Download muscles, skeletal system

SKELETAL SYSTEM
FUNCTIONS:
1. Gives the body shape and support
2. Protection of vital organs
3. Mineral storage, especially calcium
4. Formation of blood cells in the marrow
CARTILAGE
Cartilage is not as strong as bone, but it is more flexible. Unlike bone, cartilage has no
blood supply, so when it is damaged it takes a long time to heal, if ever.
FUN FACTS ABOUT BONES
Bone is made of the same type of minerals as limestone.
How many bones are there in the body? No one can say because it varies from person to
person, and it varies with age.
Babies are born with 300 bones, but by adulthood we have only 206 in our bodies.
The giraffe has the same number of bones in its neck as a human: seven in total.
The long horned ram can take a head butt at 25 mph. The human skull will fracture at
5mph.
LONG BONES. What’s an example of a long bone? The large bones in the thigh and
the arms are long bones. The ends of the bone are the EPIPHYSIS and the shaft is
called the DIAPHYSIS.
The middle cavity is a space in the center of the bone called the MEDULLARY
(“middle”) CANAL, which is filled with yellow marrow (fat tissue). The
epiphyses contain RED MARROW, which is involved in RBC production. As a
person grows older, the red marrow is replaced by yellow marrow (fat).
The word “articulation” means where two bones meet. Where one long bone
articulates with another bone is the joint. The surface of each bone at the joint has
ARTICULAR CARTILAGE, which provides a smooth surface with no friction.
On the very outside of every bone is an onionskin thin layer of tough tissue
called PERIOSTEUM. Its function is for the attachment of tendons and ligaments.
The periosteum has a lot of nerves in it, so tearing it is painful. Shin splints are when
the muscle pulls on the periosteum.
TERMINOLOGY
FLEXION decreases the angle of a joint like bending an elbow.
EXTENSION increases the angle of a joint like straightening the arm.
ROTATION moves a part around its own axis, like shaking the head “no”
HOW BONES GROW: Ossification
Bone Growth and Repair
Bones are composed of living tissues, so they can grow and undergo repair. Several
different types of cells are involved in bone growth and repair. Don’t get these mixed up!
Osteoblasts are bone-forming cells. They take calcium from the blood to make new bone.
Osteocytes are mature bone cells
Osteoclasts break down bone cells and send the calcium back to the blood.
Bone Development and Growth
A band of cartilage called the epiphyseal (growth) plate remains in the epiphysis of the
bones. The limbs keep increasing in length as long as the epiphyseal plates are still
present. Eventually the growth plates become ossified (the cartilage turns to bone, and the
bone stops growing.
Remodeling of Bones
In the adult, bone is continually being broken down and built up again. Osteoclasts
remove worn out cells, and deposit calcium in the blood. Osteoblasts take calcium
from the blood and make new bone cells.
Thus, through this process of remodeling, old bone tissue is replaced by new bone tissue.
Because of continual remodeling, the thickness of bones can change. Physical use
(exercise) and hormone balance affect the thickness of bones. Strange as it may seem,
adults apparently require more calcium in the diet (about 1,000 to 1,500 mg daily) than
do children. Otherwise, osteoporosis, a condition in which weak and thin bones easily
fracture, may develop.
Bone Repair is required after it breaks or fractures.
1. Hematoma (mass of clotted blood in the space between the broken bones) forms six
to eight hours after fracture. The area is inflamed and swollen.
2. The hematoma becomes a fibrous callus that lasts about three weeks. Tissue repair
begins, and the osteoblasts make fibrous to form a boney callus.
3. Bony callus lasts about three to four months.
4. Remodeling: Osteoclasts reabsorb the irregularities in the bone callus, returning it to
a normal appearance.
BONE REMODELING: Change in shape and size in bone with time; due to forces.
Osteoblasts and clasts are sensitive to pressure.
Increase pressure, osteoblasts increases bone.
No pressure, osteoclast decreases bone.
Exercise increases bone.
If you didn’t have your fruit loops and milk this morning, the body’s calcium needs will
come out of the bone. Having milk for lunch will replenish it.
BONE SPURS: abnormal growth in response to pressure. Can occur on any bone (e.g. heel).
OSTEOPOROSIS: bones are weakened due to a decrease in the bone mass.
Osteoclasts break down bone, fewer minerals make it fragile. Men get it as well as
women. What’s the best way to prevent osteoporosis? Exercise! What does exercise
do? Makes bones bigger.
BONE FRACTURES: The naming of fractures tells you what kind of break occurred.
COMPLETE: bone is broken clear through
INCOMPLETE bone is not separated into two parts.
SIMPLE: does not pierce the skin
COMPOUND if it pierces the skin. Increased chance of infections, maybe life-threatening.
STRESS: least serious, get tiny, almost invisible breaks. Usually from overexertion.
Muscle builds up faster than bone. Six weeks into military basic training camp, see lots
of stress fractures.
VERTEBRAE
These form the “back bone” which protects the spinal cord. They form normal
curvatures in the spine, and are separated by intervertebral discs.
