Action Potentials (Nervous System 2) Flashcards
____ are the basic units of the Nervous System
Neurons
CC Neuron Anatomy: What are the 6 components of a Neuron
1.) Cell Body
2.) Axon Hillock
3.) Axon
4.) Dendrites
5.) Synaptic Terminals
6.) Nerves
What is the Axon Hillock?
- Base of the Axon, site of signal production
What component passes on signals produced by the Axon Hillock?
Axons
What are two functions of Dendrites?
1.) Receive Information
2.) Increase Surface Area
What are Nerves?
Axons of many neurons held together by connective tissue
List the 3 Types of Neurons and their functions.
1.) Affruent Neurons - Sensory - Receive signals
2.) Interneurons - Integration - Interpret signals
3.) Efferent Neurons - Motor - Target the Muscle or Endocrine Gland
Saying a Membrane is polarized means:
There is a difference in electrical charge on either side of the membrane
_____ ____ can rapidly change Membrane Potential
Excitable Cells
What is the membrane potential of a resting cell?
-70mV (millivolts)
Resting Potential is achieved by these two things.
1.) Sodium/ Potassium Pump
2.) Ion Channels
In a sodium/ potassium pump, ___ Na+ ions are expelled, and ___ K+ ions are taken in
3 Na+ Ions are removed( Na, get out)
2 K+ ions are taken in( K, come in)
Ion Channels are an example of ____ diffusion
Facilitated
Facilitated Diffusion requires a protein channel
What type of Ion Channel do we cover? What happens?
- Leaky K+ channels
Potassium is pumped in, diffuses out
Calcium is pumped in, cannot diffuse out
What are two ways in which membrane potential can change?
1.) Hyperpolarization (further from 0, more negative - below -70)
2.) Depolarization (closer to 0, more positive - above -70)
What is the threshold for most neurons? What happens when the threshold is crossed
(-55mV). Depolarization must occur to cross the threshold
- Once the threshold is crossed, voltage-gated channels are activated (membrane proteins that allow for passage of specific ions)
SEQ Action Potential pathway
- At resting potential (-70mV), voltage-gated channels are closed
- Large Stimuli cause depolarization. Must be large stimulus to cross the threshold.
- Depolarization crosses the threshold and activates Sodium (Na+) channels (-55mV reached)
- Na+ channels cause rapid depolarization (MP reaches +35mV)
- Na+ channels close, membrane becomes impermeable to Na
Voltage gated K+ channels open at 30mv, K+ diffuses out, repolarization occurs
K+ channels close, Membrane potential returns to resting potential (-70mV)
-
Describe two types of Conduction.
1.) Continuous Conduction - occurs in unmyelinated axons, gray matter
Good for Short Distances
2.) Saltatory Conduction - Occurs in myelinated axons (White matter)
Good for Long Distances
