Neurological Systems Flashcards
What is the CNS and what is it composed of ?
The central nervous system: Brain and the spinal cord.
What is the PNS, what is it composed of and how it is divided?
The peripheral nervous system : Cranial and spinal nerves.
It can be divided in the Somatic (voluntary) and Autonomic (ANS, Involuntary).
How is the ANS divided?
Into the Sympathetic (Flight-or-fight) and the Parasympathetic (rest and digest).
What kind of communication happens in Neurons ?
Chemical (Neurotransmitters) communication and Electrical (Action Potential) communication.
Gives at least 5 examples of neurotransmitter.
Acetylcholine, Glutamine, Gutamate, Norepineprhine, Dopamine, Histamine, Serotonin, Endocannabinoids, Endorphins.
What is the purpose of Neuroglial cells ?
To Support and nourish the neurons. To clean and to improve communication speed. For memory.
What supports and nourishes the neurons, cleans and improves communication speed. Helps for memory.
Neuroglial Cells
What is the “nerve glue” or “nerve cement”?
50% of the brain, its Neuroglia.
What are the 3 types of neurons ?
-Sensory (afferent, mostly pseudounipolar)
-Associational (interneurons, multipolar)
-Motor (efferent, multipolar).
What is the role of each types of neurons ?
-Sensory : carry signals from peripheral sensory receptors to the CNS
-Associational : send signals from neurons to neurons
-Motor
What is the function of Astrocytes ?
Form specialized contacts between neuronal surfaces and blood vessels. Provide quick transport for nutrients and metabolites. Form a key part of the blood-brain barrier. Appear to be scar-forming cells of CNS, which may be a focus for seizures. Appear to work with neurons in processing information and memory storage.
What are the functions of Oligodendroglia ? (Oligodendrocytes)
Form of the myelin sheath in the CNS.
What are the functions of Schwann cells ?
Form the myelin sheath in the PNS.
What are the functions of nonmyelinating Schwann cells ?
Provide metabolic support and regeneration of neurons in the PNS.
What are the functions of Microglia ?
Clear cellular debris (phagocytic properties)
What are the functions of Ependymal cells ?
Line the ventricles and choroid plexuses involved in making cerebrospinal fluid.
What are the steps of Wallerian degeneration and where does it occur?
It occurs in the distal axon.
1-Typical swelling appears at the axon distal to the cut.
2-The neurofilaments therapy.
3-The myelin sheath shrinks and break down.
4-Axon collapses and disapears
TZ is a 26-year-old who was in a snowboarding accident. TM was found by a tree, unconscious, with a laceration to the forehead. TM was transported to the local hospital where they regained consciousness. TM is taken for MRI to investigate the extent of their injuries.
- TZ is sitting up, breathing and awake after the MRI. Which of the major structural divisions of the brain are responsible for vital reflexes such as respiration?
- A cranial nerve exam is done on TZ. All findings are normal, except for one. When TZ is asked to stick out their tongue, it deviates to the left side. Which cranial nerve is affected?
A. Abducens (VI)
B. Glossopharyngeal (IX)
C. Vagus (X)
D. Hypoglossal (XII)
- The brainstem, composed of the midbrain, medulla, and pons, are responsible for vital reflexes such as respiration. The brainstem connects the hemispheres of the brain, cerebellum, and spinal cord. A collection of nerve cell bodies (nuclei) within the brainstem makes up the reticular formation. The reticular formation is a large network of diffuse nuclei that connect the brainstem to the cortex and control vital reflexes, such as cardiovascular function and respiration. It is essential for maintaining wakefulness and attention and, therefore, is referred to as the reticular activating system (RAS). This means that TZ’s RAS is currently functioning properly, since they are awake and breathing.
- D. Hypoglossal (XII)
The fibres of the hypoglossal nerve arise from the medulla and exit from the skull to travel to the tongue. The hypoglossal nerve carries motor fibres to muscles of the tongue; when affected, abnormalities will be noticed when the person tries to stick out their tongue.
The MRI did not show any bleeding in the brain. Explain what the circle of Willis provides to the cerebral circulation, and the vessels that make it up.
The circle of Willis provides an alternative route for blood flow when one of the contributing arteries is obstructed. The circle of Willis is formed by the posterior cerebral arteries, posterior communicating arteries, internal carotid arteries, anterior cerebral arteries, and anterior communicating artery. The anterior cerebral, middle cerebral, and posterior cerebral arteries leave the circle of Willis and extend to various brain structures.
VN is a six-month-old infant. Her mother brings her in to the pediatrician’s office because she has not been feeding well, and has been pulling at her right ear. When the doctor takes her temperature, it is 38.4°C. The pediatrician tells VN’s mother that she suspects VN has an ear infection, and gives VN acetaminophen for the pain.
- What are the three portions of the nervous system that are responsible VN’s sensation of, perception of, and response to pain?
- What is the difference between VN’s pain threshold and pain tolerance?
- VN’s temperature is high at 38.4°C. What are the benefits of VN having a moderate fever?
