Divisions of the nervous system

Question 1

What is the ventral root?

Answer 1

• Contains the axons of motor neurons
• Their cell bodies are located in the grey matter of the spinal cord
• Have nerves which carry impulses away from the spinal cord

Question 2

What is the dorsal root?

Answer 2

• Contains the axons of sensory neurons

- Their cell bodies are in a small swelling on the dorsal root known as the dorsal root ganglion

Question 3

What makes up the afferent, sensory division?

Answer 3

The somatic sensory and the visceral sensory

Question 4

Somatic sensory

Answer 4

• Carried into the CNS by sensory serve cells from receptors in the skin and around the muscles and joints
• Is conscious

Question 5

Visceral sensory

Answer 5

• Sensory nerve cells that take impulses from the internal organs in to the CNS
• Is unconscious

Question 6

What makes up the efferent (motor) division?

Answer 6

The somatic and the autonomic

Question 7

The somatic division (motor)

Answer 7

Takes impulses from the CNS to skeletal muscles

Question 8

Autonomic division

Answer 8

• Carries impulses from the CNS to heart muscle, involuntary muscle and glands

Consists of the sympathetic and parasympathetic divisions

Question 9

What is the autonomic nervous system?

Answer 9

Responsible for the control of the bodies internal environment

• Operates without conscious control
• Is regulated by groups of nerve cells in the medulla oblongata, hypothalamus and cerebral cortex

Question 10

What is the parasympathetic division?

Answer 10

Produces responses that maintain the body during relatively quiet conditions

Question 11

What is the sympathetic division?

Answer 11

produces responses that prepare the body for strenuous physical activity.
‘fight or flight’

Question 12

What does the pathway travelled by an impulse from the CNS to an organ controlled by the ANS consist of?

Answer 12

Consists of two neurons

One has its cell body in the CNS and the other in a ganglion

Question 13

What is a ganglion?

Answer 13

is a group of nerve cell bodies outside the CNS

Question 14

What are the differences between nerves of the sympathetic and parasympathetic division?

Answer 14

• Sympathetic has a shorter pre-ganglionic neuron than the parasympathetic
• Sympathetic uses acetylcholine at first synapse and noradrenaline at the second synapse
• Parasympathetic uses acetylcholine at the first and second synapses

Question 15

Where does the cerebellum receive input from?

Answer 15

1. The cerebrum- information about conscious awareness of body position
2. The semi-circular canals of the inner ear- movement of the head
3. The saccule and utricle of inner ear- position of the head
4. The eyes
5. Pressure receptors in the skin
6. Stretch receptors
   Integrates and co-ordinates impulses
   - Association tract in the cortex plans impulses
   - Motor tract in cortex initiates impulses

Question 16

What are the differences between the nervous system and the endocrine system?

Answer 16

Nature of the message

• NS uses electrical impulses and neurotransmitters
• Es uses hormones

Transport of the message

• NS along the membrane of neurons
• ES by the blood stream

Cells affected

• NS muscles ad gland cells
• ES all body cells

Type of response

• NS usually local and specific
• ES May be very general and widespread

Time taken to respond

• NS rapid- within milliseconds
• ES slower- from seconds to days

Duration of response
NS brief- stops quickly when the stimulus stops
ES longer lasting- response may continue long after the stimulus has stopped

Question 17

Similarities between the nervous and endocrine systems

Answer 17

• Some substances function as both hormones and neurotransmitters. EG. Noradrenaline, antidiuretic hormone and dopamine
• Some hormones such as oxytocin and adrenaline are secreted by neurons into the extracellular fluid
• Some hormones and neurotransmitters have the same effect on the same target cells