Nerve Cells 1 Flashcards
There are ___ types of cells in the nervous system. They are:
Two.
- Neurons.
- Supporting cells.
The nervous system is divided into:
–Central nervous system (CNS): •Brain. •Spinal cord. –Peripheral nervous system (PNS): •Cranial nerves. •Spinal nerves.
The basic structural and functional units of the nervous system is…
Neuron
Neurons can’t divide by mitosis. True or false?
True
Properties of neurons
- They respond to physical and chemical stimuli.
- They produce and conduct electrochemical impulses.
- They release chemical regulators.
A nerve is…
A bundle of axons located outside CNS, most are composed of both motor and sensory fibers.
Parts of a neuron
Cell body (perikaryon)
Dendrites
Axon
Which part of the neuron is the “Nutrition center”?
Cell body
Cell bodies within the CNS are clustered into ____, and in PNS in ____.
Nuclei, Ganglia
Functions of dendrites
They provide receptive area and transmit electrical impulses to cell body.
Functions of axons
They conduct impulses away from cell body.
What happens in axoplasmic flow?
Proteins and other molecules are transported by rhythmic contractions to nerve endings.
What happens in axonal transport?
Microtubules are employed for transport and may occur in orthograde or retrograde direction.
Functional classification of neurons is based on…
…direction of impulses conducted
Classes of neurons based on function
- Sensory or afferent – Conduct impulses from sensory receptors into CNS.
- Motor or efferent – Conduct impulses out of CNS to effector organs.
- Association or interneurons – Located entirely within the CNS and serve an integrative function.
Which functional class of neurons are located entirely within the CNS?
Association or interneurons:
Structural classification of neurons is based on…
…the number of processes that extend from cell body.
Classes of neurons based on structure
– Pseudounipolar - Short single process that branches like a T
– Bipolar neurons - Have 2 processes.
–Multipolar neurons - Have several dendrites and 1 axon
Examples of the neurons that make up the structural classes of neurons
– Pseudounipolar, e.g. sensory neurons
– Bipolar neurons, e.g. Retina of the eye
–Multipolar, e.g. Motor neuron.
Supporting cells in the nervous system are located in the CNS alone. True or false?
False. They’re in CNS and PNS
Types of supporting cells in the CNS
Oligodendrocytes
Microglia
Astrocytes
Epyndymal cells
Types of supporting cells in the PNS
Schwann cells
Satellite cells
What is a diffusion potential?
It is the potential difference generated across a membrane when a charged solute ( an ion) diffuses down its concentration gradient.
What is the Equilibrium Potential?
The diffusion potential that exactly balances or opposes the tendency for diffusion down the concentration difference
At electrochemical equilibrium, the chemical and electrical driving forces acting on an ion are equal and opposite, and no further net diffusion occurs. True or false?
True
What is the Nerst Equation?
The Nernst Equation is used to calculate the equilibrium potential for an ion at a given concentration difference across a membrane, assuming the membrane is permeable to that ion.
What is the Resting Membrane Potential (RMP)?
RMP is the potential difference that exists across the membrane of excitable cells, such as nerve and muscle, in the period between action potentials.
The RMP is established by…
diffusion potentials, which results from concentration differences from various ions across the cell membrane.
The concentration differences resulting from RMP is established by what mechanisms?
Primary and secondary active transport mechanisms.
Each permeant ion attempts to drive the membrane potential towards another’s equilibrium potential. True or false?
False, it’s towards its own
Which ions exert the greatest contribution to RMP and which ones exert the least?
Those with the greatest permeability or conductance exert the most while those with lower permeability will make little or no contribution.
The RMP of excitable cells falls between ___.
-70 to -80mV
Which ions are most permeable at rest? On the other hand, the RMP is far from those of Calcium and Sodium because the permeability to this ions at rest is low.
Those of potassium and chloride to whom the RMP of excitable cells are closest
On the other hand, the RMP is far from those of Calcium and Sodium because the permeability to this ions at rest is low.
Hh
