Cardiovascular System Flashcards
The heart function
-contracts at a constant rhythm that may speed up or slow down depending on need for blood & oxygen
Sinus node
-governs the beating of the heart
-a small bundle of nerve fibres in the wall of the RA
-generates action potential
Action potential
-causes the muscle walls of the heart to contract
-travels through the 2 atria & th 2 ventricles via the A-V node & the purkinje fibres
Neural drive
Involuntary & responsive to:
-emotional changes
-CO2 &O2 blood levels
-proprioceptive changes
Average heart rate
60-85 bpm
Tachycardia
Persistent resting rate >100
Bradycardia
President resting rate <60
Systole -contractions (pulse)
-ventricles contract
-pressure is the highest
-average = 120mmHg
Diastole- relaxation
-ventricles relax & fill with blood
-indicates ease of blood flow to limbs
Average - 80 mmHg
Stroke volume
= volume from left ventricle = ml/beat
-60-80ml/beat
Cardiac output
=heart rate (bpm) x stroke volume (ml/beat)
-80bpm x 60ml/beat = 4.8L
-80bpm x 80ml/beat = 6.4L
Max Hr estimated
Using 220pbm - age
Arteries
Carry blood away from the heart
Arteries—>arterioles—>capillaries
Capillaries
-allow for the exchange of oxygen & nutrients from the blood to muscles & organs
-allow blood to pick up the waste products & carbon dioxide from metabolism
Veins
-have valves that open as blood returns to the heart
-valves that close as blood flows away from heart
