Week 3 - Nervous System (Autonomic) Flashcards
Describe the role of the autonomic nervous system
The autonomic nervous system regulates processes like heart rate, blood pressure, respiration, digestion, and sexual arousal involuntarily
What are the main neurotransmitters in the ANS system
S2-S4 is ACh
T1-T2 is ACh & NE
T10-L1 is ACh
How does the nervous system regulate heart rate during exercise onset
Initially, heart rate increases due to parasympathetic withdrawal, followed by an increased due to increased sympathetic nervous system outflow
Define end-diastolic volume
Volume of blood in the ventricles at the end of diastole
Define Frank-Starling mechanism
Greater end-diastolic volume results in a more forceful contraction due to stretch of the ventricles
Define average aortic blood pressure
Pressure the heart must pump against to eject blood (Mean arterial pressure)
How is the strength of the ventricular contraction enhanced by
Circulating epinephrine and norepinephrine
Direct sympathetic stimulation of the heart
What factors are involved in the regulation of venous return
Venoconstriction (SNS)
Skeletal muscle pump (Rhythmic skeletal muscle contractions)
Respiratory pump (Changes in thoracic pressure)
Define cardiac output
The amount of blood pumped by the heart each minute
Q = Heart rate x Stroke volume
Define systolic pressure
Pressure generated during ventricular contraction
Define diastolic pressure
Pressure in the arteries during cardiac relaxation
Define pulse pressure
Difference between systolic and diastolic pressure
Define mean arterial pressure
Average pressure in the arteries
What are the determinants of mean arterial pressure
Cardiac output
Total vascular resistance
MAP = CO x TVR
How is arterial blood pressure regulated
Short term: SNS activity & Baroreceptors
Long term: Kidneys through control of blood volume
What are the two changes in cardiovascular variables during exercise onset
Increase in cardiac output
A redistribution of blood flow form inactive organs to working skeletal muscle
What non-physiological factors affect changes in heart rate and blood pressure
Type, intensity and duration of exercise
Environmental conditions
Emotional influence
What physiological transitions occur from rest to exercise & exercise to recovery
Onset of Exercise: Rapid increase in HR, stroke volume and cardiac output
Plateau in submaximal exercise
During recovery: Decrease in HR, stroke volume and cardiac output
What factors affect the rate of recovery in factors such as HR and BP after intermittent exercise
Fitness level
Temperature & humidity
Duration & intensity of exercise
What happens to heart rate, cardiac output and blood pressure during incremental exercise
Heart rate & cardiac output: Increases linearly with increasing work rate
Reaches plateau at 100% VO2 max
Blood pressure increases linearly: Systolic blood pressure increases, diastolic blood pressure stays constant
