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Nervous System (Brain Stem (Brain stem is stalk like structure inferior…
Nervous System
Brain Stem
Brain stem is stalk like structure inferior and partially covered by cerebrum
medulla oblorigate: continuous with spinal cord, responsible for impulses and control heart beat, respiration, and blood vessel diameter. it is the reflex center for coughing, sneezing, swallowing and vomiting
pons: just superior to medulla oblongata and it plays rule in breathing
Mid brain: most superior portion of brain stem and is completely covered by cerebrum
the brain stem contains of brain system, diffuse network of brain stem neurons responsible for "walking up" cerebral cortex
general anesthesia inhibits reticulated system, causing unconsciousness
injury to reticular system can lead to coma
Brain stem receives sensory information and contains control systems for vital processes such as blood pressure, heart rate, and ventilation (breathing)
meninges is infection of meninges, a possibly fatal condition that can rapidly spread and affect brain and spinal cord through this common covering
"Islands"
there are also "Islands" of grey matter deep inside brain, islands are called nucler, examples of nuclei
basal nuclei: motor coordination system
limbic system: controls emotion, mood, and memory
inside of cerebrum is a reflection of the external anatomy; lobes (frontal, parietal termporal, and occipital) are clearly visible
on either side of central sulcus are two gyri
precentral gyrus anterior to central sulcus
postcentral gyrus posterior to central sulcus
responsible for concious thought, judgment, reasoning, memory and will power
Alzheimer's disease
progressive degenerative disease of the brain, most common among 65 years or older
5-18 years from time of onset until death
as the disease progresses, tangles of fiber develop in nerve cells and abnormal protein
memory loss, and diminished cognitive functions
2nd stage: pts increase in in memory loss, have difficult time recognizing people trouble remembering worlds, sleeplessness, confusion, motor problems, loss of social skills
3rd stage: difficulty speaking reading writing and maintaining personal hygiene
led to the four A's: anger, anxiety, aggression, and apathy
no cure certain medications can slow progression of early and middle stages
Stroke
Stroke (3rd leading cause of death in U.S)
caused by disrupted of blood flow to portion of brain
if oxygen disrupted for long enough, brain tissue will die
symptoms of stroke occur suddenly and vary depending on location involved; can include sensory, language motor, and memory difficulties
sudden severe ha dizziness, loss of vision in one eye, aphasia dysphagia, coma, and possible death paralysis, and hemiplegia can result clots major cause
risk factor: smoking, 1 HTN, heart disease, and family history
cerebrovascular (CVA); major stroke, brain tissue dies due to in sufficient, blood supply, and symptoms largely permanent
Nervous Tissue
organs the make up of the nervous system is made up of tissue but not like epithelium, connective or muscle up of two different types of cells ; necrophilia and neurons
Specialized cells in nervous system called neuronglia or glial cells perform specialized functions
Schwann cells: make myelin for the PNS
Satellite Cells: support cells
All of control functions of nervous system must be carried (out) by groups of cells called neurons
Neurons are bizarre looking cells, often with many branches and even what appears to be a tall
How neurons work
Neurons are called excitable cells, this simply means that if cell is stimulated it can carry small electrical charge
each time charged particles flow across cell membrane, there is tiny charge generated
cells are like miniature batteries, able to generate tiny currents simply by changing permeability of their membranes
a cell that is not stimulated or excited is called a resting cell, it is said to be polarized
sodium are positively charged so cell becomes more positve as they enter
size or amount of stimulus determines excitement of cell; many sensory cells work via local potentials which is how CNS determines size of environmental change
Symptoms for Spinal Cord
paralysis and sensory loss below injury; extent of paralysis affected depends on location of injury
Cervical Injuries: patients become quadriplegic (paralyzed in all four limbs) Some patients have paralysis of diaphragm, and require assistance to breathe, sensory perception is also lost below injury
Thoracicand Lumbar injuries: patients become paraplegic (paralyzed in legs); patients who experience paralysis of abdominal muscles may have difficulty coughing or taking deep breaths; sensory information is lost below injury
