cardiac conduction system Flashcards
cardiac conduction system
group of specialised cells located in walls of the heart send impulse to cardiac muscles causing it to contract
heart muscles are myogenic (define)
capacity of heart to generate its own impulse
what order does an impulse travel in
sinoatrial node atrial systole atrioventricular node bundle of his purkinje fibres ventricular systole
explain the cardiac conduction system
sinoatrial node generates impulse which creates atrial systole. It goes to atrioventricular node where impulse is held for 0.1-0.2 secs. Impulse is sent down the bundle of his to purkinje fibres where atria contracts = ventricular systole
why is the conduction system important
it ensures that heart rate increases during exercise to allow the working muscles to receive more oxygen
sympathetic nervous system
part of the autonomic nervous system that speeds up heart rate
- sympathetic nervous impulses are sent to the SAN and there is a decrease in parasympathetic nerve impulse so that heart rate increases
parasympathetic nervous system
part of the autonomic nervous system that decreases heart rate
nervous system is made up of two parts;
- CNS - consists of brain and spinal cord
- peripheral nervous system - consists of nerve cells that transmit info from the CNS
- these are coordinated by the cardiac control centre located in the medulla oblongata
the cardiac control centre is stimulated by:
chemoreceptors
baroreceptors
baroreceptors
chemoreceptors
detect change in C02 and acidity
baroreceptors
detect change in blood pressure/ fall in heart rate
proprioceptors
detects change in muscle movement
how does hormones affect heart rate
adrenaline released by sympathetic nervous system stimulates SAN = increases HR
- therefore increase cardiac output so more blood and oxygen to working muscles
