CCMA Training Notes: Nervous system

·      Nervous system

o   Anatomy

§  Nerves

-       Neurons: nerve cells.

-       Nerve: Made of bundles of neurons connecting the brain and spinal cord with other parts of the body.

-       Tract: Is a bundle of nerve fibers actually within the brain and spinal cord.

-       Ascending Nerve Tracts: Carry nerve pulses toward the brain.

-       Descending Nerve Tracts: Carry nerve pulses away from the brain.

-       Endoneurium: Protects the neurons.

-       Perineurium: Those neurons are then bundled together and protected by this.

-       Epineurium: Those neurons then are bundled together again to form a nerve protected by this.

-       Ganglion: Is a nerve center made up of a cluster of nerve cell bodies outside the central nervous system.

-       Plexus: Is a network of intersecting spinal nerves.

-       Innervation: The supply of nerves to a specific body part.

-       Receptors: Are sites in the sensory organs (eyes, ears, skin, nose, and taste buds) that receive external stimulation.

・The receptors receive the electrical stimulus and then transmit the signal to the brain for interpretation.

-       Stimulus: Is anything that excites or activates a nerve and causes the electrical impulse to move along the nerve. 

-       Reflex: An automatic, involuntary response to some change, either inside or outside of the body.

・Examples include a change in heart rate, a change in respiration rate, a change in blood pressure, coughing, sneezing, and deep tendon reflexes.

§  Neurons: relies on impulse on electrochemical processes to generate the impulse and transmit the impulse.

-       Cell body: The main part of the neuron is the cell body, and it holds the nucleus, mitochondrion, and other cell structures just like any other cell.

-       Dendrites: These are the processes that receive impulses and conduct them TOWARD the cell body.

-       Axon: These are the processes that conduct impulses AWAY from the nerve cell.

• Depending on the area of the body, an axon can be more than 3 ft. long.

• At the end of the axon are terminal end fibers ending in the axon terminal.

-       Myelin Sheath: Many axons are protected by a myelin sheath made of Schwann cells.

• There are periodic breaks in the myelin sheath called nodes of Ranvier.

• Nodes of Ranvier: allow the electrical impulse to move faster along the fiber.

§  The Central Nervous System (CNS): Made up of the brain and spinal cord.

-       Meninges: a system of membranes that protect the brain and spinal cord.

-       There are 3:

1.     Dura mater: Is the very thick, tough, outermost membrane that lines the inside of the cranium (skull) and vertebral column.

• Epidural Space: Between the bone, and the dura mater.

2.     Arachnoid Membrane: The middle layer that looks like a spider web and is loosely attached to the other meninges and allows fluid to flow between the layer.

• Subarchanoid Space: Located under arachnoid membrane.

3.     Pia Meter. The innermost layer of meninges is the pia mater and has a rich supply of blood vessels nourishing the membranes and nerve tissue.

-       Cerebral Spinal Fluid (CFS): Is produced by capillaries in the brain and is clear, colorless, and watery and flows throughout the brain and around the spinal cord.

• It also functions to cushion the structures and provides nourishment to the brain and spinal cord.

§  The Brain

-       Cerebrum: It is the largest part of the brain and handles controlling as well as integrating voluntary motor functions and sensory functions in the body.

• Also responsible for the highest level of thought, judgement, memory, critical thinking, and emotions.

-       Cerebral Cortex: It is made up of gray matter and is the outer layer of the cerebrum that is made up of elevated folds (gyri) and deep fissures (sulci), or cracks.

-       Cerebral Hemispheres: Brain is divided into left and right cerebral hemispheres. In which the left mainly controls the functions of the right side of the body while the right controls the left side of the body.

-       Lobes of the brain: Each cerebral hemisphere is subdivided into lobes and is named for the bone directly underneath the brain area.

1.     Frontal Lobe: This lobe controls skilled motor functions, memory, and behavior.

2.     Peripheral Lobe: It receives and interprets nerve impulses to form sensory receptors in the tongue, skin, and muscles.

3.     Occipital Lobe: Controls eyesight.

4.     Temporal Lobe: This one controls hearing and smell as well as the ability to create, store, and access unfamiliar information.

-       Thalamus: Is located below the cerebrum where it relays sensory stimuli from the spinal cord and midbrain to the cerebral cortex.