There difference between breathing on your own and being dependent on the ventilator is only a matter of centimeters
Phrenic Nerve: this is the motor nerve for your diaphragm. if the spinal cord is damaged below the cervical plexus (like the high thoracic region) the phrenic nerve can receive signals from the brain and the person can breath their own
If damage is done between the brain ad the cervical plexus, he path is blocked and the person will need/require a ventilator to breathe for them
Sexual Function
penile erection is a reflex, so it can still occur
ejaculation may be impaired, but sperm are normal and can be used for conception with medical intervention
quadriplegic men can still father a child
Menstrual-cycle may be abnormal due to normal changes post injury
However, many women remain fertile, and may be able to carry a child with adequate medical supervision
Sensory information below the injury is lost so there is no sense of touch-- includes pain, pressure, temperature, or position
Introduction
Nervous System is complex and important to body's control system
Nervous system monitors conditions and takes corrective action when necessary to keep everything running smoothly
The control systems of the body are nervous and endocrine systems which receive help from special serises
Senses: keyboard, mouse, microphone internet connection
control system, have large complex job that is sometime difficult to understand
Motor system
Somatic Nervous System: Controls skeletal muscle and voluntary movements
Autonomic Nervous System: controls smooth and cardiac muscle in your organs and also several glands; is involuntary and not under conscious control
Can be further divided into parasympathetic and sympathetic nervous system
Autonomic Nervous System: controls smooth muscle and cardiac muscle, along with several glands
Autonomic nervous System is divided into parasympathetic system that deals with normal body functioning and maintenance of homeostasis while sympathetic nervous system controls "fight or Flight" response system
Myelin Disorder
Multiple Sclerosis (MS): disorder where myelin in CNS is destroyed
in areas without myelin impulse conditions is slow or impossible
There areas of damaged myelin often have plaques or scarred areas
cause is probably auto-immune attack
symptoms vary depending on where patients myelin has been damaged; possible symptoms include disturbances in vision balance, speech, and movement
Guillan Barre syndrome
course of disease has three phases
acute phase: initial onset of disease, in which patient becomes steadily worse
plateau phase: period of days to weeks in which patient's condition is stable
recovery phase: period of time during which patients recover function
some recover full function, over a period of up to 2 years; significant portion of patients with severe cases have measurable disability two years after recovery
Spinal Nerves
Spinal Nerves from thoracic spinal column project directly to thoracic body wall without branching
all other spinal nerves branch extensively, recombing with nerves from other spinal cord segments before projecting to peripheral structures, these complex branching patterns are called plexuses
nerves are connection between CNS and world outside CNS
All nerves consist of bundles of axons, blood vessels, and connective tissue
nerves run between CNS and organs or tissue, carrying information into and out of CNS
Reflexes
simples form of motor output you can make
generally protective, keeping you from harm
involuntary and usually response gets bigger as stimulus gets bigger
Some familiar reflexes are vestibular reflex which keeps you vertical, and startie reflex, which causes you to jump at loud sounds, withdrawel reflex
Amazing thing about reflexes is that they can often occur without brain being involved, involving only spinal cord
Peripheral nephropathy
Family of disorders involving damages to Peripheral nerves
Because peripheral nerves are involved sensory motor and autonomic functions symptoms can very greating among patients
Possible symptoms include: muscle weakness, decreased reflexes, numbness, tinging, paralysis, pain, difficulty controlling, blood pressure, abnormal sweating, and digestive abnormalilties
Most common overall cause of peripheral neuropathy
anything that causes mechanical injury to nerves, such as falls, or car accidents
Cerebral Cortex
somatic motor system controls voluntary movements under orders from cerebral cortex
in frontal lobe are premotor and prefrontal areas, which plan movements
when you decide to move- it has already been planned
the plan from these two areals (premotor and prefrontal area) is sent to primary motor cortex, located in prefrontal gyrus
