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Nervous &
Musculoskeletal
System
Skeleton
• The human skeleton has 206
bones.
• They are made of bone marrow
surrounded by Calcium.
• These bones are either fused
together or held together by
ligaments.
• Attached to our bone are muscles.
They are attached by tendons.
• Bones provide the body with
structure and protection for
organs
These lines
represent Sutures,
which are immobile
joint lines that fuse
when you are about
2 years old.
Cartilage
Between
bones that
are not
fused,
there is
cartilage.
Acts like a
shock
absorber.
Function of Bones
• Head bones: Encase the
encephalon, provide passageways
for sensory and motor nerves
• Torso Bones: house heart and lungs
for protection. Vertebrae allow
movements.
• Upper limb bones: shoulder joint is
the most mobile in our body.
• Lower limb bones: bear the entire
weight of the body and support its
motion
Bone Make-up
• Bone is made up of
spongy bone,
compact bone, blood
vessels, and red
marrow and yellow
marrow in the
medullar cavity. Red
marrow makes red
and white blood cells
and platelets.
Muscles
• Striated (skeletal)
Voluntary movement
• Smooth (organs)
Involuntary movement
• Cardiac (heart only)
Muscles
• Inside muscles are
filaments. When
these filaments
contract, so does the
muscle.
• Each muscle cell is
connected to the next.
• So, when one
contracts, so do the
others.
• Muscles are arranged
in paired groups. As
one group flexes, the
other relaxes, so the
body can move.
• When working out, the
muscle is damaged.
The body responds to
that damage by
building more muscle
cells to reduce
damage in the future.
• Bones also thicken to
handle the new
muscles.
Types of Joints
Ball &
Socket
joint (Hip,
Shoulders)
Hinge
Joint
(Knee,
Elbow,
Fingers)
Saddle
Joint
(Wrist)
Pivot Joint
(Neck)
Sprain, Separation, Dislocations,
and Tears
• A Sprain is when the ligaments around a joint
are stretched or torn.
• A Separation is when the ligaments around a
joint are stretched or torn usually in the
shoulder.
• A Dislocation is when the two bones in a joint
no longer meet up.
Movements of
mobile joints
• Flexion (bending)
• Extension (stretching)
• Abduction (lateral movement
bringing limb away from body)
• Adduction (lateral movement
bringing limb toward body)
• Rotation
Anabolic Steroids
(Testosterone)
• Effects:
– Joint damage
• The body adds muscle that
the persons joints are not
ready or able to handle.
– Liver Damage
– Shrinking of the testis
– Breast development
– Mood changes – “roid rage”
– Affects heart (left ventricle)
Nervous System
• The Nervous System has two
parts:
The Central Nervous System
&
The Peripheral Nervous System.
Nerve cells are called
Neurons
A nerve impulse
is an electrical
impulse
Axons send
nerve impulses
AWAY from the
body
Dendrites
receive nerve
impulses
The cell body is
called the SOMA
Synapse
• The space between two neurons is
called the synapse.
• Neurons release chemical
messages (Neurotransmitters)
from the axon which cross the
synapse to the dendrite of the next
neuron.
The Central Nervous
System
• The central nervous system is made up of the
Encephalon (Brain, Cerebellum & Brain stem)
and Spinal Cord.
• The brain is made up of several parts which
control different functions.
The Brain
• The brain will control speech,
voluntary movement from motor
neurons, thoughts, emotions, and
interprets sensory input from sensory
neurons. (taste, sight, sound, touch,
and smell)
• The left side of the brain controls the
right side of the body
• The right side of the brain controls
the left side of the body.
Cerebellum
• Determines force and
speed required for
specific movements
(conscious movements)
• Coordinates movement
and balance
The Brain stem
• The Brain stem
connects the
brain to the
spinal cord.
• It also controls
involuntary
muscle
movement
such as heart
beat and
breathing, and
reflexes like
coughing,
swallowing…
Protection of your
Brain
• Your brain is protected by your
scalp (skin), your skull and
three membranes called the
MENINGES.
• It is also cushioned by
CEREBROSPINAL FLUID
• Meningitis is an infection which
causes swelling of the
meninges
Spinal cord
• The spinal cord is a
long string of nerves
that transmits
messages from the
brain to the body.
• What happens if the
spine is damaged?
• Messages can not
reach to the body parts
below the damage.
Myelin Sheath
• Neurons act like wires
in an electron device.
• Like most wires, they
have a layer of
insulation called the
Myelin Sheath which
is found on the Axon.
• The Myelin sheath
helps keep the
signal flowing
quickly and
efficiently without
getting lost.
The Peripheral Nervous
System
The Peripheral nervous system
consists of nerves that connect
the Central Nervous system to
the limbs and organs. It can be
divided into two parts:
1) The Autonomic Nervous
System
2) The Somatic Nervous
System
The Autonomic
Nervous System
The autonomic nervous system sends
and receives signals to/from the CNS to
control automatic functions.
• Ex:
– Heart rate
– Breathing
– Blood pressure
– Fear response (Adrenaline)
– Digestion
These are coordinated in the Brain Stem.
Somatic Nervous System
Conscious
movements
Sensory Input
Running
Touch
Jumping
Sight
Speech
Smell
Grabbing
Taste
Sitting
Hearing
• The Somatic
nervous system
receives signals
from the CNS to
control Conscious
Movements &
sends signals to
the CNS to control
Sensory Input.
• These are
coordinated in the
Cerebellum
Pathways in Somatic
Nervous System
• If muscles are found below head
level, the nerve impulses must
travel down the spinal cord to the
motor nerve that commands that
muscle
• If the muscles are found at head
level (ex: winking) the nerve
impulses follow a motor nerve
directly to the desired muscle
Reflex Arc
• A Reflex Arc is simply your reflexes,
which involve voluntary muscles
without the person having to think
• Part of the Autonomic Nervous system
• Ex: If you put your hand on a hot
stove, your hand will jump away
before you even feel the heat.
• Why? The sensation of heat is
processed in the brain. The
reaction to heat is handled by the
spine.
• So before the heat signal makes it
to the brain, your body has told
your hand to move!
Drugs, Disease, and Injury
• Alcohol: Dissolves brain cells,
cutting neural pathways.
• Marijuana: Leaves deposits that
block the synapses affecting
learning, memory, depression,
and schizophrenia.
• Concussion: Temporary or
permanent disruption of brain
function usually from head
trauma.
Continued..
• Parkinson’s Disease: A
neurotransmitter is randomly
produced causing the body to
have spontaneous uncontrolled
movements.
• Multiple Sclerosis: The myelin
sheath is eaten away so the
neurons are not able to pass
messages along properly.
• Ecstasy: Causes nerves to be
overloaded and burned out.
Measurable, permanent
damage is caused with even
just one use.
Lastly
The Central Nervous System:
has only a very limited ability
to regenerate
The Peripheral Nervous
System: can regenerate to a
significant degree