Skeletal muscle is striated muscle Striated muscle One of two types of muscle in the body, characterized by the array of bands observed under microscope. Striated muscles can be divided into two subtypes: the cardiac muscle and the skeletal muscle. Muscle Tissue: Histology containing organized contractile structures known as sarcomeres that are made up of overlapping myofilaments Myofilaments Refers to individual proteins that together cause muscle contraction. Muscle Tissue: Histology: actin and myosin. When a nerve impulse arrives from a motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron, the signal triggers Triggers Hereditary Angioedema (C1 Esterase Inhibitor Deficiency) an action potential Action Potential Abrupt changes in the membrane potential that sweep along the cell membrane of excitable cells in response to excitation stimuli. Membrane Potential (AP) in the sarcolemma Sarcolemma The excitable plasma membrane of a muscle cell. Muscle Tissue: Histology (muscle cell membrane Cell Membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane), resulting in the release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology of Ca CA Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding. Condylomata Acuminata (Genital Warts) ions from the sarcoplasmic reticulum Sarcoplasmic Reticulum A network of tubules and sacs in the cytoplasm of skeletal muscle fibers that assist with muscle contraction and relaxation by releasing and storing calcium ions. Muscle Tissue: Histology (SR) within the muscle cell. The Ca CA Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding. Condylomata Acuminata (Genital Warts) causes a conformational change in regulator proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis (troponin and tropomyosin), exposing myosin-binding sites on the actin filaments Actin filaments Fibers composed of microfilament proteins, which are predominately actin. They are the smallest of the cytoskeletal filaments. The Cell: Cytosol and Cytoskeleton. Using ATP energy, the myosin heads pull the myosin along the actin, shortening the sarcomere Sarcomere The repeating contractile units of the myofibril, delimited by z bands along its length. Muscle Tissue: Histology and resulting in muscle contraction. The ATP can be produced via anaerobic and aerobic mechanisms, and the primary source of ATP energy in a muscle fiber determines its functional characteristics.
Last updated: 15 Feb, 2022
Transverse tubules (T-tubules) and their associations with the sarcoplasmic reticulum Sarcoplasmic Reticulum A network of tubules and sacs in the cytoplasm of skeletal muscle fibers that assist with muscle contraction and relaxation by releasing and storing calcium ions. Muscle Tissue: Histology (SR): Note how the T-tubules are channels Channels The Cell: Cell Membrane through the sarcolemma Sarcolemma The excitable plasma membrane of a muscle cell. Muscle Tissue: Histology that come in direct contact with the terminal cisternae of the SR.
Image: “Narrow T-tubules permit the conduction of electrical impulses” by Phil Schatz. License: CC BY 4.0Structure of skeletal muscle: Clusters of myofilaments Myofilaments Refers to individual proteins that together cause muscle contraction. Muscle Tissue: Histology (actin and myosin) create myofibrils Myofibrils The long cylindrical contractile organelles of striated muscle cells composed of actin filaments; myosin filaments; and other proteins organized in arrays of repeating units called sarcomeres. Muscle Tissue: Histology. There are multiple myofibrils Myofibrils The long cylindrical contractile organelles of striated muscle cells composed of actin filaments; myosin filaments; and other proteins organized in arrays of repeating units called sarcomeres. Muscle Tissue: Histology within a single muscle fiber (which is a single muscle cell). The muscle fiber is surrounded by a specialized cell membrane Cell Membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane called the sarcolemma Sarcolemma The excitable plasma membrane of a muscle cell. Muscle Tissue: Histology. Multiple muscle fibers make up a muscle fascicle Muscle fascicle Muscle Tissue: Histology, and multiple muscle fascicles make up a full skeletal muscle.
Image by Lecturio.Myofilaments Myofilaments Refers to individual proteins that together cause muscle contraction. Muscle Tissue: Histology are individual proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis that together cause muscle contraction.
Structure of actin (thin filament) and myosin (thick filament): Note the globular head on myosin. The yellow dots on the actin represent the myosin-binding sites, which are covered by tropomyosin in a resting state. Troponins contain the Ca-binding sites and, when Ca CA Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding. Condylomata Acuminata (Genital Warts) is present, induce a conformational change in the troponin–tropomyosin complex, exposing the myosin-binding sites on actin. When myosin can bind BIND Hyperbilirubinemia of the Newborn actin and ATP energy is present, muscle contraction occurs.
