2A - The Nervous System

Question 1

define central nervous system

Answer 1

a major division of the nervous system comprising the brain and spinal cord, which receives and transmits neural messages to and from the peripheral nervous system

Question 2

define brain

Answer 2

a complex structure that receives and processes sensory stimuli from the body and coordinates responses, including voluntary movements, emotions and conscious thought

Question 3

define spinal cord

Answer 3

a dense bundle of nerves that carries sensory information from the body to the brain and motor information from the brain to the body

Question 4

two main roles of the spinal cord:

Answer 4

1. To carry incoming sensory information from the body (peripheral nervous system) towards the brain for processing
2. To carry motor information initiated by the brain towards relevant parts of the body (via the peripheral nervous system) to control muscles, glands and internal organs so that appropriate actions can be taken

Question 5

define spinal reflex

Answer 5

an involuntary and unconscious response to a stimulus involving the spinal cord, occuring without input from the brain

Question 6

steps involved in a spinal reflex

Answer 6

1. Sensory information from the external environment is received through sensory receptors that are sensitive to specific types of stimuli arising outside the body
2. The nervous system also receives information from within various parts of the body
3. When the sensory information is received in the brain it is processed
   - This enables perception (interpretation of the sensory information so meaning can be assigned)
4. Processing often involves integrating incoming information with other information already in the brain
5. If required, the brain will also coordinate a response by initiating appropriate action

Question 7

define sensory receptor

Answer 7

a sensory nerve ending that produces an afferent or sensory impulse when stimulated

Question 8

define sensory neuron

Answer 8

a nerve cell that carries sensory signals throughout the nervous system

Question 9

define interneuron

Answer 9

a nerve cell in the spinal cord that connects motor and sensory neurons by relaying information between the two

Question 10

define motor neuron

Answer 10

a nerve cell that transmits motor impulses from the spinal cord to the skeletal and smooth

Question 11

define peripheral nervous system

Answer 11

all the nerves outside of the cns that carry messages between the cns and muscles, organs and glands throughout the body

Question 12

two subdivisions of the peripheral nervous system

Answer 12

• the somatic nervous system
• the autonomic nervous system

Question 13

define somatic nervous system

Answer 13

a subdivision of the peripheral nervous system that carries sensory information to the CNS and motor information to the body

Question 14

role of the somatic nervous system

Answer 14

• carries sensory (afferent) information to the CNS (brain and spinal cord)
• carries motor (efferent) information from the CNS to the body

Question 15

define autonomic nervous system

Answer 15

a subdivision of the peripheral nervous system that controls the body’s internal environment in an autonomous or self-regulated manner, and transmits neural messages to the CNS about their activity

Question 16

two subdivisions of the autonomic nervous system

Answer 16

• the sympathetic nervous system
• the parasympathetic nervous system

Question 17

define sympathetic NS

Answer 17

a subdivision of the autonomic nervous system that increases our arousal, readying the body for a quick response

Question 18

Examples of responses by the sympathetic nervous system to a threat are:

Answer 18

• pupils dilating to allow more light into the eye to see better
• heart rate, blood pressure and breathing rates increasing to accelerate oxygenated blood flow to the muscles in order to respond to the threat
• energy being diverted to the muscles from functions such as digestion to conserve energy for responding to the threat
• increased sugar and fat being released into the blood to provide energy for quick action

Question 19

define parasympathetic NS

Answer 19

maintains the optimal and balanced functioning of the body’s internal environment

Question 20

parasympathetic NS two main functions

Answer 20

1. Maintaining a balanced internal state, otherwise known as homeostasis, including regulation of blood sugar or energy levels, saliva secretion and waste elimination.
2. Counterbalancing the energising function of the sympathetic nervous system by lowering arousal and restoring the body to a calm state after a threat has passed.

Question 21

define neuron

Answer 21

an individual nerve cell that is specialised to receive, process and/or transmit information within the nervous system

Question 22

There are three types of neurons:

Answer 22

• Motor neurons
• Sensory neurons
• Interneurons

Question 23

define motor neurons

Answer 23

transmit neural messages about motor movement from the central nervous system to the peripheral nervous system
- also known as efferent neurons

Question 24

define sensory neurons

Answer 24

transmit neural messages about bodily sensations from the peripheral nervous system to the central nervous system
- also known as afferent neurons

Question 25

define interneurons

Answer 25

transfer neural messages between sensory neurons and motor neurons
- the CNS is made up of interneurons