Ans, a. Acts with the cardiovagal centre to maintain BPVasomotor centre (VMC) controlling sympathetic outflow acts along with cardiovagal centre (CVC) controlling parasympathetic out flow to maintain blood pressure."Vasomotor centre (VMC) controlling sympathetic outflow acts along with cardiovagal centre (CVC) controlling parasympathetic out flow to maintain blood pressure. Baroreceptors, chemoreceptors and cortico hypothalamic inputs influence VMCG. Baroreceptors are tonically active stretch receptors located in walls of aortic arch and carotid sinus. Discharge from baroreceptors cause inhibition of Cl neurons of vasomotor center (VMC) situated in upper (rostral) half of ventrolateral medullaQ andfacilitation of cardiovagal centre (CVC) or nucleus ambiguous. "Medullary Centres regulating Blood PressureVasomotor Centre (VMC)Cardiovagal Centre (CVC)* Collection of glutaminergic neurons in superficial medullary reticular formation, known as C1 neurons, serves as pressure area of VMC. Cell bodies of C1 cells lie in ventrolateral region of upper half of medulla.* These neurons are spontaneously active day and night, tonically discharging impulses (in rhythmic manner) to the heart and blood vessels through lateral reticulospinal tract* It refers to nucleus ambiguous which lies lateral to VMC (medullary reticular neurons)* It receives afferents via Nucleus tractus solitaries (NTS) and in turn sends parasympathetic impulses to heart via the vagus, so named cardiovagal centre* The neurons in CVC do not discharge rhythmically (i.e. are not tonically active) Medullary Centres regulating Blood PressureVasomotor Centre (VMC)Cardiovagal Centre (CVC)* These reticulospinal tracts synapse with preganglionic neurons of sympathetic nervous system located in intermediolateral grey column of spinal cord (thoraoo lumbar sympathetic out flow)* Post ganglionic sympathetic neuron secrete nor adrenaline thereby increasing sympathetic activity and causing tonic vasoconstrictor and cardio accelerator activity resulting in:* The discharge increases parasympathetic activity there by resulting in: * Vasodilation* BP* Cardiac output* Heart rate * Vasoconstriction* BP* Cardiac output* Stroke volume