Chapter 14 - NS Flashcards
What is the nervous system anatomically and fuctionally?
Anatomically
Central nervous system (CNS)
CNS is composed of the brain and spinal cord
Peripheral nervous system (PNS)
PNS consists of cranial nerves from brain and Spinal Nerves From spinal cord
Somatic fibers connecting to skin and skeletal muscles and autonomic fibers connecting to vicsera divisions
What does the nervous tissue do?
Nervous tissue is excitable.
Conduct an electrical impulse also known as an “action potential” to communicate with other nerves, muscles, or glands
What does the brain do?
Thought, emotions, behavior, and memory
What does the spinal cord and nerves do?
Process stimuli that may be harmful and the body responds with a protective reflex action
What do the sensory receptors do?
Sensory receptors
Smell, touch, sight, and hearing
Regulating appetite and body temperature
What do neurons do?
Transmit electrochemical messages
Called nerve impulses or action potentials
To other neurons and effectors
Permanent cells
Do not have the ability to divide
Cell body, cell membrane, nucleus, and many of the same organelles found in other types of cells
What do axons do?
Usually only one axon
Carries an action potential away from the cell body
In the CNS, these nerve fibers form tracts
In the PNS, they form nerves
What do dendrites do?
Usually many dendrites from a single cell body
Transmit an electrical signal toward the cell body
What are Multipolar neurons ?
Most numerous
One axon and many dendrites
Brain and spinal cord
Efferent (motor) neurons - Carry messages from the CNS to the muscles and glands in the PNS
Interneurons or association neurons - Connect sensory and motor neurons and direct the impulse to other areas of the brain or spinal cord
What are bipolar neurons?
Fewest in number
One dendrite and one axon
parts of nose, eyes and ears
Afferent (sensory) Carry impulses from the periphery to the CNS
What are unipolar neurons?
Single extension that divides into two processes
Found of ganglia outside the brain and spinal cord
Afferent (sensory) Carry impulses from the periphery to the CNS
What are NeurOglia?
Also referred to as neuroglial cells or simply “glia”
Do not transmit impulses
Act as supportive cells for other neurons
Able to reproduce and replace themselves
What are astrocytes?
Neuroglia in CNS
star shaped between neurons and blood vessels
Functions - structural support, forms scar tissue, transports, communicates
What are oligiodendrocytes?
Neuroglia in CNS
star shaped not as common
Produce nerve growth factors, myelin sheaths in the brain and spinal cord
What are microglia?
Neuroglia in CNS
Small cells , found throughout CNS
Structural support and phagocytosis (immunity)
What are ependyma?
Neuroglia in CNS
cuboidal and columnar cells in lining of ventricles of brain form a porous layer where substances are able to diffuse between brain fluid, spinal cord and CSF
What are Schwann cells?
Neuroglia in PNS
Cells with lipid rich membranes wrapped around axons
F- speed neurotransmission
What are satellite cells?
Neuroglia in PNS
Cubodial cells that surround cell bodies of neurons in ganglia
Support ganglia in PNS
What is Myelin?
Fatty substance which insulates axons
Allows them to send nerve impulses more rapidly than that of unmyelinated nerves
When coated these axons are referred to as “white matter”.
Unmyelinated nerve cell bodies make up the “gray matter”
What is nerve transmission?
-action potential travels down an axon and reaches the synaptic knob (vesicles that are either excitatory or inhibitory) at the end of each axon branch
-cause the vesicles to fuse with the presynaptic membrane of the axon terminal
Causing the neurotransmitters to be released into a space called the synaptic cleft
-Neurotransmitters then combine with receptors on the postsynaptic membrane
Allows the impulse to continue on the structures on the other side of the synaptic cleft
What is Acetylcholine?
Neurotransmitter
In CNS - control skeletal muscle actions
in PNS - stimulates muscle contractions
What is norepinephrine?
