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)
During cell REPOLARISATION, the Sodium-Potassium ATP Pump moves ions in & out of the cell. What are the substances moving in & out?
REPOLARISATION- Sodium-Potassium ATP Pump:
- 3x Sodium OUT of cell
- 2x Potassium INTO cell
During cell REPOLARISATION, the Calcium ATP Pump moves ions in &/or out of the cell. What are the substances moving in &/or out?
REPOLARISATION- Calcium ATP Pump:
- Moves Calcium OUT of cell
During cell REPOLARISATION, the Sodium Calcium Exchanger Pump moves ions in &/or out of the cell. What are the substances moving in &/or out?
REPOLARISATION- Sodium Calcium Exchanger Pump:
- 1x Calcium OUT of cell in exchange for…
- 3x Sodium INTO cell
During cell REPOLARISATION, the Sodium Hydrogen Proton Exchanger Pump moves ions in &/or out of the cell. What are the substances moving in &/or out?
REPOLARISATION- Sodium Hydrogen Proton Exchanger Pump:
- 1x Hydrogen OUT
- 1x Sodium IN
Cell Depolarisation & Repolarisation allows for the generation of electrical signals in the heart. However, this doesnt cause muscular contraction of the heart. What is the name of the cellular process that allows the heart to contract?
‘Excitation Contraction Coupling’ is the name of the process which generates muscular cell contraction
There are 2 key steps in ‘Excitation Contraction Coupling’ (aka generation of cardiac muscle cell contraction). What are these 2 steps?
‘Excitation Contraction Coupling’ Generation of cardiac muscle cell contraction)-
1) Calcium outside the cell stimulates Transverse Tubules (T-Tubules) to open & allow calcium to flow INTO the cell
2) Calcium stimulates the Sarcoplasmic Reticulum (within the cell) to ‘explode’ and release a massive burst of calcium within the cell.
= As a result, calcium stimulates muscle fibres ‘Actin’ and ‘Myosin’ to contract
What ion is required to stimulate muscle fibres (eg. Actin & Myosin) to contract (& cause cardiac contraction/the heart to beat)?
CALCIUM is required to stimulats muscle fibres ‘Actin’ and ‘Myosin’ to contract
What is the name of the 2 muscle fibres within the heart that allow for cardiac contraction?
2 Muscle Fibres in the Heart=
1) Actin
2) Myosin
What is the difference between inotrope, chronotrope, and dromotrope?
Inotrope= Strength of contraction
Chronotrope= Rate of contraction
Dromotrope= Conduction velocity
What are 3 types of Catecholamines?
Catecholamines:
1- Adrenaline
2- Noradrenaline
3- Isoprenaline
What 5 key things does Adrenaline do?
Adrenaline-
⇧ Inotropy (contraction strength)
⇧ Chronotropy (increase contraction rate)
⇧ Dromotropy (increase conduction velocity/depolarisation speed/speed of impulses from SA to AV Node to thus increase contraction rate)
⇧ Cardiac Irritability
⇧ Hydrogen
What is 1 example of a Non-catecholamine drug?
Non-catecholamine:
= Metaraminol
What is 1 example of an Alpha 1 Agonist drug?
Alpha 1 Agonist:
= Phenylephrine
Catecholamines, Non-catecholamines, Alpha-1 Agonists and Glucagon are all types of _____?
Catecholamines, Non-catecholamines, Alpha-1 Agonists and Glucagon are all types of Sympathomimetics
What are the 4 categories of Sympathomimetics?
Sympathomimetics:
1- Catecholamines
2- Non-catecholamines
3- Alpha 1 Agonists
4- Glucagon
What are 2 examples of Parasympatholytics?
Parasympatholytics:
1- Atropine
2- Glycopyrrolate
What type of nerve(s) does Atropine block in order to treat Bradycardia and speed up the heart?
Atropine blocks stimulation through the vagus nerve. This subsequently speeds the heart up
What is the mechanism of action of Normal Saline Solution?
Normal Saline Solution:
Expands intravascular volume without disturbing ion concentration or causing significant fluid shifts between intracellular, intravascular, and interstitial space. The chloride in normal saline solutions acts as a buffering agent in lungs and body tissue, where it helps to facilitate binding between oxygen and carbon dioxide to haemoglobin
___% of Normal Saline Solution will end up in the interstitial space surrounding the cells.
75% of Normal Saline Solution will end up in the interstitial space surrounding the cells
Before giving another bolus of Normal Saline, what 3 things do we need to check for?
Before administering another bolus of Normal Saline check for:
1- Blood Pressure
2- Chest auscultation to check for pulmonary oedema
3- Any signs of Increasing Intracranial Pressure (Cushing’s Triad- Bradycardia, Irregular RR, Widening pulse pressure)
What is the difference between Normal Saline and Compound Sodium Lactate (Ringers Lactate/Hartmanns)
Normal Saline=Crystalloid solution containing 0.9% Sodium Chloride
Compound Sodium Lactate= Crystalloid solution containing Sodium, Chloride, Potassium, Calcium, & Lactate (in the form of sodium lactate)
The ‘___ index’ can be used to determine when fluids need to be administered
The ‘Shock index’ can be used to determine when fluids need to be administered
When using the ‘Shock Index’ to determine when to administer fluids, what is the value we look for in adults to indicate they are in shock and needing fluids?
Shock Index for adults= <0.9= shock= administer fluids
The ‘Shock index’ can be used to determine when fluids need to be administered. How is this index calculated?
Shock Index= Heart Rate/ Systolic Blood Pressure
What are the indications for supplemental oxygen? (hint- there are 7)
Indications for Supplemental Oxygen:
1- Shock
2- Sepsis
3- Major Trauma
4- Cardiac Arrest
5- Anaphylaxis
6- Carbon Monoxide Poisoning (despite often having spo2 of 100%)
7- Cyanide poisoning
What are the contraindications for supplemental oxygen? (hint- there are 5)
Contraindications for Supplemental Oxygen:
1- Paraquat poisoning
2- Concurrent Bleomycin (an antibiotic given to patients with cancer)
3- Neonates
4- Proximal to combustion/fire
5- Prolonged administration (as it can cause CNS toxicity & lung damage)
What are the 3 types of electrolytes which paramedics can administer (in some states)?
Electrolytes:
1- Calcium Gluconate
2- Magnesium Sulphate
3- Sodium Bicarbonate
