CV D3-D6 Flashcards
Nervous control of cardiac cycle
SA node sends impulse to right atrium causing it to contract. This forces blood down into ventricles.
AV node slows signal down allowing atria to contract before ventricles so ventricles fill with blood
Impulse travels down bundle of his to purkinje fibres allowing ventricles to contract forcing blood out of heart
How sympathetic and parasympathetic NS respond to increase HR
Chemoreceptors detect changes in CO2 and acidity. This sent to medulla.
Medulla sends impulse to sympathetic NS to increase HR during exercise so more O2 to muscles
Impulse to Parasympathetic NS to lower HR.
Heart rate
Num of times heart beats per minute
Stroke volume
Amount of blood pumped from heart per beat
Cardiac output
Amount of blood pumped from heart per min
Short term Response to exercise
Anticipatory rise - adrenaline released
Increased HR - medulla sends signals as muscles need more O2
Increased cardiac output - HR and SV also increase
Increased BP - systolic pressure
Redirection of blood - vascular shunt
Long term adaptations
Cardiac hypertrophy
Increase in resting and exercising SV
Decrease in resting HR
Reduction in BP
Decreased HR recovery time
More capillaries in cardiac and skeletal muscle
Increased blood volume - more O2 delivered
Additional factors
SADs
Sudden Arrhythmic death syndrome
Genetic condition that affects young and healthy people
Distorts hearts natural rhythm so heart stops
Additional factors
High/low BP
High BP - too much force on heart and arteries. Difficult for oxygenated blood tissues get to muscles. Fatty foods, no exercise
Low BP - blood moves slowly around the body. Less blood to vital organs and muscles. Fatigue. Dizziness
Additional factors
Hyper/hypothermia
Hyperthermia- body temp too high. Dehydration. Body produces or absorbs to much heat
Hypothermia- body temp too low. Shivering. Decreases performance as can’t function properly. Vasoconstriction of blood vessels near the skin. Less O2 to muscles
