Module 1 - What is a nervous system? Flashcards
Outline the four main principles of the nervous system.
- The nervous system is made up of a network of cells specialized to sense inputs
- The neurons can propagate information in the form of electrical impulses
- Neurons convey information to each other via chemical and electrical synapses
- The nervous system generates outputs that integrate sensory information to elicit behavioural and/or physiological responses
Where can signals come from?
Outside world or inside world
Give examples of inputs originating from the outside world.
Light, chemicals, temperature, gravity, touch
Give examples of inputs originating from the inside world
internal states, signals from other cells
Give two examples of electrical impulses
Graded and action potentials
True or false: graded potentials can code the strength of a stimulus
true
When is an action potential generated?
When graded depolarization is strong enough, triggering excitable neurons (ex. Ganglion cells) to generate an AP
What is an action potential?
All or none electrical response that travels very fast along nerve fibres.
Why do graded potentials “fizzle out” over time?
Ions/charges that give rise to GPs are quickly depleted
What are the two advantages of graded potentials?
- Carry intensity of stimuli
- can be excitatory (depolarizing) or inhibitory (hyperpolarizing).
What drives membrane depolarization?
sodium voltage-gated ion channels
What drives membrane repolarization/hyperpolarization?
potassium voltage-gated ion channels
What are the two key functions of action potentials in neurons?
- Transmit signals along axons
- Trigger pre-synaptic Ca2+ influx at nerve terminals, through voltage gated ion channels, causing the regulated release of neurotransmitters
What is the key function of an action potential in muscles?
Driving contractions
What is the key function of an action potential in endocrine cells?
Driving secretion of hormones
