorus
contents.
9- hyperglycemia (thyroid diabetes) .

41. II-Hypothyroidism:
A-Before Puberty (Cretinism):
It is due to mal development or complete
absence of thyroid gland in a new born.
characterized by:
1- delayed milestones as (sitting walking and
speech).
2- retarded physical growth, the height is
less than one meter.

42. 3- mental retardation due to defective
myelination of nerve fibers.
4- intolerance to cold weather and
decrease BMR.
5- abdominal muscle weakness, with
protruded viscera and enlarged
tongue.

43. 6-infantile sexual organs.
7- thick skin.
8-raised serum cholesterol level.
Cretinism

44. B-After puberty (Myxoedema):
due to atrophy of the thyroid or over thyroidectomy.
characterized by:
1- Slow mental activity.
2- Increase sensitivity to cold, the BMR decreased
(30% - 40%).
3- dry skin, firm, non pitting edema.
4- the hair is coarse and sparse.

45. 5-sexual hypofunction, in female there is irregular
cycle, in male there is impotence.
6- loss of appetite and decrease motility of the
GIT which leads to constipation.
7- deficient erythropoisis leading to anemia.
8-high level of blood cholesterol, up to 600 mg%.

46. Myxoedema

47. Parathyroid glands
• There are 4 parathyroid glands.
• two of them embedded in the superior
poles of the thyroid gland and two in its
inferior poles.
• It secretes parathyroid or parath-hormone.
• It control the blood level of Ca++ & Po++.

48. Functions of parathyroid H.:
It control the blood levels of Ca++ and PO++.
It increases Ca level in blood and decreases Po
by 3 ways:
1- On bone: It causes absorption of Ca++, Po++
from bone (so cause decalcification of bone).
2- On kidney: increases reabsorption of Ca++ from
renal tubules and increases phosphate excretion.
3- On intestine: increases Ca and Po4 absorption
from the intestine by increased formation of vit. D3.

49. Parathyroid gland and mechanism of action of the hormone

50. Deficiency of this hormone causes
• Tetany: characterized by:
- decrease of ionized calcium in the
plasma.
- spastic contraction of skeletal muscles.
- increase of neuromuscular excitability.
(normal level of plasma Ca is 9-11mg%).

51. Types and manifestation of Tetany:
I- Manifest Tetany:
• occurs if the plasma calcium level falls below
7mg %.
• occurs spontaneously during rest.
• carpo-pedial spasm and generalized convulsions.
• in severe hypocalcaemia, laryngeal muscles may
contract leading to laryngeal stridor and death.

52. II- Latent tetany:
• the plasma calcium level is above 7
mg% (7-9mg %).
• this type of tetany dose not occurs
spontaneously it needs stressing
condition: pregnancy, lactation,
emotion, exercise..

53. Tetanic manifestation

54. Increase parathyroid hormone secretion:
• It cause hypercalcemia, Ca and Po4 may be
deposited in kidney forming stone.
• Bone is affected it become decalcified and
easily fractured with any trauma.

55. The adrenal gland
The adrenal gland contains 2 endocrine
parts
1- The adrenal cortex: secretes steroid
hormones.
2- The adrenal medulla: secretes
catecholamine (epinephrine and nor
epinephrine).

56. The gland is formed from three layers,
from outside to the inside:
1-Zona glomerulosa: secretes mineralo corticoids for
regulation of electrolytes e.g. Aldosterone hormone.
2-Zona fasciculata: secretes glucocorticoids to regulate
organic metabolism e.g. cortisol hormone.
3-Zona reticularis: secretes sex hormones, mainly
androgens and small amount of estrogens.

58. Functions of Adrenal Cortical hormones:
1-Mineralocorticoids (aldosterone hormone):
• Stimulate reabsorption of Na & H2O by the renal
tubules.
• decrease reabsorption of K, Mg, H+ .
• has the same effects on G.I.T., saliva and sweat.
2- Cortisol hormone (Glucocorticoids):
stimulate gluconeogenesis and decrease glucose
utilization by the tissues (diabetogenic effect).
3- Cortisol hormone has a lipolytic effect.

