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 PSNS postganglionic neurons release:

Answer 2

Acetylcholine - they are cholinergic

Question 3

What do SNS 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

Define an artery

Answer 15

Muscular walled tubes, carrying oxygenated blood away from the heart

Question 16

Define a vein

Answer 16

Thinner walled tubes carrying oxygen poor blood back towards the heart

Question 17

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

What are the issues with the other type of circuit?

Answer 17

Parallel system

Series has high resistance, interdependence, decreased oxygenation

Question 18

Mean diastolic and systolic pressure?

Answer 18

15-30mmHg

100-140mmHg

Question 19

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

Answer 19

A-V is tricuspid and mitral valves, other is semilunar valves

Question 20

Purpose of cardiac frame?

Answer 20

Anchor and stabilise valves to the heart’s interior walls, while keeping valves in the round shape.

Also provides electrical insulation and separates atria from ventricles.

Question 21

What are systole and diastole?

Answer 21

Systole contracting, diastole relaxing

Question 22

How to calculate length of cardiac cycle from bpm?

Answer 22

60/bpm

Question 23

Five brief steps to cardiac cycle:

Answer 23

• ventricles passively fill, atria prime
• ventricles are full, aortic and pulmonary arteries open
• 60% of blood ejected in systole
• ventricles relax, backpressure from arteries close semilunar valves
• diastole begins as atria and ventricles fill again

Question 24

Define the Frank-Starling mechanism

Answer 24

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

(More the heart is stretched, the more force of contraction, more blood pumped into aorta)