-       Hypothalamus: Is found below the thalamus. It performs many regulatory functions for the body.

-       Brain Stem: A stock-like structure that connects the cerebral hemispheres with the spinal cord.

• It is made up of the midbrain, pons, and medulla oblongata.

§  The Spinal Cord

-       A long, tube-like structure beginning at the brainstem in the brain and ending at the bottom of the spinal column that has all the nerves that control the limbs and lower part of the body

-       It is protected by the meninges and the vertebral column of the skeletal system.

§  The Peripheral Nervous System

-       Consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves extending from the spinal cord. These nerves control the functions of body parts and muscles away from the spinal column and brain.

-       There are 3 types of specialized peripheral that transmit signals to and from the CNS:

1.     Automatic Nerve Fibers: These carry instructions to the organs and glands from the autonomic nervous system.

2.     Sensory Nerve Fibers: These receive the external stimuli for feelings and then transmit this information to the brain. The brain interprets the information to make meaning.

3.     Somatic Nerve Fibers: These are the motor nerve fibers that convey information controlling the body's voluntary muscular movements.

-       Peripheral Spinal Nerves: These are grouped together and named based on the region of the body they innervate. Within each region, the nerves are referred to by number:

-       Cervical Nerves: C1-C8

-       Thoracic Nerves: T1-T12

-       Lumbar Nerves: L1-L5

-       Sacral Nerves: S1-S5

§  Automatic Nervous System

-       It is organized in 2 divisions:

1.     Sympathetic Nerves: They prepare the body for emergencies and stress as well as increase the respiratory rate, heart rate, and blood flow to the muscles.

2.     Parasympathetic Nerves: They return the body to normal after the stress response.

o   Physiology

§  Nerve Physiology

▫   Nerve impulse is initiated and moves across the neuron from the dendrite and toward the cell body and then out the axons.

▫   At the end of the axon are the Axon Terminals.

▫   Here, neurotransmitters are excreted into Synaptic Cleft:

-      Which is the space between the axon terminal of one neuron and the dendritic of another neuron.

▫   Neurotransmitter travels across the synaptic cleft and then lands in a receptor site on the opposite side.

-      A chemical reaction keeps the impulse moving from one neuron to another.

§  Neurotransmitters: Chemical substances that make it possible for messages to be transmitted from one neuron to another and to the target receptor. There are 200 to 300 neurotransmitters at work in the body such as...

▫   Adrenaline: Fight or Flight which is produced in stressful situations with increases in heart rate and blood flow leading to physcial boost and heightened awareness.

▫   GABA: Calms firing nerves in the CNS with high levels of improve focus and low levels which cause anxiety also it contributes to motor control and vision.

▫   Noradrenaline: Affects attention and responding actions in the brain which contracts blood vessels, increasing blood flow.

▫   Acetylcholine: Is released at some synapses in the spinal cord and at neurotransmitter junctions as well as involved in the impulses of muscle action such as learning, memory, attention, and awakening.

▫   Dopamine: Is released in the brain and in the adrenal glands also called Adrenal.

-      They give feelings of pleasure/addiction, movement, and motivation in which people repeat behaviors just to get dopamine release.

▫   Glutamate: Most common one that is involved in learning and memory as well as regulates development and creation nerve contracts.

▫   Epinephrine: Is released in the brain and in the adrenal glands and it is also called Adrenal.

▫   Norepinephrine: Impacts arousal and alertness by increasing blood pressure, heart rate, and respiration. Like epinephrine, it is also produced by adrenal gland.

▫   Serotonin: Is released in the brain and impacts hunger, pleasure, and sleep. It contributes to well-being and happiness as well as being affected by exercise and light exposure.

▫   Endorphins: Like serotonin it is affected by exercise in the sense that is released during exercise as well as by excitement and sex. It produces well-being and euphoria as well as reduces pain.

§  Functions of the Cranial Nerves

▫   Each of the 12 pairs of those nerves originate from under the surface of the brain.

▫   There are 2 nerves of each pair that do the same thing on each side of your body:

1.     Cranial Nerves which are indentified by roman numerals and each pair performs a specific function.

§  Functions of the Peripheral Nerves

▫   There are 31 pairs of peripheral spinal nerves grouped together into cervical, thoracic, lumbar, and sacral divisions.

