What is the neurotransmitter in Parasympathetic Nervous System and what receptors does it target
Acetylcholine
Muscarinic Receptors
The SA Node, Atria and AV Node have what type of innervation
Parasympathetic Vagal innervation
What is mechanism in the Negative Chronotropic Effect and what 2 outcomes occur because of it
Mechanism: Decreases If, the inward Na current that is responsible for Phase 4 depolarization in the SA Node
- Heart rate decreases by decreasing phase 4
- Fewer action potentials occur per unit time because the threshold is reached slower and therefore, less frequently
What 4 things in the heart have sympathetic nervous system innervation?
- SA Node
- Atria
- AV Node
- Ventricles
- (T1-T4 innervation)
What is the neurotransmitter and receptors involved in Sympathetic nervous system
- Norepinephrine
- B1receptors
What is the mechanism in Positive Chronotropic effect and what 2 outcomes?
Mechanism: Increased If, the inward Na current that is responsible for Phase 4 depolarization in the SA Node
- More action potentials per unit time, more frequent because threshold is reached more quickly
- Increases HR by increasing Phase 4 depolarization
What 2 hormones can act like the sympathetic nervous system in producing a Positive Chronotropic effect
- Epinephrine/NE (important during exercise)
2. Thyroid hormones (T3 and T4) (important at rest)
What ion can affect the HR
Postassium
Hyperkalemia and Hypokalemia can both decrease the HR
- Age, gender, physical fitness and temperature also affect HR
Sure can
