Nerves Flashcards
What are nerve cells also known as?
Neurons
Neurons are the structural and functional units of the nervous system.
What are the two types of extensions of a neuron?
Dendrites and axon
Dendrites carry impulses toward the cell body, while the axon carries impulses away.
What does the cell body of a neuron contain?
Nucleus and cytoplasm
The cytoplasm includes typical organelles.
What is the function of dendrites?
Carry nerve impulses toward the cell body
Dendrites are short and highly branched extensions.
What is the role of the axon?
Carries nerve impulses away from the cell body
Axon length varies significantly between different parts of the body.
What is the myelin sheath?
A fatty layer surrounding the axon
It acts as an insulator, protects the axon, and speeds up impulse transmission.
What produces myelin in the Peripheral Nervous System (PNS)?
Schwann cells
Schwann cells wrap around the axon to form the myelin sheath.
What are nodes of Ranvier?
Gaps in the myelin sheath
They facilitate faster impulse conduction.
What type of cells produce myelin in the Central Nervous System (CNS)?
Oligodendrocytes
Myelinated fibers in the CNS appear white, forming white matter.
What is the difference between myelinated and unmyelinated fibers?
Myelinated fibers have myelin; unmyelinated fibers do not
Axons covered in myelin are called myelinated fibers.
What is a synapse?
The junction where a nerve impulse passes from one neuron to another
The impulse crosses the synaptic gap via neurotransmitters.
What are the two main functional classifications of neurons?
Sensory neurons and motor neurons
Sensory neurons transmit impulses to the CNS; motor neurons carry impulses to muscles and glands.
What type of neuron connects sensory and motor neurons?
Interneurons
Interneurons are located within the CNS.
What is the most common type of neuron?
Multipolar neurons
They have one axon and multiple dendrites.
Where are bipolar neurons found?
In the eye, ear, and nose
They transmit impulses from receptor cells to other neurons.
What is unique about unipolar neurons?
They have only one axon
Unipolar neurons are exclusively found in insects.
What is the structure of pseudounipolar neurons?
The axon splits into two branches, with the cell body offset from the axon
They are found in sensory neurons carrying impulses to the spinal cord.
What do nerve fibers group together to form outside the CNS?
A nerve
Nerve fibers are bundled by connective tissue.
What forms a nerve?
Multiple bundles of nerve fibers
These bundles are grouped together by connective tissue.
