Wk5- incomplete Flashcards
The heart is controlled by 3 groups of cells. What are these 3 groups?
Control of the Heart:
1- Automaticity Cells (Pacemaker cells)
2- AV Node Cells
3- Contracticle Cells
The Autonomic Nervous System controls the electrical conduction & contractility of the heart. What are the 2 main sub-sections of the Autonomic NS?
Autonomic Nervous System=
1- Parasympathetic NS
2- Sympathetic NS
What is the physiological pathway that allows the Parasympathetic Division of the Autonomic Nervous System to convey a message from the BRAIN to the HEART to slow it?
AUTONOMIC NS/ PARASYMPATHETIC NS CONTROL OF THE HEART:
1. Stimuli eg. Deep Breathing
2. Brain
3. Medulla Oblongata (base of brain stem)
4. Cardiac Inhibitory Centre
5. Parasympathetic Nerves (specifically left & right vagus nerves)
6. Left & Right Vagus Nerve → Cardiac Plexus → Postganglionic Nerve → Artia (not ventricles*)
7. Postganglionic Nerves stimulate acetylcholine release which activates Muscarinic Receptors in heart
8. Acetylcholine makes heart slower, weaker, more vulnerable to acidosis
What is the physiological pathway that allows the Sympathetic Division of the Autonomic Nervous System to convey a message from the BRAIN to the HEART to speed it up?
AUTONOMIC NS/ SYMPATHETIC NS CONTROL OF THE HEART:
1. Stimuli eg. Rapid Breathing
2. Brain
3. Medulla Oblongata (base of brain stem)
4. Cardiac Acceleratory Centre
5. Sympathetic Nerves
6. Preganglionic Neuron → Sympathetic Chain Ganglia → Postganglionic Nerve→ Atria & Ventricles
7. Postganglionic Nerves stimulate Noradrenaline release which activates Beta 1 Receptors (aka Beta Adrenergic Receptors) in heart
8. Noradrenaline makes the heart quicker, stronger, more resistant to acidosis
What is the name of the LIGAND that the Sympathetic Nervous System stimulates release of to activate Beta 1 receptors to speed up the heart?
Sympathetic Nervous System:
Stimulates release of Noradrenaline which then stimulates Beta 1 receptors to increase HR
What is the name of the LIGAND that the Parasympathetic Nervous System stimulates release of to activate Muscarinic receptors to slow down heart?
Parasympathetic Nervous System:
Stimulates release of Acetylcholine which then stimulates Muscarinic receptors in the heart to decrease HR
What is the name of the RECEPTOR that Noradrenaline activates to speed up the heart? (following sympathetic NS activation)
Noradrenaline activates Beta 1 receptors to increase HR
What is the name of the RECEPTOR that Acetylcholine activates to slow down the heart? (following parasympathetic NS activation)
Acetylcholine activates Muscarinic receptors in the heart to decrease HR
What is the pathway of message transmission from the Cardiac Acceleratory Centre to the Heart?
- Cardiac Acceleratory Centre
- Preganglionic Neuron
- Sympathetic Chain Ganglia
- Postganglionic Nerve
- Noradrenaline
- Beta 1 Receptors
- HR increase
What is the pathway of message transmission from the Cardiac Inhibitory Centre to the Heart?
- Cardiac Inhibitory Centre
- Left & Right Vagus Nerve
- Cardiac Plexus
- Postganglionic Nerve
- Acetylcholine
- Muscurinic Receptors
- HR decrease
What happens during cardiac cell DEPOLARISATION?
DEPOLARISATION=
1. Sodium INTO cell
2. Calcium INTO cell
3. Both join Potassium IN cell
[all 3 are positively charged ions, making the cell more positive]
Does cell DEPOLARISATION make the cell more Positive or more Negative?
Depolarisation makes a cell more POSITIVE (due to an influx of positively charged ions INTO the cell)
If the Sympathetic Nervous System is activated, how does this change what happens during cell DEPOLARISATION?
Sympathetic Nervous System influence on DEPOLARISATION:
= ⇧Sodium Influx
= ⇧ Depolarisation Speed (⇧Dromotropy)
⇧Calcium Influx & ⇧Potassium Efflux
= Shorter Action Potential (Shorter Contraction)
= ⇧ AV Node Conduction (⇧Dromotropy)
= ⇧ Contraction Strength (⇧Inotropy)
If the Parasympathetic Nervous System is activated, how does this change what happens during cell DEPOLARISATION?
Parasympathetic Nervous System influence on DEPOLARISATION:
⇩Na Influx
= ⇩ Depolarisation Speed (⇩Dromotropy)
⇩Calcium Influx
= Longer Action Potential (Longer Contraction)
= ⇩ AV Node Conduction (⇩Dromotropy)
= ⇩ Contraction Strength (⇩ Inotropy)
What are the 4 Voltage Gated Channels which allow movement in & out of cells during Repolarisation?
Repolarisation=
1) Sodium Potassium ATP Pump
2) Calcium ATP Pump
3) Sodium Calcium Exchanger Pump
4) Sodium Hydrogen Proton Exchanger Pump
If the Parasympathetic Nervous System is activated, how does this change what happens during cell REPOLARISATION?
If Parasympathetic NS is Activated, the following effects will occur during REPOLARISATION:
⇩Na Influx
= ⇩ Depolarisation Speed (⇩Dromotropy)
⇩Calcium Influx
= Longer Action Potential (Longer Contraction)
= ⇩ AV Node Conduction (⇩Dromotropy)
= ⇩ Contraction Strength (⇩ Inotropy)
If the Sympathetic Nervous System is activated, how does this change what happens during cell REPOLARISATION?
If Sympathetic NS is Activated, the following effects will occur during REPOLARISATION:
⇧Sodium Influx
= ⇧ Depolarisation Speed (⇧Dromotropy)
⇧Calcium Influx & ⇧Potassium Efflux
= Shorter Action Potential (Shorter Contraction)
= ⇧ AV Node Conduction (⇧Dromotropy)
= ⇧ Contraction Strength (⇧Inotropy)