ADRENAL GLAND : ADRENAL GLAND Slide 3: There are two adrenal glands . The two glands have a similarity in anatomical structure , function , secreted hormones and almost in every thing .
The two glands are located above the two kidneys , i.e. one gland above each kidney ; exactly at the position of 12 th thoracic vertebra . (A) Position Slide 5: So , adrenal glands are also termed ,
The term (suprarenal) comes from the anatomic description of the position of the glands as ( supra means above ) while ( renal means belongs to kidney ).
On the other side , the term (adrenal) comes from the fact that these glands secrete the hormone (adrenaline) in cases of stress. Slide 6: Adrenal gland consists of two distinct parts ; Cortex and Medulla .
These two parts differ in their anatomical structure and in their functions (Hormones). (B) Structure Slide 7: Cross – sectional view of the adrenal gland Slide 9: Adrenal cortex is devoted to the synthesis of CORTICOSTEROID HORMONES
due to the presence of large amounts of fats specially cholesterol which is the precursor of these hormones .
Adrenal cortex exhibits a functional zonation into three distinct zones ; Cortex Slide 10: Zona glomerulosa
(3)Zona reticularis (1) Zona glomerulosa : (1) Zona glomerulosa The outer most layer of the cortex .
It is the main site for production of
( Mineralcorticoids )
The main mineralcorticoid in human is aldosterone while there are some endogenous hormones which have a mineralcorticoid function (progesterone & deoxycorticosterone) . Aldosterone : Aldosterone Slide 13: Aldosterone hormone is a derivative of cholesterol .
Its normal level is about (4-9 Mg per 100 ml blood) .
About 2-18 Mg of aldosterone are wasted with urine daily .
Aldosterone acts on kidneys to provide active reabsorption of sodium and passive absorption of water . (increases blood pressure)
In addition to that , it causes secretion of both potassium ions and protons from the collecting
ducts and distal tubules . Factors affecting secretion of aldosterone : Factors affecting secretion of aldosterone Angiotensin II .
Adrenocrticotropic hormone (ACTH) .
(3)Blood level of Na and K ions . DISORDERS OF ALDOSTERONE : DISORDERS OF ALDOSTERONE (A) Natural increase in cases of ,
( 1 ) Deficiency of sodium and plenty of potassium in the diet .
( 2 ) Heavy sweat .
(B) Natural decrease in cases of ,
( 1 ) Deficiency of potassium in the diet .
( 2 ) Having large amounts of water and drinks . Slide 16: (C) Addison disease
Occurs when about 90% of cortex cells are damaged . So , it is very rare ( 8 / million person ) .
Addisonian has a remarkable depression in aldosterone level which is accompanied by a low blood pressure , high temperature , weight loss , decreased blood sodium and increased blood potassium . Slide 17: (D) Conn disease
Occurs due to increased activity of zona glomerulosa .
Leads to increased secretion of aldosterone which results in a high blood pressure , low blood potassium and high blood sodium levels . (2) Zona fasciculata : (2) Zona fasciculata The central region of the adrenal cortex .
It is the main site for production of
( Glucocorticoids )
The primary glucocorticoid in human is (cortisol) .
Zona fasciculata secretes a basal level of cortisol but also produce a small amount of hormone in response to ACTH . Cortisol : Cortisol Slide 20: It is usually referred to as the “stress hormone” as it is involved in response to stress and anxiety .
Its primary function is to increase blood sugar and stores of sugar in the liver as glycogen .
Cortisol also can suppress immune system .
Zona fasciculata can produce (7-7.5 mg/day) of cortisol hormone .
Highest amount of cortisol can be reached in the early morning (165-744 nM) while the lowest amount occurs approximately at the midnight (83-358 nM) . Factors affecting cortisol secretion : Factors affecting cortisol secretion ( 1 ) Corticotropin releasing hormone (CRH)
This hormone controls secretion of adrenocorticotropic hormone (ACTH) . It is secreted from hypothalamus .
(2) Adrenocorticotrpic hormone (ACTH)
Which is responsible for delivery of calcium ions to cortisol secreting cells in the adrenal cortex . Physiological effects of cortisol : Physiological effects of cortisol ( 1 ) Anti – insulin effect .
cortisol contributes to “hyperglycemia” by stimulation of hepatic gluconeogenesis and inhibition of peripheral utilization of glucose .
