Physio L6 Sympathetic Supply to Thorax & Abdomen PDF

Data Zone 44 General Physiology Physio L 6 : sympathetic supply of thorax & abdomen Outlines : Origin , Relay & Function 1 – Sympathetic supply to thorax Origin Relay Latera...

Data Zone 44 General Physiology Physio L 6 : sympathetic supply of thorax & abdomen Outlines : Origin , Relay & Function 1 – Sympathetic supply to thorax Origin Relay Lateral horn cells ( LHCs ) of upper 4 Preganglionic fibers: relay in all cervical thoracic segments. ( T1+T2+T3+T4 ) ganglia and upper 4 thoracic ganglia. Postganglionic fibers: arise from this ganglion to supply the following structure:  Heart  Lungs Function : Heart: Stimulatory, i.e. 1. increases heart rate 2. Increases force of contraction. 3. Coronary vasodilatation leading to increase blood supply of the cardiac muscle ( indirect effect through accumulation of metabolites). Lung: 1. Bronchodilatation (widening of air passages) due to relaxation of wall smooth muscle. 2. Vasoconstriction of pulmonary blood vessels. 3. Decreases mucous secretion in the air passages. 2 – Sympathetic supply to abdomen Origin Rely  LHCs of 6-12 thoracic segments (T6-  Celiac ganglon T12).  Renal ganglion  The preganglionic fibers form the  superior mesenteric ganglion greater splanchnic nerve 1  Data Zone 44 General Physiology Function :  Relax wall of stomach, small intestine & proximal part of the large intestine  Contraction of sphincters (leading to food retention)  Liver : stimulation of glycogenolysis leading to increase blood glucose.  Spleen : contraction of splenic capsule release of stored blood to the general circulation(about 200 ml).  Suprarenal medulla : secretory to 80% adrenaline and 20% noradrenaline.  V.C of blood vessels of the stomach, small intestine, proximal part of large intestine, liver, kidney ,and pancreas 3 – Sympathetic supply to pelvis Origin Relay  L.H.Cs of the 12th thoracic segment Inferior mesenteric ganglion and the upper 3 lumber segments.  The preganglionic fibers form right and left lesser splanchnic nerves which are joined to form the pre- sacral nerve. Function : 1- Rectum: a. Relaxation of the wall b. Contraction of internal anal sphincter leading retention of stool. 2- Urinary bladder: a. Relaxation of the wall. b. Contraction of internal urethral sphincter leading to retention of urine. 3- genital organs : a. Ejaculation of semen due to contraction of vas deferens, seminal vesicle and prostatic muscles. b. V.C of blood vessels of pelvic viscera including external genital tract leading to shrinkage of penis. 2  Data Zone 44 General Physiology 4 – Sympathetic supply to upper & lower limbs Origin Relay Upper limb From LHCs of (5-9) Middle and inferior thoracic segments cervical ganglia and upper (T5-T9). 2 thoracic ganglia lower limb From LHCs of (10- 12) Lumbar, sacral thoracic segments (T10-T12). Function : In both upper and lowe limbs :  Skeletal muscle blood vessels ; vasodilatation -causing better contraction, delayed fatigue and rapid recovery (Orbelli phenomenon). Mechanism: 1) An increase in blood flow due to vasodilatation this help supply of more oxygen and nutrients and easy removal of waste products. 2) Increase sensitivity of the motor end plate to acetyl choline. 3) Activation of phosphorylase enzyme which help glycogen breakdown and release of energy in the muscle  Skin : 1. Vasoconstriction. 2. Contraction of piloerector muscles causing erection of hair. 3. Secretory to sweat glands. 3 Data Zone 44 General Physiology 4