A muscle is a group of muscle tissues that contract to produce a force. A muscle consists of muscle cell fibers surrounded by protective tissue, grouped together into many more fibers, all surrounded by thick protective tissue. A muscle uses ATP to contract and shorten, producing a force on the objects it is connected to. There are several types of muscles, which act on various parts of the body.
A muscle consists of many muscle tissues grouped together and surrounded byepimysium, a tough connective tissue similar to cartilage. The epimysium surrounds bundles of nerve cells that run in long fibers calledfascicles. These fascicles are surrounded by their own protective layer, theperimysium. This layer allows nerves and blood to flow to the individual fibers. Each fiber is then wrapped in aendomysium, another protective layer. As seen in the image below, a muscle is organized into 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 surrounding each bundle allows the different bundles to slide over each other as they contract. The epimysium connectstendons, which are linked toperiosteumconnective tissue that surrounds bones. Being anchored to two bones allows the skeleton to move when the muscle contracts. A different type of muscle surrounds many organs, and the epimysium connects to other connective tissues to produce forces in the organs, controlling everything from circulation to food processing.
Whether it's the biggest muscle in the body or the tiny muscle that controls eye movement, all muscles work in a similar way. A signal is sent from the brain along a bundle of nerves. The electronic and chemical message is passed rapidly from nerve cell to nerve cell and finally reaches theengine end plate. This interface between muscle and nerve cells releases a chemical signal,acetylcholine, which tells the muscle fiber to contract. This message is distributed to all cells in the fiber connected to the nerve.
This sign makesmyosinproteins to grab the actin filaments around them. These are the purple proteins in the image below. Myosin uses ATP as an energy source to crawl along the green filament,actin. As you can see, the many small heads of myosin fibers crawling along the actin filaments effectively shorten the length of each muscle cell. The cells, which are connected end to end in long fibers, contract at the same time and shorten 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 applied.
A muscle can be used in many different ways throughout the body. A given muscle may rarely contract with great force, while a different muscle will continuously contract with minimal force. Animals have developed a myriad of uses for the forces a muscle can create. Muscles evolved for flying, swimming, and running. They also evolved to be 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 muscle types will be discussed below.
When you think of a muscle, most people usually think of a skeletal muscle. The biceps, triceps and quadriceps are common names for muscles that bodybuilders tend to focus on. In fact, these general muscles are often made up of many small muscles that attach in different places to give a joint its full range of motion. Skeletal muscle is aStriated muscle. This means that each muscle fiber hasstretch marks, or linear marks, which can be seen when this muscle is placed under a microscope. The streaks correspond tosarcomerespresent in striated muscles, which are highly organized bundles of muscle cells that can rapidly contract together.
Skeletal muscle is controlled through 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.
Cardiac muscle, although similar to skeletal muscle in some ways, is connected to theautonomic nervous system. This system controls vital organs like the heart and lungs and allows us to not have to concentrate on pumping the heart every time it needs to beat. While there is a certain amount of conscious control we have over the autonomic nervous system, it always kicks in when 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 chambers of the heart and is used to pump blood around the body.
Cardiac muscle is similar to skeletal muscle in that it is striated. Unlike skeletal muscle, cardiac muscle fibers are arranged in a branching pattern rather than a linear pattern. Both skeletal muscle and cardiac muscle need to contract quickly and frequently, which is why stretch marks can be seen.
Unlike skeletal and cardiac muscle, smooth muscle is not striated. This is because individual muscle cells are not perfectly aligned in the sarcomeres. Instead, they are moved along the fibers. This gives smooth muscle the ability to contract for a longer time, although the contraction occurs more slowly. Consider the muscle that contracts the sphincter in your bladder. This muscle may need to be locked in for hours on end and it only gets a minute of relief when you go to the bathroom. Many other smooth muscles operate 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 that all the hairs stand on end when it's cold. Smooth muscle is found almost everywhere in the body and helps with everything from circulation to digestion.
1. A big, strong bear goes into a cave to hibernate for the winter. In the spring, a thin and weak bear appears. What happened to the bear's muscles?
A.They stayed the same size, they were just hidden under the fat
B.The bear used them as energy during hibernation.
C.The bear's fur is thinner, making it look weaker.
Answer to question #1
Bis correct. Muscles that aren't being used are wasted energy. The bear will use the proteins and nutrients available in its muscles and fat cells to survive the winter. Some muscles, such as the diaphragm used to control breathing, will not lose weight. Other muscles, such as leg muscles, are not needed during hibernation and may atrophy or shrink in size.
