Endocrine System Practical Lesson 7 PDF

Endocrine system 2 Dr / alaa wahdan  ENDOCRINE SYSTEM It is the study of glands of internal secretion (hormones) Hormones are chemical substancessecreted into the body fluid by endocrine glands The secretion is delivered directly into the blood Exocrine glands: secrete through ducts...

Endocrine system 2 Dr / alaa wahdan  ENDOCRINE SYSTEM It is the study of glands of internal secretion (hormones) Hormones are chemical substancessecreted into the body fluid by endocrine glands The secretion is delivered directly into the blood Exocrine glands: secrete through ducts PI TU I TARY GLAND Lies in Sella turcica beneath the base of the brain divided into anterior and posterior pituitary Hypothalamus secretes: RH: Releasing hormone IH: Inhibiting hormone Hypothalamus synthesized: ADH Oxytocin Anterior Pituitary is connected to Hypothalamus via vascular connection Posterior Pituitary is connected to Hypothalamus via nervous connection & stores ADH & Oxytocin HORMONES SECRETED BY PITUITARY GLAND Control of Anterior Pituitary Gland I - Hypothalamus Median eminence secretes Releasing & inhibiting hormones: Mode of delivery: Hypothalamo- hypophysial portal circulation Types: GHRH / GHIH (somatostatin) PIH (dopamine) / TRH / CRH FSH-RH & LH-RH (gonadotropin releasing hormone)  Growth Hormone (somatotropin) Secreted from A. pituitary gland Functions: Growth & Metabolic effect GROWTH Indirect: stimulation of liver to produce a "somatomedin" 🢝 Before closure of epiphysis: in children: 🢝 linear growth 🢝 After closure of epiphysis: in adult: 🢝 thickness of bones only  METABOLIC ACTION Protein CHO Fat metabolism metabolism metabolism ▲ protein ▲ blood ▲lipolysis synthesis glucose* ▲ketone bodies (Anabolic effect) due to anti- (lipolytic & ▼protein insulin action Ketogenic catabolism (diabetogenic effect) (Protein sparing effect) effect) *excessive GH  insulin resistance (IR)  hyperglycemia  Growth Hormone (Somatotropin) GH is secreted in a pulsatile pattern ++ by: fasting, exercise and stress  HYPERFUNCTION Gigantism Acromegaly  Before puberty  After puberty  Height > 2 meters  Large hands, feet & jaw  Hyperglycemia  Hyperglycemia  HYPOFUNCTION Dwarfism Infantilism  ↓ GH  ↓ GH & sex hormones  Short  Short  Normal mentality  Normal mentality  Normal sexuality  No sexual development  POSTERIOR PITUITARY Stores 2 hormones:  Antidiuretic hormone (ADH)  Oxytocin ADH (vasopressin): ↑ renal water absorption ↑ABP Deficiency of ADH: Diabetes insipidus: Polyurea Higher secretion at night 🢝 uterine contraction during delivery 🢝 milk letting reflex by contraction of myoepithelial cells in breast  Bonding between mother & baby OXYTOCIN  CONTROL OF THYROID THYROID SECRETION GLAND It secretes:  Thyroxine (T4) & triiodothyronine (T3) (from follicular cells)  Calcitonin (from parafollicular cells) 🢝 T3,T4  NEGATIVE FEEDBACK  🢝 TRH & TSH  ACTIONS OF THYROID HORMONES Metabolic & CNS: development & Growth maturation especially in fetus 🢝 Number & size of mitochondria , and early life enzymes synthesis and activities  ↑ O2 consumption, ↑CO2 production ↑ energy production & consumption Res: ↑respiratory rate ↑ Basal metabolic rate Protein: Anabolic  physical growth CVS: ↑HR & positive CHO: ↑ blood glucose inotropic ↑ RBCs formation Lipid: ↑lipolysis GIT:↑ appetite, ↑motility & Thyroid hormones are essential for secretions mental, physical, & sexual growth DISORDERS OF THYROID FUNCTION Hyperthyroidism Hypothyroidism (Thyrotoxicosis) Myxodema (adult) (Graves' disease) ↑ BMR heat intolerance ↓ BMR  cold intolerance ↓ Weight but ↑ appetite 🢝 Weight & Edema 🢝 HR  heart failure ↓ HR Diarrhea Constipation Tremors, irritability, Slow