Cardiovascular response to exercise Flashcards
What is CO at rest in L/min?
5.8 - changes during exercise
What can happen during exercise?
HR increase by 250%
stroke volume can double blood distribution changes
What happens before exercise?
anticipatory responses mediated by activation of sympathetic ns increase heart rate and CO and vasoconstriction
What 3 Interrelated changes take place during light exercise?
Increase vasodilation in skeletal muscle o2 quick
Increase VR skeletal fibres squeeze
Increase CO due to atrial reflex - demand in BF
What happens in heavy exercise?
cardiac and vasomotor centres activate sympathetic ns CO increase to 20-25L/min increase BF Skin perfusion only blood supply to brain is unaffected
What are short term responses for haemorraging?
Decrease in BP detected by baroreceptors increases peripheral vasoconstriction
Second phase - stress and anxiety sympathetic
Sympathetic release NA from adrenal medulla and ADH and angiotension II released
What are long term response?
restore normal blood volume, increase ADH and secrete EPO - counter blood losses, can suffer circulatory shock if BP very low
What are causes of circulatory shock?
a drop in BP
damage to the heart
External pressure on heart
Extensive peripheral vasodilation
What are symptons of circulatory shock?
Hypotension Pale cool clammy skin Confusion disorientation increase HR cessation of urine and acidosis
What happens with Low BP decrease blood to heart?
Heart muscle suffers from ischemia
What happens at ABP of 50mm?
Vasoconstriction occurs , if untreatead irreversible shock occurs