orders are then sent to spinal cord directly and also to number of coordination centers, including thalamus, basal nuclei, and cerebellum
Nervous Tissue
Neurons can be classified by how they look (Structure) or what they do (function)
neurons can have one axon and one dendrites or branches (multipolar)
Input neurons are known as sensory neurons while output neurons are known as motor neurons
neurons which carry information between neurons are called inter neurons (inter-between) or assoccation neurons
How Synapse Work
neurontransmitter bind to cell receiving signal, opening or closing gate, some excite receiving cell and some calm it down (hammer on thumb)
last step in transfer of information is to clean up removing neurontransmitter from synapse to prevent it from binding to receiving cell
using an in activator, usually an enzyme; use of neurontrans is called chemical synapse because chemicals carry information form one cell to another
many medications on market today are designed to modify synapses; many antidepressents and anti-anxiety drugs are SSRIs
Meninges
between dura mater and vertebral column is space filled with fat and blood vessels called epidral space
between dura mater and arachnoid mater is subdural space filled with tiny bit of fluid
between arachnoid mater and pia mater is large subarachnoid space filled with CSF that acts as fuild cushion
three membranes and their fluid filled spaces, together with bones of skull and vertebral column, form strong protective system against CNS injury
Polio
Polio: paralysis caused by poliomyelitis virus
epidermiology: common prior to start of large scale vaccination in 1950s, now extremely rare
99% of patients suffer only mild upper respiratory or digestive illness (which lasts only a few days)
1% of patients develop [aralytic form; virus kills motor neurons in ventral horn of spinal cord; cell death result in paralysis; sensation, however, remains intact
Cerebrospinal Fluid and Ventricles
CSF is filleted form blood inventricles by tissue called chorid plexus (750 ml/day)
CSF, made in lateral ventricles (remember ventricles are just cavities in the brain) flows through opening into third ventricle and then though another opening into fourth ventricles
CSF flows into central canal of spinal cord and subarachroid space
CSF is returned to blood via special "ports" (arachniod villi) between subarachnoid space and blood spaces in dura mater (dura sinuses)
Cerebellum
cerebellum has both motor and sensory inputs and outputs from cerebral cortex, thalamus, basal nuclei, and spinal cord
cerebellum gets information about planned movement and actual movement and compares plan to actual; if plan and actual don't match, cerebellum can adjust movement to fit plan
function of cerebellum is subtle and still a bit of mystery, but without cerebellum movements would be inaccurate at best
after movement information is processed by thalamus and basal nuclei, it moves to spinal cord and brain stem via conspiratorial and corticobullar tracts
Basic Operations
Brain and spinal cord are central nervous system (CNS) which controls total nervous system
everything outside brain and spinal cord is part of peripheral nervous system (PNS)
Input side of nervous system is sensory system ; takes everything in and brings it to the nervous system
Types of MS
relapsing remitting: characterized by symptomatic flare-ups (called relapses) followed by periods of time where patient has no symptom (called remission)
Chronic progressive: has no remission periods; patients become steadily more disabled
most patients initially diagnosed with relapsing remitting, but at least 50% will progress to chronic progressive form
Spinal Cord and Spinal Nerves
spinal cord is hollow tube running inside vertebral column, from foramen magnum to the second lumbar vertebrae
spinal cord: is like sophisticated neural information superhighway that allows nerve impulse to travel to and fom the brian
spinal cord can be thought of as a nerve center that controls reflexes; there are 31 segments each with pair of spinal nerves, named for corresponding vertebrae
Charcot Mane Tooth
Diagnosis NOT easy, based on history of symptoms and pressure of other conditions that can cause neuropathy
Treatment underlying cause is treatment symptoms are managed with medication and therapy
Diagosis testing include CT, MRI, electromyogram (EMG, biopsy)
lobes for skull bones
lobes named for skull bones that cover them and occur in pairs, one in each hemisphere
the most anterior lobes, separated from the rest of brain by central sulic, are frontal lobes, frontal lobes are responsible for motor activities, conscious thought, and speech
posterior to parietal lobes are occipital : lobes, which are responsible for vision