Muscular System

Vocabulary Words

Function of Muscle TissueThe main function of the muscular system is movement. Muscles are the only tissue in the body that has the ability to contract and therefore move the other parts of the body.

the maintenance of posture and body position. Muscles often contract to hold the body still or in a particular position rather than to cause movement. The muscles responsible for the body’s posture have the greatest endurance of all muscles in the body—they hold up the body throughout the day without becoming tired.

Another function related to movement is the movement of substances inside the body. The cardiac and visceral muscles are primarily responsible for transporting substances like blood or food from one part of the body to another.

The final function of muscle tissue is the generation of body heat. As a result of the high metabolic rate of contracting muscle, our muscular system produces a great deal of waste heat. Many small muscle contractions within the body produce our natural body heat. When we exert ourselves more than normal, the extra muscle contractions lead to a rise in body temperature and eventually to sweating.

The muscular system makes up nearly half the weight of the human body, this is why when we train we sometimes put on weight instead of losing it. We put on muscle weight.

The muscles provide the forces that enable the body to move. Muscles stretch across joints to link one bone with another and work in groups to respond to nerve impulses.

There are three types of muscle:

Skeletal muscle•There are nearly 650 skeletal muscles in the

human body!

•Skeletal muscles are attached to the skeleton•They work in pairs: one muscle moves the bone in

one direction and the other moves it back again•Skeletal muscles are voluntary muscles - in other

words we think about what movements we want to make (at least, usually!) and send messages via our nervous system to tell the appropriate muscle(s) to contract.

•Muscle contractions can be short, single contractions or longer ones.

Smooth/Visceral Muscle

Smooth muscle is found in our internal organs: in our digestive system, our blood vessels, our bladder, our respiratory organs and, in a female, the uterus. Smooth muscle can stretch and maintain tension over extended periods Smooth muscles are involuntary muscles - in other words we do not have to think about contracting them because they are controlled automatically by the nervous system. It would be pretty inconvenient if we had to think about digesting our food, for example! The term “smooth muscle” is often used to describe visceral muscle because it has a very smooth, uniform appearance when viewed under a microscope. This smooth appearance starkly contrasts with the banded appearance of cardiac and skeletal muscles.

Cardiac muscleAs the name should tell you, cardiac muscle is found only in the heart. It can stretch, just like smooth muscle, and contract like skeletal muscle. It is a twitch muscle - it only does short single contractionsLike smooth muscle, cardiac muscle is involuntary. It'd be rather dangerous if it were voluntary - we could stop our heart beating any time we wanted! , cardiac muscle stimulates itself to contract. The natural pacemaker of the heart is made of cardiac muscle tissue that stimulates other cardiac muscle cells to contract.

Gross Anatomy of a Skeletal MuscleMost skeletal muscles are attached to two bones through tendons. Tendons are tough bands of dense regular connective tissue whose strong collagen fibers firmly attach muscles to bones. Tendons are under extreme stress when muscles pull on them, so they are very strong and are woven into the coverings of both muscles and bones. Muscles move by shortening their length, pulling on tendons, and moving bones closer to each other. One of the bones is pulled towards the other bone, which remains stationary. The place on the stationary bone that is connected via tendons to the muscle is called the origin. The place on the moving bone that is connected to the muscle via tendons is called the insertion. The belly of the muscle is the fleshy part of the muscle in between the tendons that does the actual contraction.

STRENGTH is the amount of force a muscle can exert. All of us need strength to perform our daily activities. If you use muscles regularly they will stay strong. If not, they will weaken. Strength in muscle relates to good health by helping you: 1)maintain good posture, 2)reduce fatigue, 3)prevent muscle injuries and soreness, 4)prevent backache.

Muscles use oxygen when contracting. The oxygen needed is carried from the lungs to the muscles by blood (red blood cells). The more a muscle works (contracts), the more oxygen is needed. Although muscles can store some oxygen temporarily, eventually muscle cannot get enough oxygen. The process of using stored oxygen in a muscle creates a substance called lactic acid. An accumulation of lactic acid causes a muscle to lose its’ ability to contract and sometimes causes cramping.

Principles of Strength Exercising

Overload – a muscle must contract harder than normal if it is to become stronger; a muscle must work more than normal.

Progression – overload gradually, increase the load over a period of time to get the best muscle strength.

Specificity – exercise the specific muscles you want to develop. Leg exercises develop the legs, arm exercises develop the arm, etc.

IMPROVING MUSCLE STRENGTH : You must exert muscular force against a resistance

ISOTONIC EXERCISES: muscles contract and body parts move ( i.e. weightlifting)

ISOMETRIC EXERCISES: the muscle contracts when working against stationary object. The muscles work, but the body parts do not move. Isometric muscles are often recommended after an extended period of inactivity, such as a broken limb.

MUSULAR ENDURANCE: the ability of a muscle to work for long periods of time without getting tired. Muscular endurance depends on the kind of muscle fibers that make up the muscles.

LOW INTENSITY EXERCISES - build the muscular endurance needed for daily activities – use only the body parts you use daily (in other words, do nothing).

MEDIUM INTENSITY EXERCISES - build the muscular endurance needed for good fitness. Do exercises and body weight calisthenics (pull-ups, push-ups, etc.).

HIGH INTENSITY EXERCISES - build muscular endurance for high-level performance. Combine strength training with increased repetitions for endurance.

There are 2 kinds of muscle fibers: SLOW-TWITCH FIBERS. contract at a slow rate. •1) use oxygen from the blood to release energy •2) do not tire easily •3) have the most endurance of all muscles.

FAST-TWITCH FIBERS contract at a fast rate. •1) do not use oxygen from the blood to release energy •2) have greater strength •3) have less endurance.

The relative number of the kind of fibers in a given muscle does not change, but the kind of exercise you do influences the size of the fibers and their ability to use oxygen.

Muscle Facts •Muscle is a soft tissue in the body of humans and animals. Main purpose to produce force and motion.•The word muscle is derived from the Latin term musculus, meaning "little mouse". This Latin term could be due to the shape of some muscles or because muscles contracting under the skin can look like a mouse moving under a rug.•Skeletal muscle can be further divided into two types, slow twitch and fast twitch.•Slow twitch (Type I) muscle contain proteins that give it a rich red color. This muscle carries more oxygen efficiently and using fats, proteins or carbs as energy slow twitch muscle fibers contract over a long period of time. Therefore type I muscle fiber works well for aerobic sports i.e. long distance running and cycling.•Fast twitch (Type II) muscle is whiter in color as it has less myoglobin (a oxygen carrying protein). Fast twitch fibers contract quickly and powerfully, however they fatigue rapidly. •Therefore type II muscle fiber is useful for anaerobic exercise such as sprinting or for strength sports like weightlifting.•Muscle makes up around half of the total human body weight. Muscle tissue is also around 15% denser than fat tissue.•It takes 17 muscles in the face for us to smile and 43 muscles to frown.•If muscle strength is regarded as the ability to use force on something then the jaw muscle (masseter) is the strongest in the body.•The strongest muscles in relation to the job they do is the external muscles of the eye which are large and about 100 times stronger than they need to be in relation to the small size and weight of the eyeball.•The tongue has 8 muscles, so is technically not the strongest muscle in the body.•The heart cardiac muscle does the most work of any muscle over a lifetime. •Cerebral palsy is a disorder that affects balance and motor functions, while muscular dystrophy is a genetic disease that damages muscle fibers.•Muscle memory is created by practicing an action over and over again. Our muscles fine tune themselves, becoming more precise and exact in what they do. So practice is very important when learning a sport!!