Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
126 Cards in this Set
- Front
- Back
Functions of the Nervous System
|
Controls skeletal muscle movement
Helps regulate cardiac and visceral smooth muscle activity Enables reception, integration, and perception of sensory information |
|
Functions of the Nervous System (cont.)
|
Provides substratum necessary for intelligence, anticipation, and judgment
Facilitates adjustment to ever-changing external environment |
|
Components of the Nervous System
|
CNS
PNS |
|
CNS
|
Consists of the brain and spinal cord, which are protected by the skull and vertebral column
Concentration of computational and control functions |
|
PNS
|
Found outside structures of CNS
Functions as input-output system for relaying information to CNS and transmitting output messages to control effector organs |
|
Structures of the Brain
|
Hindbrain
Midbrain Forebrain |
|
Hindbrain
(Brain Stem) |
medulla oblongata
pons cerebellum |
|
Midbrain
|
Include two pairs of dorsal enlargements
- superior coliculi - inferior colliculi |
|
Forebrain
|
Consists of two hemispheres covered by cerebral cortex
Contains central masses of gray matter, basal ganglia, diencephalon with its derivatives—thalamus and hypothalamus |
|
Lobes of the Brain
|
frontal lobe
parietal lobe temporal lobe occipital lobe |
|
Frontal lobe
|
extends from frontal pole to central sulcus (fissure)
- separated from temporal lobe by lateral sulcus |
|
Parietal lobe
|
lies behind central sulcus (postcentral gyrus); above lateral sulcus
|
|
Temporal lobe
|
lies below the lateral sulcus and merges with the parietal and occipital lobes
|
|
Occipital lobe
|
- lies posterior to temporal and parietal lobes
- arbitrarily separated from them |
|
Levels of the Spinal Cord
|
- spinal cord is shorter than spinal column in adult
Cauda Equina - collection of spinal nerves that travel down spinal canal below termination of spinal cord |
|
Spinal Nerves
|
Each exits at a vertebral level that corresponds to its level in the cord
|
|
Horns of the Spinal Cord
|
- extensions of gray matter that form the letter “H”
- White matter of the cord is composed of myelinated axons traveling up cord to the brain (sensory) or down cord from brain (motor). - dorsal horns - ventral horns |
|
Dorsal Horns
|
Contain neurons that receive afferent impulses through dorsal roots
|
|
Ventral Horns
|
Contain neurons and the efferent lower motor neurons that leave the cord through the ventral roots
|
|
Information Flow
|
- cranial and spinal nerves come out from the CNS
BUT - information flowing through may be coming out (efferent; motor information) - OR coming in (afferent; sensory information) to the CNS |
|
Afferent Nerve
|
- carries information from sensory receptors in skin to brain
|
|
Efferent Nerve
|
- carries information from brain to neurons controlling leg muscle, causing response
|
|
Nerves
Cranial or Spinal |
- collections of nerve fibers (individual axons or dendrites of individual neurons)
Individual fibers within nerve may be transmitting motor information out to periphery or sensory information in to CNS |
|
Major Cells of the Nervous System
|
- neurons
- glia |
|
Neurons
(Functioning Cells) |
- Afferent (sensory) neurons carry information to CNS
- Efferent (motor neurons) carry information from CNS to effector organs |
|
Neurons
(Functioning Cells) cont. |
- gray matter: nerve cell bodies in CNS
- white matter: myelinated axons forming tracts in CNS |
|
Glia
|
- protect nervous system; supply metabolic support
- astrocytes contribute to blood-brain barrier; also give metabolic support - oligodendrocytes in brain and Schwann cells in periphery make myelin to insulate nerve fibers - microglia: immune cells in brain |
|
Sensory Component of Nervous System
Function |
Provides awareness of body sensations (i.e. body position in space, sight, hearing, touch, temperature, limb position, pain)
|
|
Sensory Component of Nervous System
Composition |
- sensory receptors: consist of discrete nerve endings in skin and other body tissues
- dermatomes: areas of skin supplied by discrete levels of spinal nerves |
|
Major Modalities of Sensory Experience
|
Discriminative Touch
Temperature Sensation Body Position Nociception (Pain sense) |
|
Discriminative Touch
|
Location, Sharp, Dull, Soft, Fuzzy, Scratchy
|
|
Temperature Sensation
|
Hot, Warm, Cool, Cold
|
|
Body Position
|
Flexion, Extension, Position in Space, Balance
|
|
Nociception (Pain sense)
|
Sharp, Dull, stabbing, Aching, Burning
|
|
Neurons Found in Sensory Systems
|
First-order neurons
Second-order neurons Third-order neurons |
|
First-Order Neurons
|
Transmit sensory information from periphery to spinal cord.
