Nervous System Slides PDF

3.03 Understand Structures, Functions and Disorders of the Nervous System. HU40 Health Science I STRUCTURES AND FUNCTIONS OF THE NEURON (Nerve Cell) Dendrite: many tree-like projections from the neuron that carry messages to the cell body Axon: the single long ar...

3.03 Understand Structures, Functions and Disorders of the Nervous System. HU40 Health Science I STRUCTURES AND FUNCTIONS OF THE NEURON (Nerve Cell) Dendrite: many tree-like projections from the neuron that carry messages to the cell body Axon: the single long arm of the neuron that carries messages away from the cell body Myelin Sheath: insulating layer around neurons that allow nerve impulses to be transmitted quickly and efficiently Synapse: space separating two neurons NERVE IMPULSE Stimulus creates an impulse Impulse travels into the neuron on the dendrite and out on the axon At the end of the axon a NEUROTRANSMITTER is released Neurotransmitter carries the impulse across the synapse to the next dendrite Types of Neurons Sensory Neurons: sends information from sensory receptors (ie. Skin, eyes, ears, nose, tongue) to the spinal cord and brain Motor Neurons: sends information from central nervous system back to body Associative: (aka interneurons) sends information between sensory and motor neurons Divisions of the Nervous System  Divisions Of Nervous System: Central Nervous System: made up of brain and spinal cord Peripheral Nervous System: consists of cranial and spinal nerves Autonomic Nervous System: part of the peripheral nervous system that controls involuntary functions such as heart and smooth muscle Somatic Nervous System: part of peripheral nervous system that controls voluntary movement via skeletal muscle Central Nervous System CENTRAL NERVOUS SYSTEM: BRAIN  CEREBRUM Largest part of the brain Divided into R and L hemispheres by a deep grove called the longitudinal fissure Convolutions—elevated folds on the surface of the cerebrum that increase surface area of the brain Divided into four lobes: Frontal; Parietal; Occipital and Temporal FUNCTIONS OF THE CEREBRUM Frontal Lobe: Emotions; Personality; Morality; Intellect; Speech; Smell Parietal Lobe: Receives and interprets nerve impulses from sensory receptors for pain, touch, heat and cold Occipital Lobe: houses the visual area, controlling eyesight Temporal Lobe: Hearing, facial recognition Cerebral Cortex: Controls conscious thought, judgment, memory, reasoning and willpower Diencephalon Located between the cerebrum and midbrain Two major structures: thalamus and hypothalamus Vital functions of the hypothalamus: Autonomic Nervous Control Cardiovascular Control Temperature Control Appetite Control Sleep Control Limbic System Located in the center of the brain Surrounds the brain stem Complex set of structures that includes the hypothalamus, hippocampus, amygdala, and several other nearby areas Involved with motivation, emotion, mood and memory  Cerebellum Located behind the pons and below the cerebrum Composed of two hemispheres Controls all body functions related to skeletal muscles, including: Balance Muscle Tone Coordination of muscle movements Brain Stem Made up of PONS, MEDULLA, and MIDBRAIN Controls the flow of messages between the brain and the body Controls basic body functions such as breathing, swallowing, heart rate, blood pressure, consciousness, and whether one is awake or sleepy Meninges Three membranes that line the skull and vertebral canal and protect the brain and spinal cord Dura mater: tough outermost meningeal layer that lines the skull Arachnoid: middle layer of the meninges that resembles a fine cobweb Pia Mater: delicate inner layer  Ventricles of the Brain Brain has 4 cavities filled with cerebrospinal fluid called cerebral ventricles Cerebrospinal fluid is a clear, colorless fluid that acts as a shock absorber and a source of nutrients for the brain A network of blood vessels lining the cerebral ventricles called the choroid plexus produces cerebrospinal fluid Central Nervous System: SPINAL CORD Begins at foramen magnum Continues down to 2nd lumbar vertebrae White and soft in spinal canal Surrounded by cerebrospinal fluid Functions as a reflex center and a conduction pathway to and from the brain Peripheral Nervous System Made up of all the nerves outside of the central nervous system (CNS) Includes 12 pairs of cranial nerves and 31 pairs of spinal nerves Provides a complete network of motor and sensory fibers connecting the CNS with the rest of the body Divided into two divisions— SOMATIC nervous system and Autonomic Nervous System Acts involuntarily to control internal organs and body functions such as heart rate, digestion, respiratory rate, pupillary response, and urination Divided into Sympathetic and Parasympathetic Sympathetic: “Fight or Flight” : When body perceives danger prepares to run away or stand and fight. Heart rate increases; mouth becomes dry; pupils and bronchi dilate Parasympathetic: Counteracts the effects of the sympathetic nervous system. For example sympathetic nervous system increases heart rate and parasympathetic decreases the heart rate. Nervous System and Communication It is through the nervous system that we communicate with the