Topic 3: Nervous System 1 - Neurons + Electrical Properties of Cells Flashcards
What does it mean by “neurons are excitable?”
responsive to stimuli
What occurs when neurons are stimulated? (3)
- stimulated usually on cell body or dendrites
- an electrical impulse may be generated and propagated along the axon
- called a nerve impulse
What causes electrical properties of cells? (2)
- ionic concentration differences across membranes (gradients)
- Permeability of cell membrane to ions
What are the four important ions?
- K+
- Na+
- Cl-
- Ca++
what are large negatively charged organic ions? (2)
org-
- non-diffusable proteins
Diagram of cell with important ions
What is the concentration of sodium and potassium due to?
- due to and maintained by the activity of Na+/K+ - ATPase pump in cell membrane
What is the concentration of calcium due to?
- due to various transporters in cell and ER membranes
What is Chlorine repelled by, and what does it cause?
- repelled by org- (large, - organic ions)
- therefore its [] is higher outside of cell than inside
Where do org- stay?
inside the cell
What does permeability of cell membrane to ions determined by?
- determined by ion channels
- bc ions diffuse through them down CG
what are non-gated channels? (2)
- always open
- more K+ than Na+, so cell membrane is more permeable to K+ at rest (no stimulus)
Why are non-gated channels important?
- these channels (esp. K+ is more numerous) establish the resting membrane potential (RMP)
What are gated ion channels?
- not involved at rest
- open in response to stimuli
What are voltage gates?
- Membrane voltage changes
What are chemicals gates for?
- chemicals, like binding of hormone or neurotransmitter
What are thermal gates for?
temperature
What are mechanical gates for?
- mechanical deformation