Muscle - Definition, Function, Types and Structure | biology dictionary (2023)

muscle definition

A muscle is a group of muscle tissues that contract to produce force. A muscle consists of muscle cell fibers surrounded by protective tissue and bundled together in a bundle of many other fibers, each surrounded by thick protective tissue. A muscle uses ATP to contract and shorten, exerting a force on the objects it is attached to. There are different types of muscles that work in different parts of the body.

muscle building

A muscle is made up of many muscle tissues grouped together and surrounded byepimission, a tough cartilage-like connective tissue. The epimysium surrounds bundles of nerve cells that run in long fibers called neurons.it rocks. These fascicles are surrounded by their own protective layer, theperimysium. This layer allows nerves and blood to flow to the individual fibers. Then, each fiber is wrapped in aendometriosis, another layer of protection. As seen in the image below, a muscle is laid out in a basic pattern of grouped fibers separated by protective layers.

These layers and bundles allow different parts of a muscle to contract differently. The protective layer that surrounds each bundle allows the different bundles to slide over each other when pulled together. the epimysium followstendonswho joinsperiosteumConnective tissue that surrounds bones. Being anchored to two bones allows the skeleton to move when the muscle contracts. Another type of muscle wraps around many organs, and the epimysium connects with other connective tissues to create forces in the organs that control everything from circulation to food processing.

muscle function

Whether it's the biggest muscle in the body or the tiny muscle that controls eye movement, every muscle works in a similar way. A signal is sent from the brain along a bundle of nerves. The electronic and chemical message travels rapidly from one nerve cell to another, finally arriving at theengine plate. This interface between muscle and nerve cells triggers a chemical signalacetylcholine, which tells the muscle fiber to contract. This message is relayed to every cell in the fiber that connects to the nerve.

This sign makesmyosinproteins bind to the actin filaments that surround them. These are the purple proteins in the image below. Myosin uses ATP as an energy source to crawl along the green filament,Aja. As you can see, the many small myosin fiber heads that pull on the actin filaments effectively shorten the length of each muscle cell. Continuously connected cells in long fibers contract at the same time, shortening the entire fiber. When a signal is sent to an entire muscle or muscle group, the resulting contraction leads to the application of movement or force.

A muscle can be used in many different ways throughout the body. A given muscle may rarely contract with great force, while another muscle continually contracts with minimal force. Animals have developed a myriad of uses for the forces a muscle can generate. Muscles evolved for flying, swimming, and running. They also evolved into pumps used in the circulatory and digestive systems. The heart is a specialized muscle used exclusively to pump blood throughout the body. These different muscle types are discussed below.

muscle types

skeletal muscles

When you think of a muscle, most people usually think of skeletal muscle. Biceps, triceps and quadriceps are common names for muscles that bodybuilders tend to focus on. In fact, these general muscles are usually made up of many small muscles attached in different places to give the joint its full range of motion. Skeletal muscle is aStriated muscle. This means that everyone has muscle fibers.Stretch marks, or linear markings seen when this muscle is placed under a microscope. The streaks correspond tosarcômeroFound in striated muscles, which are highly organized bundles of muscle cells that can contract rapidly.

Skeletal muscles are controlled by thesomatic nervous system, also known as the voluntary nervous system. Point your finger at the ceiling. This is your somatic nervous system in action, controlling your skeletal muscles.

Herzmuskel

Cardiac muscle, although similar in some ways to skeletal muscle, is related to it.vegetative nervous system. This system controls vital organs like the heart and lungs, allowing us to not have to focus on pumping our heart every time it needs to beat. Although we have some level of conscious control over the autonomic nervous system, it will kick in whenever we are unconscious. For example, you can hold your breath if you like, but you don't have to remember to breathe all the time. Cardiac muscle surrounds the ventricles of the heart and is used to pump blood throughout the body.

Cardiac muscle is similar to skeletal muscle in that it is striated. Unlike skeletal muscle, myocardial fibers are arranged in a branching pattern rather than a linear pattern. Both skeletal muscle and cardiac muscle must contract quickly and frequently for stretch marks to appear.

smooth muscle cells

Unlike skeletal and cardiac muscle, smooth muscle is not striated. This is because the individual muscle cells in the sarcomeres are not perfectly aligned. Instead, they migrate along the fibers. This allows the smooth muscle to contract longer, although the contraction is slower. Consider the muscle that contracts the sphincter in your bladder. This muscle can need to be closed for hours and you only get a minute of relief when you go to the bathroom. Many other smooth muscles work in the same way.

Like cardiac muscle, smooth muscle is primarily controlled by the autonomic nervous system. The many muscles that line the digestive tract work together to move food through the digestive system. The muscles attach to the hair follicles, so all the hair stands on end when it's cold. Smooth muscle is found almost everywhere in the body and helps with everything from blood circulation to digestion.

Test

1. A big strong bear goes into a cave to hibernate there. In the spring, a thin and weak bear appears. What happened to the bear's muscles?
AN.They remained the same size, just hidden under the fat.
B.The bear used them as a source of energy during hibernation.
C.The bear's fur is thinner, which makes it look weaker.

2. Growing muscles is called hypertrophy. Bodybuilders do this when they train to increase the size of their muscles. Often the trained muscle hurts a few days after a good workout. What is causing this?
AN.lactic acid buildup
B.Not enough protein!
C.Microscopic tears in muscle fibers.

3. Endurance runners are told to eat pasta the night before a big race. Why is it useful?
AN.Paste won't spill as you run
B.Carbohydrates help you absorb more water, which helps you run.
C.Carbohydrates break down easily and load your cells with ATP

references

• Lodish , H. , Berk , A. , Kaiser , C.A. , Krieger , M. , Scott , M.P. , Bretscher , A. , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Matsudaira , P. ( 2008 ).Molecular Cell Biology 6th EditionNova York: WH Freeman und Company.
• Nelson, D.L. e Cox, M.M. (2008).principles of biochemistry. Nova York: WH Freeman und Company.