Endocrine System Week 8 Dr. Walid Daoud A. Professor

Adrenal Glands 1- Inner medulla: secretes catecholamines: - Epinephrine (adrenaline) - Epinephrine (adrenaline) - Norepinephrine (noradrenaline) - Norepinephrine (noradrenaline) 2- Outer cortex: secretes steroid hormones - Outer layer secretes mineralocorticoids - Outer layer secretes mineralocorticoids - Middle layer secretes glucocorticoids - Middle layer secretes glucocorticoids - Inner layer secretes sex hormones. - Inner layer secretes sex hormones.

Adrenal cortex A. Glucocorticoids 95% cortisol Effects of glucocorticoids: 1- On metabolism:. On carbohydrate :. On carbohydrate : - ↑ Gluconeogenesis. - ↑ Gluconeogenesis. - ↓ Glucose utilization by tissues - ↓ Glucose utilization by tissues - ↑ Glycogen storage by the liver - ↑ Glycogen storage by the liver

Adrenal cortex A. Glucocorticoids Effects of glucocorticoids:. On protein metabolism: ↑ protein catabolism in muscles and ↑ protein catabolism in muscles and ↑ gluconeogenesis in liver. ↑ gluconeogenesis in liver.. On lipids: ↑ lipolysis. ↑ lipolysis.

Adrenal cortex A. Glucocorticoids 2- Permissive effects: Cortisol requires other hormones to do Cortisol requires other hormones to do their actions: their actions: - For glucagon and catecholamines to - For glucagon and catecholamines to cause gluconeogenesis. cause gluconeogenesis. - For catecholamines to cause pressor - For catecholamines to cause pressor response and bronchodilatation. response and bronchodilatation.

Adrenal cortex A. Glucocorticoids 3- Effects on CNS: Cortisol deficiency causes personality Cortisol deficiency causes personality changes. changes. 4- Weak mineralocorticoid action. 5- Anti-stress effect. 6- Anti-allergic effect (in excessive amount). 7- Anti-inflammatory effects (in excessive amount). amount).

Control of Glucocorticoid Secretion 1- ACTH from anterior pituitary gland. 2- CRF from hypothalamus. 3- Circadian rhythm of CRF. 4- Stress increases CRF & ACTH secretion. 5- Cortisol has negative feedback effect on CRF and ACTH secretion. CRF and ACTH secretion.

B. Mineralocorticoids Actions of mineralocorticoids (Aldosterone): 1- On kidney: reabsorption of Na + from distal tubules & collecting ducts in exchange of K + secretion. 2- On sweat, saliva, milk & GIT: increases reabsorption of Na + & increases K + secretion.

Disorders of Adrenocortical hormone Secretion 1- Cushing,s Syndrome: It is hypersecretion of glucocorticoids. It is hypersecretion of glucocorticoids. Features: Features: - Excess protein metabolism. - Excess protein metabolism. - Disturbance of fat deposition. - Disturbance of fat deposition. - Anti-insulin effect. - Anti-insulin effect. - Mineralocorticoid effect. - Mineralocorticoid effect.

Disorders of Adrenocortical hormone Secretion 2-Addison,s Disease: Hyposecretion of adrenocortical hormones Hyposecretion of adrenocortical hormones A- Mineralocorticoids deficiency: A- Mineralocorticoids deficiency: ↓ Na + in ECF, ↓ blood volume ↓ BP ↓ Na + in ECF, ↓ blood volume ↓ BP Hyperkalemia leads to muscle weakness. Hyperkalemia leads to muscle weakness. B - Glucocorticoid deficiency: B - Glucocorticoid deficiency: ↓ blood glucose, ↓ mobilization of protein ↓ blood glucose, ↓ mobilization of protein & fat, muscle weakness, loss of appetite & fat, muscle weakness, loss of appetite & body weight, ↓ resistance to stress and & body weight, ↓ resistance to stress and pigmentation. pigmentation.

Adrenal Medulla It secretes catecholamines: - Epinephrine (adrenaline) and - Epinephrine (adrenaline) and - Norepinephrine (noradrenaline). - Norepinephrine (noradrenaline). It is a modified sympathetic ganglion. Catecholamines are formed from amino acid tyrosine.

Actions of Catecholamines In states of emergency (stress). 1- CVS: -Epinephrine ↑ heart rate. -Epinephrine ↑ heart rate. -Norepinephrine causes generalized -Norepinephrine causes generalized vasoconstriction while epinephrine vasoconstriction while epinephrine causes vasodilatation of coronaries and causes vasodilatation of coronaries and skeletal muscles blood vessels. skeletal muscles blood vessels. Overall effect is ↑ ABP. Overall effect is ↑ ABP.

Actions of Catecholamines 2- Nervous system: - ↑ blood glucose & ↑ alertness. - ↑ blood glucose & ↑ alertness. 3- Metabolism: Glycogenolysis, lipolysis & ↑ metabolic rate. Glycogenolysis, lipolysis & ↑ metabolic rate. 4- Smooth muscle: Inhibitory to smooth muscles. Inhibitory to smooth muscles. Motor to sphincters. Motor to sphincters.

Pancreas Exocrine part: Pancreatic juice for digestion. Endocrine part (islets of Langerhans): It regulates blood glucose level through: 1- Insulin: secreted by beta cells It ↓ blood glucose (hypoglycemic hormone) It ↓ blood glucose (hypoglycemic hormone) 2- Glucagon: secreted by alpha cells It ↑ blood glucose (hyperglycemic hormone) It ↑ blood glucose (hyperglycemic hormone)

Actions of Insulin 1- On carbohydrate metabolism: It facilitates diffusion of glucose to cells It facilitates diffusion of glucose to cells 2- On lipid metabolism: It causes lipolysis. It causes lipolysis. 3- On protein metabolism: It promotes protein anabolism & synthesis It promotes protein anabolism & synthesis 4- On growth: It is essential for growth (anabolism) It is essential for growth (anabolism)

Actions of Glucagon 1- On carbohydrate metabolism: Glycogenolysis & gluconeogenesis. Glycogenolysis & gluconeogenesis. 2- On lipid metabolism: Lipolysis. Lipolysis. 3- On protein metabolism: Catabolism. Catabolism.

Diabetes mellitus Deficiency in insulin secretion. Manifestations: 1- Hyperglycemia. 2- Glucosuria. 3- Plyuria. 4- Polydipsia. 5- Hyperphagia.

Glucose homeostasis Normal fasting blood glucose level: Up to 126 mg% Glucose is the only nutrient for brain, retina & germinal epithelium. Glucose in ECF causes cellular dehydration. Glucose is lost in urine. Excess glucose in urine causes osmotic diuresis (depletion of fluids & electrolytes).

Mechanism of controlling blood glucose level 1- Glycolytic activity of the liver. 2- Hormonal control.