|
|
Second-Order Neurons
|
Relay sensory information up spinal cord to thalamus.
|
|
Third-order neurons
|
Relay information from the thalamus to the cerebral cortex
|
|
Pathways from Spinal Cord to Thalamic Level of Sensation
|
- anterolateral pathways (spinothalamic tracts)
- discriminative pathway (posterior columns) |
|
Anterolateral Pathways (Spinothalamic Tracts)
|
- bilateral multisynaptic slow-conducting tracts
- provide for transmission of sensory information that does not require discrete localization of signal source or fine discrimination of intensity |
|
Discriminative Pathway (Posterior Columns)
|
- crosses at base of medulla
- relays information to brain for perception, arousal, and motor control |
|
Corticospinal (Pyramidal) Tracts
|
-Nerve cell bodies: pyramid-shaped neurons in motor cortex
-myelinated axons pass down through brain in bundle called internal capsule. - In brain stem, axons cross to opposite side: decussation of pyramids - axons then course down ventral lateral spinal cord - individual axons peel off from rest at particular levels; then synapse with primary motor neurons - important in gross motor movement |
|
Extrapyramidal Tracts
|
Nerve cell bodies originate in the motor cortex and send axons to the thalamus or globus pallidus, where they synapse with other neurons.
|
|
Extrapyramidal Tracts
|
Additional synapses may be present in midbrain and pons and finally at the lower motor neurons at each level of cord.
Serves to smooth and integrate movement |
|
Requirements of Motor Systems
|
Upper motoneurons project from motor cortex to brain stem or spinal cord
Directly or indirectly innervate lower motoneurons or contracting muscles |
|
Requirements of Motor Systems
|
Lower motoneurons project from spinal cord to skeletal muscle
Sensory feedback from involved muscles Continuously relayed to cerebellum basal ganglia and sensory cortex |
|
Requirements of Motor Systems
|
Functioning neuromuscular junction that links nervous system activity with muscle contraction
|
|
Motor Systems
|
Pyramidal motor system
Extrapyramidal system |
|
Pyramidal Motor System
|
Originates in motor cortex
Provides control of delicate muscle movement |
|
Extrapyramidal System
|
Originates in basal ganglia
Provides background for more crude, supportive movement patterns |
|
Motor Unit
|
Excitatory & inhibitory influences come from higher centers.
Excitatory influences may come from sensory input at same level. |
|
Neuromuscular Junction
|
Serves as a synapse between a motor neuron and a skeletal muscle fiber
Consists of the axon terminals of a motor neuron and specialized region of muscle membrane called endplate |
|
Neuromuscular Junction
|
The transmission of impulses is mediated by release of neurotransmitter acetylcholine from axon terminals
|
|
Neuromuscular Junction
|
Acetylcholine binds to receptors in the endplate region of the muscle fiber surface to cause muscle contraction
|
|
Mechanisms Controlling Coordinated Movement
|
Extensors
- Muscles that increase angle of a joint Flexors - Muscles that decrease angle of a joint Agonists - Promote movement |
|
Mechanisms Controlling Coordinated Movement
|
Antagonists
- Oppose movement Synergists - Assist agonist muscles by stabilizing a joint or contributing additional force to movement |
|
Spinal Cord Injury (SCI)
Definition |
Damage to neural elements of spinal cord
|
|
Spinal Cord Injury (SCI)
Causes |
Motor vehicle crashes, falls, violence and sporting activities
|
|
Spinal Cord Injury (SCI)
Involvement |
Most SCIs involve damage to vertebral column and/or supporting ligaments as well as spinal cord
Commonly involve both sensory and motor function |
|
Types of Injuries to Vertebral Column
|
Fractures
Dislocations Subluxations |
|
Incomplete Spinal Cord Injuries
|
Central Cord Syndrome
Brown-Séquard Syndrome Anterior Cord Syndrome |
|
Types of Paralysis
|
Monoplegia
Hemiplegia Tetraplegia or quadriplegia Paraplegia |
|
Areas Affected by SCI
|
Spinal reflexes
Ventilation and communication Autonomic nervous system Temperature regulation |
|
Areas Affected by SCI
|
Edema and deep vein thrombosis
Sensorimotor function Skin integrity |
|
Areas Affected by SCI
|
Pain Transmission
Bladder and bowel function Sexual function |
|
Disorders of Motor Function
|
Upper motoneuron lesions
Lower motoneuron lesions |
|
Upper Motoneuron Lesions
|
Can involve motor cortex, internal capsule, or other brain structures through which corticospinal or corticobulbar tracts descend, or spinal cord
|
|
Lower Motoneuron Lesions
|
Disrupt communication between muscle and all neural input from spinal cord reflexes, including stretch reflex, which maintains muscle tone
|
|
Muscle Spasm
|
Sudden violent involuntary contraction of a muscle or group of muscles
|
|
Spasticity
|
Certain muscles are continuously contracted leads to
- muscle stiffness/tightness -may interfere with gait, movement, or speech: = Damage to the portion of brain or spinal cord that controls voluntary movement usually causes spasticity |
|
Diseases Associated with Spasticity
|
Spinal cord injury
Multiple sclerosis Cerebral palsy ALS (Lou Gehrig’s disease) Phenylketonuria |
|
Diseases Associated with Spasticity
|
Brain damage due to lack of oxygen
Brain trauma Severe head injury Metabolic disease (adrenoleukodystrophy |
|
Spastic Contractions
|
- often triggered by sensory stimuli that normally elicit motor reflex
- sensory stimulus that evokes contraction much smaller than normal - contraction evoked much stronger than normal |
|
Spasticity (cont.)