2. Muscle growth is known as hypertrophy. Bodybuilders do this when they work out to increase the size of their muscles. Often days after a good workout, the muscle that was worked will hurt a little. What causes it?
A.lactic acid buildup
B.Not enough protein!
C.Microscopic tears in muscle fibers
Answer to question #2
Cis correct. When you really push your muscles to their limits, they start to break down. If you try to lift too much weight, you'll tear your muscles in half. When doing repetitive sets of heavy weight, a muscle will get small breaks in several muscle fibers. When these tears heal, more muscle cells are used and overall muscle mass and size increase. XX
3. Endurance runners are told to eat pasta the night before a big race. Why is this useful?
A.Dough doesn't spread out 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
Answer to question #3
Cis correct. Carbohydrates found in pasta can be easily broken down into glucose, which muscle cells convert to ATP for energy storage. This ATP is then used to activate the myosin heads and help them walk along the actin filament. In fact, any balanced meal will load your cells with glucose and prepare you for exercise.
- Lodish , H. , Berk , A. , Kaiser , C. A. , Krieger , M. , Scott , M. P. , Bretscher , A. , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Matsudaira , P. ( 2008 ).Cell Molecular Biology 6th. ed.New York: W. H. Freeman and Company.
- Nelson, D.L., & Cox, M.M. (2008).Principles of Biochemistry. New York: W. H. Freeman and Company.
Each type of muscle tissue in the human body has a unique structure and a specific role. Skeletal muscle moves bones and other structures. Cardiac muscle contracts the heart to pump blood. The smooth muscle tissue that forms organs like the stomach and bladder changes shape to facilitate bodily functions.What is muscle anatomy dictionary? ›
A muscle is a group of muscle tissues which contract together to produce a force. A muscle consists of fibers of muscle cells surrounded by protective tissue, bundled together many more fibers, all surrounded in a thick protective tissue.What are the 4 main functions of muscles in the body list and describe? ›
One of the most predominant characteristics of skeletal muscle tissue is its contractility and nearly all movement in the body is the result of muscle contraction. Four functions of muscle contraction are movement, posture, joint stability, and heat production.What are the 3 types of muscles and define its function? ›
There are three types of muscles: skeletal, cardiac, and smooth. Skeletal muscles help us move and are voluntary. Cardiac muscles make our heart beat and are involuntary. Smooth muscles are in hollow organs and blood vessels, working automatically.What is muscle function and definition? ›
Muscles have a range of functions from pumping blood and supporting movement to lifting heavy weights or giving birth. Muscles work by either contracting or relaxing to cause movement. This movement may be voluntary (meaning the movement is made consciously) or done without our conscious awareness (involuntary).What are the 4 main types of muscles? ›
- Skeletal Muscle. Skeletal muscle, attached to bones, is responsible for skeletal movements. ...
- Smooth Muscle. Smooth muscle, found in the walls of the hollow internal organs such as blood vessels, the gastrointestinal tract, bladder, and uterus, is under control of the autonomic nervous system. ...
- Cardiac Muscle.
Muscles allow a person to move, speak, and chew. They control heartbeat, breathing, and digestion. Other seemingly unrelated functions, including temperature regulation and vision, also rely on the muscular system.What are the 4 structures of the muscular system? ›
Your musculoskeletal system includes bones, muscles, tendons, ligaments and soft tissues.What are the four functional and four structural characteristics of muscle tissue? ›
Excitability: an ability to respond to stimuli. Contractibility: an ability to contract. Extensibility: an ability to be stretched without tearing. Elasticity: an ability to return to its normal shape.What are the 3 structures of muscles? ›
The 3 types of muscle tissue are cardiac, smooth, and skeletal.
Each muscle is made up of groups of muscle fibers called fascicles surrounded by a connective tissue layer called perimysium. Multiple units of individual muscle fibers within each fascicle are surrounded by endomysium, a connective tissue sheath.What is a muscle simple definition? ›
: a body tissue consisting of long cells that can contract and produce motion. : an organ that is a mass of muscle tissue attached at either end to a fixed point (as to bones) and that by contracting moves or stops the movement of a body part.What is muscle terminology? ›
Naming of Muscles
size – maximus (largest), minimus (smallest) shape – deltoid (triangular), trapezius (trapezoid) action – flexor (to flex), adductor (towards midline of the body)
There are a number of terms used in the naming of muscles including those relating to size, shape, action, location, their orientation, and their number of heads. brevis means short; longus means long; major means large; maximus means largest; minor means small, and minimus smallest.What are the 5 major muscle groups? ›
- Shoulder and back muscles. Slouching over our screens and sitting too much makes it crucial to work your shoulder and back muscles. ...