▫   Each pair controls specific organs and areas of the body.

o   Common Diseases and Disorders

§  Headaches

▫   Cephalalgia: Is the medical term for headache or pain in the head.

▫   Migraine Headache: Is a severe headache that causes throbbing pain typically on one side of the head.

-      It mainly affects women, and many patients experience sensitivity to light or sound, nausea and vomiting, and a warning aura, or visual disturbance prior to the headache.

-      Some patients experience associated epileptic seizures.

▫   Cluster Headaches: These painful headaches affect one side of the head, and patients may experience excessive tearing or nasal congestion.

-      These headaches mainly affect men.

▫   Encephalocele: Is the result of a herniation of the brain tissue through a gap in the skull and it is present at birth.

▫   Meningocele: To a hernination of the meninges through a defect in either the skull or spinal column.

▫   Meningitis: Inflammation of the meninges of the brain and spinal cord.

-      It can be caused by a virus or bacteria.

▫   Meningioma: Is a slow growing tumor in the meninges and typically benign.

§  Disorders of the Brain

▫   Cognitive Impairment: A mental disorder that disrupts mental activities of thinking, learning, and memory. Typically impacting recent memory but can impact long term memory as well.

▫   Dementia: A slowly progressive decline in mental abilities, including thinking, judgement, and memory. It often includes personality changes.

▫   Encephalitis: An inflammation of the brain tissue caused by an infection of a virus or bacteria.

▫   Reyes’s Syndrome: This disorder occurs in children that often follow a viral illness where the child was treated with aspirin, and it is potentially deadly.

▫   Tetanus: Is commonly called lockjaw and this infection is caused by a toxin produced by the tetanus bacteria.

▫   Tourette Syndrome: Involuntary grunts, utterances, and tics, including obscenities.

§  Neuro-degenerative Diseases: A group of disorders where there is a progressive loss of structure and/or functions of the neurons.

▫   Alzheimer’s Disease: Disease that involves parts of the brain involved in thought, language, and memory.

-       Patients experience progressive deterioration of reasoning abilities and memory.

▫   Parkinson’s Disease: A degenerative disease of the central nervous disorder in which patients experience fine muscle tremors and rigidity.

-       They often experience a slow, shuffling way of walking.

▫   Lewy Body Dementia: A type of dementia that occurs when abnormal proteins interfere with cell function in the brain.

▫   Huntington's Disease: A progressive disorder caused by a defective gene where patients experience problems in movement, mood, and thinking skills.

▫   Amyotrophic Lateral Sclerosis (ALS): Rapidly progressive neurological disease attacks the nerve cells that control the voluntary muscles and patients become progressively weaker until they are completely paralyzed and die.

§  Brain Injuries

▫   Concussion: Results from a violent shaking or jarring of the brain where the brain is slammed against the side of the skull resulting in damage.

-       Patients may experience a temporary loss of awareness and function.

▫   Cerebral Contusion: Bruising of the brain tissue as a result of a brain injury. 

▫   Cranial Hematoma: A collection of blood trapped in the brain tissue, and they are named for their location either epidural hematoma or subdural hematoma.

▫   Amnesia: A memory disturbance where patients cannot recall past experiences and can result from a brain injury, an illness, medications, or psychological disturbance.

▫   Traumatic Brain Injury: Damage caused by a blow to the head or penetrating head injury.

-       A coup describes the injury occurring within the skull near the point of impact.

-       The contrecoup describes the injury that occurs beneath the skill opposite to the area of impact.

▫   Shaken Baby Syndrome: This describes when a child is violently shaken causing a brain injury that can also cause blindness, seizures, paralysis, fractures, and death.

▫   Cerebral Palsy: A condition caused by damage that affects the cerebrum where patients experience poor muscle control, spasticity, speech defects, and neurologic deficiencies.

§  Strokes

▫   Cerebrovascular Accident (CVA): medical term for stroke and is damage to the brain when blood flow is disrupted because the vessel is either blocked or has ruptured.

-       They are the 3rd-leading cause of death and the primary cause of long-term disability in the U.S.

-       Symptoms of a stroke include, though the location of the damage determines the exact symptoms.

• Facial droop

• Arm drift

• Speech abnormalities

-       When these symptoms are first seen, it is essential to get the patient to emergency care as quickly as possible for treatment for the best outcome.

▫   Ischemic Stroke: Is the most common type in older people and occurs when the flow of blood to the brain is blocked by the narrowing of the carotid artery.