Biogenic amines
CNS- creates sense of well being- low levels may cause depression
PNS- May excite or inhibit autonomic actions
What is dopamine?
Biogenic amines
CNS- Creates sense of well being. Not enough of it leads to Parkinsons
PNS - Limited actions in autonomic nervous system
What is seratonin?
Biogenic amines
CNS - Inhibitory . sleepyness, blocked by LSD. enhanced by antidepressants
What is histamine?
Biogenic amines
CNS - Release in hypothalamus promotes alertness
What are amino acids in the CNS?
GABA (inhibit), Glutamate (excitatory),
What are some neuropeptides ?
Endorphins (cns - inhibitory reduce pain), Substance P - PNS (Excitatory - pain perception)
What are some gases?
Nitric oxide - CNS - memory
PNS - vasodialation
What is action potential propagation?
Speed of conductance down an axon
Larger-diameter axon will conduct an impulse faster than smaller diameter axons
Myelinated nerve will conduct an action potential faster than an unmyelinated axon
In myelinated nerves, there are bare areas on the axon called Nodes of Ranvier.
Action potential jumps from node to node.
Called saltatory conductance
What is the Blood brain barrier?
Protects the brain by not allowing harmful substances to enter it from the blood
Tight junctions between endothelial cells of the brain capillaries
Astrocytes help maintain the tight junctions
BBB restricts most large molecules and hydrophilic substances from entering the cerebrospinal fluid (CSF
Develops early in embryonic life
CNS begins as a simple tubelike structure called the neural tube
What are the major regions and areas of the brain?
Three regions of the brain can be identified: the forebrain, midbrain, and hindbrain.
Forerunners of the adult brain
Adult brain
Four major areas: cerebrum, diencephalon, brainstem, and cerebellum)
What is cerebrum?
Largest division of the brain
Longitudinal fissure
Divides into right and left halves called cerebral hemispheres
Corpus callosum
Thick bundle of axons fibers connects the two hemispheres
Grooves on the surface called sulci
Folds between the sulci are called gyri or convolutions
What is basal nuclei?
Gray matter in cerebral hemispheres
Motor impluses starts in cortex to spinal cord
What is diencephalon?
Located between the cerebral hemispheres and is superior to the brainstem
Thalamus
Serves as the relay station for sensory information that is conveyed to the cerebral cortex for interpretation
Hypothalamus
Maintains homeostasis by regulating many vital activities such as heart rate (pulse), blood pressure (BP), and respiration (breathing) rate
What are parts of brainstem?
-Midbrain or mesencephalon
Beneath the diencephalon
Controls both visual and auditory reflexes
-Pons
Rounded bulge on the underside of the brainstem
Nerve tracts to connect the cerebrum to the cerebellum
Also regulates respiration
-Medulla oblongata
Most inferior portion of the brainstem
Directly connected to the spinal cord
Controls heart rate, BP, and respiration
Controls reflexes associated with coughing, sneezing, and vomiting
What is cerebellum?
Inferior to the occipital lobes of the cerebrum and posterior to the pons and medulla oblongata
Coordinates complex skeletal muscle activity that is needed for body movements
Coordinates fine-motor movements such as threading a needle, playing an instrument, and writing
What is grey and white matter?
-Gray matter
Two dorsal horns receive afferent (sensory) information from the body
Two ventral horns carry efferent (motor) information to the body
-White matter
Anterior (ventral), lateral, and posterior (dorsal) columns
Contain the groups of axons called nerve tracts
What are tracts?
carry sensory information up to the brain - ascending or afferent tracts
Transmits motor information from the brain to muscles and glands. Called descending or efferent tracts
What is Alzheimer’s Disease
Progressive, degenerative disease of the gray matter of the brain
No single “cause” of Alzheimer’s
Loss of memory, confusion, personality changes, language deterioration, impaired judgment, and restlessness
Medications and proper nutrition, physical and mental exercise, social activity, and calm environments
What is Parkinsons?
