HEALTH SCIENCE HONORS UNIT 3 PART 2

  • 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, mpulse 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

  • 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: consists of the brain and spinal cord, serving as the main control center for processing information and directing responses.

  • Cerebrum: 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


  • Brain divided into four lobes: Frontal; Parietal; Occipital and Temporal

  • 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

  • HYPOTHALAMUS FUNCTIONS: 

    •    Autonomic Nervous Control

    •    Cardiovascular Control

    •    Temperature Control

    •    Appetite Control

    •    Sleep Control

  • LIMBIC SYSTEM FUNCTIONS

    • 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 CHORD

    • 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

  • 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.

  • Alzheimer's:

    • A progressive neurodegenerative disease that causes memory loss, cognitive decline, and personality changes.

    • 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

  • Epilepsy:

    • A neurological disorder characterized by recurrent seizures due to abnormal electrical activity in the brain.

    • 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

  • Multiple Sclerosis (MS):

    • An autoimmune disease where the immune system attacks the protective covering of nerves, leading to physical and cognitive impairments.

    • 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

  • Cerebral Palsy:

    • A group of disorders affecting movement and muscle coordination, often caused by brain damage before or during birth.

    • 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

  • Meningitis:

    • Inflammation of the protective membranes surrounding the brain and spinal cord, typically caused by infection.

    • 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

  • Hemiplegia:

    • Paralysis of one side of the body, often resulting from a stroke or brain injury.

    • 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):

    • Brain dysfunction caused by an external force, often leading to cognitive, emotional, and physical impairments.

    • 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.

  • Parkinson's Disease:

    • A progressive neurological disorder that affects movement, causing tremors, stiffness, and difficulty with balance.

    • 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:

    • A viral disease that can affect the spinal cord, leading to paralysis and muscle weakness.

    • 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 can result in loss of motor function, sensation, and autonomic regulation below the injury site.

    • 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, often due to viral infections, causing fever, headache, and neurological symptoms.

    • 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):

    • A medical emergency where blood flow to a part of the brain is interrupted, leading to potential brain damage.

    • 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

  • CVA SYMPTOMS:

    • Hemiplegia—on opposite side of the body

    • Sudden, severe headache

    • Dizziness

    • Sudden loss of vision in one eye

    • Aphasia

    • Dysphagia

    • Coma

    • Possible death

  • CVA TREATMENT

    • Treatment:  Get to the hospital immediately

      CT done to determine etiology

      If a clot, treatment aimed at dissolving clot

  • Concussion:

    • A mild traumatic brain injury caused by a blow to the head, resulting in temporary cognitive and physical symptoms.

    • 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