|
generalized,
- involving all motor centers in cord and therefore all muscle groups |
|
Spasticity (cont.)
|
can be focal
– involving one or a few motor centers |
|
Spasticity (cont.)
|
- may involve one limb or all
- Motor impulses may go to all muscles: flexors & extensors - strongest muscles prevail: usually flexors |
|
Spasticity (cont.)
|
when chronic can result in contractures
|
|
Basal Ganglia
|
- deep, interrelated subcortical nuclei that play an essential role in control of movement
|
|
Basal Ganglia
|
- receive indirect input from cerebellum, all sensory systems
- including vision - direct input from motor cortex |
|
Basal Ganglia
|
function in inherited & highly learned & rather automatic
- involved in cognitive and perception functions |
|
Dopamine pathway & effects
|
Mesocortical - Cognition
Mesolimbic - Emotions Nigrastriatal - Extra-pyramidal system that modulate movement |
|
Cholinergic pathway & effects
Cortex and Limbic System |
-Learning and memory;
-Wakefulness and attention |
|
Cholinergic pathway & effects
PNS |
Useful throughout the body
- Regulation of Parasympathetic Nervous System - Excitatory transmission at neuromuscular junction |
|
Disorders of the Basal Ganglia
Characteristics |
Involuntary movements
Alterations in muscle tone Disturbances in body posture |
|
Involuntary Movement Disorders Types
|
Tremor
Tics Chorea Athetosis Ballismus Dystonia Dyskinesias |
|
Parkinson Disease
Definition |
degenerative disorder of basal ganglia function that results in variable combinations of tremor, rigidity, and bradykinesia
|
|
Parkinson Disease
Characteristics |
- progressive destruction of nigrostriatal pathway
- subsequent reduction in striatal concentrations of dopamine |
|
Multiple Sclerosis (MS)
|
- most common non-traumatic cause of neurologic disability among young & middle-aged adults
|
|
Multiple Sclerosis (MS)
Characteristics |
- exacerbations and remissions over many years in several different sites in CNS
- starts with normal or near-normal neurologic function between exacerbations - during progression, less improvement between exacerbations, neurologic dysfunction increases |
|
Brain Injury Causes
|
Trauma
Tumors Stroke Metabolic derangements Degenerative disorders |
|
Brain Injury Manifestations
|
Alterations in sensory and motor function
Changes in the level of consciousness |
|
Levels of Consciousness
|
Confusion
Delirium Obtundation Stupor Coma |
|
Signs of Decreased LOC
|
Earliest
- Inattention, mild confusion, disorientation, and blunted responsiveness Later - marked inattention; variable lethargic or agitated - may progress to obtunded; may respond only to vigorous or painful stimuli |
|
Common Pathways of Brain Damage
|
Effects of ischemia
Excitatory amino acid injury Cerebral edema Injury due to increased intracranial pressure (ICP) |
|
Hypoxia
|
deprivation of oxygen with maintained blood flow
|
|
Ischemia
|
- greatly reduced or interrupted blood flow
- interferes with O2 and glucose delivery, and metabolic waste removal |
|
Injury From Excitatory Amino Acids
Definition |
Injury to neurons caused by overstimulation of receptors for specific amino acids that act as excitatory neurotransmitters
|
|
Injury From Excitatory Amino Acids
Causes |
Stroke
Hypoglycemic injury Trauma Chronic degenerative disorders (Huntington’s disease,Alzheimer’s dementia) |
|
Cerebral Edema
|
Vasogenic Edema
Cytotoxic Edema |
|
Vasogenic Edema
|
- occurs with conditions that impair the function of blood-brain barrier
- allows transfer of water and protein from vascular into interstitial space |
|
Cytotoxic Edema
|
- increase in intracellular fluid
|
|
Brain Injury Types
|
Primary or Direct
Secondary Injuries |
|
Primary or Direct Brain Injuries
|
Damage is caused by impact
Include diffuse axonal injury and focal lesions of laceration, contusion, and hemorrhage |
|
Secondary Brain Injuries
