Semester 1 Final: Nervous System Flashcards
dendrites
receive signals from sensor cells & other neurons
cell body
contains main organelles and nucleus
axon hillock
the region where the action potential is generated
axon
transmits the signal (action potential) to other cells
myelin sheath
insulating cells surrounding the axon that increase conduction speed of action potential
synaptic (axon) terminal
the site where neurotransmitters are released into the synapse to communicate with other cells
synapse/synaptic cleft
gap between two neurons where communication through neurotransmitters occurs
types of supporting cells
glial cells (astrocytes, radial glial cells, oligodendrocytes/Schwann cells)
astrocytes
regulate the concentration of ions and neurotransmitters and forms the blood-brain barrier in the CNS
glial cells
responsible for structural support & functioning of neurons
Oligodendrocytes
form the myelin sheath in the CNS
Schwann Cells
form the myelin sheath in the PNS
neurotransmitters
chemical messengers
radial glia
CNS, lay the foundation for the development neural tube in fetuses
resting potential
-70mV
-results from differences in ionic concentration between the inside and outside of the cell
-higher concentration of Na+ on the outside
-higher concentration of K+ on the inside
Na+/K+ pumps are used to maintain resting potential once it has been achieved
steps of action potential
- resting potential
- depolarization
- rising phase
action potential - falling phase (repolarization)
- undershoot
Depolarization
stimulus depolarizes membrane opening some gated Na+ channels & allowing a small increase in Na+
Rising phase
threshold (-55mV) is crossed opening most gated Na+ channels & inside of membrane becomes positive as Na+ rushes in
Falling phase/Repolarization
Na+ gated channels close & K+ gated channels open allowing K+ ions to exit which restores the negative charge
Undershoot/Hyperpolarization
K+ gated channels cause temporary extra negative charge until the membrane returns to resting potential as Na+ pass through open channels
- after -80mV, K+ gated channels close and the Na+/K+ pump restores resting potential
Chemical Communication
- Action potential reaches synaptic terminal & opens voltage-gated calcium channels
- Vesicles fuse and release neurotransmitters into synaptic cleft via exocytosis
- Neurotransmitters bind to ligand-gated ion channels on postsynaptic cell & opens channels
- Excitatory postsynaptic potentials
- Inhibitory postsynaptic potentials
- Neurotransmitters degraded (by enzymes) or are recycled to presynaptic cell (reuptake)
Central Nervous System (CNS)
- Consists of the brain & spinal cord
* Integration center for complex behaviors
Peripheral Nervous System (PNS)
- Consists of cranial & spinal nerves along with associated ganglia
- Transmits information to and from the CNS
PNS: somatic nervous system
the voluntary system because it is under conscious control to move skeletal muscles in response to external stimuli
PNS: autonomic nervous system
the involuntary system because it regulates internal conditions by contracting smooth & cardiac muscles
parasympathetic: rest and digest
sympathetic: fight or flight response
ion channels
Either *Always open
or
- Gated until opened by stimuli
- Ligand-gated ion channels
- Voltage-gated ion channels
- Selective for specific ions