-       Thrombotic Strokes: A type of stroke that Ischemic strokes can become when a blood clot forms in the carotid artery and blocks it.

-       Embolic Stroke: Type of stroke that Ischemic strokes can also become when a clot from somewhere else in the body travels through the bloodstream and lodges in a brain artery.

▫   Hemorrhagic Stroke: A brain bleed that occurs when a blood vessel in the brain leaks or when an aneurysm within the brain ruptures.

§  Levels of Consciousness: describes a person's response to arousal and stimulus.

▫   Altered Levels of Consciousness (ALOC): A decrease in consciousness caused by injury, disease, or substances (medications, drugs, alcohol, poisons, etc.).

▫   Conscious: The state of being awake, alert, aware, and responding appropriately.

▫   Unconscious: The state of being unaware and unable to respond to any stimuli.

▫   Lethargy: A lowered level of consciousness in which patients exhibit listlessness, drowsiness, and apathy.

▫   Stupor: An unresponsive state where a person can be aroused only briefly with vigorous and repeated attempts.

▫   Syncope: Common term for fainting and is the brief loss of consciousness caused by decreased flow of blood to the brain.

▫   Coma: A deep state of unconsciousness where there is no spontaneous eye movement, no response to painful stimuli, and no speech.

▫   Persistent Vegetative State: Is a coma where the patient exhibits alternating sleep and wake cycles.

-       During the wake cycle, the person is still unconscious because of the damage to the brain.

▫   Brain Dead: When the brain has ceased functioning, but vital functions may sometimes be maintained artificially.

▫   Delirium: A condition of confusion, disorientation, disordered thinking and memory, agitation, and hallucination.

§  Brain Tumors: Abnormal growths inside the skull. Brain tumors can be of 2 main types:

1.     Benign: Type of tumor that does not invade the brain tissue. In the brain, however, as the tumor grows, it can damage the brain tissue by placing pressure against the tissues. The extra tissue in the space also increases intracranial pressure.

2.     Malignant: Type of tumor that destroys tissue and it can either initiate in the brain or metastasize to the brain from another area of the body.

§  Conditions of the Spinal Cord

▫   Myelitis: An inflammation of the spinal cord.

▫   Myelosis: A tumor of the spinal cord.

▫   Poliomyelitis: Medical term for polio which is a contagious viral infection of the brainstem and spinal cord that can lead to paralysis.

-      It’s prevented through vaccination and there is NO cure.

▫   Spinal Cord Injuries: These result in weakness or paralysis of the areas supported from the damaged area of the cord.

▫   Radiculitis: Medical term for a pinched nerve where there’s an inflammation of the root of a spinal nerve that leads to pain and numbness radiating down the affected limb.

▫   Multiple Sclerosis: A progressive autoimmune disorder caused by inflammation that causes demyelination of the myelin sheath.

-      It leads to scars in the brain, on the spinal cord, and on the optic nerves that disrupt the transmission of nerve impulses.

-      Patients experience pain as well as physical and cognitive problems.

§  Conditions of the Nerves

▫   Bell’s Palsy: A temporary paralysis of the 7th cranial nerve leading to face paralysis and only affects one side.

-      Additional symptoms can include the inability to close the eye, tearing of the eye, pain, drooling, hypersensitivity to sound, and taste abnormalities.

▫   Guillain-Barre Syndrome: An inflammation of the myelin sheath of peripheral nerves where there is progressive muscle weakness leading to temporary paralysis.

-      It is seen after viral infections and immunizations come.

▫   Neuritis: An inflammation of a nerve in which patients experience severe pain and potential loss of function.

▫   Sciatica: An inflammation of the sciatic nerve in which patients experience pain, tinglining, and burning along the thigh, leg, as well as foot.

▫   Trigeminal Neuralgia: A severe intense pain because of inflammation of the 5th cranial nerve where the patient experiences these brief pain attacks in the cheek, lips, and gums on one side of the face.

§  Seizures

▫   Epilepsy: A chronic neurological condition where patients have recurrent episodes of seizures.

▫   Tonic-Conic Seizure: A grand mal seizure that involves the entire body which becomes rigid and jerks uncontrollably.

▫   Absence Seizures: A petit seizure in which patients experience a brief distutbance of brain function where there is loss of awareness.