Physiological response in Valsalva maneuver The normal physiological response consists of4 phases 2 10 rEE Puse Rat
Physiological response in Valsalva maneuver • The normal physiological response consists of 4 phases
Physiological response in Valsalva maneuver The normal physiological response consists of 4 phases Initial pressure rise: On application of expiratory force, pressure rises inside the chest forcing blood out of the pulmonary circulation into the left atrium. This causes a mild rise in stroke Reduced venous return and compensation: Return of systemic blood to the heart is impeded by the pressure inside the chest. The output of the heart is reduced and stroke volume falls. This occurs from 5 to about 14 seconds in the illustration. The fall in stroke volume reflexively causes blood vessels to constrict with some rise in pressure(15 to 20 seconds). This compensation can b quite marked with pressure returning to near or even above normal, but the cardiac output and blood flow to the body remains low. During this time the pulse rate increases Pressure release: The pressure on the chest is released, allowing the pulmonary vessels and the aorta to re-expand causing a further initial slight fall in stroke volume(20 to 23 seconds) due to decreased left ventricular return and increased aortic volume, respectively. Venous blood can once more enter the chest and the heart, cardiac output begins to increase Return of cardiac output: Blood return to the heart is enhanced by the effect of entry of blood which had been dammed back, causing a rapid increase in cardiac output(24 seconds on). The stroke volume usually rises above normal before returning to a normal level with return of blood pressure, the pulse rate returns towards normal
Physiological response in Valsalva maneuver • The normal physiological response consists of 4 phases – Initial pressure rise: On application of expiratory force, pressure rises inside the chest forcing blood out of the pulmonary circulation into the left atrium. This causes a mild rise in stroke volume. – Reduced venous return and compensation: Return of systemic blood to the heart is impeded by the pressure inside the chest. The output of the heart is reduced and stroke volume falls. This occurs from 5 to about 14 seconds in the illustration. The fall in stroke volume reflexively causes blood vessels to constrict with some rise in pressure (15 to 20 seconds). This compensation can be quite marked with pressure returning to near or even above normal, but the cardiac output and blood flow to the body remains low. During this time the pulse rate increases. – Pressure release: The pressure on the chest is released, allowing the pulmonary vessels and the aorta to re-expand causing a further initial slight fall in stroke volume (20 to 23 seconds) due to decreased left ventricular return and increased aortic volume, respectively. Venous blood can once more enter the chest and the heart, cardiac output begins to increase. – Return of cardiac output: Blood return to the heart is enhanced by the effect of entry of blood which had been dammed back, causing a rapid increase in cardiac output (24 seconds on). The stroke volume usually rises above normal before returning to a normal level. With return of blood pressure, the pulse rate returns towards normal
EFFECTS OF SYMPATHETIC AND PARASYMPATHETIC PATHWAYS ON THE CARDIOVASCULAR SYSTEM NEUROTRANSMITTER ANATOMIC RELEASED AT ENZYME OR EFFECTOR RESPONSE PATHWAY EFFECTOR RECEPTOR G PROTEIN PROTEIN 2nd MESSACE Tachycardia Sympathetic Norepinephrine B, on cardiac Go Activates AC↑ CAMPY Bradycardia Parasympathetic Acetylcholine M on car. Direct action GIRK K diac pace. of dimeric channels GBy Increase cardiac con Sympathetic Norepinephrine B, on cardiac Gc Activates AC↑ ICAMP tractility myocyte Direct action of Go or L-type Ca channels Decrease cardiac con- Parasympathetic Acetylcholine M, on car. ↓ [CAMP tractility diac myo te Presynaptic ↓ ICAMP in M, recep tor on nor adrenergic neuron
Interaction of sympathetic and ymp parasympathetIc NE nerves ACh ATP GTP GDP NE NPY - ACh
Interaction of sympathetic and parasympathetic nerves
Predominance of autonomic nerves 120 110 Propranolol e100 At pIne 90 80 70 60 Propranolol Atropine 50 Control 1 First drug administered Second drug administered
Predominance of autonomic nerves