Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
47 Cards in this Set
- Front
- Back
What is the most distinctive feature of a neuron?
|
|
|
Motor neuron
|
Soma in the spinal cord; receives excitation through dendrites and conducts impulses along axon to a muscle. |
|
Sensory neuron |
Specialized at one end to be highly sensitive to a particular type of stimulation (light, sound, touch). Conducts touch information from skin to spinal cord. |
|
Dendrites |
Greater surface area- more info can receive. |
|
Cell body
|
Responsible for metabolic work of neuron. Covered with synapses on its surface in many neurons. |
|
Axons |
Thin fiber of a neuron responsible for transmitting nerve impulses toward other neurons, organs and muscles. Myelin sheath- insulated material that contains interruptions known as nodes of Ranvier. Presynaptic terminals at the end points of an axon release chemicals to communicate with other neurons. |
|
Two kinds of cells in the nervous system:
|
|
|
Structures of a neuron: |
|
|
Membrane |
|
|
Nucleus
|
Contains the chromosomes. |
|
Mitochondria |
Performs metabolic activities and provides energy that the cell requires.
|
|
Ribosomes |
|
|
Endoplasmic reticulum |
|
|
Afferent axon
|
|
|
Efferent axon |
Carrying information away from a structure. |
|
Interneurons/ intrinsic |
Dendrites and axons are completely contained within a single structure. |
|
Astrocytes |
Type of glia that helps synchronize activity of an axon by wrapping around the presynaptic terminal and taking up chemicals released by the axon. |
|
Microglia |
|
|
A branching fiber that forms the information- receiving pole of the nerve cell.
|
Dendrite. |
|
Name the correct order of transmission of information to a neuron? |
Dendrite- cell body- axon |
|
What does myelin cover?
|
Some axons in vertebrates; none in invertebrates.
|
|
Where do axons convey information? |
Towards other neurons, an organ or a muscle. (Away from their own cell body.) |
|
The Blood- Brain Barrier
|
-The immune system destroys damaged or infected cells throughout the body. - Because neurons in the brain generally do not generate, it is vitally important for the blood brain barrier to block incoming viruses, bacteria or other harmful material from entering. |
|
Which of the following is most likely to cross the cell membrane by simple diffusion? |
Small, uncharged molecules. |
|
Why do neurons rely so heavily on glucose as their source of nutrition? |
Other fuels do not readily cross the blood-brain barrier. |
|
Presynaptic neuron |
sending signal; to presynaptic terminal (axon terminal) -holds a bunch of tiny synaptic vesicle sacs- each loaded with thousands of molecules of a given neurotransmitter. |
|
Postsynaptic neuron |
receiving cell; accepts neurotransmitters in the receptor region usually on dendrite or cell body itself.
|
|
Why does the brain need thiamine (vitamin B1)?
|
As a building block for making proteins. |
|
Resting Neuron
|
Outside the membrane contains positively charged sodium ions (more of these). Inside contains positive potassium ions mingled with bigger negatively charged proteins. |
|
Resting Membrane Potential
|
-70 mV |
|
Polarized
|
Neuron has negative membrane potential.
|
|
Sodium Potassium Pump
|
Different charges- electrochemical gradient- nature doesn't like this. |
|
Ion channels
|
1. Voltage gated channels 2. Ligand gated channels 3. Mechanically gated channels |
|
Voltage gated channels |
open and close in response to changes in membrane potential. |
|
ligand gated channels |
open with a neurotransmitter- latches onto receptor (serotonin, hormones) |
|
Mechanically gated channels
|
open in response to physical stretching of membrane. |
|
Graded potential
|
Only a few channels open and only a little sodium enters the cell= little change in membrane. |
|
Action potential
|
depolarize resting neuron. |
|
Repolarization |
voltage gated potassium ions open up- potassium ions flow out to attempt rebalance charges. |
|
Hyperpolarization
|
voltage briefly drops to -75mV before all gates close and sodium potassium pumps take over and bring things back to resting level. |
|
Refractory period |
an axon cannot respond to any other stimulus- prevent signals from traveling in both directions down axon at once. |
|
Initial threshold
|
-55mV |
|
Peak depolarization |
40 mV |
|
Conduction velocity |
speed |
|
Electrical synapses |
immediate |
|
Chemical synapses |
More precise/ selective, take more time, used more often, more control, much more abundant. sends signals to certain recipients.
|
|
|
|