The Nervous System

Nervous system One of the two main communication systems in the body One of the two main communication systems in the body Coordinates all the activities of the body carrying messages from one cell to the next Coordinates all the activities of the body carrying messages from one cell to the next Enables the body to respond and adapt to changes that occur inside and outside the body Enables the body to respond and adapt to changes that occur inside and outside the body Basic structural unit is the NEURON or nerve cell Basic structural unit is the NEURON or nerve cell

The Nervous System Each neuron consists of: The cell body. The cell body. Dendrites. Dendrites. The axon. The axon.

Neurons Cell body consists of nucleus Cell body consists of nucleus Dendrites consist of nerve fibers that carry impulses toward the cell body Dendrites consist of nerve fibers that carry impulses toward the cell body Axon is a single nerve fiber that carries impulses away from the cell body Axon is a single nerve fiber that carries impulses away from the cell body Myelin sheath covers the axon (fat covering) that insulates and maintains the axon Myelin sheath covers the axon (fat covering) that insulates and maintains the axon Nodes of Ranvier are areas where no myelin is present Nodes of Ranvier are areas where no myelin is present

The axon of one neuron lies next to the dendrites of another neuron The axon of one neuron lies next to the dendrites of another neuron The spaces between them are called synapses The spaces between them are called synapses Impulses coming from one axon “jump” the synapse to get to the dendrite of another neuron which carry it in the right direction Impulses coming from one axon “jump” the synapse to get to the dendrite of another neuron which carry it in the right direction Special chemicals, neurotransmitters, found at the end of each neuron allow impulses to pass from one neuron to another so impulses can follow many different routes Special chemicals, neurotransmitters, found at the end of each neuron allow impulses to pass from one neuron to another so impulses can follow many different routes

Nerve fibers Nerves are a combination of many nerve fibers found in the brain and spinal cord Nerves are a combination of many nerve fibers found in the brain and spinal cord 3 types: 3 types: Afferent – sensory nerves Afferent – sensory nerves Nerves carry messages from body to the brain and spinal cord Nerves carry messages from body to the brain and spinal cord Efferent – motor nerves Efferent – motor nerves carries messages from the brain and spinal cord to the body carries messages from the brain and spinal cord to the body Associative - interneurons Associative - interneurons Carries impulses from the sensory neuron to the motor neuron Carries impulses from the sensory neuron to the motor neuron

3 Divisions Central nervous system Central nervous system Brain Brain Spinal cord Spinal cord Peripheral nervous system Peripheral nervous system Nerves Nerves Autonomic nervous system Autonomic nervous system Controls involuntary body functions Controls involuntary body functions Autonomic nervous system Autonomic nervous system Includes peripheral nerves and ganglia (group of cell bodies outside the CNS that carry impulses to involuntary muscles and glands) Includes peripheral nerves and ganglia (group of cell bodies outside the CNS that carry impulses to involuntary muscles and glands)

Central nervous system BRAIN – mass of nerve tissue protected by membranes and skull BRAIN – mass of nerve tissue protected by membranes and skull Cerebrum Cerebrum Largest and highest section Largest and highest section Has convolutions (folds) that separates the lobes Has convolutions (folds) that separates the lobes 4 lobes: 4 lobes: Frontal Frontal Parietal Parietal Temporal Temporal Occipital Occipital

Frontal lobe Links all components of behaviors Links all components of behaviors Impulse control Impulse control Injury here may cause lose of function on one side of the body Injury here may cause lose of function on one side of the body Speech may become halted or disorganized Speech may become halted or disorganized Personality changes can occur Personality changes can occur Social rules are disregarded Social rules are disregarded Sustained attention and “insight” are affected Sustained attention and “insight” are affected

Temporal lobe Perceives and recognizes verbal material Perceives and recognizes verbal material Most commonly injured Most commonly injured Causes misunderstandings in what is said Causes misunderstandings in what is said Emotional changes such as unexplained panic or tearfulness can occur Emotional changes such as unexplained panic or tearfulness can occur Left temporal lobe involved in production of speech, naming and verbal memory Left temporal lobe involved in production of speech, naming and verbal memory Right temporal lobe involves musical ability, foreign language, visual memory and comprehension of the environment Right temporal lobe involves musical ability, foreign language, visual memory and comprehension of the environment