reactions Sleepiness. insomnia Exophthalmos & goiter Sterility & goiter Goiter:  Abnormal 🢝 in the size of thyroid gland  The thyroid function may be normal, decreased, increased DISORDERS OF THYROID FUNCTION Congenital hypothyroidism Cretinism Delay in all milestones of development Dwarfs & mental retard Deficient sexual maturation Distended abdomen. Delay dentition, protruding tongue  GOITER  Abnormal increase in size of thyroid gland  The thyroid function may be normal, decreased, increased PTH Vit D Normal plasma Ca level Calcitonin 10 mg/ dl  Parathormone Calcitonin Vitamin D3 Ac tions on bones 🢝 activity of osteoclasts 🢝 activity of deposits and mobilizes Ca+2 osteoclasts & PO43-  bone remodeling kidneys 🢝 Reabsorption of Ca2+ 🢝 Excretion 🢝 Reabsorption of Ca+2 & 🢝 PO43- reabsorption of PO43 + + 1 alpha hydroxylase both Ca and (++ vit D) PO43- GIT 🢝 Reabsorption of Ca++ 🢝 absorption of Ca+2 and phosphate  TETANY ↑neuromuscular excitability due to ↓ ionized Ca+2 Mechanism: ↑ Na + Permeability  ↑ excitability  contractions ↑Causes: Hypocalcaemia due to  ↓ PTH or Vit D  Renal failure Types : Latent : plasma ca+2 7-9 mg %  carpopedal spasm Manifest : plasma calcium level < 7 mg %  asphyxia and cyanosis due to spasmodic contractions of laryngeal & respiratory muscles TETANY  2 suprarenal (adrenal) glands over both superior poles of each kidney Zona Mineralocorticoids Glomerulos mainly aldosterone a Zona Glucocorticoids Fasciculata mainly cortisol Zona Sex hormones Reticularis mainly androgen  Actions of Cortisol CHO metabolism (Diabetogenic) Weak mineralocorticoid activity ↓ glucose uptake & utilization (i.e. ↑renal Na and water reabsorption) 🢝 gluconeogenesis Effect on blood cells Fat metabolism (lipolysis) ↓↓ WBCs & ↑↑ RBCs Protein metabolism (catabolic) Anti-stress Except on liver (anabolic) Anti-inflammatory Pharmacological in liver actions 🢝 Glycogenesis & protein synthesis Anti-allergic CONTROL OF SECRETION OF SUPRARENAL CORTEX ACTH is under the control of Hypothalamic CRH -ve feedback: 🢝 cortisol  🢝 ACTH & CRH secretion Circadian Rhythm: High in early morning  ADRENAL HYPOFUNCTION (ADDISON’S DISEASE) ↓ Mineralocorticoids  ↓ABP, ↑K+ & H+ 🢝 ↓Glucocorticoids  ↓ glucose, pigmentation Resistance to stress ↓Androgen  ↓ weight, weaknesses ↑ Pigmentation of skin, gum & oral mucosa  HYPERFUNCTION (CUSHING SYNDROME) causes Adrenal tumors Pituitary tumors  hyperplasia of adrenal cortex Large amounts of exogenous cortisone for long time 🢝 ACTH, CRH  Manifestations of Cushing Syndrome 1.Catabolic (↓ protein synthesis) severe muscle weakness  fatigue osteoporosis & fracture very thin skin poor wound healing purple abdominal stria Suppress immunity Recurrent infection 2. Abnormal central Fat deposition moon face buffalo hump trunkal obesity Thin limbs Manifestations of Cushing Syndrome 3. Hyperglycemia, glucosuria & diabetes mellitus 4. Hypertension (mineralo-corticoid like activity) 5. Hirsutism (excess body & face hair in females) 6. Gynecomastia (breast enlargement in males) Pancreas Cells of Islets of Langerhans: -cells Glucagon β Insulin cells δ Somatostatin cells F cells Pancreatic polypeptide NORMAL BLOOD GLUCOSE: 70- 100 MG%  MECHANISM OF ACTIONS ↑ glucose transporters on the cell membrane ↑ glucose uptake Anabolic effect  important for growth N.B Some tissues are insensitive to insulin: Brain, kidney, intestine, gonads, & RBCs. they takes glucose independent of insulin  DIABETES MELLITUS Diabetes Mellitus: > 126 mg/dl Symptoms: Polyurea Polydipsia Polyphagia Weight loss (fat & protein catabolism) Glucosuria: -Def. presence of glucose in urine -Cause: high blood glucose that exceeds renal threshold (>180mg/dl)