AP2 1.2: Neurons

Question 1

Neurons

Answer 1

Neurons are nerve cells that conduct electrical impulses and relay information throughout the body. All neurons have three basic parts: the dendrites, cell body , and axon. Neurons do not undergo mitosis (cell division). Neurons can survive a person’s entire lifetime, which is why brain and spinal cord damage is so serious. Any neurons that die due to brain damage cannot be replaced. Neurons can survive just minutes without oxygen.

Question 2

neuron cell body

Answer 2

The neuron cell body, which synthesizes all nerve cell products, consists of a large nucleus with surrounding cytoplasm containing the normal organelles. Information is received and sent in the same direction within a neuron

Question 3

dendrites

neuron cell body

Answer 3

The dendrites are the receiving end of a neuron. Dendrites are numerous short extensions that emanate from the cell body, which receive information from other neurons and conduct those nerve impulses toward the cell body.

Question 4

axon

neuron cell body

Answer 4

The single axon conducts nerve impulses away from the cell body to its axon terminals . Axons can vary in length, being very short or very long, up to three feet. Axons are composed of cell components like the cell body but lack rough endoplasmic reticulum. The axon depends upon the neuron’s cell body to send the necessary proteins down the length of the axon.

Question 5

axon terminals

neuron cell body

Answer 5

The single axon conducts nerve impulses away from the cell body to its axon terminals

Question 6

cell body contains

neuron cell body

Answer 6

The cell body contains the nucleus and other organelles typically found in cells, except for centrioles, which are not capable of mitosis. One of the main functions of the cell body is to manufacture neurotransmitters

Question 7

Neurotransmitters

neuron cell body

Answer 7

Neurotransmitters are chemicals stored inside secretory vesicles (axon terminal vesicles) at the end of the axon terminals. When neurotransmitters are released by the axon terminal vesicles, they carry the transmission of the nerve impulse from one neuron to another

Question 8

synapse

Answer 8

Neurotransmitters are emitted across a synapse to the dendrite of another neuron. A synapse is a gap between two neurons, as neurons do not physically touch one another

Question 8

presynaptic neuron

Answer 8

A presynaptic neuron means before the synapse. Neurotransmitters are sent from a presynaptic neuron through the synapse to the postsynaptic neuron. The message continues in this same manner from one neuron to the next.

Question 9

postsynaptic neuron

Answer 9

A postsynaptic neuron is a neuron that is found after the synapse. Neurotransmitters are sent from a presynaptic neuron through the synapse to the postsynaptic neuron. The message continues in this same manner from one neuron to the next.

Question 10

Multipolar neurons

Answer 10

Multipolar neurons have three or more extensions from the cell body. Multipolar neurons have one axon and many dendrites. They can be called motor neurons

Question 10

Neuron Shape and Function

Answer 10

Structurally, neurons are classified according to the number of extension from their cell body, as multipolar, bipolar, and unipolar neurons

Question 11

Unipolar neurons (pseudounipolar)

Answer 11

Unipolar neurons (pseudounipolar) have one extension off the cell body that branches into two: one central process running to the CNS and another peripheral process running to the sensory receptor. These neurons are sensory neurons in the peripheral nervous system.

Question 12

Functionally, neurons can be classified

Answer 12

Functionally, neurons can be classified as sensory, motor, or interneurons.

Question 13

Sensory neurons (afferent)

Answer 13

Sensory neurons (afferent) are unipolar and function to carry information from the peripheral to the central nervous system. Most sensory neurons carry impulses from the skin or internal organs to the CNS.

Question 14

Interneurons,

Answer 14

Interneurons, called association neurons, are found only in the central nervous system. Interneurons are typically multipolar neurons and transmit impulses within different parts of the central nervous system.