Nervous System Flashcards
The nervous system
Coordinates all activities inside and outside the body
Entire body covered with fibres called nerves
Over 100 billion nerve cells in the body called neurons
What are the 3 divisions of the nervous system?
- Central nervous system
- Peripheral nervous system (outer)
- Autonomic nervous system
Central nervous system
Brain, spinal cord, spinal nerves and cranial nerves
Controls consciousness, mental activities, involuntary functions of five senses (seeing, hearing, feeling, smelling and tasting) and voluntary muscle actions including all body movements and facial expressions
Peripheral nervous system
Connect outer part of the body to CNS (Central nervous system)
It has both sensory and motor nerves
It carries impulses, or messages to and from the central nervous system
Autonomic nervous system
Controls involuntary muscles
Regulate smooth muscles, glands, blood vessels, the heart and breathing
The organs affected by the autonomic system receive nerve cells or fibres from its two divisions which are
Sympathetic division
Parasympathetic division
Sympathetic division
Stimulate or speed up activity and prepares the body for stressful situation
Parasympathetic division
Operates under normal, no stressful conditions and help restore and slow down activity, thus keeping the body in balance
The brain and spinal cord
The brain is the largest and most complex nerve tissue in the body
Contained in the cranium
Control sensation, muscles, glands, thinking and feeling
Send telegraphic images through 12 pairs of cranial nerves
Spinal cord part of the CNS originates in the brain and travels down the trunk - protected by the spinal column
31 pairs of nerves exit the cord and supply the body
Nerve cell structure and function
A neuron or nerve cell is the primary structural unit of the nervous system
It is composed of: cell body, nucleus, dendrites and an axon
Dendrites
Receive information from other neurons
Axons
Send messages away from the cell body to other neuron, glands, muscles and organs
Nerves
Are whitish quartz, made up of bundles of nerve fibres held together by connective tissue, through which impulses are transmitted
Nerves have their origin in the brain and spinal cord and send their branches to all parts of the body
What are the two types of nerves?
- Sensory nerves / afferent nerves 
2. Motor nerves/ efferent nerves
Sensory nerves
Carries impulses or messages from the organs to the brain where sensation such as touch, cold, heat, sight, hearing, taste, smell, pain and pressure are experienced
Sensory nerve endings called receptors are located close to the surface of the skin, as impulses pass from the sensory nerves to the brain and back through the motor nerves to the muscles; A complete circuit is established, resulting in movements of the muscles