Summary

In study session V you have learnt

• The nervous system is an organ system containing network of specialized cells called neurons.
• The nervous system has three major subdivisions: The central nervous system (CNS) consists of the brain and spinal cord, which are enclosed and protected by the cranium and vertebral column, The peripheral nervous system (PNS) and The autonomic nervous system (ANS).
• A nerve is a bundle of nerve fibers wrapped in fibrous connective tissue
• Ganglion/ganglia are a knot like swelling in a nerve where the cell bodies of neurons are concentrated.
• CNS is central in both location and function. A fiber tract is a collection of neuron processes, together and inside the CNS
• The three major levels of the central nervous system are the spinal cord level: Lower brain or sub cortical level and the higher brain or cortical level.
• Peripheral nerves are nerves which pass from the CNS to the periphery of the body carry commands for skeletal muscles and other muscles made up of striated muscle tissue, as well as sensory information from the periphery of the body is carried to the CNS where it is processed.
• The autonomic nervous system (ANS) is that portion of the nervous system concerned with commands for smooth muscle tissue, cardiac muscle tissue, and glands responsible for those functions in the body which are carried out automatically
• The autonomic nervous system is divided into two separate parts sympathetic & parasympathetic, on the basis of their anatomical origins and physiological actions.
• Parasympathetic system is concerned with conservation and restoration of energy, as it causes a reduction in heart rate and blood pressure, and facilitates digestion and absorption of nutrients, and consequently the excretion of waste products. The chemical transmitter at both pre and postganglionic synapses in the parasympathetic system is Acetylcholine (Ach).
• In contrast to the parasympathetic system, the sympathetic system enables the body to be prepared for fear, flight or fight. Sympathetic responses include an increase in heart rate, blood pressure and cardiac output, a diversion of blood flow from the skin and splanchnic vessels to those supplying skeletal muscle, increased pupil size, bronchiolar dilation, contraction of sphincters and metabolic changes such as the mobilization of fat and glycogen.
• Ach is also the neurotransmitter at sympathetic preganglionic synapses, some sympathetic postganglionic synapses, the neuromuscular junction (somatic nervous system), and at some sites in the CNS. Nerve fibers that release Ach from their endings are described as cholinergic fibers.
• The Glasgow Coma Scale (GCS) is an assessment tool or scale that is used for assessing the patient's response to tactile stimuli (if unconscious), pupillary response to light, corneal and gag reflexes, and motor function.
• The GCS ( Table ) is based on the three criteria of eye opening, verbal responses, and motor responses to verbal commands or painful stimuli. It is particularly useful for monitoring changes during the acute phase, the first few days after a head injury.