Parietal lobe Construction of language Construction of language Recall of long term memories may be mixed up in time and sequencing Recall of long term memories may be mixed up in time and sequencing Easily lost or confused about left/right Easily lost or confused about left/right Difficulty recognizing and naming what they see Difficulty recognizing and naming what they see May affect ability to read, write or perform calculations May affect ability to read, write or perform calculations Conscious sensation and voluntary movement is affected Conscious sensation and voluntary movement is affected Injury to front part of the lobe may cause loss of body sensation Injury to front part of the lobe may cause loss of body sensation

Occipital lobe Injury usually results in blindness to part or all of the visual field Injury usually results in blindness to part or all of the visual field People may experience “blind spots” or “holes” People may experience “blind spots” or “holes” May misperceive pictures they see May misperceive pictures they see Recognition of colors may be distorted Recognition of colors may be distorted

Main functioning unit of the nervous system is the neuron A.) True B.) False

Lobe that controls hearing & is most often injured A.) Frontal B.) Parietal C.) Temporal D.) Occipital

Lobe that controls vision A.) Frontal B.) Parietal C.) Temporal D.) Occipital

Lobe that controls long term memory A.) Frontal B.) Parietal C.) Temporal D.) Occipital

Lobe that coordinates all behaviors A.) Frontal B.) Parietal C.) Temporal D.) Occipital

Cerebellum Cerebellum Below cerebrum Below cerebrum Responsible for Responsible for muscle coordination, muscle coordination, balance and posture, balance and posture, muscle tone muscle tone Diencephalon Diencephalon Section between the cerebrum and midbrain Section between the cerebrum and midbrain Contains 2 structures Contains 2 structures Thalamus – acts as a relay center and directs sensory impulses to the cerebrum Thalamus – acts as a relay center and directs sensory impulses to the cerebrum Hypothalamus – regulates and control the autonomic nervous system, temperature, appetite, water balance, sleep, etc. Also involved in emotions such as fear, anger, pleasure, pain and affection Hypothalamus – regulates and control the autonomic nervous system, temperature, appetite, water balance, sleep, etc. Also involved in emotions such as fear, anger, pleasure, pain and affection

Midbrain Midbrain Below the cerebrum and top of the brain stem Below the cerebrum and top of the brain stem Responsible for conducting impulses between brain parts and certain eye and auditory reflexes Responsible for conducting impulses between brain parts and certain eye and auditory reflexes Pons Pons Below the midbrain and in the brain stem Below the midbrain and in the brain stem Responsible for conducting messages to other parts of the brain, chewing, tasting, saliva production and assists with breathing Responsible for conducting messages to other parts of the brain, chewing, tasting, saliva production and assists with breathing Medulla oblongata Medulla oblongata Lowest part of the brain stem Lowest part of the brain stem Connects with the spinal cord and is responsible for breathing, heartbeat, swallowing, coughing and blood pressure Connects with the spinal cord and is responsible for breathing, heartbeat, swallowing, coughing and blood pressure

Spinal cord Spinal cord Continues down from the medulla oblongata Continues down from the medulla oblongata Ends at the first or second lumbar vertebrae Ends at the first or second lumbar vertebrae Surrounded and protected by vertebrae Surrounded and protected by vertebrae Responsible for many reflex actions and carrying afferent and efferent nerves Responsible for many reflex actions and carrying afferent and efferent nerves Meninges Meninges 3 membranes that cover and protect the brain and spinal cord 3 membranes that cover and protect the brain and spinal cord Dura mater – outer layer Dura mater – outer layer Arachnoid membrane – middle, delicate layer Arachnoid membrane – middle, delicate layer Pia mater – attached to the brain and contains blood vessels that nourish the nerve tissue Pia mater – attached to the brain and contains blood vessels that nourish the nerve tissue

