Date post: | 18-Jul-2015 |
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Health & Medicine |
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Central Nervous System(CNS) : Brain and Spinal Cord
Peripheral Nervous System(PNS) : Autonomic Nervous
System (Sympathetic and Parasympathetic Nervous
System) and the Somatic Nervous System
(The PNS is made up of Nerves connecting the CNS to
the rest of the body)
Structure of the Nervous System
Efferent nerves fibers/cells that cause muscles to
contract, glands to secrete and organs to function
properly
Motor Neurons
Afferent nerves cells/fibers that carry our feelings
(heat/ pain/ cold etc..) to the Central Nervous System
Sensory Neurons
Neurons that form a connection between other
neurons (e.g. in-between a motor and a sensory nerve
cell/fiber. They are neither motor nor sensory neurons
Interneurons
Junction where neurons pass neurotransmitters (chemical
signals) or electrical signals to other neurons, muscle
cells, or gland cells. Composed of:
- A presynaptic ending that contains mitochondria, other
cell organelles and neurotransmitters that are released
in the synaptic space
- A synaptic space or cleft between the presynaptic and
postsynaptic endings
- A postsynaptic ending on the target cell (other neuron/
muscle cells/gland cells) that contains receptor sites for
the neurotransmitters that crossed the synaptic space
Synapse
Several small molecules function as neurotransmitters.
- Glycine and glutamate (amino acids)
- Dopamine (DA), Norepinephrine (NE) & Dopamine
(DA) (cathecholamines derived from amino acids)
- Acetylcholine (ACh) & Serotonin (derived from
amino acids)
- Prostaglandins, Histamine and Y- Aminobutyric
acid (GABA) are other neurotransmitters
Brain : The outside is covered with gray matter and
the inside is filled with white matter
Spinal Cord : Gray matter forms an H shape in the
inside and white matter surrounds the gray matter
Central Nervous System
Protected by- Cranium/Skull
Meninges (Pia Mater, Arachnoid and
Dura Mater)
Cerebrospinal fluid (water, glucose,
protein, sodium, chloride and nutrients such as oxygen)
Blood brain barrier (glial astrocytes and
capillary cells)
Divided into the Cerebrum, the Diencephalon, the Brainstem and the Cerebellum
Brain
Divided into the right and left Cerebral Hemispheres
Contains convolutions/ gyri, sulcus and fissures
Controls all sensory and motor activity
Cortex is divided into the Frontal lobe, R & L
Parietal lobes, R & L Temporal lobes and the
Occipital lobe covered each by bones bearing the
same name
Cerebrum
Frontal Lobe : Executive function (speaking, learning,
reasoning, problem solving, judging, planning),
Voluntary motor activity, Emotion and Behavior
Parietal Lobe : Pain, Pressure, T°, Touch and Speech /
Language comprehension
Temporal Lobe : Memory, Hearing, Taste, Speech
Reading, Writing and Arithmetic
Occipital Lobe : Vision
Divided into the Thalamus (relays all sensory impulses
to the cerebrum) and the Hypothalamus (regulates body
temperature)
Diencephalon
Midbrain : Relays information for vision and hearing
Pons : Regulates the change from inspiration to expiration
Medulla Oblongata : Regulates several functions of the autonomic nervous system
- Respiration (chemoreceptors)
- Cardiac center (sympathetic, parasympathetic system)
- Vasomotor center (baroreceptors)
- Reflex centers of vomiting, coughing, sneezing, and
swallowing
Links the Brain with the rest of the body
Protected by – Vertebrae
Meninges (Pia mater, Arachnoid,
Dura mater)
Cerebrospinal fluid (water, glucose,
sodium, chloride and nutrients such as oxygen)
Blood-brain barrier (glial astrocytes
and capillary cells)
Spinal Cord
Somatic Nervous System : 12 pairs of cranial nerves,
8 pairs of cervical spinal nerves, 12 pairs of thoracic
spinal nerves, 5 pairs of lumbar spinal nerves, 5 pairs
of sacral spinal nerves and 1 pair of coccygeal nerves
Autonomic Nervous System : Divided into the
Sympathetic Nervous System and the
Parasympathetic Nervous
Peripheral Nervous System
SNS : Stimulates the adrenal gland to release epinephrine that prepares the body for Fight and Flight during stressful situation (Pupil dilation, Sweating, ↑RR, dilates bronchi, ↑HR and ↑BP)
PNS : Works during non-stressful situations
(Pupil constriction, not sweating, ↓RR, bronchi
constriction, ↓HR, ↓BP) and innervates the
digestive system (↑salivation, ↑ digestive
organs motility, ↑gallblader and bladder
contraction and relaxes the bladder sphincter )
Alzheimer’s Disease : Destruction of nerve cells in
the brain causing loss of recent memory
Amyotrophic Lateral Sclerosis : Destruction of the
motor nerves in the brain causing movement
impairment. Also called Lou Gehrig’s disease
Common Disorders associated with the Nervous System
Epilepsy and seizures : Interference of electrical
impulses within the brain causing uncontrollable
movement of the limbs and body
Migraine Headache : flashes of light, blind spots,
tingling in your arm/leg or sensitivity to light/noise
often precedes the headache
Tension Headache : Due to stress
Cluster Headache : Felt behind the eyes or temples.
May last for weeks to months than stops (cycle)
Post-Traumatic Headache : Post trauma
Huntington’s Chorea : Hereditary disease affecting
the cerebral and basal ganglia causing imbalance,
lack of coordination, difficulty swallowing and
rigidity
Multiple Sclerosis : Body’s antibodies become
confused and attack the myelin sheath surrounding
the nerves in the brain and spinal cord causing vision,
sensation and movement impairment
Neuralgia : Nerve pain
Parkinson’s Disease : Degeneration of nerves in the
basal ganglia causing a loss of dopamine resulting in
the lack of movement control
Spinal cord Injuries : Quadriplegia, Paraplegia and
Hemiplegia
Stroke : Cerebro-vascular accident due to ↓ or
cessation of blood flow to the brain
Transient Ischemic attack : Mini-strokes lasting a few
minutes
Concussion : Injury caused by a blow to the head.
May lead to a loos of consciousness
Contusion : Bruising of the brain