Nervous system Flashcards
What is the nervous system?
The communication network of the body, keeps the body in touch with the internal and external environment
What are the two anatomical categories of the nervous system?
Central nervous system (CNS)- brain and spinal cord
Peripheral nervous system (PNS)- other nerves
Functions of the nervous system
Coordinate the body’s activites- voluntary and involuntary movement
Allows the body to recognize and respond to changes in its external and internal environments
Function of the neuron
Receives input from the body’s internal and external environment and relays electrical impulses between the nervous system
Anatomy of the neuron
Cell body- the main part of the neuron
Dendrites- special fibers that extend from cytoplasm of cell body
Axon that divides into telodendria
End of axon has synaptic terminals
What is a telodendria?
Small branches found at the distal end of the axon
What is the axon?
A fiber that extends from a neuron cell that conducts impulses away from the cell, each nerve cell has one axon
The larger the diameter of an axon
the faster it can transmit info
What is the axon of the neuron covered by?
Myelin sheath, a fatty tissue that wraps the axon to protect it and speeds up impulses as they travel down the axon
What are dendrites?
Special fibers who extend from a neuron that conducts impulses towards the cell body
What is a synaptic terminal?
Connects one neuron to the other
What is a synapse?
The junction where the axon terminal of one neuron meets with another neuron, where the impulses between neurons are transmitted
What is the synaptic cleft?
A space where the impulses must jump because the axon terminal doesn’t directly touch the neuron
What is a neurotransmitter?
Special chemical in axon terminals that helps impulses jump the synapse cleft
Categorization of neurons
Afferent (sensory neurons), efferent (motor neurons), interneurons (central or connecting neurons)
What is an afferent neuron?
Conduct impulses to the brain and spinal chord
Afferent- direction toward a central organ
Ex: CNS
Stimulated by physical and chemical input from environment
Responsible for senses
What is an efferent neuron?
Carry impulses away from CNS to muscles, glands, and organs resulting in voluntary and involuntary movement
What is an interneuron?
Conduct impulses from sensory neurons to motor neurons, help facilitate reflexes
Function of the brain
Interprets, organizes, stores information, controls and directs bodily functions
What is the cerebrum?
The most superior part of the brain/largest portion, highly developed portion
Seperated into right and left hemispheres
What are hemispheres connected by?
Corpus callosum, allows them to communicate
Function of cerebrum
Controls thinking, sensory, speech, voluntary movement, reasoning
What is the cerebellum?
Posterior to the brain stem, responsible for coordinating voluntary muscle movement, posture, balance, muscle tone
What is the diencephalon?
Found just above brain stem, between cerebral hemispeheres
Divided into the thalamus and hypothalamus
Thalamus function
Directs much of sensory impulses to the proper locations in the cerebral cortex
Hypothalamus function
Controls bodily functions that help maintain homeostasis, plays roles in emotion, controls release of hormones of the pituitary gland
What is the cerebral cortex?
Gray matter, outside layer of cerebrum, performs most sensory processing, divided into two hemispheres
Memory, analyzation, behavior, personality
What is the frontal lobe
Largest lobe and located in front of cerebral hemipshere –> thinking, planning, personality, voluntary movement
Called executive
What is the temporal lobe? (2)
Posterior to frontal lobe, inferior to parietal lobe
Functions include hearing (auditory), smell (olfactory), language, emotion, memory, gustatory
Wernicke (understanding)
What is the parietal lobe? (2)
Posterior to the frontal lobe and superior to temporal
Language, learning, spacial recognization
Somatosensory (Pressure), gustatory (taste)
What is the occiptial lobe?
Smallest lobe of cerebral cortex
Interpreting and processing, sends interpreted visual info to other parts of the brain
Visual cortex
What is the brain stem?
