Download The Muscular and Skeletal Systems Reading and

The Muscular and Skeletal Systems Reading and Questions
When you hear the word skeleton, you may think of the remains of something that has died. But the 206 bones in your
body are very much alive. Your bones are not dry and brittle. They are just as alive as the muscles that are attached to
them. Bones do a lot more than just hold you up. They have several functions inside your body.
The Role of the Bones
Support Your skeletal system protects and supports you. Your ribs shield your heart and lungs; the vertebrae protect
your spinal cord, and your skull protects your brain. Without your skeletal system you would be a blob of flesh unable to
move or stand upright.
Storage Bones store minerals suck as calcium phosphorous. These compounds are later released into the surrounding
tissues to help the nerves and muscles function properly. The cavities inside your arm and leg bones also store fat that
can be used for energy.
Movement Skeletal muscles, which are attached to the bones by tendons, pull on the bones to produce movement.
Without bones, you would not be able to sit, stand, walk or run.
Blood Cell Formation Some of your bones are filled with special material that makes white and red blood cells.
The composition of the bones
A bone may seem lifeless but it is a living organ made up of several different tissues. Bone is composed of connective
tissue and minerals that are deposited by living cells called osteoblasts.
A living bone’s surface is covered with a tough, membrane called periosteum (pur ee AHS tee um). Small blood vessels
in the periosteum carry nutrients into the bone. If you look inside a bone, you will note that there are two different
types of bone tissue. If the tissue does not have any visible open spaces, it is called compact bone. It is located toward
the ends of long bones. Compact bone provides most of the strength and support for a bone, such as the femur. It has
a framework containing deposits of phosphate and calcium. Bone tissue that’s has many open spaces is called spongy
bone. Bones contain a soft tissue called marrow. Red marrow found in spongy bone of the legs, arms. Ribs, sternum
(breast bone) and vertebrae (backbones) makes red & white blood cells. Yellow marrow, found in the center of the long
bones, stores fat. Tiny canals within the compact bone contain small blood vessels.
The ends of bones are covered with a smooth slippery surface called cartilage. Did you know that most of your skeleton
used to be soft and rubbery? Most bones start out as sort flexible tissue cartilage. Cartilage contains mostly water,
which gives its rubbery texture. But as you grew, the cartilage was replaced by bone. During childhood, growth plates
of cartilage remain in most of the bones, providing a place for the bones to continue growing.
Some parts never become bone. Feel the tips of your ears, the end of your nose. Notice that it is flexible. That is
because it is cartilage. When you look at an x-ray, cartilage does not appear as dark as the bone because it lacks the
mineral density of bone. Did you know that some animals have no bones at all? The shark for example has only cartilage;
no bone.
Joints
Joints make all of our body movements possible. Anywhere two or more bones cone together is a joint. The bones in
healthy joints are kept far enough apart by a thin layer of cartilage so that they do not rub against each other while
they move. If cartilage wears away the joint becomes arthritic. Bones are held in place and joined together by tough
band of tissue call ligaments. If ligaments are stretched too far, they become strained. A strained ligament will heal
with time , but a torn ligament must be repaired surgically. Muscles move bones by moving joints.
Ball-and-Socket Joints
In this type of joint, the ball-shaped end of one bone fits into a cup shaped socket on the other bone allowing the
widest range of motion including rotation. They act like the joystick on a computer. Examples include the shoulder and
hip.
Hinge Joint
Hinges joint allows movements in a single plane. They are formed when a convex projection on one bone fits into a
concave depression in another. An example of this joint can be found in your knee. The hinge allows you to flex and
extend your lower leg.
Pivot Joint
This joint is formed when rounded or conical surfaces of one bone fit into a ring of one or tendon allowing rotation. The
pivot joining allows freedom of movement of somewhat between ball and socket and hinge joining. It can be found in
your wrists, ankle and neck.
Sliding Joint
This joint is formed when flat or slightly flat surfaces move against each other allowing sliding or twisting without any
circular movement. This happens in the carpals in the wrist, the tarsals in the ankle and the vertebrae in the back.
Fixed Joints
These joints do not allow any movement and are extremely strong. Examples include the joints of the skull.
Joints are held together with strong elastic bands of connective tissue called ligaments. If a ligament is stretched too
far, it becomes strained. A strained ligament will usually heal with time, but a torn ligament must be repaired surgically.
Cartilage helps cushion the area where the two bones meet. If the cartilage wears away the joint becomes arthritic.