outside world Our brain controls our emotions, speech, hearing, vision and many other processes All of these processes affect our communication with others Nervous System Disorders Alzheimer’s Disease/Dementia Progressive degenerative disease of the brain Most common cause of dementia among people 65 years or older Characterized by memory loss and diminished cognitive function Tangles of fibers develop in nerve cells which interferes with brain function Cause is unknown, but age is the most important risk factor Cerebral Palsy Permanent set of motor problems diagnosed in infants and young children—thought to be due to damage to the motor cortex Risk factors: low birth weight, premature birth, multiple births, infection during pregnancy, developmental abnormalities, brain hemorrhage, perinatal brain injury, and lack of oxygen Symptoms vary from mild foot drag and incoordination to complete paralysis and the inability to speak Some may have developmental delays, autism or seizures. Many are of normal or above normal intellect Treatment includes physical therapy, occupational therapy, assistive devices and drugs to control symptoms Epilepsy Seizure disorder Seizures believed to be a result of spontaneous uncontrolled electrical activity of neurons Diagnosed with EEG (electroencephalogram) Two types of seizures Grand Mal – severe, convulsive seizure. Petit Mal – milder (sometimes like someone is just staring) Treatment is anticonvulsant medications Meningitis Infection or inflammation of the meninges Caused by both bacteria and viral infections Symptoms – severe headache and stiff neck with pain Need to seek immediate medical attention Multiple Sclerosis Disorder in which myelin is destroyed, probably by autoimmune attack The brain, spinal cord and optic nerves are often involved The areas without myelin impairs or prevents conduction of nerve impulses May have impairments in vision, balance, speech or movement Can be relapsing-remitting with flare-ups and remissions or chronic progressive with no remissions More common in women and usually diagnosed in those under 50 Parkinson’s Disease Brain disorder caused by the loss of dopamine-producing neurons Decrease in dopamine leads to shaking, stiffness, and difficulty with walking, balance, and coordination Symptoms usually begin gradually and get worse over time Later stages affect ability to chew and swallow Risk factors: age, heredity, gender and exposure to toxins Poliomyelitis Contagious viral illness that in its most severe form causes nerve injury leading to paralysis, difficulty breathing and sometimes death Due to vaccination this disease is almost eradicated in the U.S. Despite a worldwide effort to wipe out polio, it continues to affect people in parts of Asia and Africa Spinal Cord Injury Damage to the spinal cord that results in a loss of function, such as mobility and/or feeling Frequent causes of spinal cord injuries are trauma (car accident, gunshot, falls, etc.) or disease (polio, spina bifida) The level of the injury determines the extent of loss of function Paraplegia: paralysis of legs and lower body Quadriplegia: paralysis of all 4 limbs Encephalitis Inflammation of the brain May be caused by a virus (ex. Herpes virus, West Nile Virus) Common symptoms are fever, lethargy, headache, muscle aches, and extreme fatigue Symptoms may be more severe and include confusion, hallucinations, paralysis and unconsciousness Cerebrovascular Accident (CVA) Stroke or CVA Interruption of blood and oxygen to the brain Risk factors: Smoking, Hypertension, Heart disease; Family history 90% are caused by blood clots Clots lodge in carotid arteries, blocking the flow of blood to the brain 10% caused by ruptured blood vessels in the brain Symptoms and Treatment of CVA Hemiplegia—on opposite side Treatment: Get to the of the body hospital immediately Sudden, severe headache CT done to determine Dizziness etiology Sudden loss of vision in one If a clot, treatment aimed eye at dissolving clot Aphasia Dysphagia Coma Possible death Hemiplegia Paralysis on one half of the body Caused by a brain injury Results in a varying degree of weakness, stiffness (spasticity) and lack of control in one side of the body Most common cause is stroke Traumatic Brain Injury (TBI) Sudden damage to the brain caused by a blow or jolt to the head Common causes include car or motorcycle crashes, falls, sports injuries, and assaults Ranges from mild concussions to severe permanent brain damage Those who survive a brain injury can face lasting effects in their physical and mental abilities as well as emotions and personality Most people who suffer moderate to severe TBI will need rehabilitation to recover and relearn skills. Concussion Mild traumatic brain injury Caused by an impact to your head or after a whiplash-type Symptoms include headaches and problems with concentration, memory, balance and coordination Particularly common in contact sports, such as football An athlete with suspected concussion should not return to play until undergoes medical evaluation by a health care professional trained in managing concussions  Resources File:1201 Overview of Nervous System.jpg. 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