Download Neurological Control of Movement

Neurological Control
of Movement
The Structure and Function
of the Nervous System
The Neuron
The Cell Body (nucleus)
 The Dendrites



the receivers
The Axon
the transmitter
 contains the axon
terminals
 contains the synaptic knobs that
release chemicals known as
neurotransmitters.
 The axon hillock decides if the
impulse is a graded potential or an
action potential.

The Neuron
Node of ranvier
 Myelin sheath


Saltitory conduction: the impulse
skips from node to node and is a
faster method of impulse travel.
The Nerve Impulse

Nerve Impulse: an electrical charge
that passes from one neuron to the next
neuron or muscle fiber.

Resting Membrane Potential: the
separation of charges across the membrane
(polarized).


a constant RMP of -70 mV is the function of the
sodium-potassium pump.
Depolarization: when the charge
difference decreases (< -70 mV), moving
closer to zero (ie -20 mV).

Hyperpolarization: when the charge
difference increases (> -70 mV), moving
farther from zero (ie -120 mV).
The Nerve Impulse

Graded Potentials: local changes in
the neuron membrane to cause an
inefficient charge difference.

Action Potentials: a rapid and
substantial depolarization (excitation) of the
neurons membrane.
 axon hillock- measures the summation
of impulses and determines the
threshold for an action potential
 All-Or-None Principle
 Sequence of events [3.2]
The Synapse
 Synapse: is the site of impulse
transmission from one neuron to
another neuron or muscle fiber.
 axon
terminals- release
acetylcholine
 synaptic
cleft
 receptors- of a neuromuscular
junction at the sarcolemma of a
muscle fiber. [3.4]
The Synapse

Excitatory Postsynaptic
Potential (EPSP’s) can be either
depolarizations (excites) or
hyperpolarizations (inhibits)

Inhibitory Postsynaptic
Potentials (IPSP’s) are only
hyperpolarizations (inhibits)
Organization of the
Nervous System
Central Nervous System
Brain
Spinal Cord
Sensor Division
(afferent)
Peripheral Nervous System
Cranial Nerves
Spinal Nerves
Motor Division
(efferent)
Autonomic Nervous System
(involuntary)
Somatic Nervous System
(voluntary)
The Brain and Spinal
Cord
 Cerebrum: site of mind and
intellect, motor control, sensory
input and interpretation.




Frontal Lobe: general intellect and motor
control
Temporal Lobe: auditory input and its
interpretation
Parietal Lobe: general sensory input and
its interpretation
Occipital Lobe: visual input and its
interpretation
The Brain and Spinal
Cord
 Diencephalon: sensory
integration and homeostasis of
the body’s internal environment.
Thalamus: interprets sensory input
and relays it to the appropriate area
of the brain.
 Hypothalamus: maintains
homeostasis.

The Brain and Spinal
Cord
 Cerebellum: movement control.
 Brain Stem: relays information
between the brain and the spinal cord.
 Spinal Cord: tracts of nerve fibers
that allow two-way conduction of
nerve impulses.
 afferent
-vs- efferent
The Peripheral Nervous
System
The PNS contains 12 pairs of
cranial nerves and 31 pairs of
spinal nerves.
 Sensory neurons enter the spinal
cord through the dorsal root.






mechanoreceptors (touch)
thermoreceptors (temperature)
nociceptors (pain)
chemoreceptors (oxygen,
glucose, electrolytes, etc.)
kinesthetic receptors (movement in joints,
balance, etc.) ie. golgi tendon organs
The Peripheral Nervous
System

Motor neurons leave the spinal cord
through the ventral root.


Create muscle contraction
Create muscle inhibition
The Autonomic Nervous
System

The ANS controls your body’s
involuntary internal functions.

Sympathetic Nervous System (fight or
flight mechanism)
 inc.
H.R. and cardiac contraction
 coronary vessels dilate increasing B.P. &
blood flow
 bronchodilation, inc. metabolic rate &
mental capabilities
 glucose is released from the liver into the
blood
The Autonomic Nervous
System

Parasympathetic Nervous System
(housekeeping system)
 carry’s
out digestion, urination, & life
support
 conserves energy
 decreases blood flow
 decreases breathing rate
Sensory Motor
Integration





Sensory Motor Integration: is the
communication of the sensory and
motor nerve pathways. [3.1]
Reflex: when sensory impulses
terminate at the spinal cord and are
integrated there.
Motor Control: controlled by impulses
conducted by motor (efferent) neurons
from the brain.
Muscle Spindles: create reflexive
muscle contractions of the agonist
muscle to resist further stretching.
Golgi Tendon Organs: are sensitive to
tension which excite the antagonist
muscles to contract.
Muscle Fiber Recruitment


Each muscle fiber is innervated by
only one motor neuron, but each
motor neuron innervates up to
several thousand muscle fibers.
Principle of Orderly Recruitment


Motor units with smaller motor neurons
(ST) will be recruited first, larger motor
neurons (FTb) last.
Motor units with a smaller number of
muscle fibers will be recruited first.