Progressive deterioration of neurons in the substantia nigra
Produce a neurotransmitter called dopamine
Most cases of PD are idiopathic
Some may be caused by brain tumors, certain drugs, carbon monoxide, or repeated head trauma
Resting tremor that disappears with voluntary movement, muscle rigidity, and a lack of coordination and balance
Face is said to be masklike
Stooped posture and a shuffling gait
Dopamine and Levodopa alleviate some symptoms and slow the progression of this disease
What is Cerebrovascular Accident (CVA) ?
Brain cells die because of inadequate perfusion.
Numbness or loss of function on one side of the body, paralysis of one side of the body, speech problems, memory and reasoning deficits, coma, and death
“Clot-buster drugs” such as TPA used within three hours of the first symptoms
Physical, occupational, and speech therapy
What are Occlusive or white strokes
CVA
Lack of blood to an area of the brain
Occlusion can be caused by a thrombus in a blood vessel of the neck or vein or an embolus that has traveled to the brain from elsewhere in the body
What are Hemorrhagic or red strokes ?
Blood bleeds into the surrounding brain tissue.
Ruptured aneurysm in a blood vessel to the brain
What are Episodic Tension Headaches?
Result of temporary stress or muscle tension
Pain or soreness in the temples and the contraction of head and neck muscles
OTC medicine
What are Chronic Tension Headaches?
Occur almost daily and persist for weeks or months
Result of stress or fatigue
Associated with physical problems, psychological issues, or depression
Pain or soreness in the temples and the contraction of head and neck muscles
Seek medical treatment to determine the underlying cause
What are migrane?
Hormones may influence migraines
Women experience migraines at least three times more often than men do
Considered vascular headaches
Associated with the dilation of the arteries of the brain
Sensitivity to light get nausea
What are cluster headaches?
Attacks come in groups for a period of time and often appear seasonal.
Hypothalamus may be involved
Runny nose, watery eyes, and swelling below the eyes
Various drugs are available for the treatment of these headaches.
What are brain tumors?
Abnormal growths in the brain
Caused by gene mutations
Headaches, seizures, nausea, weakness in the arms or legs, fatigue, changes in speech patterns, and a loss of memory.
Surgery, radiation therapy, chemotherapy, and gene therapy
What is Epilepsy?
Brain experiences repeated spontaneous seizures due to abnormal electrical activity of the brain
Petit mal (partial)
“Absence seizures” where the individual may have a loss of awareness of the present or appears to “space out”
Grand mal (generalized)
Classic tonic-clonic seizure
Etiology not known,, birth trauma, infections, bad visuals, uncontrolled muscle spasms
What are meninges?
Connective tissue membranes that protect the brain and spinal cord - viral or bacterial
What is Dura Mater
Meninges
Dura mater
Toughest and outermost layer
Space above the dura mater is called the epidural space; below it is the subdural space
What is Arachnoid mater
Meninges
Middle layer
Named for its spider-web-like appearance
What is Pia mater
Meninges
Innermost and most delicate layer
Holds blood vessels onto the surface of the brain and spinal cord
What is Subarachnoid space?
Meninges
Between the arachnoid mater and pia mater
Contains cerebrospinal fluid (CSF), which cushions the CNS
What are ventricles?
Interconnected cavities within the brain
Two lateral ventricles, one in each cerebral hemisphere
Third ventricle is located between the right and left halves of the thalamus.
What is CSF? know
CSF is a clear, colorless fluid when all is well. - in disease it can be a variety of colors
Cushions the brain and spinal cord
Protects them from chemical injury
Carries oxygen and nutrients to neurons and neuroglia
CSF is produced by the ependymal cells of the choroid plexuses.. Network of capillaries located with the ventricles of the brain
What is SNS?
Somatic nervous system (SNS)
Governs the body’s skeletal (voluntary) muscles
What is the ANS
Autonomic nervous system (ANS)
Governs the body’s automatic functions
What nerve systems are in the ANS?
