Lecture 2 - Neurotransmitters and Heart Anatomy Flashcards
(25 cards)
What neurotransmitter do all preganglionic neurons release, in both SNS and PSNS:
Acetylcholine - they are cholinergic
What do Parasympathetic postganglionic neurons release:
Acetylcholine - they are cholinergic
What do sympathetic NS postganglionic neurons release:
Norepinephrine - they are adrenergic
What is acetylcholine neutralised by?
Acetylcholinesterase
What is norepinephrine neutralised by?
Re-uptake, diffusion, degradation by monoamine oxidase (seconds)
You can also have epinephrine in the blood that is degraded by liver (minutes)
Acetylcholine released from PSNS nerves excites two receptors which are:
Nicotinic and Muscarinic
Where are nicotinic receptors found?
In synapses between pre- and post- ganglionic neurons, and at the neuromuscular junction
What type of receptor are nicotinic receptors?
Ligand gated ion channels
Where are muscarinic receptors found?
On all effector cells stimulated by PSNS postganglionic neurons
What type of receptor are muscarinic receptors?
G protein coupled receptors
Norepinephrine stimulates:
Alpha and beta adrenergic receptors
Where are alpha receptors located and what’s their purpose?
Blood vessels, vasoconstriction
What is the function of beta 1 and 2 receptors?
Beta 1 - increase in heart rate and contractility
Beta 2 - bronchial dilation, blood vessel dilation, glycogenolysis
What is the stress response, AKA fight or flight?
Mass sympathetic discharge to prepare body for vigorous activity
What does the stress response do physically in the body?
Increase in arterial pressure, heart rate and contractility, blood flow to muscles, blood glucose, metabolic rate, muscle strength, mental activity and blood coagulation
Define and artery
Muscular walled tubes, carrying oxygenated blood away from the heart
Define a vein
Thin walled tubes carrying oxygen-depleted blood from periphery toward heart.
Is the circulatory system akin to a parallel or series circuit?
What are the issues with the other type of circuit?
Parallel.
Series system = high resistance, interdependence, decrease oxygenation to any successive downstream organ
Mean diastolic and systolic pressure?
120/80
Name the two A-V valves and the other type of valve present:
Tricuspid and Mitral.
Semilunar
Purpose of cardiac frame?
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.
What are systole and diastole?
S: Ventricular muscle is stimulated by action potential and is contracting
D: ventricular muscle re-establishing Na+/K+/CA++ gradient and is relaxing
How to calculate length of cardiac cycle from bpm?
60 divided by bpm
Five brief steps to cardiac cycle:
- Atrial contraction forcing blood into ventricles
- Ventricular contraction, closes AV valves
- Semilunar valves open, blood is ejected
- Semilunar valves close, blood flows into atria
- Chambers relax, passive filling of ventricles