Where the spinal cord and brain connect
Midbrian, pons, medulla oblangota
Function of the brain stem
Responsible for routing impulses to and from spinal cord
Controls vital involuntary functions such as breathing, digesting, circiulation
What is the main communication system between the brain and body
Spinal cord
Where is the spinal cord located
Starts at brainstem base to the first area of the lumbar in the lower back
Encased in the vertebral column
Controls many actions and acts as pathway between brain and PNS
What helps the CNS from being damaged
Bones, membranes, fluids
Skull- protects brain
Vertebrae- protects spinal cord
Meninges- dura mater, arachnoid, pia mater
What is cerebrospinal fluid?
Fluid that moves throughout the brains four ventricles and around the spinal cord
Function of cerebrospinal fluid
Acts as shock absorber that protects brain and cord
Carries nutrients to some parts of CNS
Helps remove metabolic products and waste
Peripheral system main function
Relay impulses back and forth between CNS and rest of the body
What is the PNS divided into?
Somatic (voluntary), autonomic (involuntary) nervous systems
What is the function of the somatic nervous system?
Transmits sensory info and controls bodies voluntary actions
What is the function of the autonomic nervous system?
Controls bodies involuntary activities such as breathing
What are cranial nerves?
Directly connect to the brain and relay impulses mainly from the head and neck
Located in the PNS (except optic nerve)
12 different pairs
What are spinal nerves?
Transmit impulses between spinal cord and rest of the body, including internal organs, muscles, skin
31 pairs
What is the optic pair and what is it responsible for?
Second pair of cranial nerves, made up of nerve cells
Responsible for transferring visual impulses from retina to the brain’s vision centers
Located back of the eye, connects eye to brain
Is the optic nerve part of the PNS?
No
What is the ANS?
The automatic nerve system
Controls involuntary activities such as digestion and circulation
Made of divisons that work together to acheive homeostasis
What are the divisions of the ANS?
Enteric, sympathetic, parasympathetic
What does the enteric nervous system control?
Digestive system, also known as second brain or gut because it cannot function without being stimulated by the CNS
Sympathetic nervous system
Activated in conditions of stress and produces fight or flight response
Parasympathetic nervous system
Reverses fight or flight symptoms of the sympathetic system, returns body to a relaxed or normal state
What is a cerebrovascular accident?
Stroke
Occurs when there is a reduction in blood flow to the brain
Risk factors: Smoking, heart disease, diabetes
What can cause a stroke? Symptoms? Treatment?
Burst blood vessel, blood clot, or blocked vessel
Paralysis, difficulty swallowing, visual or speech impairment, mental confusion
Clot breaking drugs (thrombolytics) used in the first three hours of a stroke, anticoagulants prevent strokes, therapy
What is myasthenia gravis?
Neuromuscular disorder where proper nerve pulses are not sent to muscles
What causes myasthenia gravis? Symptoms? Treatment?
Abnormal reaction of the immune system that leads it to attack receptors in muscles, leads to breakdown of communication of nerves and muscles
Muscle weakness
No cure, focusing on management of symptoms
What is MS?
Multiple sclerosis, potentially disabling disorder of the CNS
MS causes? Symptoms? Treatments?
Exact cause is unkwon, considered to be an autoimmune disorder where the immune system attacks the myelin sheath
Double vision, tingling, numbness, difficulty walking, weakness, paralysis
No cure
What is autism spectrum disorder?
Broad range of characteristics to do with social skills, repetitive behavior, and communication
Cause of autism? Symptoms? Treatment?
Cause is unknown, appears to be related to genetics or environment
Delay in language or social development, repetitive behavior
No cure, symptoms can be relieved by therapies
What is alzheimers disease?
A progressive neurodegenerative disease that causes impairment in memory and cognitive functioning
What is the motor speech area?
Brocus
Motor homonculus
Representation of your body in the frontal area, shows percentages or frontal lobe devoted to motor activities
Broca’s aphasia
Limited language, you can understand everything, frontal lobe
Wernicke aphasia
Jumbled words/ can’t understand, side of brain
