Chapter 2 Flashcards
Central Nervous System (CNS)
contains the brain and spinal cord
Neurons
specialized cell that …
-convey sensory into to the brain
-carry out operations involved in thought, feeling, and action
-transmits commands out into the body
Dendrites
extensions that branch out from the cell body
Soma (cell body)
contains nucleus and organelles
Axon hillock
a site for action potential initiation
Axon
carries info to other neurons and to organs
Myelin Sheath
-made up of fatty substances (oligodendrocytes)
-allows electric impulses to transmit quickly along the axon
Axon Terminals (End Bulbs)
release neurotransmitters to communicate with neurons, muscles, and organs
Example of Multipolar Neurons
-motor neurons
-inter neurons
Interneuron
connect one neuron to another in same part of brain or spinal cord
Unipolar Neurons
-sensory neuron
-where axon leaves soma at one location
Bipolar Neurons
Sensory neuron where axon terminals extends on both sides
Motor Neuron
conducts messages from brain and spinal cord to muscles and organs
Sensory Neuron
carries information from body and world to brain and spinal cord
What is the most critical factor in a neuron’s ability to communicate?
Neural Membrane (skin)
Neural Membrane contains…
Lipids and Proteins
Neural Membrane is…
selectively permeable
Polarization
difference in electrical charge between the inside and outside of the cell
Voltage
Difference in electrical charge
Resting Potential
-difference in charge between the inside and outside of the membrane of a neuron at rest
-typically around 70mV
At rest a neuron’s outside contains…
mostly sodium (Na+) and chloride (Cl-) ions
At rest a neuron’s inside contains …
mostly potassium (K+) and organic anions
Sodium-potassium pump
moves 3 Na+ outside for every 2 K+ inside
Depolarization
-caused by a change in ion balance
-moving closer to 0mV
If depolarization reaches threshold (-60mV) at axon hillock…
an action potential will be triggered
Steps of Action Potential
- Membrane depolarized past threshold through a series of local or graded potentials
- Voltage-gated Na channels open, Na enter around +30mV
- Na channels close, Voltage gated K channels open, K exists. The cell hyperpolarizes around -80mV
- K channels slowly close and membrane returns to resting potential
Is a local or graded potential decremental or non-decremental?
Decremental- magnitude decreases with distance and time
Is an action potential decremental or non-decremental?
Non-decremental: message travels over long distances at the same amplitude
Action Potential All or None Law
always occur at full strength or not at all