Flashcards
SPECIAL CIRCULATIONS
Cards in this deck (19)
- 1Q redistribution in exercise: key facts (regarding muscle and cornonary)Skeletal muscle can take up to 90% Q in exercise
Coronary and skin also use a large proportion
-Heart is highly oxidative taking 5% of Q at rest (0.25L) and 5% in exercise (1.25L)
-our o2 extraction (by heart) at rest is 60-70%
-rises to 90% in exercise and relies of coronary blood flow increase
-level of 02 leaving the heart obviously declines - 2metabolic factors influencing coronary circulationcoronary blood flow closely related to work rate
-chronotropic metabolic factors work to increase HR
-ionotropic will alter contractility
-adenosine = main metabolic vasodilator - 3mechanical factors regulating coronary BF-80% flow occurs in diastole due to vessel compression and reduced downstream perfusion in systole
-rhythmic contractions impede flow profile - 4exercise stress test for CHD-restricted coronary blood flow due to CAD can be detected
-it can lead to downstream blockage as some vessels are undersupplied
-if CAD is present tissue ischaemia can be observed on an EMG
-cardiac cycle will shorten in exercise and HR will increase
-diastole shortens more than systole meaning there is even less time for efficient flow - 5summary of coronary circulation in exercise (iFADE)-potential for ischaemia
-high flow to heart (highly oxidative tissue)
-Adenosine = vasodilator to facilitate flow
-Flow occurs in Diastole
-High oxygen extraction - 6cutaneous circulation in exercise-skin BF hard to measure due to huge surface area
-100-300ml/min/m2 at rest
-7-16L in exercise
-neural regulation by adrenergic vasocontrictors and cholinergic vasodilators - 7skin BF depends on:SNA
-ambient temperature
-core temperature - 8thermoregulation with skin BF (heat and cold stress)heat stress: vasodilation to lose heat
cold stress: increase constrictor activity to retain heat - 9effect of exercise onset on skin BFat initial onset: vasoconstriction to redistribute Q to active muscle
follwed by: vasodilation to thermoregulate and lose heat (inc. core temp) - 10active vasodilation of skin in exercisedynamic exercise induces an active vasodilation at a HIGHER THRESHOLD than heating at rest
-due to sympathetic cholinergic nerve activity and NO - 11how can skin circulation control heart performance (BP)-In the heat, flow shifts from the core to the surface
-the muscle pump is unable to assist with venous return
-heart filling is reduced and we must vasoconstrict to maintain blood pressure - 12sweating-sweat glands secrete a plama-like (but with no plasma proteins) hypotonic fluid
-usually follows skin BF in exercise and heating - 13Integrative control of CNSreceives input from:
-central modifiers (acclimatization, hydration, circadian rhythm)
-Thermoregulatory (internal temp)
-non-thermoreg (baroreceptors, exercise) - 14competing influences in dynamic exercise-vasoconstriction at exercise onset due to SNA (adrenergic)
-active vasodilation at a threshold core temp to lose heat
-vasoconstriction in prolonged exercise to maintain central blood volume and VR - 15splanchnic BF in exercisesympathetic vasoconstrcition reduces flow
-increased oxygen extraction from 15 to 75% to compensate
-flow markedly reduces from 1500ml to only 350ml
oxygen consumption remains at 50-60ml - 16key facts about splanchnic circulation-contains 20-25% total BV
-constriction/restriction of flow can add blood volume to heart and facilitate VR
-flow is lower for any given o2 uptake in the heat, to direct flow to skin - 17Renal BF in exercise-reduced flow from 1.2L to just 360ml
-consumption increases x3 (6-18%)
-potential for proteinurea - 18catecholamine contribution to flow profile-in dynamic exercise NorA and Adrenaline increase to constrict vessels
-NorA spillover from the muscle represents activation of SNS
-adrenaline contricts vessels in dynamic exercise, acting on a-receptors
-adrenaline dilates vessels via b-receptors in light exercise - 19define static and dynamic exercise:static exercise involves muscle contraction and force generation without any muscle shortening
-dynamic exercise involves muscular contraction and force generation which results in a change of joint angle
Information
- Description
- Flashcards on SPECIAL CIRCULATIONS, created by rachii24-7 on 20/05/2014.
- Created by
- rachii24-7
- Views
- 15
- Rating