- VN is diagnosed with acute otitis media. What would the doctor see when she looks in VN’s ear?
- The three portions of the nervous system that are responsible for VN’s sensation of, perception of, and response to pain are: 1. The afferent pathways, which begin in the peripheral nervous system (PNS), travel to the spinal gate in the dorsal horn and then ascend to higher centres in the CNS; 2. The interpretive centres located in the brainstem, midbrain, diencephalon, and cerebral cortex; 3. The efferent pathways that descend from the CNS back to the dorsal horn of the spinal cord.
2.Pain threshold is the lowest intensity of pain that VN can recognize. Pain tolerance is the greatest intensity of pain that VN can endure. Pain tolerance varies greatly among people and in the same person over time because of the body’s ability to respond differently to noxious stimuli.
- Moderate fever helps the body respond to infectious processes through several mechanisms:
* Raising of the body temperature kills many micro-organisms and adversely affects their growth and replication;
* Higher body temperatures decrease serum levels of iron, zinc, and copper—minerals needed for bacterial replication;
* Increased temperature causes lysosomal breakdown and autodestruction of cells, preventing viral replication in infected cells;
* Heat increases lymphocytic transformation and motility of polymorphonuclear neutrophils, facilitating the immune response;
* Phagocytosis is enhanced, and the production of antiviral interferon is augmented. - The doctor would likely see an inflamed tympanic membrane and fluid in the middle ear. The tympanic membrane would progress from erythema to opaqueness with bulging as fluid accumulates.
XW is an 87-year-old woman who has suffered a devastating stroke. Her husband (TW) tried to wake her up in the morning, but she was found to be unresponsive. TW called for an ambulance, and she was brought into the emergency department. XW remains unconscious.
- What are the five patterns of neurological function? Explain how the medical team would assess each of the five patterns on XW.
- The five patterns of neurological function are (1) level of consciousness, (2) pattern of breathing, (3) pupillary reaction, (4) oculomotor responses, and (5) motor responses.
Level of consciousness: XW is currently unconscious. The medical team would attempt to rouse XW with stimulation to see a response could be elicited. If they could not elicit a response, XW would be considered to be in a deep coma.
Pattern of breathing: XW’s breathing pattern would be evaluated. Hemispheric breathing patterns include normal respirations, posthyperventilation apnea, and Cheyne-Stokes respirations. Brainstem breathing patters include central neurogenic hyperventilation, apneusis, cluster breathing, ataxic breathing, and gasping.
Pupillary reaction: Evaluating XW’s pupils will indicate the presence or absence, or level of brainstem dysfunction because brainstem areas that control arousal are adjacent to areas that control the pupils. The medical team would shine a light in XW’s eyes to see if the pupils construct. If XW has suffered severe ischemia and hypoxia, her pupils may be dilated, and not receptive to light.
Oculomotor responses: Oculomotor responses (resting, spontaneous, and reflexive eye movements) change at various levels of brain dysfunction in comatose individuals. The medical team would test for oculocephalic reflex response, also known as “Doll’s Eyes Phenomenon.” An abnormal finding for XW, demonstrating brainstem injury, would be if her eyes move in the same direction of her head when moved.
Motor responses: XW’s motor responses will be evaluated to determine the level of brain dysfunction. The pattern of XW’s response can be noted as purposeful, inappropriate generalized motor movement, or not present. The team would assess for primitive reflexes and rigidity.
XW is an 87-year-old woman who has suffered a devastating stroke. Her husband (TW) tried to wake her up in the morning, but she was found to be unresponsive. TW called for an ambulance, and she was brought into the emergency department. XW remains unconscious.
- XW is displaying signs of increased intracranial pressure. What is occurring in the three stages of intracranial hypertension, and what symptoms would XW display in each stage?
In stage 1 of intracranial hypertension, vasoconstriction and external compression of the venous system occur in an attempt to further decrease the ICP by minimizing blood flow. During the first stage of intracranial hypertension, XW’s ICP may not change because of the effective compensatory mechanisms, and XW may not display any detectable symptoms.
In stage 2 of intracranial hypertension, there is continued expansion of intracranial contents. The resulting increase in ICP may exceed the ability of XW’s brain’s compensatory mechanisms to adjust. The pressure begins to compromise neuronal oxygenation. Systemic arterial vasoconstriction occurs in an attempt to elevate the blood pressure sufficiently to allow blood flow to overcome the increased ICP. XW may display symptoms of confusion, restlessness, drowsiness (if she was conscious), and slight pupillary and breathing changes. In stage 3 of intracranial hypertension, ICP begins to approach arterial pressure, XW’s brain tissues begin to experience hypoxia and hypercapnia, and XW’s condition rapidly deteriorates. In stage 3, XW may display decreasing levels of arousal or central neurogenic hyperventilation, widened pulse pressure, bradycardia, and small, sluggish pupils.
