Week 5 Flashcards
What is the role of Acetylcholine in Cardiac regulation ?
- Slows heart rate by delaying sinus discharge
Name the two ways in which parasympathetic stimulation slows heart rate
- Via Acetylcholine release
- Vagus Nerve stimulation
Sympathetic nerve fibres innervate the ________ and the ________
SA node
Ventricles
Sympathetic nervous system releases __________ and activates ___________ receptors in the heart
Noradrenaline
Beta-Adrenergic
Where is the cardiac control centre ?
Medulla Oblongata
What are the two factors affecting blood flow
- Pressure gradient between the two ends of the vessel
2. Inversely to the resistance encountered to fluid flow
What are the three factors determining resistance to blood flow ?
- Blood thickness/viscosity
- Length of the conducting tube
- Vessel radius
Name local factors causing vasodilation
- decreases tissue O2
- local increase in blood flow
- Body temp.
- CO2 levels
- acidity
- NO Production
Name three factors that stimulate NO production as a result from increased blood flow
Signal chemicals
Sheer stress
Vessels stretch
What is considered a reflection of the functional capacity of the CV system ?
Cardiac Output
At rest, why does CO vary ?
Emotional conditions that alter cortical outflow to Cardioaccelorator nerves
Name two factors decreases HR in Endurance athletes
- Increased Vagal Tone
2. Decreased sympathetic drive
Name 3 factors contributing to increased stroke volume in endurance athletes
- Increased blood volume
- Increased ventricular volume
- Increased compliance of left ventricle
What 2 mechanisms aid in venous return
Skeletal muscle pump
Respiratory (abdomino-thoracic) pump
Define Cardiovascular Drift
Gradual time-dependent downward drift in several CV responses