ABNORMALITIES OF THE SPINE
SCOLIOSIS is a lateral curve in the spine
KYPHOSIS is a hunchback curve
LORDOSIS is a swayback in the lower region.
ANKYLOSIS is severe arthritis in the spine and the vertebrae fuse.
INTERVERTEBRAL DISCS
These are made of connective tissue (cartilage) that is solid, yet flexible. Function is
for shock absorption, and a little movement.
HERNIATED intervertebral disc happens when stress is put on it the wrong way. When
you bend over, the disc compresses anteriorily. If there’s a weakness there, it herniates
(pokes out). It can press on the spinal nerves and cause a lot of pain or some paralysis.
Improper lifting and pushing with the back can cause this. One treatment is to put a
metal rod in to maintain the distance between the discs.
KNEE JOINTS
Around this is a JOINT CAPSULE of fibrous connective tissue, which gives it strength.
The joint capsule alone is not strong enough, so they are reinforced by ligaments.
LIGAMENTS connect bone to bone.
Inside the knee joint are two tough pieces of cartilage. If you keep your weight on one foot
and then pivot your body, it can tear this knee cartilage. Common problem in athletes.
Never heals, needs surgery to remove the torn piece; ends a sports career. If really bad, bone
will scrape against bone, causing severe arthritis in the joint; will need total knee replacement
eventually.
CRACKLING SOUNDS in joints are from the release of gas bubbles in the joint. It does
not lead to arthritis.
SPRAINS: when a ligament is torn from its attachments. They can be fairly serious.
When a tendon or ligament is sprained, it can take 6 months to heal, and may even need
surgery. Even a partial tear, you have to be careful.
STRAINS: are injuries where the muscle is overstretched and tears. They are not as bad
since there is a lot of blood supply to muscle, so they heal faster. You can walk on it and it
heals in a couple of days, it’s a strain.
ARTHRITIS: (“itis” means inflammation). Types:
1. OSTEOARTHRITIS: common in older people. Known as “wear and tear
arthritis”. The articular cartilage begins to break down, and bone spurs start to grow.
The surface is no longer smooth, and movement now causes pain. Can be mild to
severe, needing joint replacement. These people can actually predict the weather,
since the fluid in the joint is under pressure. As air pressure changes, fluid expands
and hurts more.
2. RHEUMATOID ARTHRITIS: not a disease of old age. It’s an autoimmune
disease where body attacks and destroys the cartilage in synovial joints. They swell
and become unusable, causing knarled hands and feet. Usually need joint
replacements.
3. GOUTY ARTHRITIS (gout). Caused by eating too much red meat or protein.
These foods break down into urea, an acid, which causes uric acid crystals in the
joints. They form in the cooler areas of the body, especially big toes. Was more
common years ago when people ate nothing but meat. The crystals cause the joint to
swell up.
CLASSIFICATION OF THE BONES
1. THE AXIAL SKELETON
A. THE SKULL (cranium)
FACIAL BONES: maxilla (upper jaw bone), mandible (lower jaw bone)
HYOID BONE is the only bone that does not articulate with another bone.
The tongue is attached here, so it assists the digestive system.
B. VERTEBRAL COLUMN
C. STERNUM
D. RIBS:
True ribs attach to the sternum directly.
False ribs attach to the sternum indirectly by joining to the cartilages of the rib above it.
Floating ribs do not attach to the sternum.
2. APPENDICULAR SKELETON
A. SHOULDER GIRDLE AND ARM BONES
B. PELVIC GIRDLE AND LEG BONES
NAMES OF BONES OF THE APPENDICULAR SKELETON
SHOULDER GIRDLE
Scapula is the shoulder blade
Clavicle is the collar bone
ARM BONES
Humerus is the arm bone
Radius and Ulna are the arm bones
Carpals are the wrist bones
Metacarpals make up the palm of the hand
Phalanges are the bones of the fingers and toes
PELVIC GIRDLE AND LEG BONES
Pelvic bone is the hip bone and pelvis
Femur is the thigh bone
Patella is the knee cap
Tibia and Fibula are the leg bones
Tarsals are the ankle bones
Calcaneus is the heel bone
Metatarsals make up the arch and ball of the foot.
COMPARISON CHART
UPPER LIMB
Humerus
Radius and Ulna
Carpals
LOWER LIMB
Femur
Tibia and Fibula
Tarsals
Metacarpals
Phalanges
Metatarsals
Phalanges
MUSCULAR SYSTEM
Muscles have only one function; to contract.
Bend your arm (this muscle- biceps- is contracting).
To extend the arm, I need another muscle. MUSCLES WORK IN PAIRS.
The muscle which opposes the action of the primary mover is called the antagonist.
If there is another muscle which helps another muscle, it is called a synergist.
Therefore, you need lots of muscles for all the complex movements of the body.
TENDONS are structures that attach a muscle to bone.
LIGAMENTS are structures that connect one bone to another bone.
TERMS:
ORIGIN = The region which usually doesn’t move when the muscle contracts. Look at
the biceps brachii; does the shoulder move when I bend my arm? No; the shoulder = origin.