Bone Disorders
Osteoporosis, porous bone, is a disease characterized by low bone mass and structural deterioration of bone tissue
leading to bone fragility and an increased susceptibility to fractures of the hip, spine, and wrist. Men as well as women
suffer from osteoporosis, a disease that can be prevented and treated. Some risk factors which are related to
osteoporosis include a lifestyle with little calcium or vitamin d, cigarette smoking and lack of physical activity.
Osteomyelitis is bone inflammation that often results from bacterial infection, often times resulting from trauma or a
puncture wound (stepping on a nail). It can lead to complete destruction of the bone. Staphylococcus aureus, often
introduced into the body through wounds, is a common cause of osteomyelitis.. People with osteomyelitis often fell
severe pain in the infected bone. They may have fever and chills, feel tires or nauseated, or have a general open wound,
the injured area may begin to hurt again after initially seeming to get better. Osteomyelitis can be treated without
surgery if diagnosis early enough.
Arthritis is the most common joint problem. Arthritis describes over 100 diseases that can damage joints. About one
out of every seven people in the US suffers from arthritis. All forms of arthritis begin with pain, stiffness, and
swelling in the joints. Arthritis is often treated with pain medication, in severe cases, joint replacement may be
necessary.
Muscular System
Without muscles our body would not be able to move or carry out many of the normal everyday function. There are over
600 skeletal muscles functions for body movement. Fibers. These muscles are attached, and are typically under
conscious control for locomotion, facial expressions, posture and other body movements. Muscles account for
approximately 40% of body weight. The metabolism that occurs in this large ass- produces heat essential for the
maintenance of body temperature. During muscle contractions, muscle cells expend (use up) much energy, most of which
is converted to heat. To prevent overheating, glands in the skin produce sweat to cool the skin and the body radiates
heat from the blood and tissues through the skin. When the body is chilly shivering causes quick muscle contractions
that generate heat.
Each muscle is served by nerves, which link the muscle to the brain and spinal cord. Your hand and arms and other
muscles are voluntary. So are the muscles in your face. Muscles that you are able to control are called voluntary
muscles. These muscles are attached to bones and are typically under conscious control for locomotion, facial
expressions, posture, and other body movements. It is true that it takes more muscles to frown, 43, than to smile, 13.
In contrast, involuntary muscles are muscles you cant consciously control. Blinking and the movement of food through
you digestive system are just a few of the involuntary muscles.
Cardiac Muscle (heart)
Cardiac muscle is only in the heart and makes up the atria and ventricles, heart walls. Like Skeletal muscle, cardiac
muscle contains striated and smooth fibers. Cardiac muscle is considered an involuntary muscle. Specialized cardiac
muscle cells maintain a consistent heart rate.
Smooth Muscle
Smooth muscle is throughout the body, it is extensively within the walls of digestive tract organs, causes peristalsis,
wave-like contractions, that aids in food digestion and transport. Like cardiac muscles, smooth muscle is involuntary.
Unlike skeletal and cardiac muscle, smooth muscle is nonstriated, not banded. Except for the heart, any action that the
body performs with out conscious thought is done by smooth muscle contractions. This includes diverse activities such
as constricting, closing, the bronchioles, air passages, of the lungs or pupils of the eye or causing goosebumps in cold
conditions.
Skeletal muscle
Skeletal muscles allow our bones to move. They are the most common type of muscles and attached to bones by thick
bands of tissue called tendons skeletal muscles are voluntary and striated in appearance skeletal muscles tend to
contrast quickly and tire more easily than involuntary muscles.
Tendons attach most skeletal muscles to bones tendons are strong sheets of connective tissue that are identical with
ligaments. Tendons and ligaments differ in function only: tendons attach muscle to bone and ligaments attach bone to
bone. Physical exercise strengthens the attachment of tendons to bones.
Skeletal muscles have muscle tone; remain partly constracted, which helps maintain body posture. Ongoing signals from
the nervous system to the muscle cells help maintain tone and readiness for physical activity. A muscle fiber divides
into even smaller parts. Within each fiber are strands of myofibrils. These long cylindrical structures appear striped
due to strands of tiny. Myofilaments have two types of protein: actin, thin myofilaments, and myosin, thick
myofilaments.
A muscle fiber divides into even smaller parts. Within each fiber are strands of myofibrils. These long cylindrical
structures appear striped due to strands of tiny myofilaments. Myofilaments have two types of protein:actin, thin
myofilaments and myosin, thick myofilaments.
