Section 2C

Question 0

What is the neurotransmitter in Parasympathetic Nervous System and what receptors does it target

Answer 0

Acetylcholine

Muscarinic Receptors

Question 1

The SA Node, Atria and AV Node have what type of innervation

Answer 1

Parasympathetic Vagal innervation

Question 2

What is mechanism in the Negative Chronotropic Effect and what 2 outcomes occur because of it

Answer 2

Mechanism: Decreases If, the inward Na current that is responsible for Phase 4 depolarization in the SA Node

1. Heart rate decreases by decreasing phase 4
2. Fewer action potentials occur per unit time because the threshold is reached slower and therefore, less frequently

Question 3

What 4 things in the heart have sympathetic nervous system innervation?

Answer 3

1. SA Node
2. Atria
3. AV Node
4. Ventricles
   - (T1-T4 innervation)

Question 4

What is the neurotransmitter and receptors involved in Sympathetic nervous system

Answer 4

• Norepinephrine

- B1receptors

Question 5

What is the mechanism in Positive Chronotropic effect and what 2 outcomes?

Answer 5

Mechanism: Increased If, the inward Na current that is responsible for Phase 4 depolarization in the SA Node

1. More action potentials per unit time, more frequent because threshold is reached more quickly
2. Increases HR by increasing Phase 4 depolarization

Question 6

What 2 hormones can act like the sympathetic nervous system in producing a Positive Chronotropic effect

Answer 6

1. Epinephrine/NE (important during exercise)

2. Thyroid hormones (T3 and T4) (important at rest)

Question 7

What ion can affect the HR

Answer 7

Postassium

Hyperkalemia and Hypokalemia can both decrease the HR

Question 8

• Age, gender, physical fitness and temperature also affect HR

Answer 8

Sure can