Dominic Stone
Muscles are pieces of soft tissue that allow animals to move their bodies and perform functions necessary to stay alive. Humans have over 600 muscles that help them do everything from breathing and eating to running marathons. There are three types of muscles in the human body: skeletal, smooth, and cardiac. Skeletal muscles are the most common type of muscle in the body, making up between 30% and 40% of total body mass. They are attached to bones and controlled consciously, allowing humans to perform voluntary movements. Smooth and cardiac muscles are involuntary muscles that contract without conscious intervention. Smooth muscles are found in the walls of organs and blood vessels, while cardiac muscles make up the heart and are responsible for pumping blood throughout the body.
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What You'll Learn
Skeletal muscle
The human body has over 600 muscles, which help us do everything from moving our bodies to breathing and keeping us alive. Skeletal muscle is the most common type of muscle in the body, accounting for between 30% and 40% of total body mass. Skeletal muscles are voluntary muscles, meaning we control how and when they move. They are attached to bones and allow us to perform a wide range of movements and functions. For example, if you reach for a book on a shelf, you are using skeletal muscles in your neck, arm, and shoulder.
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Cardiac muscle
Muscle is a soft tissue that makes up a large part of the human body. There are over 600 muscles in the human body, and they help us do everything from moving our bodies to breathing and staying alive. There are three types of muscle tissue: skeletal, smooth, and cardiac.
The cardiac muscle is responsible for the contractility of the heart and, therefore, the pumping action. The primary function of cardiac muscle is to pump blood into circulation by generating sufficient force. The contractile functions of the heart require ATP, which can be obtained through various substrates, including fatty acids, carbohydrates, proteins, and ketones. The cardiac muscle must contract with enough force and blood to supply the metabolic demands of the entire body.
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Smooth muscle
The human body has more than 600 muscles, which help us do everything from moving our bodies to breathing and staying alive. There are three types of muscle in the body: skeletal, cardiac, and smooth muscle.
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Voluntary vs involuntary muscle
The human body has over 600 muscles, which can be categorised into two main types: voluntary and involuntary. Voluntary muscles are under conscious control, allowing us to move and perform actions. Involuntary muscles, on the other hand, work without conscious effort and control essential functions like digestion, heartbeat, and breathing.
Voluntary muscles, also known as skeletal muscles, are attached to bones and respond to nerve signals from the brain that lead to muscle contraction. They make up between 30% and 40% of the average human body weight. Skeletal muscles are typically striated, meaning they have a striped appearance under a microscope. They are involved in the movement of body parts and locomotion of the body. However, they also tire quickly and require regular intervals of rest. Examples of voluntary muscles include the biceps, triceps, quadriceps, diaphragm, pectoral muscles, abdominals, and hamstrings.
Involuntary muscles, on the other hand, are controlled by the autonomic nervous system and are often associated with organs that exhibit slow and regular contractions and relaxation. They are also known as smooth muscles because they lack the striated structure of skeletal muscles. Instead, they consist of sheets or layers of smooth muscle cells. Involuntary muscles have amazing endurance and can work tirelessly without tiring. They are involved in the movements of internal organs and aid in the passage of fluids and food in the digestive system. Examples of involuntary muscles include the cardiac muscle of the heart and smooth muscle lining the intestinal tracts, blood vessels, urogenital tracts, and respiratory tract.
The cardiac muscle is composed of individual heart muscle cells called cardiomyocytes, which are joined together by intercalated discs. These muscle cells are encased by collagen fibres and other substances that form the extracellular matrix. The contraction of cardiac muscle differs from that of skeletal and smooth muscles, as it is stimulated by electrical signals generated within the muscles. This electrical stimulation causes the release of calcium ions, which in turn causes the myofilaments to slide past each other, resulting in muscle contraction.
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Muscle fibres
The human body has over 600 muscles, which are made up of thousands of small fibres woven together. These fibres can stretch and press together, enabling movement of the body and internal organs. There are three types of muscle tissue: skeletal, cardiac, and smooth muscle.
Skeletal muscle is the most common type of muscle in the body, accounting for between 30% and 40% of total body mass. Skeletal muscles are attached to bones by tendons and are under conscious control. They are used for voluntary movements such as walking, bending, and picking up objects. Skeletal muscle fibres are classified into two types: type 1 and type 2. Type 1 fibres use oxygen to generate energy for movement and have a higher density of mitochondria, giving them a darker appearance. Type 2 fibres are further divided into subtypes 2A and 2B. Type 2A fibres can use oxygen to generate energy but contain fewer mitochondria, making them lighter in appearance. Type 2B fibres do not use oxygen and instead store energy for short bursts of movement; they appear white. Skeletal muscle fibres are also known as muscle fibres and are much longer than other types of muscle tissue fibres. They are formed from the fusion of developmental myoblasts in a process called myogenesis, resulting in long multinucleated cells. Skeletal muscle fibres can be fast-twitch or slow-twitch, with the former being more common in people who excel at sprint events and the latter more common in endurance athletes.
Cardiac muscle makes up the middle layers of the heart and is responsible for pumping blood throughout the body. Cardiac muscle tissue is branched and interconnected, with special pacemaker cells generating impulses that cause the muscle to contract. Cardiac muscle is striated, with a banded appearance due to the arrangement of protein fibres inside the cells. These fibres are strong, allowing them to resist high blood pressures and the strain of pumping blood over a lifetime.
Smooth muscle, also known as visceral muscle, is found in organs and moves substances through them. It is controlled by the unconscious part of the brain and is, therefore, an involuntary muscle. Smooth muscle has a smooth, uniform appearance under a microscope, in contrast to the banded appearance of skeletal and cardiac muscles.
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Frequently asked questions
Muscles are pieces of soft tissue throughout your body. They help you do everything from holding your body still to running a marathon. There are more than 600 muscles in the human body.
There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Skeletal muscle is the most common type of muscle in the body and is the only voluntary muscle tissue. Cardiac and smooth muscles are involuntary.
Muscles are responsible for movement, posture, joint stability, and heat production. Nearly all movement in the body is the result of muscle contraction.
Muscles are made of thousands of small fibres woven together. These fibres stretch and press together to move the organs or body parts that they are attached to.