GB is a 47-year-old individual who was in a motor vehicle accident. At the scene, GB was able to open their eyes to painful stimuli. GB was confused about where they were and what had happened. When asked, GB would squeeze the paramedic’s hand, but was unable to move the lower half of their body. GB was transported to the local hospital under spinal precautions, meaning they used a collar to stabilize their neck, and kept GB on a spinal board to ensure their spine was immobilized.
Using the information provided above, what is GB’s Glasgow Coma Scale score at the scene?
GB’s Glasgow Coma Scale score is 12/15 at the scene. GB receives 2/4 points for the Best Eye Response for opening the eyes to painful stimuli, 4/5 points for Best Verbal Response because they are confused, and 6/6 points for Best Motor Response for obeying commands.
GB is a 47-year-old individual who was in a motor vehicle accident. At the scene, GB was able to open their eyes to painful stimuli. GB was confused about where they were and what had happened. When asked, GB would squeeze the paramedic’s hand, but was unable to move the lower half of their body. GB was transported to the local hospital under spinal precautions, meaning they used a collar to stabilize their neck, and kept GB on a spinal board to ensure their spine was immobilized.
When they arrive at the hospital, GB is now opening their eyes spontaneously, oriented to where they are and what has happened, and is able to follow commands. GB is still unable to move the lower extremities. What is GB’s Glasgow Coma Scale score now?
GB’s Glasgow Coma Scale score is 15/15. GB receives 4 points for the Best Eye Response for opening the eyes spontaneously, 5 points for Best Verbal Response because they are oriented, and 6 points for Best Motor Response for obeying commands.
GB is a 47-year-old individual who was in a motor vehicle accident. At the scene, GB was able to open their eyes to painful stimuli. GB was confused about where they were and what had happened. When asked, GB would squeeze the paramedic’s hand, but was unable to move the lower half of their body. GB was transported to the local hospital under spinal precautions, meaning they used a collar to stabilize their neck, and kept GB on a spinal board to ensure their spine was immobilized.
GB is diagnosed with a spinal cord injury at the level of T6. Explain the difference between a primary and secondary spinal cord injury, and what happens in the weeks following the injury.
Primary spinal cord injury occurs with the initial mechanical trauma and immediate tissue destruction. In GB’s case, this could have occurred during the motor vehicle accident, or if the spine was not adequately immobilized immediately following the injury.
Secondary spinal cord injury is what occurs within minutes to weeks after the injury. It is a pathophysiological cascade of vascular, cellular, and biochemical events which include edema, ischemia, excitotoxicity, inflammation, oxidative damage, and activation of necrotic and apoptotic cell death. Microscopic hemorrhages appear in the central grey matter and pia-arachnoid, increasing in size until the entire grey matter is hemorrhagic and necrotic. Edema in the white matter occurs, impairing the microcirculation of the cord. Hemorrhages and edema are followed by reduced vascular perfusion and development of ischemic areas, which are maximal at the level of injury and two cord segments above and below it. Cellular and subcellular alterations and tissue necrosis occur. Cord swelling increases the individual’s degree of dysfunction, making it difficult to distinguish functions permanently lost from those temporarily impaired. Circulation in the white matter tracts of the spinal cord returns to normal in about 24 hours, but grey matter circulation remains altered. Phagocytes appear 36–48 hours after injury, and microglia proliferate with altered astrocytes. Red blood cells then begin to disintegrate, and resorption of hemorrhages and edema begins. Degenerating axons are engulfed by macrophages in the first 10 days after injury. The traumatized cord is replaced by acellular collagenous tissue, usually in 3–4 weeks. Meninges thicken as part of the scarring process.
GB is a 47-year-old individual who was in a motor vehicle accident. At the scene, GB was able to open their eyes to painful stimuli. GB was confused about where they were and what had happened. When asked, GB would squeeze the paramedic’s hand, but was unable to move the lower half of their body. GB was transported to the local hospital under spinal precautions, meaning they used a collar to stabilize their neck, and kept GB on a spinal board to ensure their spine was immobilized.
Six months later, GB is doing rehabilitation physiotherapy. GB suddenly feels extremely unwell with a pounding headache, blurred vision, and nausea. What is likely happening, and what needs to happen next?
GB is likely experiencing autonomic hyperreflexia (dysreflexia). This is a syndrome of injury at level T6 or above where descending inhibition is blocked. In autonomic hyperreflexia, sensory receptors below the level of the cord lesion are stimulated. The intact autonomic nervous system reflexively responds with an arteriolar spasm that increases blood pressure. Baroreceptors in the cerebral vessels, the carotid sinus, and the aorta sense the hypertension and stimulate the parasympathetic system. The heart rate decreases, but the visceral and peripheral vessels do not dilate because efferent impulses cannot pass through the cord.
What needs to happen next is that GB must figure out which stimulus is causing them to experience autonomic hyperreflexia. It could be a distended bladder or rectum, or skin or pain receptors. For example, GB may have sat on something sharp, and did not notice until their body responded with the symptoms of autonomic hyperreflexia.