The brain has 4 ventricles (hollow spaces that connect with each other and the space under the arachnoid membrane) The brain has 4 ventricles (hollow spaces that connect with each other and the space under the arachnoid membrane) Filled with fluid called cerebrospinal fluid Filled with fluid called cerebrospinal fluid Circulates continuously Circulates continuously Serves as shock absorber to protect brain and spinal cord Serves as shock absorber to protect brain and spinal cord Carries nutrients to parts of the CNS and helps remove waste products Carries nutrients to parts of the CNS and helps remove waste products

Peripheral Nervous System Consists of the somatic and autonomic nervous systems Consists of the somatic and autonomic nervous systems Somatic nervous system Somatic nervous system 12 pairs of cranial nerves 12 pairs of cranial nerves 31 pairs of spinal nerves 31 pairs of spinal nerves Spinal nerves carry messages to and from the spinal cord and are mixed nerves (both afferent and efferent) Spinal nerves carry messages to and from the spinal cord and are mixed nerves (both afferent and efferent)

Autonomic Nervous System Branch of peripheral nervous system Branch of peripheral nervous system Maintains balance in the involuntary functions of the body and allows the body to react in times of emergency Maintains balance in the involuntary functions of the body and allows the body to react in times of emergency 2 divisions: 2 divisions: Sympathetic Sympathetic Parasympathetic Parasympathetic Work together to maintain homeostasis Work together to maintain homeostasis

In times of emergency the sympathetic nervous system prepares the body to act In times of emergency the sympathetic nervous system prepares the body to act Increased heart rate Increased heart rate Increased respirations Increased respirations Increased blood pressure Increased blood pressure Decreased digestion Decreased digestion After the emergency, the parasympathetic nervous system counteracts actions of the sympathetic nervous system After the emergency, the parasympathetic nervous system counteracts actions of the sympathetic nervous system Decreased heart rate Decreased heart rate Decreased respirations, etc. Decreased respirations, etc.

Diseases/disorders Traumatic disorders – caused by injury: Traumatic disorders – caused by injury: Concussion. Concussion. Brain contusion. Brain contusion. Congenital disorders – present at birth: Congenital disorders – present at birth: Spina bifida. Spina bifida. Hydrocephalus. Hydrocephalus. Cerebral palsy. Cerebral palsy. Cerebrovascular accident (CVA). Cerebrovascular accident (CVA). Encephalitis. Encephalitis. Epilepsy. Epilepsy. Meningitis. Meningitis. Multiple sclerosis (MS) Multiple sclerosis (MS) Neuralgia. Neuralgia. Paralysis. Paralysis. Parkinson’s disease. Parkinson’s disease. Dementia. Dementia. Alzheimer’s disease. Alzheimer’s disease.

Spina Bifida Opening in the spinal column Opening in the spinal column At delivery, spinal cord and nerves are exposed causing nerve damage At delivery, spinal cord and nerves are exposed causing nerve damage Results in paralysis Results in paralysis

Cerebral Palsy Caused by brain damage at birth Caused by brain damage at birth Lack of oxygen, birth injuries, infection, etc. Lack of oxygen, birth injuries, infection, etc. Symptoms: Symptoms: Tense muscles leading to Tense muscles leading to contractures contractures Tremors Tremors Mental retardation Mental retardation Treatment: Treatment: Therapy, anticonvulsants, braces, surgery Therapy, anticonvulsants, braces, surgery

Cerebrovascular accident (CVA) a.k.a. stroke a.k.a. stroke Blood flow to the brain is impaired resulting in brain tissue damage Blood flow to the brain is impaired resulting in brain tissue damage Causes Causes Cerebral hemorrhage Cerebral hemorrhage Aneurysm Aneurysm Weak blood vessels Weak blood vessels Blood clot Blood clot Treatment depends on cause Treatment depends on cause

Encephalitis Inflammation of the brain resulting in weakness, visual disturbances, vomiting, stiff neck and back, coma Inflammation of the brain resulting in weakness, visual disturbances, vomiting, stiff neck and back, coma Caused Caused Virus Virus Chemical Chemical Bacteria Bacteria Treatment is supportive including medications and monitoring Treatment is supportive including medications and monitoring

Epilepsy Seizure syndrome Seizure syndrome Disorder associated with abnormal electrical impulses in the neurons of the brain Disorder associated with abnormal electrical impulses in the neurons of the brain Causes Causes Trauma Trauma Toxins Toxins Idiopathic (spontaneous) Idiopathic (spontaneous) Treated with medications Treated with medications

