Transcript 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 S ystem
B rain
S pinal Cord
S ensor Division
(afferent)
P eripheral Nervous S ystem
Cranial Nerves
S pinal Nerves
M otor Division
(efferent)
A utonom ic Nervous S ystem
(involuntary)
S om atic Nervous S ystem
(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.