the major external structures of neurons
Soma
Dendrites
Axon
cell membrane
is a selectively permeable barrier made of phospholipids and proteins that protects the cell, regulates exchange of materials, and enables communication and signaling
glial cells
Supporting cells of the nervous system that insulate, protect, and metabolically support neurons.
how ion distribution is responsible for the cell’s resting potential
–70 mV in neurons — is created and maintained by the uneven distribution of ions across the cell membrane and the selective permeability of the membrane to these ions.
The resting membrane potential of a cell — typically around –70 mV in neurons — is created and maintained by the uneven distribution of ions across the cell membrane and the selective permeability of the membrane to these ions.
Here’s a breakdown of how ion distribution causes this:
- Unequal Ion Concentrations
Potassium (K⁺): High inside the cell, low outside.
Sodium (Na⁺): Low inside, high outside.
Chloride (Cl⁻): High outside, low inside.
Negatively charged proteins (A⁻): Abundant inside, almost absent outside.
This creates chemical concentration gradients — K⁺ wants to leave the cell, and Na⁺ wants to enter.
- Selective Permeability of the Membrane
The cell membrane is much more permeable to K⁺ than to Na⁺ because of leak channels.
K⁺ diffuses out of the cell down its concentration gradient, leaving behind negatively charged proteins and ions.
This movement makes the inside of the cell more negative relative to the outside.
- Electrical Forces and Equilibrium
As K⁺ leaves, the inside becomes negative, which electrically attracts K⁺ back in.
Eventually, the outward chemical force (diffusion) and inward electrical force balance — the point at which this occurs for K⁺ is its equilibrium potential (~–90 mV).
Because Na⁺ also leaks in slightly (and Cl⁻ plays a minor role), the actual resting potential stabilizes at around –70 mV, a compromise between the K⁺ and Na⁺ equilibrium potentials.
- Role of the Sodium–Potassium Pump (Na⁺/K⁺-ATPase)
This pump actively transports 3 Na⁺ out and 2 K⁺ in for each ATP molecule used.
It maintains the ionic gradients that allow diffusion to continue and contributes slightly to the negative charge inside the cell.
Summary
The resting potential results from:
Uneven ion distribution (Na⁺ high outside, K⁺ high inside),
Selective permeability (more K⁺ leaks out than Na⁺ enters),
Active transport (Na⁺/K⁺ pump maintaining gradients).
Together, these create a steady electrical potential difference — the resting membrane potential — essential for nerve impulses and muscle contraction.
differences between local potentials and action potentials
local potentials are (small) activated locally with short changes in voltage following the opening of a legand-gated channel at the cell body.
action potentials are (large) the depolarization created in the axon running along its length.
local potentials
Small localized short-lived change in voltage across the cell membrane following the opening of ligand-gated channels.
action potentials
rapid change in membrane potential, Major depolarization, that is propagated down the length of the axon
divisions of the nervous system
CNS
SNS
ANS
PNS
distinct regions of the CNS
brain and the spinal cord
hind brain
mid brain
forebrain
the division of the cerebral cortex
1) frontal
2) parietal
3) temporal
4) occipital
Differentiate between rat and human brains
What is a neuron?
Nerve cells that form the brain, spinal cord, and nerves that transmit electrical signals throughout the body.
What are the parts of a neuron?
dendrites
soma
axon
synaptic terminal
dendrites
Projections from the soma that receive signals and information from other cells.
soma
Cell body of a neuron, containing all of the organelles needed to maintain the cell.
axon
Long tubular extention from the soma that conducts electrical signals away from the cell body and toward the axon terminals.
synaptic terminal
synaptic terminal (also called a axon terminal or synaptic bouton) is the end point of a neuron’s axon where communication with another cell occurs.
End of an axon that releases neurotransmitters into the synaptic cleft
four types of glial cells
- Oligodendroglia
- Schwann Cells
- Astrocytes
- Microglia
functions of Oligodendroglia glial cells
produce myelin sheath on neuronal axons of the PNS and CNS
resting potential
The difference in the electrical charge inside a neuron at rest compared to the outside. The inside of the cell is more negative, and that potential is −70 mV.
epilepsy
Epilepsy is a neurological disorder of abnormal neuronal firing.
Epilepsy is a neurological disorder characterized by recurrent, unprovoked seizures caused by abnormal electrical activity in the brain.
the functions of the spinal cord
- Transmission of Nerve Impulses
- Reflex Actions
- Coordination and Communication
- Neural Integration
the diencephalon
a region of the brain located between the cerebrum and the brainstem. It acts as a relay and control center for sensory information and many autonomic (involuntary) functions.
INCLUDES THALAMUS AND HYPOTHALAMUS
functions of the diencephalon
relay and control center for sensory info and ANS functions.
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Unit 131
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Unit 228
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Unit 322
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Unit 414
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Unit 575
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Unit 654
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Unit 736
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Unit 845
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Unit 9 Addiction27
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Unit 10 Alcohol22
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Unit 11 Opioids13
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Unit 12 Psychomotor Stimulants21
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Unit 13 Caffiene Nicotine49
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Unit 14 Cannibis62
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Unit 15 Psychedelics60
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Unit 16 Inhalants Ghb Asa45
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Unit 17 Anxiety86
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Unit 18 Affective Disorders60
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Unit 19 Schizophrenia61
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Unit 20 Neurodegenerative Conditions43
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Definitions All Units203
