lecture 2 -functional capacity of the cardiovascular system Flashcards
cardiac output
functional capacity of the heart
What are the methods used to assess cardiac output
- direct flick method
- indicator dilution
- CO2 breathing method
What does the direct flick method measure
the difference between oxygen in the arteries and veins
describe the indicator dilution method
injection of dye of a quantity into a large vein to vizualise the blood flow around the body
describe the CO2 rebreathing method
uses a rapid CO2 gas analyser to determine CO2 levels
what are the influencing factors of cardiac output at rest
emotional conditions, corticol outflow of cardioaccelerator nerves
describe the mechanisms that increase stroke volume during activity
- enhanced diastolic filling followed by forceful systolic contraction
- normal ventricle filling with forceful ejection and systolic emptying
- training adaptions that expand blood volume and reduce resistance to blood flow
explain the term ‘cardiovascular drift’
an individuals heart rate steadily increases even when intensity is not which results in stroke volume to gradually decrease
what occurs to blood during exercise
hydrostatic pressure increases in capillaries, which force water into interstitial compartment
define ‘VO2 max’
the maximum amount of oxygen that can be transported and utilised within the working muscle
what is VO2 max influenced by
genetics, training history, age, gender, specificity of testing
what is the primary criteria for attaining VO2 max
VO2 consumption plateau with increase in workload
what are the secondary criteria for attaining a VO2 max
- blood lactate reading of less than 8mmol
- HR max of 10bpm from 220-age
- RPE of more than 17 during exercise
- respiratory exchange rate of more than 1.10
define ‘a-vO2diff’
amount of oxygen in the veins vs the arteries
what is the formula of a-vO2diff
cardiac output x a-vO2diff
describe the factors of haemoconcentration
- increase in capillary hydrostatic pressure as blood pressure rise
- metabolic byproducts of exercise metabolism that draw fluid from plasma into tissue spaces
describe the factors that affect the a-vO2diff during physical activity
- central - heart and lungs which influence oxygen delivery
- peripheral - muscle tissue which influence oxygen utilisation
why do upper body exercises require higher VO2 compared to lower body exercises?
- lower mechanical efficiency
- recruitment of additional musculature to stabilise torso
