Physiology Lecture (7) PDF

Physiology Sympathetic NV to Thorax , Abdomen & Pelvis LECTURE (7) DR. El-Sawy 0  Physiology Sympathetic NV to...

Physiology Sympathetic NV to Thorax , Abdomen & Pelvis LECTURE (7) DR. El-Sawy 0  Physiology Sympathetic NV to Thorax , Abdomen & Pelvis  Lateral horn cells of upper 4 or 5 thoracic segments of spinal Origin cord. Relay  3 cervical ganglia and upper 4 thoracic ganglia. (Ganglia) Functions Heart a. It increase all cardiac properties :→↑ effectiveness of heart as a pump. Rhythmicity Excitability Conductivity Contraction b. Coronary vessels: Direct effect → vasoconstriction. Indirect effect → vasodilatation (due to accumulation of metabolites) Lung Inhibition of bronchial muscles → Pulmonary V.C Bronchodilatation Inhibition of bronchial mucus glands → ↓ mucus secretion DR. El-Sawy 1  Physiology Sympathetic NV to Thorax , Abdomen & Pelvis Origin :  Lateral horn cells of T6 → T12 ( Splanchnic Nerves ) Relay (Ganglia) :  Collateral (Prevertebral) Ganglia (Celiac, Superior Mesenteric & Aortico-Renal) Functions : Relaxation of wall and contraction of ↑ Glycogenolysis → ↑glucose. sphincter of Oddi → retention of ↑ Fibrinogen synthesis. bile & delayed emptying. Decrease both endocrine & exocrine Contraction of Splenic capsule → secretion. push blood (250 ml) to circulation DR. El-Sawy 2  Physiology Sympathetic NV to Thorax , Abdomen & Pelvis Relaxation of walls. Contraction of sphincters. Inhibition of digestion & delayed evacuation of contents. Stimulation of juxta glomerular Mixed supply (vasoconstriction and cells → ↑ renin → VC. vasodilatation) ↓ renal blood flow → ↓ urine. DR. El-Sawy 3  Physiology Sympathetic NV to Thorax , Abdomen & Pelvis Origin  LHCS of T10 & 11 segments of spinal cord.  Supplied by sympathetic preganglionic nerve fibers (with no Relay postganglionic nerve fibers) which relay directly with the SRM cells (chromaffin cells).  Secretes adrenaline (80%) and noradrenalin (20%)  These hormones have prolonged action due to their slow clearance from the circulation. Function  Adrenaline acts more on metabolic actions of the body while Noradrenalin acts more on blood vessels.  In stress conditions , SRM acts together with sympathetic nervous system (sympatho-adrenal system). DR. El-Sawy 4  Physiology Sympathetic NV to Thorax , Abdomen & Pelvis Origin :  Lateral horn cells of L1 → L3 Relay (Ganglia) :  Inferior mesenteric & Hypo-gastric Ganglia. Functions : Relaxation of wall. Relaxation of wall Contraction of internal urethral Contraction of internal anal sphincter. sphincter ↓ Micturition → retention of urine. ↓ defecation → retention of stool. Contraction of seminal vesicles → Inhibitory effects on uterus, but ejaculation. excitatory in late pregnancy. VC → shrinkage of penis. VC → shrinkage of clitoris. DR. El-Sawy 5  Physiology Sympathetic NV to Thorax , Abdomen & Pelvis a. Upper limb → from LHCs of T2-9. Origin b. Lower limb →from LHCs of T10-L2. c. Thoracic and abdominal walls → from LHCs of T1-L2.  Skin : VC of blood vessels. Hair erection. Sweat secretion.  Skeletal muscles : VD of skeletal muscle blood vessels. Functions Orbelli phenomenon:  Better contraction Character  Delayed onset of fatigue  Early recovery after fatigue  Due to VD of blood vessels which : Supply O2 & nutrients to contracting muscles Mechanism Remove CO2 & waste products from muscles so prevent or delay fatigue. DR. El-Sawy 6  Physiology Sympathetic NV to Thorax , Abdomen & Pelvis DR. El-Sawy 7