Image by Lecturio.The myofibrils Myofibrils The long cylindrical contractile organelles of striated muscle cells composed of actin filaments; myosin filaments; and other proteins organized in arrays of repeating units called sarcomeres. Muscle Tissue: Histology are organized in a pattern that creates different bands and zones when viewed under microscopy. These bands are created by overlapping actin and myosin strands.
Diagram depicting the microscopic structure of two adjacent sarcomeres: a
sarcomere
Sarcomere
The repeating contractile units of the myofibril, delimited by z bands along its length.
Muscle Tissue: Histology is the area between Z-lines.
A band: anisotropic band
I band: isotropic band
Skeletal muscle cell contraction requires stimulation by an action potential Action Potential Abrupt changes in the membrane potential that sweep along the cell membrane of excitable cells in response to excitation stimuli. Membrane Potential from somatic motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neurons Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the nervous system. Nervous System: Histology.
Motor
Motor
Neurons which send impulses peripherally to activate muscles or secretory cells.
Nervous System: Histology end-plate and innervation
ACh
ACh
A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.
Receptors and Neurotransmitters of the CNS:
acetylcholine
Acetylcholine
A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.
Receptors and Neurotransmitters of the CNS
Electron micrograph showing a cross section through the neuromuscular junction: “T” is the axon terminal, and “M” is the muscle fiber. The arrow shows junctional folds with basal lamina Basal Lamina Capillaries: Histology. Postsynaptic densities are visible on the tips TIPS A type of surgical portasystemic shunt to reduce portal hypertension with associated complications of esophageal varices and ascites. It is performed percutaneously through the jugular vein and involves the creation of an intrahepatic shunt between the hepatic vein and portal vein. The channel is maintained by a metallic stent. The procedure can be performed in patients who have failed sclerotherapy and is an additional option to the surgical techniques of portocaval, mesocaval, and splenorenal shunts. It takes one to three hours to perform. Cirrhosis between the folds. The scale Scale Dermatologic Examination is 0.3 µm.
Image: “Electron micrograph showing a cross-section through the neuromuscular junction” by National Institute of Mental Health. License: Public DomainDepiction of a motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology unit: A single motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron innervates multiple different muscle fibers (i.e., individual muscle cells). The group of muscle fibers innervated by the same motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron are called a motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology unit.
Image by Lecturio.Physiology of
Ca
CA
Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding.
Condylomata Acuminata (Genital Warts)2+
release
Release
Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane.
Virology from the
sarcoplasmic reticulum
Sarcoplasmic Reticulum
A network of tubules and sacs in the cytoplasm of skeletal muscle fibers that assist with muscle contraction and relaxation by releasing and storing calcium ions.
Muscle Tissue: Histology in response to an
action potential
Action Potential
Abrupt changes in the membrane potential that sweep along the cell membrane of excitable cells in response to excitation stimuli.
Membrane Potential:
A wave
A wave
Cardiac Cycle of
depolarization
Depolarization
Membrane Potential (i.e., the
action potential
Action Potential
Abrupt changes in the membrane potential that sweep along the cell membrane of excitable cells in response to excitation stimuli.
Membrane Potential) travels down the T-tubules and
triggers
Triggers
Hereditary Angioedema (C1 Esterase Inhibitor Deficiency) the voltage-dependent
dihydropyridine
Dihydropyridine
Pyridine moieties which are partially saturated by the addition of two hydrogen atoms in any position.
Class 4 Antiarrhythmic Drugs (Calcium Channel Blockers) (DHP)
receptors
Receptors
Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell.
Receptors. These
DHP receptors
DHP receptors
Malignant Hyperthermia are mechanically tethered to
ryanodine receptors
Ryanodine Receptors
Malignant Hyperthermia, which normally keep the
Ca
CA
Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding.
Condylomata Acuminata (Genital Warts)2+-release
channels
Channels
The Cell: Cell Membrane closed. When
DHP receptors
DHP receptors
Malignant Hyperthermia are stimulated by an
action potential
Action Potential
Abrupt changes in the membrane potential that sweep along the cell membrane of excitable cells in response to excitation stimuli.
Membrane Potential, they remove the
ryanodine receptors
Ryanodine Receptors
Malignant Hyperthermia from the
Ca
CA
Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding.
