Week 4 Flashcards
CO _____ proportional to O2 consumptions during exercise
increases
CO is typically ___L to every ____L of oxygen
6L CO to 1L O2
Activity of left and right cardiac vagus nerves ______ heart rate
decrease
Activity of right sympathetic nerves ______ heart rate
increase
Reducing the brake (L and R cardiac vagus nerves) ____ the heart
speeds
Reducing the accelerator (right sympathetic nerves) ____ the heart
slows
Heart rate is increased by _______ parasympathetic activity (vagal withdrawal) and ______ sympathetic activity
decreasing, increasing
At low HR (<100bpm), it is varied by adjusting _____ activity
vagal
At high HR (>100bpm), it is varied by adjusting _____ activity
sympathetic
Size-dependent cardiac variable (SV and CO) are traditionally related to …?
Body surface area (however, BSA does not account for body fat/composition)
According to dimensionality theory, heart mass or volume should related to BSA by exponent ____??
1.5 -> (heart mass/volume is 3 dimensional, and BSA is 2 dimensional —> 3/2 = 1.5)
What are 4 indirect methods of measuring CO in children?
- Indirect Fick (CO2 breathing)
- Acetylene-rebreathing
- Electrical bioimpedance
- Doppler ultrasound
Resting CO progressively ______ relative to body mass as children grow
decreases
Why does CO decrease relative to body mass as children grow?
Due to decrease in resting HR as children age
How much does the HR decrease in children as they grow?
Falls 10-20 bpm between ages 5 to 15 yrs (it stays 3-5 bpm higher in girls)
SV ______ in direct proportion to body mass
increases (or stays in proportion with body mass)
At rest, HR is _____ related to mass and age in children
inversely (decreases as they get bigger)
In maximal exercise, max HR is _______ of body size between ages 6-16yrs
independent (stays fairly consistent regardless of body size)