Studied by 18 people
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Input
Obtaining information from the environment through the senses
Decision-making
input processed by the brain through the NS, relevant cues identified, appropriate response selected
Output
The response, motor units are recruited in a specific order/force/timing to produce desired movement of skeletal muscle
Feedback
Info about the performance of movement and its quality can be used to improve decision-making in future
NS information-processing 4 steps
Input -> decision-making -> output -> feedback
Neurons
Basic structural unit of NS
The primary purpose of CNS is to...
React to stimuli
neurons have 2 primary characteristics, what are they?
Irritability, conductivity
Action potential principles
Short-term event initiated by depolarization
Electric potential of a cell rapidly rises and falls, due to the influx and efflux of ions
Mandatory for initiation of muscle contraction
Concentration gradient
Concentration gradient
Na+ wants to move into the cell
K+ wants to move out of the cell
Cell is polarized when
The inside of the cell is more negative relative to the outside
Depolarization
occurs when inside of cell becomes less negative
Hyperpolarization
Occurs when inside of cell becomes more negative
Graded potential (gp)
localized changes in resting membrane potential
Graded potentials can
Help cell body decide whether to pass signal to axon
usually found in dendrites, cell body
Action potentials can
Propagated down axon, then transmitted to next cell
only travel one way
If GP reaches threshold mV ...
AP will occur
Resting state
no movement of ions (Na+ and K+ channels closed)
Depolarization Phase
Na+ gates open, Na+ moves into cell. Membrane potential of cell increases due to (+) ions coming into cell (becomes +); K+ gates remain closed
Repolarization Phase
Na+ gates close, Na+ cant move; K+ gates open, causing K+ to travel out of cell. Membrane potential of cell decreases because (+) ions are moving out of the cell
Undershoot/ Afterhyperpolarization
K+ gates still open, K+ continues to move out of cell, further decreasing membrane potential
Back to resting state
Na+ and K+ gates close, no movement of ions
Absolute refractory period
During depolarization
Neuron unable to respond to another stimulus
Na+ channels already open, can't open more
relative refractory period
During repolarization
Neuron responds only to very strong stimulus
K+ channels open (Na+ closed, could open again)
Site of neuron-to-muscle communication
Uses ACh as its neurotransmitter (chemical messenger)
Postsynaptic cell = muscle fiber
ACh binds to receptor at motor end plate, causing depolarization of muscle cell
ACh
stimulates skeletal muscle contraction, mediates parasympathetic nervous system effects
Norepinephrine (NE)
Mediates sympathetic nervous system effects
Cholinergic
Referring to cells that use acetylcholine as their synaptic transmitter.
Adrenergic
Pertaining to nerves that release the neurotransmitter norepinephrine, or noradrenaline
excitatory postsynaptic potential (EPSP)
Depolarizing, promotes AP
inhibitory postsynaptic potential (IPSP)
Hyperpolarizing, prevents AP
Summation at axon hillock will determine ...
If an AP will happen
Left and right hemispheres
Connected by corpus callosum, which allows interhemisphere communication
Cerebral cortex
Outermost layer of cerebrum
Gray matter
Conscious brain
Frontal Lobe
General intellect, motor control
Temporal Lobe
Auditory input, interpretation
Parietal Lobe
General sensory input, interpretation
Occipital Lobe
Visual input, interpretation
Insular Lobe
Emotion, self-perception
Basal Ganglia (White matter)
Clusters of nerve cell bodies deep in cerebral cortex
Help initiated sustained or repetitive movements
Primary somatosensory cortex (parietal lobe)
Relays tactile sense/"touch"
Specific areas are associated with collecting information from specific parts of body
Thalamus
Major sensory integration center
Determines what we are consciously aware of
Hypothalamus
maintains homeostasis
Cerebellum
Controls rapid, complex movements
Coordinates timing, sequence of movements
Not under conscious control
Enables rapid progression of one movement to the next
Compares actual to intended movements and initiates correction
Brain stem is composed of
midbrain, pons, medulla oblongata
Brain stem
Relays information between brain and spinal cord
reticular formation
Bundles of nerves in brainstem
Coordinates skeletal muscle function and tone
Controls cardiovascular & respiratory function
Analgesia system
Endogenous opioid substances modulate pain
Ex: Endorphin release with exercise
Afferent
sensory
Efferent
motor
Somatic
stimulates skeletal muscle activity (voluntary functions)
Autonomic
regulates visceral activity (involuntary)
Autonomic Nervous System
controls involuntary functions such as HR, BP & lung function
Fight or flight
Prepares body for stress of exercise
sympathetic stimulation
increases heart rate
increase blood flow to muscles
increase airway diameter
increase metabolic rate, glucose and FFA plasma levels
increase in mental alertness
Rest and digest
parasympathetic nervous system
Parasympathetic stimulation
Increase digestion, urination
increase conservation of energy
decrease heart rate
decrease diameter of vessels and airways
Mechanoreceptors
physical forces
Thermoreceptors
temperature
Nociceptors
pain receptors
Photoreceptors
light
Chemoreceptors
respond to chemicals
kinesthetic receptors
Receptors in the muscles, joints, and skin that provide information about movement, posture, and orientation.
Muscle spindles
receptors sensitive to change in length of the muscle and the rate of that change
Golgi tendon organs
receptors that sense movement of the tendons, which connect muscle to bone
Process of communication and interaction
stimulus sensed by sensory receptor
Sensory AP sent on sensory neurons to CNS
CNS interprets sensory information, sends out response
Motor AP sent out on delta motor neurons
Motor AP arrives at neuromuscular junction on skeletal muscle, response occurs
Note
Flashcard