Control Of The Heart

Question 1

What part of the nervous system control involuntary activities of internal muscles/glands

Answer 1

Automatic NS

Question 2

What i the automatic NS made up of

Answer 2

Sympathetic and parasympathetic NS

Question 3

Role of sympathies nervous system in controlling the heart

Answer 3

• Secretes a neurotransmitter noradrenaline into sinoatrial node of the heart and speeds it up
• SNOR

Question 4

Role of the parasympathetic NS in controlling the heart

Answer 4

Secretes a neurotransmitter acetylcholine into sinoatrial node of the heart and slows it down

Question 5

Define myogenic

Answer 5

Contractions is initiated from within muscle itself, rather than from nerve impulses from outside

Question 6

Define sinoatrial node

Answer 6

• Impulses generating tissue located in the right atrium of the heart
• where heart begins to beat
• pacemaker

Question 7

Atrioventricular septum

Answer 7

Layers of non conductive tissue between atria and ventricles

Question 8

Bundle of his / purkyne

Answer 8

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

Question 9

Are cardiac muscles mygenic

Answer 9

Yes meaning they beat spontaneously without nervous stimulation

Question 10

Stage 1 of electrical activity in the heart

Answer 10

• SAN initiates electrical impulses in the right atrium
• determine the heart beat

Question 11

Stage 2 of electrical activity in the heart

Answer 11

• impulses pass over atria cause them both to contract
• atrial systole

Question 12

Stage 3 of electrical activity in the heart

Answer 12

Non conductive connective tissue (atrioventricular septum) prevent impulses passing to ventricles

Question 13

Stage 4 of electrical activity in the heart

Answer 13

Impulse enters atrioventricular node and is delayed allowing ventricles to fill with blood

Question 14

Stage 5 of electrical activity in the heart

Answer 14

Impulse move from atrioventricular node between ventricles via budge of his to the bottom (apex) of the heart

Question 15

Stage 6 of electrical activity in the heart

Answer 15

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

Question 16

What is resting heart rate for a human

Answer 16

70bpm

Question 17

What part of the Bain controls heart rate

Answer 17

Medulla oblongata

Question 18

What centre in the brain increases heart rate

Answer 18

Cardio accelerated centre liked to sinoatrial node by sympathetic NS

Question 19

What centre decrease heart rate

Answer 19

Cardio inhibitor centre lied t sinoatrial node by parasympathetic NS

Question 20

What receptors stimuli the centres

Answer 20

Chemoreceptors and pressure receptors

Question 21

What are chemoreceptors

Answer 21

Found in carotid artery and aorta and detect chemical changes in the blood

Question 22

What are pressure receptors

Answer 22

Found in the carotid armies and orate and respond to pressure changes in the blood

Question 23

Process of cortisol by chemo receptors

Answer 23

• 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

Question 24

Control by pressure receptors

Answer 24

• 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