L5&6 - Cardiovascular Flashcards
what does the involuntary nervous system consist of?
2 neurone system
neurotransmitters ACh snd noradrenaline
2 anatomical divisions
what is the two neurone system?
preganglionic neurones which synapse on postganglionic neurones
what are the 2 anatomical divisions of the involuntary nervous system?
sympathetic and parasympathetic
what division of the sympathetic nervous system innervates almost every organ?
thoraco-lumbar division
what division does the parasympathetic nervous system consist of?
cranio-sacral division
what is the function of the sympathetic nervous system?
important for reactions - fight or flight
what is the function of the parasympathetic nervous system?
maintaining and restoring body energy - rest and digest
what is the adrenal medulla innervated by?
preganglionic sympathetic nerves
what are adrenal medulla cells?
modified ganglion cells
what does the adrenal medulla do?
- release adrenaline into bloodstream (80% adrenaline 20% noradrenaline)
- regulates primary metabolic events
what does the hypothalamus regulate?
- reproduction
- thirst/hunger
- reaction to stress
- emotion control
- sleep cycle/circadian rhythm
what are the layers of the heart?
- pericardium
- epicardium
- myocardium
- endocardium
what phase comes after depolarization in cardiac action potential?
plateau phase due to movement of extracellular calcium into the muscles
what phase of the action potential is longer to ensure tetany does not occur?
refractory period - relaxation of the muscle has started by the time this period ends
what are the 2 sources of calcium in the cardiac muscle?
sarcoplasmic reticulum and extracellular
what is auto-rhythmicity?
the heart can spontaneously generate its own action potentials without external stimulation from nerves - thanks to the conduction system
what is the conduction system and where does it originate?
small network of contractile cells in the right atrium as an area called the sino-atrial node
what are the 5 areas of generation through the conduction system?
- sino-atrial node
- atrioventricular node
- atrioventricular bundle (bundle of His)
- right and left bundle branches
- purkinje fibres
explain how the SA node is innervated by the parasympathetic nervous system
increased parasympathetic nerve (vagus nerve) activity decreases heart rate
explain how the SA node is innervated by the sympathetic nervous system
increased sympathetic nerve activity increases heart rate
explain how the myocardium is innervated by the sympathetic nervous system
increased sympathetic nerve activity increases cardiac contractility while decreased sympathetic activity decreases contractility
what is diastole?
relaxation period
what is systole?
contraction
explain the lead up to the 1st heart sound
- ventricular diastole and the pressure within them falls
- AV valves open and blood flows from both atria into the ventricles
- as the ventricles fill up, the pressure rises and the AV valves snap shut