|
Damage results from subsequent brain swelling, infection, cerebral hypoxia
Often diffuse or multi-focal, including concussion, infection, and hypoxic brain injury |
|
Epidural Hematoma
|
- Usually caused by head injury with skull fracture
- between inner table of bones of skull and dura |
|
Subdural Hematoma
|
- Usually result of tear in small bridging veins that connect veins on surface of cortex to dural sinuses
- Develops in area between dura and arachnoid (subdural space) |
|
Blood Supply to Brain
|
Anterior
- two internal carotid arteries Posterior - vertebral arteries |
|
Cerebral Blood Flow
Metabolic Factors |
Carbon dioxide
Hydrogen ion Oxygen concentration |
|
Ischemic Strokes
|
- interruption of blood flow in cerebral vessel
- most common type of stroke (70%-80%) |
|
Hemorraghic Strokes
|
- bleeding into brain tissue
- blood vessel rupture -- HTN, aneurysms, AVM, head injury, blood dyscrasias |
|
Stroke Risk Factors
|
Age, sex, race
Family history Hypertension Smoking Diabetes mellitus Asymptomatic carotid stenosis Sickle cell disease Hyperlipidemia Atrial fibrillation |
|
Stroke Related Deficits
|
Motor deficits
Dysarthria and Aphasia Cognitive and Other Deficits |
|
Seizure
|
- uncontrolled, chaotic activity in brain
- produces muscular activity -- tonus (muscle contraction) -- clonus (alternate contraction and relaxation -- complete relaxation/ paralysis |
|
Seizure Risk Factors
|
Lifetime risk - 10%
Epilepsy at some point: 3-4% Epilepsy at any given time: 0.5-1% Acute reaction seizure: 3-4% Single unprovoked seizure: 1% Active epilepsy >55 yrs: 0.9% |
|
Seizure Activity Risk Factors
Specific Populations |
Acute stroke – ~ 25%
Brain tumor – 30% as first symptom -- 18% with brain metastasis Infection -- Bacterial meningitis – 25% -- Herpes encephalitis – 50% Dialysis encephalopthy – 50% Alzheimer's – 16% |
|
Seizure Classification
|
Partial
Generalized |
|
Partial Seizures
|
Simple - no impairment of consciousness
Complex - impairment of consciousness Partial seizures evolving to secondarily generalized seizures |
|
Generalized Seizures
|
Absence seizures (typical or atypical)
Atonic seizures Myotonic seizures Clonic seizures Tonic seizures Tonic-clonic seizures |
|
Status Epilepticus
|
Definition
- Rapid succession of epileptic seizures Sudden withdrawal of AEDs may precipitate seizures or status epilepticus First drug of choice - IV diazepam (benzodiazepine) |
|
Status Epilepticus
(cont.) |
- possible intubation, ventilation
- after IV benzo, give loading dose of phenytoin (long-acting anticonvulsant) - Possible complications: lactic acidosis, hyperthermia |
|
Bacterial Meningitis
|
“Meningococcal meningitis” = Neisseria meningitides.
“Pneumococcal meningitis” = Streptococcus pneumonae. Other bacterial causes: - Haemophilus influenza - Mycobacterium tuberculosis. |
|
Bacterial Meningitis
(cont.) |
- after infecting meninges, rapidly destroy capillary structure and invade brain
- can be rapidly fatal (hours) - prophylactic abx w/exposure |
|
Viral Meningitis
|
- caused by various viruses
- usually mild Immunosuppressed patients (HIV, chemotherapy) can get fulminant, fatal viral meningitis caused by - Epstein Barr virus - herpes simplex virus - West Nile virus |
|
Alzheimer's Disease Stages
|
- progressive, unrelenting
- NO KNOWN CURE - few therapeutic options - > 4 million Americans - by 2010, Medicare/Medicaid costs will be >$79 billion - other costs include informal caregiving (can cost businesses $61 billion/yr in lost work days |
|
Clinical Hallmarks/Major Symptoms Of Alzheimer’s Disease
|
Progressive cognitive impairment, particularly memory loss.
Impaired judgment and decision-making ability. Difficulty orienting to physical surroundings. Language problems |
|
Neuropathological Hallmarks of Alzheimer’s Disease
|
Neuron Death
Neurofibrillary Tangles Amyloid Plaques |