4. neurons

Question 1

what is the key term for neuron

Answer 1

basic buildings blocks of the nervous system - nerve cells that process and transfer messages through electrical and chemical signals.

Question 2

what is the key term for synapses

Answer 2

the site of transmission of electric nerve impulses between two nerve cells (neurons or between a neuron and a gland or muscle cell (effector).

Question 3

what is the key term for myelin sheath

Answer 3

an insulating layer that forms around nerves and allows electrical impulses to transmit quickly and efficiently along the nerve cells.

Question 4

what is the key term for soma

Answer 4

spherical part of the body that contains the nucleus - cell body connects to the dendrites.

Question 5

what is the key term for axon

Answer 5

long projection of a nerve cell or neuron (vertebrates) that typically conduct action potentials.

Question 6

what is the key term for nucleus

Answer 6

command center of the cells - contains chromosomes and genetic information needed for reproduction.

Question 7

what is the key term for dendrites

Answer 7

projections of neurons that receive signals from other neurons.

Question 8

what is the key term for nodes of ranvier

Answer 8

gaps in the myelin sheath on the axon that serves to facilitate the rapid conduction of nerve impulses.

Question 9

what is the key term for terminal bulbs

Answer 9

small knobs at the end of an axon that release neurotransmitters.

Question 10

name three key facts about neurons

Answer 10

100 billion of these in our bodies - 80% of them are in our brain.

they allow the brain to send electrical impulses and chemical messages around the body.

Question 11

how do neurons communicate

Answer 11

they receive messages from sensory organs or other neurons.

messages pass between two neurons by neurotransmitters diffusing across the synaptic cleft (gap between neurons).

messages run through neurons by becoming electrical impulses triggered by neurotransmitters reaching the postsynaptic receptor site.

Question 12

what are the characteristics of the relay neuron

Answer 12

short dendrites and short axons.

Question 13

what are the functions of the relay neuron

Answer 13

connect the sensory and motor neuron and allow them to communicate.

found in the brain and spinal cord.

allows fast reflex actions to take place by bypassing the brain.

Question 14

what are the characteristics of the sensory neuron

Answer 14

long dendrites and short axons.

Question 15

what are the functions of the sensory neuron

Answer 15

found in receptors and carry nerve impulses to the brain and spinal cord. when they reach the brain they are translated into sensations.

however, not all sensory neurons reach the brain as some stop at the spinal cord to allow quick reflex actions.

Question 16

what are the characteristics of the motor neuron

Answer 16

short dendrites and long axons.

Question 17

what are the functions of the motor neuron

Answer 17

found in and connect the CNS to effectors (muscles and glands) to control muscle movements.

when motor neurons are stimulated they release neurotransmitters that bind to the receptors on muscles to trigger a response - leads to movement.

Question 18

how can the transmission of messages through the neuron be electric

Answer 18

neuron in resting state = negatively charged.

neuron activated by stimulus = inside of cell becomes positively charged for a split second.

an action potential will pass through the neuron when it is positively charged - allows an electrical impulse to travel down the axon and towards the end of the neuron.

Question 19

explain the knee jerk response

Answer 19

when a stimulus (hammer) hits the knee - detected by the sense organs found in the PNS which conveys a message along the sensory neuron.

messages reach the CNS where it connects with a relay neuron which transfers messages to a motor neuron - causes muscles to contract and therefore the knee jerks.