Endocrine Adrenal gland And Pancreas

Adrenal gland Structure Cortex ◦ Glucocorticoids  Chemical nature  Effects  Control of secretion ◦ Mineralocorticoids  Effects  Control of secretion Medulla ◦ Catecholamine s

Adrenal gland

Adrenal cortex ◦ 80% of an adrenal gland’s total weight ◦ Zona glomerulosa  Mineralocorticoids ◦ Zona fasciculata  Glucocorticoids ◦ Zona reticularis  Androgens

Adrenal cortex Cortex ◦ Activity stimulated by ACTH (regulates mainly glucocorticoids & androgens). Cortical hormones ◦ Mineralcorticoids  Aldosterone  regulate salt and water balance ◦ Glucocorticoids  Cortisol  regulate glucose metabolism and the immune system. ◦ Gonadocorticoids  Androgens  Estrogens

Adrenal cortex Glucocorticoid hormones  Most potent naturally occurring glucocorticoids is cortisol  They are carried by plasma proteins: albumin and globulin.  Only 2% are not bound, free in the circulation and are biologically active.  It shows diurnal variation; increases early morning and decreases at night.

Effects of cortisol  On carbohydrates ◦ Stimulation of gluconeogenesis by the liver ◦ Increase in glycogen storage in liver cells ◦ Decreased glucose utilization by the cells  On protein ◦ Catabolic effect in all body cells except the liver ◦ Mobilization of amino acids from muscles. ◦ Decreased protein synthesis  On fat ◦ Mobilization of fatty acids from adipose tissue

Effects of cortisol Anti-inflammatory ◦ Stabilizes lysosomal membrane ◦ Reduces degree of vasodilatation ◦ Decreases permeability of capillaries ◦ Decreases migration of white blood cells ◦ Suppresses immune system

On blood cells Increase RBCs Decrease lymphocytes & eosinophils. Increase neutrophils. Skin Decrease collagen & protein synthesis. Decrease fibroblast proliferation and healing.

Bone Inhibit bone matrix formation. Anti-vitamin D effect on bones GIT: Increases HCL formation.

Abnormal high cortisol level Cushing’s sydndrome Causes ◦ Pharmacologic ◦ Pituitary adenoma % ◦ Adrenal adenoma, carcinoma ◦ Ectopic ACTH

Characteristics of Cushing’s disease Hyperglycemia Hypertension (Salt & water retention). Moon face, buffalo neck, abdominal obesity, thin limbs, due to redistribution of fat and lipolytic effect and catabolic effect on proteins. Increased susceptibility to infection. Frequent fractures.

Adrenal cortex Mineralocorticoid hormones: Aldosterone  Most potent naturally occurring mineralocorticoid is aldosterone  Effects:  Affect ion transport by epithelial cells  Increase the activity of the sodium pump of the epithelial cells; distal tubules of the nephron, sweat glands, salivary & intestinal glands.  Cause sodium retention and potassium and hydrogen loss by the kidney. Water is secondarily absorbed following sodium.  Regulated by the renin-angiotensin system

Aldosterone Regulation of secretion Angiotensin II Angiotensin II S K (serum potassium conc.) S K (serum potassium conc.) Major modulators Minor regulators: ACTH Serum sodium

Regulation of Aldosterone secretion

Adrenal medulla  Innervated by the sympathetic nervous system& secretes nor-adrenallin

Endocrine function of pancreas

Pancreas Endocrine Exocrine Islets of Langerhans Clusters of cells scattered between the acini between the acini 4 types of cells

Endocrine Pancreas

Major cell types of the Islets of Langerhans and the Hormones they produce Name Hormone produced Percentage of total Islet* Alpha cell Beta cell Delta cell F cell GlucagonInsulinSomatostatin Pancreatic polypeptide *The remaining 4% consists of connective tissue and blood vessels.

Endocrine Pancreas Insulin ◦ Secretion is promoted by increased blood glucose levels. ◦ Facilitates the rate of glucose uptake into the cells of the body& decrease blood sugar level. ◦ Anabolic hormone: Synthesis of proteins, ◦ Lipogenic: (+)lipids formation in adipose tissues& inhibit lipid breakdown by lipase

 Blood glucose  Cells in pancreatic islets  Insulin secretion  Cellular uptake of blood glucose  Blood glucose GlucoseGlycogenGlucoseTriglyceride    Liver and skeletal muscle Adipose tissue Effects of Insulin

Endocrine Pancreas, cont,…. Glucagon ◦ Secretion is promoted by decreased blood glucose levels ◦ Stimulates glycogenolysis, gluconeogenesis, and lipolysis Somatostatin ◦ Possible involvement in regulating alpha and beta cell secretions

Cause Inadequate secretion of insulin Defects in the action of insulin hyperglycemia and glycosuria) Metabolic disturbances ( hyperglycemia and glycosuria)

Types of Diabetes Type 1 Diabetes Affects children Cause : inadequate insulin secretion Treatment : insulin injection Type 2 diabetes Affects adults Cause defect in insulin action Treatment : diet or OHA diet or OHA