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 grouped together from many other fibers, each surrounded by thick protective tissue. A muscle uses ATP to contract and shorten, exerting a force on the objects to which it is attached. There are several types of muscles that work in different parts of the body.

muscle structure

A muscle is made up of many muscle tissues grouped together and surroundedepimissio, a tough connective tissue similar to cartilage. The epimysium surrounds bundles of nerve cells that run in long fibers called neurons.it sways. These fascicles are surrounded by their own protective layer, theperimysium. This layer allows nerves and blood to flow to individual fibers. Then each fiber is wound into aendometriosis, another layer of protection. As seen in the image below, a muscle occurs in a basic pattern of bundled 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 as they are brought together. the epimysium continuestendons, which are linked toperiosteumConnective 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 to other connective tissues to exert forces on organs and control everything from circulation to food processing.

muscle function

Whether it's the largest muscle in the body or the tiny muscle that controls eye movement, each muscle works in a similar way. A signal is sent from the brain along a bundle of nerves. The electronic and chemical message passes rapidly from one nerve cell to another and finally reaches the recipient.engine plate. This interface between muscle and nerve cells triggers a chemical signal.acetylcholine, which tells the muscle fiber to contract. This message is transmitted to all the cells of the fiber connected to the nerve.

This sign doesmyosinProteins bind to 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 little heads of myosin fibers trailing along the actin filaments effectively shorten the length of each muscle cell. The cells, connected end-to-end in a long fiber, contract simultaneously, shortening the entire fiber. When a signal is sent to an entire muscle or group of muscles, the resulting contraction results in movement or force being exerted.

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

muscle types

skeletal muscles

Generally, when most people think of a muscle, they 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 that come together in different places to give the joint its full range of motion. Skeletal muscle is aStriated muscle. This means that everyone has muscle fibers.stripes, or linear markings seen when this muscle is placed under a microscope. The stripes correspond tosarcomeropresent 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 somewhat similar to skeletal muscle, is connected to it.Autonomic nervous system. This system controls vital organs like the heart and lungs, allowing us to not 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 always occur while we are unconscious. For example, you can hold your breath if you want, but you don't have to remember to breathe all the time. Heart muscle surrounds the ventricles and serves 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 need to contract quickly and frequently so stretch marks are visible.

smooth muscle cells

Unlike skeletal and cardiac muscle, smooth muscle is not striated. This is because individual muscle cells are not perfectly aligned with the sarcomeres. Instead, they are displaced by the fibers. This allows the smooth muscle to contract longer, although the contraction is slower. Consider the muscle that contracts the sphincter of the bladder. This muscle may need to stay closed for hours and only gets 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 controlled primarily 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 to keep all the hair standing up in cold weather. 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 spring, a thin and weak bear appears. What happened to the bear's muscles?
AND.They stayed the same size, just hidden under the fat.
B.The bear used them for energy during hibernation.
C.The bear's fur is thinner, making it appear weaker.

2. Growing muscles are called hypertrophy. Bodybuilders do this when they train to increase the size of their muscles. Days after a good workout, the trained muscle often hurts a bit. What is causing this?
AND.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?
AND.The noodles don't splash when you walk
B.Carbohydrates help you absorb more water, which helps you run.
C.Carbohydrates are easily broken down 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 ed.New York: WH Freeman and Company.
• Nelson, DL y Cox, MM (2008).principles of biochemistry. New York: WH Freeman and Company.