- Chest and arm muscles. ...
- Abdominal muscles. ...
- Leg muscles. ...
- Calves muscles.
- Skeletal: As part of the musculoskeletal system, these muscles work with your bones, tendons and ligaments. ...
- Cardiac: These muscles line the heart walls. ...
- Smooth: These muscles line the insides of organs such as the bladder, stomach and intestines.
Muscles allow a person to move, speak, and chew. They control heartbeat, breathing, and digestion. Other seemingly unrelated functions, including temperature regulation and vision, also rely on the muscular system.What are the 6 main functions of the musculoskeletal system? ›
The human skeleton serves six major functions: support, movement, protection, production of blood cells, storage of ions, and endocrine regulation.What are the 4 types of tissue structure and function? ›
Overview. There are 4 basic types of tissue: connective tissue, epithelial tissue, muscle tissue, and nervous tissue. Connective tissue supports other tissues and binds them together (bone, blood, and lymph tissues). Epithelial tissue provides a covering (skin, the linings of the various passages inside the body).What are the functions of the 4 different types of tissue? ›
Epithelial tissues act as coverings controlling the movement of materials across the surface. Connective tissue integrates the various parts of the body and provides support and protection to organs. Muscle tissue allows the body to move. Nervous tissues propagate information.
Skeletal muscle fibers are cylindrical, multinucleated, striated, and under voluntary control.What is the structure and function of muscle protein? ›
The proteins that comprise the myofibril, including actin and myosin and several more. The myofibrillar protein components most important for muscle fiber structure are actin and myosin. They are the most abundant proteins in muscle and are directly involved in the ability of muscle to contract and to relax.What are the 8 major muscles of the body? ›
Again, the eight major muscle groups that are most commonly worked on in a group fitness setting includes the shoulders, arms, chest, abdomen, back, butt, thighs, and calves.What is the major function of muscle? ›
The 5 main functions of the muscular system are movement, support, protection, heat generation, and blood circulation.How many muscle types are there? ›
There are three major muscle types found in the human body: skeletal, cardiac, and smooth muscle.What are the structures of the muscles? ›
An individual skeletal muscle may be made up of hundreds, or even thousands, of muscle fibers bundled together and wrapped in a connective tissue covering. Each muscle is surrounded by a connective tissue sheath called the epimysium. Fascia, connective tissue outside the epimysium, surrounds and separates the muscles.What is the structure and function of the smooth muscle? ›
Structure and Function
Smooth muscle differs from skeletal muscle in function. Unlike skeletal muscle, smooth muscle is capable of maintaining tone for extended periods and often contracts involuntarily. At a cellular level, smooth muscle can be described as an involuntary, non-striated muscle.
Your musculoskeletal system includes bones, muscles, tendons, ligaments and soft tissues.What is protein structure and types? ›
Protein structures are made by condensation of amino acids forming peptide bonds. The sequence of amino acids in a protein is called its primary structure. The secondary structure is determined by the dihedral angles of the peptide bonds, the tertiary structure by the folding of protein chains in space.What are protein structures and definitions? ›
A protein's primary structure is defined as the amino acid sequence of its polypeptide chain; secondary structure is the local spatial arrangement of a polypeptide's backbone (main chain) atoms; tertiary structure refers to the three-dimensional structure of an entire polypeptide chain; and quaternary structure is the ...
These include antibodies, contractile proteins, enzymes, hormonal proteins, structural proteins, storage proteins, and transport proteins. Antibodies: Antibodies are specialized proteins that defend the body against antigens or foreign invaders.What is the structure of skeletal and smooth muscle? ›
Muscle tissues differ in structure. Skeletal muscle fibres are packed into regular parallel bundles. Smooth muscle has bundles of thin and thick filaments. Cardiac muscle bundles are branched but connected.What is the function of the skeletal muscle? ›
The main functions of skeletal muscle are to contract to produce movement, sustain body posture and position, maintain body temperature, store nutrients, and stabilize joints.What is the function of the muscle cells? ›
Tissues, organs and systems
Muscle cells are specialized to contract, i.e. create a pulling force to stabilize or move parts of the body. There are three types of muscle cell: skeletal, visceral and cardiac.