Hydrocephalus Excessive accumulation of cerebrospinal fluid in the ventricles Excessive accumulation of cerebrospinal fluid in the ventricles Symptoms include abnormally large head, prominent forehead, irritability, retardation Symptoms include abnormally large head, prominent forehead, irritability, retardation Treated with Treated with surgical shunt between ventricles

Meningitis Inflammation of the meninges of the brain and/or spinal cord Inflammation of the meninges of the brain and/or spinal cord Caused by bacteria or virus Caused by bacteria or virus High fever, headaches, back and neck pain, n/v, delirium, convulsions and death High fever, headaches, back and neck pain, n/v, delirium, convulsions and death Treatment includes medications and anticonvulsants Treatment includes medications and anticonvulsants

Multiple sclerosis Chronic, progressive disabling condition resulting from degeneration of the myelin sheath Chronic, progressive disabling condition resulting from degeneration of the myelin sheath Occurs between 20 and 40 y.o. Occurs between 20 and 40 y.o. Cause is unknown Cause is unknown Progresses at different rates depending on the person Progresses at different rates depending on the person No cure No cure

Neuralgia Nerve pain Nerve pain Caused by inflammation, pressure, toxins and other disease Caused by inflammation, pressure, toxins and other disease Treatment directed at eliminating the cause of the pain Treatment directed at eliminating the cause of the pain

Paralysis Usually results from brain or spinal cord injury Usually results from brain or spinal cord injury Hemiplegia Hemiplegia Paralysis on one side Paralysis on one side Quadriplegia Quadriplegia Paralysis of the arms, legs, and body below the spinal cord injury Paralysis of the arms, legs, and body below the spinal cord injury No cure, treatment is supportive No cure, treatment is supportive

Parkinson’s disease Chronic, progressive degeneration of brain cells usually in people over 50 y.o. Chronic, progressive degeneration of brain cells usually in people over 50 y.o. Tremors, stiffness, muscular rigidity, forward leaning position, shuffling gait, mood swings, etc. Tremors, stiffness, muscular rigidity, forward leaning position, shuffling gait, mood swings, etc. Treatment is supportive and symptomatic Treatment is supportive and symptomatic

Shingles Herpes zoster Herpes zoster Inflammation of nerve cells caused by herpes virus Inflammation of nerve cells caused by herpes virus Same virus that causes chicken pox Same virus that causes chicken pox Occurs in thoracic area on one side of the body and follow path of affected nerves Occurs in thoracic area on one side of the body and follow path of affected nerves Itching, fever, increased skin sensitivity Itching, fever, increased skin sensitivity Treatment is to relieve pain and itching until inflammation subsides Treatment is to relieve pain and itching until inflammation subsides

Dementia General term defining a loss in at least two areas of complex behavior such as language, memory, visual/spatial abilities or judgment General term defining a loss in at least two areas of complex behavior such as language, memory, visual/spatial abilities or judgment Does not mean that everyone that is forgetful has dementia Does not mean that everyone that is forgetful has dementia

Alzheimer’s disease Progressive disease where initial symptom is usually a problem with remembering recently learning information Progressive disease where initial symptom is usually a problem with remembering recently learning information Nerve endings in the cortex of the brain degenerate and block signals Nerve endings in the cortex of the brain degenerate and block signals Cause is unknown and has 3 stages: Cause is unknown and has 3 stages: 1 st stage lasts 2-4 years and involves short-term memory loss, anxiety and poor judgment 1 st stage lasts 2-4 years and involves short-term memory loss, anxiety and poor judgment 2 nd stage lasts 2-10 years and increases memory loss, difficulty recognizing people, motor problems, loss of social skills 2 nd stage lasts 2-10 years and increases memory loss, difficulty recognizing people, motor problems, loss of social skills 3 rd stage lasts 1-3 years and includes inability to recognize self, weight loss, seizures, mood swings, and aphasia (loss of speech). 3 rd stage lasts 1-3 years and includes inability to recognize self, weight loss, seizures, mood swings, and aphasia (loss of speech).