Lecture 2 - Neurotransmitters and Heart Anatomy

Question 1

What neurotransmitter do all preganglionic neurons release, in both SNS and PSNS:

Answer 1

Acetylcholine - they are cholinergic

Question 2

What do Parasympathetic postganglionic neurons release:

Answer 2

Acetylcholine - they are cholinergic

Question 3

What do sympathetic NS postganglionic neurons release:

Answer 3

Norepinephrine - they are adrenergic

Question 4

What is acetylcholine neutralised by?

Answer 4

Acetylcholinesterase

Question 5

What is norepinephrine neutralised by?

Answer 5

Re-uptake, diffusion, degradation by monoamine oxidase (seconds)

You can also have epinephrine in the blood that is degraded by liver (minutes)

Question 6

Acetylcholine released from PSNS nerves excites two receptors which are:

Answer 6

Nicotinic and Muscarinic

Question 7

Where are nicotinic receptors found?

Answer 7

In synapses between pre- and post- ganglionic neurons, and at the neuromuscular junction

Question 8

What type of receptor are nicotinic receptors?

Answer 8

Ligand gated ion channels

Question 9

Where are muscarinic receptors found?

Answer 9

On all effector cells stimulated by PSNS postganglionic neurons

Question 10

What type of receptor are muscarinic receptors?

Answer 10

G protein coupled receptors

Question 11

Norepinephrine stimulates:

Answer 11

Alpha and beta adrenergic receptors

Question 12

Where are alpha receptors located and what’s their purpose?

Answer 12

Blood vessels, vasoconstriction

Question 13

What is the function of beta 1 and 2 receptors?

Answer 13

Beta 1 - increase in heart rate and contractility

Beta 2 - bronchial dilation, blood vessel dilation, glycogenolysis

Question 14

What is the stress response, AKA fight or flight?

Answer 14

Mass sympathetic discharge to prepare body for vigorous activity

Question 15

What does the stress response do physically in the body?

Answer 15

Increase in arterial pressure, heart rate and contractility, blood flow to muscles, blood glucose, metabolic rate, muscle strength, mental activity and blood coagulation

Question 16

Define and artery

Answer 16

Muscular walled tubes, carrying oxygenated blood away from the heart

Question 17

Define a vein

Answer 17

Thin walled tubes carrying oxygen-depleted blood from periphery toward heart.

Question 18

Is the circulatory system akin to a parallel or series circuit?

What are the issues with the other type of circuit?

Answer 18

Parallel.

Series system = high resistance, interdependence, decrease oxygenation to any successive downstream organ

Question 19

Mean diastolic and systolic pressure?

Answer 19

120/80

Question 20

Name the two A-V valves and the other type of valve present:

Answer 20

Tricuspid and Mitral.

Semilunar

Question 21

Purpose of cardiac frame?

Answer 21

Anchors & stabilises valves to wall of heart,
Keeps AV valves round,
Provides point of insertion for bundles and keeps atria and ventricles separate,
Acts as an electrical insulator.

Question 22

What are systole and diastole?

Answer 22

S: Ventricular muscle is stimulated by action potential and is contracting

D: ventricular muscle re-establishing Na+/K+/CA++ gradient and is relaxing

Question 23

How to calculate length of cardiac cycle from bpm?

Answer 23

60 divided by bpm

Question 24

Five brief steps to cardiac cycle:

Answer 24

1. Atrial contraction forcing blood into ventricles
2. Ventricular contraction, closes AV valves
3. Semilunar valves open, blood is ejected
4. Semilunar valves close, blood flows into atria
5. Chambers relax, passive filling of ventricles

Question 25

Define the Frank-Starling mechanism

Answer 25

“Within physiological limits, the heart pumps all the blood that returns to it”