Control Of The Heart Flashcards
What part of the nervous system control involuntary activities of internal muscles/glands
Automatic NS
What i the automatic NS made up of
Sympathetic and parasympathetic NS
Role of sympathies nervous system in controlling the heart
- Secretes a neurotransmitter noradrenaline into sinoatrial node of the heart and speeds it up
- SNOR
Role of the parasympathetic NS in controlling the heart
Secretes a neurotransmitter acetylcholine into sinoatrial node of the heart and slows it down
Define myogenic
Contractions is initiated from within muscle itself, rather than from nerve impulses from outside
Define sinoatrial node
- Impulses generating tissue located in the right atrium of the heart
- where heart begins to beat
- pacemaker
Atrioventricular septum
Layers of non conductive tissue between atria and ventricles
Bundle of his / purkyne
Between ventricles a bundle of specialised heart fibre that transmit wave of electrical activity from the AV nod to the apex of the heart whee it branches into sampler purkyne fibres
Are cardiac muscles mygenic
Yes meaning they beat spontaneously without nervous stimulation
Stage 1 of electrical activity in the heart
- SAN initiates electrical impulses in the right atrium
- determine the heart beat
Stage 2 of electrical activity in the heart
- impulses pass over atria cause them both to contract
- atrial systole
Stage 3 of electrical activity in the heart
Non conductive connective tissue (atrioventricular septum) prevent impulses passing to ventricles
Stage 4 of electrical activity in the heart
Impulse enters atrioventricular node and is delayed allowing ventricles to fill with blood
Stage 5 of electrical activity in the heart
Impulse move from atrioventricular node between ventricles via budge of his to the bottom (apex) of the heart
Stage 6 of electrical activity in the heart
Impulses moves up ventricle via smaller fibres of the purkyne tissue and causes both ventricles to contract ( ventricular systole) from the apex of the heart to expel all blood out the heart
What is resting heart rate for a human
70bpm
What part of the Bain controls heart rate
Medulla oblongata
What centre in the brain increases heart rate
Cardio accelerated centre liked to sinoatrial node by sympathetic NS
What centre decrease heart rate
Cardio inhibitor centre lied t sinoatrial node by parasympathetic NS
What receptors stimuli the centres
Chemoreceptors and pressure receptors
What are chemoreceptors
Found in carotid artery and aorta and detect chemical changes in the blood
What are pressure receptors
Found in the carotid armies and orate and respond to pressure changes in the blood
Process of cortisol by chemo receptors
- exercise = more co2 = more respiration
- more co2 in blood = lowered, more acidic this is detected by chemoreceptors in carotid artery and aorta
- impulses sent more frequently to centre in the medulla oblongata via sensory neurones
- impulses sent down sympathies nerves more frequently
- noradrenaline secreted into sinoatrial node which increases rate of production of electrical waves
- heart rate increases
- increased blood flow -more blood flow to lungs = more co2 removed
- co2 and ph levels return to normal
Control by pressure receptors
- increase in blood pressure detected by pressure receptors in aorta and carotid artery
- increase in nerve impulses sent to cardiovascular centre in the bran via sensory neurones = decrease in heart rate
- increase in nerve impulses sent down parasympathetic nerve
- acetylcholine s secreted into the sinoatrial node of the heart which decreases heart rate
