Nervous system divided-
1. Central nervous system (CNS); Brain and Spinal cord
2. Peripheral nervous system (PNS); Nerves
Nervous system consist of brain, spinal cord and peripheral nerve.
The structure and organization of the tissue that formed these compartments enables rapid communication between different parts of the body.
Response to changes in internal environment regulated involuntary function. For example, Blood pressure, digestive activities.
Response to change in external environment posture and other voluntary activities.
Peripheral Nervous System (PNS), nervous system outside CNS.
PNS consist mainly of the nerves (bundles of exons) that extend from brain (cranial nerves) and spinal nerve, ganglia and sensory receptors.
43 pairs of nerves originated from CNS to PNS.
31 pairs of spinal nerve originates from spinal cord and carry impulse to and from spinal cord.
12 pairs of cranial nerve originate from brain and carry impulses to and from brain.
These peripheral nerve serves as communication line that link all part of body to CNS.
Ganglia are collection of cell bodies of neurons located outside CNS.
Peripheral nervous system have two functional sub division, made up of 2 types of neurons.
1. Sensory (afferent) division
2. Motor (efferent) division
1. Somatic nervous system
a. Somatic afferent (voluntary)
b. Visceral different (involuntary)
2. Autonomic nervous system (ANS)
a. Sympathetic nervous system
b. Parasympathetic nervous system
1. Sensory or afferent division
Conduct impulse from receptors to CNS.
detect various sensation such as pain, heat.
Consist of nerve fibers that convey impulse to CNS from sensory receptor located throughout body.
Sensory fibers conveying impulse from skin, skeletal muscles and joints are called somatic afferent fibers.
Sensory fibers that transmitting impulses from visceral organs called visceral afferent fibers.
Sensory division transmit message towards CNS and constantly informed of events going on both inside and outside the body.
2. Motor or efferent division
Conduct impulse from CNS to effectors (muscle and glands).
Transmit message away from CNS.
Stimulate effectors (skin, sense organs, muscles, gland) to perform function or reflex (action).
These impulse activate muscle to contract and glands to secrete.
1. Somatic Nervous System; somatic motor voluntary
Composed of somatic nerve fibers that conduct impulses from CNS to skeletal muscles.
Somatic Nervous system is voluntary nervous system because it allows as to consciously control our skeletal muscles.
Responsible for relaying sensory and motor information between the outside environment and CNS.
Innervate outer sections of body such as skin, skeletal muscle.
Any muscle movement or voluntary motor output uses somatic nervous system.
Conduct impulses from CNS to skeletal muscle.
2. Autonomic nervous system (ANS)
PNS division that handles involuntary movement in body.
ANS consist of visceral motor nerve fibers that regulate activity of smooth muscles, cardiac muscles, glands, heart rate, digestion, respiration and breathing.
Innervate our internal organ.
ANS
1. Sympathetic
Fight or flight response system
Causes general alertness and excitement
Body's way of responding a perceived threat.
For example, vasoconstriction, vasodilation, pupillary dilation,
Contraction and relaxation pyloric sphincter.
2. Parasympathetic
Rest and digest response system
Restores the body to calm or restful state.
For example, urination, defecation.
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