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Organisation of Nervous System
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Nervous system
*complex communication system that uses nerve impluse to communicate.
*NS works closely with Endocrine system to regulate and maintain cell function and homeostasis
Function is to control and co-ordinates cell activity throughout the body.
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Central nervous system
- *consists of brain and spinal cord
- *acts as the integrating and command centers of the NS.
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Peripheral nervous system
- *includes all neural tissue outside the CNS
- *deliver sensory infomation to the CNS
- *Carry motor commands to the peripheral tissues and systems
- *consists of nerves that acts as communicating lines
- *nerves carry impulses from sensory receptors (skin) to CNS and from CNS to appropriate muscles and glands.
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Neurons
*cells of the nervous system specialized to transmit messages throughout the body
- consists of:
- *sensory (afferent) neurons that conduct impulses to spinal cord and brain
- * Motor (efferent) neurons that conduct impulses away from spinal cord or brain toward muslces and glands
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Neurotransmitter
Neurotransmitters are the chemicals which allow the transmission of signals from one neuron to the next across synapses
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Action Potential
An action potential is part of the process that occurs during the firing of a neuron. During the action potential, part of the neural membrane opens to allow positively charged ions inside the cell and negatively charged ions out. This process causes a rapid increase in the positive charge of the nerve fiber. When the charge reaches +40 mv, the impulse is propagated down the nerve fiber. This electrical impulse is carried down the nerve through a series of action potentials.
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functional division of PNS
Afferent (sensory) division > carries sensory info from PNS sensory receptors to CNS
Efferent (motor) division> Carries motor commands from CNS to PNS muscles and glands
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Somatic NS
Regulates and control skeletal muscel contractions
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Enteric NS
*third division of autonomic NS, meshwork of nerve fibers that innervate the viscera.
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Autonomic NS
Regulates and controls internal organs by involuntary control
>Sympathetic division - Prepares the body to deal with immediate threat, stimulating fight and flight response.
>Parasympathetic division - Co-ordinates the body's resting activities to maintain homeostasis. Has a relaxing effect Eg, rest and digest
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Cerebral Cortex
- Structures:
- Frontal lope
- Parietal lope
- Temporal lobe
- Occipital lobe
- Insula
Function: Integration, movement and senses such as touch and pressure
- Contain a sensory map of the body
- Able to compare, evaluate and responds to bits of information and then integrate then in a whole picture
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Diencephalon
- *located between cerebrum and midbrain
- *consists of:
- Thalamus- serves as a major relay station for sensory inpulses on their way to the cerebral cortex
Hypothalamus- small but functionally important area of the brain.
Pineal gland regulates the body's biological clock
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Cerebellum
- *located below the posterior portion of the cerebrum
- *second largest part of brain
- *contains more neurons than the rest of the NS, transverse fissure separates the two parts of the brain
- Function:
- Fine Movement Coordination
- Balance and Equilibrium
- Muscle Tone
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Brainstem
*perform senosory, motor, and reflex functions
*Spinothalamic tracts is important sensory tracts that pass through the brainstem
- *Pons contains pneumotaxic centers that help regulate respiration
- *Midbrain contains centers for certain cranial nerve reflexes
- *Medulla oblongata
- lowest part of the brainstem. Attached to spinal cord.
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Cerebrospinal fluid
- Functions:
- *provides a supportive, protective cushion.
- * Resevoir of circulating fluid monitored by the brain to detect changes in the internal enviroment
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Blood Brain barrier
permits the passage of essential substances while excluding unwanted material.
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Meninges: covering of the brain
The three membranous layers that surround the brain
- *Pia mater
- *Arachnoid mater
- *Dura mater
space between each layer are potential spaces.
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Spinal cord
- *main pathway for information connecting the brain and peripheral NS.
- *located in the vertebral foramen and made up of 31 segments
- *8 Cervical
- *12 thoracic
- *5 lumbar
- *5 Sacral
- *1 coccygeal
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Spinal reflex
- *produce spinal reflexes without any input from the brain
- *They are automatic, no conscious effort
- *protective mechanism
- *can be influence by thought and emotion Eg touching hot oven.
A spinal reflex is an automatic, rapid response to a stimulus. The action is involuntary and occurs without any involvement of thought or the brain
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Mini-mental status examination
*offer quick and simple way to vertify cognitive function and screen for cognitive loss*tests orientation, attention, calculation
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