( 2 ) It increases gastric acid secretion .
( 3 ) It cooperates with adrenaline to create memories of short – term events .
( 4 ) It has an anti – inflammatory action as inhibits secretion of histamine from basophils and mast cells . Slide 23: ( 5 ) Elevates blood pressure .
( 6 ) Stimulates hepatic detoxification by inducing ;
- Tryptophan oxygenase to reduce serotonin level in the brain .
- Glutamine synthase to reduce glutamate level in the brain .
( 7 ) Suppresses immune system .
( 8 ) It inhibits secretion of CRH resulting in a feed – back inhibition for ACTH . Disorders of cortisol : Disorders of cortisol (1) Cushing syndrome
A hormone disorder caused by high levels of cortisol in the blood .
It may be caused by ;
( 1 ) Taking glucocorticoid drugs .
( 2 ) Tumors in cortisol secreting cells .
( 3 ) Tumors in ACTH secreting cells .
Cushing syndrome is not confined to humans but relatively common in domestic animals . Symptoms of Cushing syndrome include ; : Symptoms of Cushing syndrome include ; ( 1 ) Rapid weight gain specially from face , trunk and limbs .
( 2 ) very high blood sugar which may lead to diabetes mellitus .
( 3 ) High blood pressure (secondary) .
( 4 ) Osteoporosis due to increased protein breakdown .
Cushing syndrome can be treated by surgery . Slide 27: ( 2 ) Addison disease
Deficiency in cortisol level in the blood .
Leads to ;
( 1 ) Low blood sugar .
( 2 ) Low blood pressure .
( 3 ) High potassium levels in the blood .
( 4 ) Full body weakness . (3) Zona reticularis : (3) Zona reticularis The interior layer of the adrenal cortex .
It is responsible for production of
( Androgens )
( Estrogens )
The main adrenal androgen is Testosterone
while the main adrenal estrogen is Estradiol . Testosterone : Testosterone Slide 30: Testosterone is secreted in both males and females , but in males in a larger amount so , its effects appear clearly on males and therefore , it is the “masculinity hormone”
In males , it is secreted mainly from Leyding cells in the testes , and a small amount from adrenal reticularis .
In females , it is secreted from Thecal cells in the ovaries , placenta and a small amount from adrenal reticularis .
Its activity is mediated by LH and FSH . D H E A : D H E A Physiological effects of testosteron : Physiological effects of testosteron After puberty , testosteron amount in the body increases to cause ;
( 1 ) Development and growth of reproductive organs .
( 2 ) Appearence of secondary sex characteristics such as ; deepening in voice , growth of beard , growth of Adam apple , increase in height , ….etc.
( 3 ) Maintains males fertility . Estradiol : Estradiol Slide 34: Estradiol is the predominant sex hormone in females .
It is produced primarily by granulosa cells in ovaries , in addition to small amount from adrenal reticularis .
During pregnancy , its amount increases due to secretion from placenta also .
It is present in males but in lower amounts than females .
Its activity is mediated by LH and FSH . D H E A - S : D H E A - S Physiological effects of estradiol : Physiological effects of estradiol ( 1 ) Growth of female reproductive organs .
( 2 ) Maintaining of oocytes in ovaries .
( 3 ) During pregnancy , it promotes uterine blood flow and stimulates breast growth .
( 4 ) Regulation of menstrual cycle .
( 5 ) Affects liver to synthesize lipoproteins , binding proteins and proteins of blood clotting . Slide 37: Adrenal medulla is the second part of adrenal gland .
Devoted to synthesis of
which include adrenaline ( epinephrine ) and noradrenaline ( norepinephrine ) .
Both hormones are secreted in stressful situations . Medulla Physiological effects of catecholamines : Physiological effects of catecholamines Catecholamines causes general physiological changes that prepare the body for physical activities .
In case of ( fight or flight ) , catecholamines cause ;
( 1 ) Elevation of blood pressure .
( 2 ) Increasing blood sugar .
( 3 ) Increasing heart rate .
( 4 ) Increased metabolic rate .
( 5 ) Affects peripheral nervous system . pheochromocytoma : pheochromocytoma Very rare state .
A tumor In the adrenal medulla that causes hypersecretion of catecholamines which leads to ;
( 1 ) Hypertension .
( 2 ) Very high blood sugar .
( 3 ) High rate of heartbeat .