INSERTION= The point of attachment that moves; when you bend the arm, the muscle
insertion must be in the arm.
There are three types of muscles:
Skeletal, Smooth, and Cardiac.
MUSCLE FIBERS (Muscle cells)
1. SKELETAL MUSCLE FIBERS
Theses are the muscles you usually think of that move the skeleton.
They move body parts and also protect internal organs.
Skeletal muscle is under voluntary control; we can move it when we want to.
Skeletal muscles are named according to their size, location, and/or action.
A muscle cell torn in half can regenerate two cells, like a worm.
There are almost no muscle diseases, because muscle can heal.
For contraction to take place, need two things: nerve signal and calcium
Need a signal from a nerve which causes Ca ++ to leak out and cause the muscle to
contract.
Muscles respond to forces:
Exercise  HYPERTROPHY (growth in size)
Lack of use  ATROPHY. This happens quickly. Astronauts can lose 40% of their
muscle in two weeks! It is regained quickly, too.
After exercise, you can get sore…why? Muscle is torn.
Strength training should be done every day. No Pain – No Gain is a fallacy. You can
gain strength and size without pain. Eating protein also does not increase muscle. The
average person only needs one ounce of protein a day, two if you work out. Two ounces
is like one mini hamburger. Most people eat too much meat.
FUN FACTS ABOUT STRENGTH
The strongest humans can lift about 3 times their own body weight, but the average
gorilla can lift 10 times its own body weight! Gorillas can lift 4,600 pounds.
But the strongest creature is the ant. If you had the strength of an ant, you could lift over
your head and carry 6,600 pounds.
The flea, however, can jump up to 200 times its own height. This is equivalent to a man
jumping the Empire State Building in New York.
MUSCLE DISEASE: MUSCULAR DYSTROPHY
This is a genetic lack of a protein so the cell won’t contract = paralysis.
2. SMOOTH MUSCLE
Found around internal organs, blood vessels, bladder, GI tract, around the tubes to
the lungs. Smooth muscle is involuntary because we can’t consciously move it.
You don’t say, “Gee, I think I’ll move something through my small intestine now”.
1. smooth muscles cause peristalsis (rhythmic contraction) in digestive tract
2. It doesn’t get tired (“I’m too tired to urinate!”)
3. Contracts in response to neurons as well as hormones and changes in local
environment (amount of oxygen, etc).
3. CARDIAC MUSCLE: Only found in heart.
1. Cardiac muscle is also involuntary.
2. As one cell contracts, the action potential goes through all the cells, and they all
contract as a unit. That’s why the heart contracts all at once. Cardiac muscle
propels blood.
3. It has an intrinsic beat. The cells contract on their own, without a signal.
Even if you chop a heart up, each piece will beat by itself!
MUSCLE TONE
Even when muscles are relaxed, some of their fibers are still contracting, giving the
muscle some tone. Therefore, the normal state of a muscle, with some contraction, is
called muscle tone. This is important in posture so you can stand upright but mostly
relaxed.
ENERGY FOR MUSCLE CONTRACTION
What do you think is the energy molecule needed? ATP.
In order for the mitochondria to produce enough ATP, it needs oxygen and the sugars that
are in storage.
MUSCLE SPASMS are sudden and involuntary muscle contractions. Usually caused
from overexertion. Needs heat and massage to increase circulation. Avoid them by
stretching before and after activities.
OXYGEN DEBT
The amount of oxygen needed to replenish the supply following anaerobic demand
is called the oxygen debt. When you continue to breathe heavily after exercising, it
means you have an oxygen debt.
Muscles can do without oxygen for a while pretty well, unlike the brain. To pay back a
minor oxygen debt, you just have to breathe heavily for a while. But for marathon runners
to pay back an extreme oxygen debt, they have to eat a lot of carbohydrates over a two-day
period. That’s why they load up on pasta before a marathon.
EXERCISE
There are many physiological benefits of exercise:
1. improved muscular strength, endurance, flexibility
2. improved cardio-respiratory endurance
3. increased bone density and strength
4. relief from depression and increased HDLs
MOVEMENT TERMS
FLEXION: Joint angle decreases
EXTENSION: Joint angle increases
ADDUCTION: Body part moves toward midline
ABDUCTION: body part moves away from midline
ROTATION: Body part moves around its own axis
CIRCUMDUCTION: Body part can draw a circle
SKELETAL MUSCLE NAMES (They are named by shape, size, action, or location)
DELTOID: raises the arm at the shoulder
TRAPEZIUS: extends the head and shrugs the shoulders
TRICEPS extends the forearm
BICEPS flexes the forearm
PECTORALIS: pulls arm across chest
RECTUS ABDOMINUS: compresses abdomen
GLUTEUS MAXIMUS large buttock muscle is associated with walking upright
QUADRICEPS: large muscle group on thing that extends the leg
HAMSTRINGS muscle group flexes the lower leg
TIBIALIS ANTERIOR on the front of the lower limb, on the shin.
Tibialis anterior is what causes shin splints if you exercise without stretching
GASTROCNEMIUS large calf muscle that extends the foot