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 JointsBall & 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• 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

Conscious movements

Sensory Input

Running Touch

Jumping Sight

Speech Smell

Grabbing Taste

Sitting Hearing

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