59. 4- They are catabolic, helping the break down
of proteins.
5- Decreases eosinophil and lymphocytes, but
increase erythrocytes & neutrophils.
6- Anti-inflammatory effect:
It causes rapid healing of wounds.
7- Anti-allergic action:
cortisol oppose the effect of histamine.
8- Anti-stress action: in cases of shock,
infection or surgical operation.

60. Control of cortical secretion:
1- Hypothalamus secretes ACTRH, which
increase secretion of ACTH from the A.P.
2- Anterior pituitary secret ACTH which
increases activity of adrenal cortical cells.
3- Physical or mental stress increases the
secretion .

61. Adrenal cortex dysfunctions
I- hypo function of adrenal cortex
(Addison disease)
It is characterized by:
a- loss of appetite, vomiting, and diarrhea.
b- muscle weakness.
c-decrease Na and increase K in the blood.

62. d- hypovolumia and hypotension.
e- hypoglycemia.
f- hyper pigmentation of the skin:
ACTH has melanocytic stimulating
effect.
g- decrease sexual function.

63. II-Hyperfunction of Adrenal cortex:
(Cushing’s syndrome):
It is characterized by:
a- wasting and weakness of muscles,
(catabolic effect).
b- Na & H2O retention in the blood leading
to edema and hypertension with decrease
level of plasma potassium.

64. c- redistribution of fat: (moon face)
and (buffalo trunk).
d- hyperglycemia (steroid diabetis).
e- gonadal disturbances.
f- thin skin.

65. Moon face and thin skin

66. The adrenal medulla
• It is a modified sympathetic ganglia.
• post ganglionic neuron have lost their
axons and converted to secretary cells.
• releases adrenaline about 85% and
noradrenaline about 15%.
• Hormones are derivatives of a.a tyrosine.
• noradrenaline is adrenaline - CH3.

67. 1-Nor adrenaline (nor epinephrine):
• its main action is on the C.V.S.
• leading to vasoconstriction and
hypertension.
The adrenal medulla

68. • increase the rate and force of cardiac contraction.
• vasoconstriction of cutaneous and visceral blood
vessels.
• vasodilator for the coronaries and skeletal
muscle blood vessels.
• it stimulates glycogenolysis (hyperglycemic).
• increases oxygen consumption by the tissues and
delays the onset of fatigue.
• adrenaline relaxes the bronchi.
2-Adrenaline (epinephrine):

69. Endocrine part of the pancreas
• Beta cells secrete insulin hormone.
• Alpha cells secrete glucagon hormone.
• Both of these hormones are protein in
nature.
• The normal blood glucose is 70-110 mg %.

70. Insulin hormone:
It lower the blood glucose by:
1-increases glycogen deposition in the liver and
muscle.
2-it increases glucose uptake and its oxidation.
3-it inhibits gluconeogenesis and glycogenolysis.
4-insulin helps protein deposition in cells.
5-it promotes formation of fats from glucose.

71. Glucagon hormone:
• secreted by alpha cells of the pancreas.
• it is a hyperglycemic hormone.
• it elevates the blood glucose level by
glycogenolysis and gluconeogenesis.
• also increases heart rate and force of
cardiac contraction.

72. Diabetes mellitus (D.M.):
• D.M. is a very common disease.
• Characterized by hyperglycemia,
glycosuria, polyuria, polydipsia and
polyphagia.
Types:
-Type 1 diabetes: begins in early life and is
due to insufficient insulin.
-Type 2 diabetes: begins in later life and is
due to insulin resistance.

73. Manifestation of D.M.:
1- polyuria and Polydipsia.
2- dehydration and hypovolemia.
3- polyphagia and loss of weight.
4- hyperglycemia and glycosuria.

74. 5- rate of growth is decreased in
children and it causes asthenia in
adults.
6- increase protein catabolism.
7- poor resistance to infection
8- disturbance in fat metabolism leads
to atherosclerosis and fatty liver.