Parasympathic system “Rest and digest” Acetylcholine Neurons are located in the brainstem and the sacral regions of the spinal cord. Craniosacral division
Sympathetic nervous system “Fight or flight” Norepinephrine Neurons are located in the thoracic and lumbar regions of the spinal cord Thoracolumbar division
What is Bells Palsy?
Facial muscles are very weak or temporarily totally paralyzed.
Damage to cranial nerve VII
Many times the cause is unknown
Loss of feeling in the face, the inability to produce facial expressions, headache, and excessive tearing or drooling
What are NeurAlgias
Group of disorders commonly referred to as nerve pain
Trauma, chemical irritation of the nerves, bacterial infections, and diabetes
Sudden and severe skin pain and numbness are the most common symptoms
Only pain meds are given
What is Guillain-Barré Syndrome?
Body’s immune system attacks part of the peripheral nervous system.
Viral infections, immunizations, and pregnancy
Weakness or tingling sensations in the legs or arms that can progress to paralysis, dyspnea and an abnormal heart rate
IV gamma globulin treatments, rest, nutritional support including NG tubes, and respiratory and cardiac monitoring
What is Sciatica?
Sciatic nerve is commonly damaged by excessive pressure on the nerve from prolonged sitting or lying down.
Numbness, pain, or tingling sensations on the back of a leg or foot
Pain and anti-inflammatory medication or steroids
What is MS?
Chronic disease of the CNS in which myelin is destroyed
Causes are mostly unknown
Severe cases, a person loses the ability to walk or speak
No cure for MS
Medications, including interferon, are available to treat and slow the progression of symptoms.
What is Amyotrophic Lateral Sclerosis (ALS)
Lou Gehrig’s disease
Fatal disorder characterized by the degeneration of neurons in the spinal cord and brain
Most causes are unknown.
Early symptoms include cramping of hand and feet muscles, persistent tripping and falling, chronic fatigue, and slurred speech.
Later stages include dyspnea and muscle paralysis
Help manage using physical, speech and respiratory therapies
What are the types of Neuro testing?
State of Consciousness- Vary from normal to a state of coma
Reflex Activity- Primarily determine the health of the peripheral nervous system
Speech Patterns- Abnormal speech patterns include a loss of the ability to form words correctly or to form sentences that make sense
Motor Patterns-Abnormal motor patterns include the loss of balance, abnormal posture, or inappropriate movements of the body
What is Lumbar Puncture? know
Sometimes called a “spinal tap”
Needle is used to remove CSF from the subarachnoid space.
Space below the third lumbar vertebra
What is Magnetic Resonance Imaging (MRI)?
Brain and spinal cord to be visualized
Uses powerful magnets
Useful at detecting tumors and bleeding
What is Positron Emission Tomography (PET) Scan
Uses radioactive chemicals that collect in specific areas of the brain
Useful in detecting blood flow to areas of the brain, brain tumors, and the diagnosis of such diseases as Parkinson’s and Alzheimer’s
What is Cerebral Angiography?
Uses contrast material so that the blood vessels in the brain can be visualized
Useful in detecting aneurysms
What is Computerized Tomography (CT) Scan?
Images that provide more information than a standard x-ray
Useful in detecting tumors and other abnormal structures
What is Electroencephalogram (EEG)
Detects electrical activity in the brain
Useful in diagnosing seizures and various states of consciousness
What is xray?
Useful in detecting skull or vertebral fractures
Nearing end of lifespan?
Brain starts to atrophy and we may see changes in memory or cognitive skills
More likely to get stroke, Alz or Parkinsons
slower reflexes
Connective tissue - What is lymph lfuid
Fluid component-Consists of water, glucose , fat , protein and salt
Cellular component –lymphocytes and granulocytes
Transports fluid and cellular components from the tissues to the circulatory system via the lymphatic vessels