The actin and myosin myofilaments align evenly, producing dark and light bands on the myofibril. Each dark band depicts
an area where the myofilaments overlap, causing the striated appearance of skeletal muscle. All dark and light bands of
the myofilaments have names. At the Z line, actin strands interweave. The region between two Z- lines is a sarcomere,
the functional unit of skeletal muscle. Muscle contraction occurs when overlapping actin and myosin myofilaments
overlap further and shorten the muscle cell. The myofilaments keep their length. The overlapping of myofilaments is
the basis for the sliding filament theory of contraction.
Movement
You move because of pairs of skeletal muscles working together. Muscles are attached to an origin, a point of
attachment on a stationary bone. Muscles are attached to moving bones at the insertion point. When one muscle of the
pair contracts, get shorter, the other muscle relax, elongates or returns to its normal length. Muscles always pull, never
push. Skeletal muscle is a system of pairs that relax and contract to move a joint. For example, when front leg muscles
contract, the knee extends, straightens, while back leg muscles relax. Conversely to flex, bend the knee back leg
muscles contract while front leg muscles relax. Agonists are muscles primarily responsible or an action due to their
contraction. Antagonists are the muscles that relax to smooth the action of the agonists.
Often times after exhaustive exercises, sprinting or high repetition weight training, ones muscles begin to burn become
fatigues and weak. Lactic acid has formed within the muscles and blood. To explain what it is we first have to look
briefly into how the working muscles use energy, ATP. Actively contracting muscles obtain adenosine triphosphate, ATP
from glucose, sugar, stored in the blood stream and the breakdown of glycogen stored in the muscles. Initially pyruvic
acid and small amounts of ATP are generated from the breakdown of glucose. The pyruvic acid mixed with oxygen is
converted to carbon dioxide, water and ATP, and our muscles carry on normally. When muscles contract vigorously for
long periods the circulatory system begins to lose ground in delivery of oxygen to the cells in these conditions most of
the pyruvic acid produced in the breakdown of glucose is converted to lactic acid, la. As the lactic acid is produced in
the muscles it leaks out into the blood and is carried around the body. If this condition continues the functioning of the
body will become impaired and the muscles will fatigue very quickly. When Oxygen becomes available the lactic acid is
converted to pyruvic acid and then into carbon dioxide, water and ATP.
Muscular Disorders
Muscular dystrophy is the name given to a group of genetic diseases characterized by progressive weakness and
degeneration of the skeletal or voluntary muscles which control movement. This group of diseases has three features in
common: they are inherited, they are progress, and they gradually get worse. The prognosis of MD varies according to
the type of MD and the progression of the disorder. Life expectancy depends on the degree of progression and late
respiratory deficit. Some cases may be mild, progress slowly and have normal lifespan. Other cases may a more rapid
progression of muscle weakness, functional disability, and loss of ambulation. Currently there is no specific treatment
for any of the forms of MD. However there are treatments that address the symptoms. Such treatments may include
physical therapy, orthopedic appliances for support, corrective surgery or medication or muscular contractions.
Spinal muscular atrophy (SMA) is as disease of the anterior horn cells. Anterior horn cells are located I the spinal
cord. SMA effect the voluntary muscles for activities such as crawling walking, head and neck control and swallowing. It
mainly affect the proximal muscles, or in other words the muscles closest to the point of origin, in this case those
closest to the trunk of one’s body. Weakness in the legs is generally greater than weakness in the arms. Some abnormal
movements of the tongue, called tongue fasciculation may be present in patients with type 1 and some patients with
type2. the senses/feelings are normal as is intellectual activity. In fact it is often observed that patients with SMA are
unusually bright and sociable. SMA is an autosomal recessive disease, which means that both parents must be carriers.
Both parents must have the gene responsible and these genes must be passed onto their child. When a child has
received this gene from each of its parents it will then be affected by SMA. Although both parents are carriers the
likelihood of passing this gene along to a child and having an affected child is 24% or 1 in 4
Question: answer the following on a separate piece of paper w/ complete sentences. Do not use the words it or they
1.
2.
3.
4.
5.
What are the major junctions of the skeletal system?
Describe the function of cartilage and ligaments?
Where is marrow found? What is the function?
What are the three types of muscles/ give a place where each type is found?
Explain how muscles and bones to interact to cause movement.