Divisions of the nervous system Flashcards
What is the ventral root?
- 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
What is the dorsal root?
- Contains the axons of sensory neurons
- Their cell bodies are in a small swelling on the dorsal root known as the dorsal root ganglion
What makes up the afferent, sensory division?
The somatic sensory and the visceral sensory
Somatic sensory
- Carried into the CNS by sensory serve cells from receptors in the skin and around the muscles and joints
- Is conscious
Visceral sensory
- Sensory nerve cells that take impulses from the internal organs in to the CNS
- Is unconscious
What makes up the efferent (motor) division?
The somatic and the autonomic
The somatic division (motor)
Takes impulses from the CNS to skeletal muscles
Autonomic division
- Carries impulses from the CNS to heart muscle, involuntary muscle and glands
Consists of the sympathetic and parasympathetic divisions
What is the autonomic nervous system?
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
What is the parasympathetic division?
Produces responses that maintain the body during relatively quiet conditions
What is the sympathetic division?
produces responses that prepare the body for strenuous physical activity.
‘fight or flight’
What does the pathway travelled by an impulse from the CNS to an organ controlled by the ANS consist of?
Consists of two neurons
One has its cell body in the CNS and the other in a ganglion
What is a ganglion?
is a group of nerve cell bodies outside the CNS
What are the differences between nerves of the sympathetic and parasympathetic division?
- 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
Where does the cerebellum receive input from?
- The cerebrum- information about conscious awareness of body position
- The semi-circular canals of the inner ear- movement of the head
- The saccule and utricle of inner ear- position of the head
- The eyes
- Pressure receptors in the skin
- Stretch receptors
Integrates and co-ordinates impulses
- Association tract in the cortex plans impulses
- Motor tract in cortex initiates impulses
What are the differences between the nervous system and the endocrine system?
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
Similarities between the nervous and endocrine systems
- 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