Condylomata Acuminata (Genital Warts)2+-release
channels
Channels
The Cell: Cell Membrane, allowing
Ca
CA
Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding.
Condylomata Acuminata (Genital Warts)2+ to spill out of the
sarcoplasmic reticulum
Sarcoplasmic Reticulum
A network of tubules and sacs in the cytoplasm of skeletal muscle fibers that assist with muscle contraction and relaxation by releasing and storing calcium ions.
Muscle Tissue: Histology and into the
sarcoplasm
Sarcoplasm
Muscle Tissue: Histology, where they can
bind
BIND
Hyperbilirubinemia of the Newborn to troponin and stimulate muscle contraction.
Dantrolene
Dantrolene
Skeletal muscle relaxant that acts by interfering with excitation-contraction coupling in the muscle fiber. It is used in spasticity and other neuromuscular abnormalities. Although the mechanism of action is probably not central, dantrolene is usually grouped with the central muscle relaxants.
Spasmolytics binds to
ryanodine receptors
Ryanodine Receptors
Malignant Hyperthermia, preventing
Ca
CA
Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding.
Condylomata Acuminata (Genital Warts)2+
release
Release
Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane.
Virology and muscle contraction.
Crossbridge cycling Crossbridge cycling Smooth Muscle Contraction is the process by which the myosin and actin move along each other, shortening the sarcomere Sarcomere The repeating contractile units of the myofibril, delimited by z bands along its length. Muscle Tissue: Histology and causing muscle contraction. This process is also known as the sliding filament theory of muscle contraction Sliding filament theory of muscle contraction Smooth Muscle Contraction.
The process of cross-bridge cycling
Image by Lecturio.Crossbridge cycling Crossbridge cycling Smooth Muscle Contraction: The myosin-binding site on actin is exposed when Ca2+ binds to troponin. Adenosine Adenosine A nucleoside that is composed of adenine and d-ribose. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Class 5 Antiarrhythmic Drugs triphosphate binds to the myosin head. Myosin ATPase hydrolyzes the ATP to ADP and phosphate Phosphate Inorganic salts of phosphoric acid. Electrolytes, and this moves the myosin head into a cocked position. With ADP and phosphate Phosphate Inorganic salts of phosphoric acid. Electrolytes still bound and the head in a cocked position, myosin is able to bind BIND Hyperbilirubinemia of the Newborn to the active sites on actin, forming a crossbridge. The ADP and phosphate Phosphate Inorganic salts of phosphoric acid. Electrolytes are released, and the stored potential energy is released, generating the power Power The probability that a test will correctly reject a false null hypothesis. Statistical Tests and Data Representation stroke: the myosin head returns to its flexed position, pulling the actin filament with it. Adenosine Adenosine A nucleoside that is composed of adenine and d-ribose. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Class 5 Antiarrhythmic Drugs triphosphate binds the myosin head, causing it to release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology from the actin and begin the cycle Cycle The type of signal that ends the inspiratory phase delivered by the ventilator Invasive Mechanical Ventilation over again. This process allows the myosin to “walk” along the actin filament, shortening the sarcomere Sarcomere The repeating contractile units of the myofibril, delimited by z bands along its length. Muscle Tissue: Histology.
Image by Lecturio.The resting length of the sarcomere Sarcomere The repeating contractile units of the myofibril, delimited by z bands along its length. Muscle Tissue: Histology has a direct influence on the force generated when the sarcomere Sarcomere The repeating contractile units of the myofibril, delimited by z bands along its length. Muscle Tissue: Histology shortens. This is called the length–tension relationship Relationship A connection, association, or involvement between 2 or more parties. Clinician–Patient Relationship.
Length–tension relationship Relationship A connection, association, or involvement between 2 or more parties. Clinician–Patient Relationship in skeletal muscle
Image by Lecturio.A single isolated twitch of a single muscle fiber cannot do meaningful work, and increasing the voltage of the stimulus does not increase the strength of a twitch. Ways to increase the strength of a muscle contraction include:
Principles of muscle stimulation: Increasing the frequency of stimulation increases the strength of the muscle contraction.
Image by Lecturio.There are multiple types of muscle contraction based on how the muscle fiber changes length during the contraction:
Adenosine Adenosine A nucleoside that is composed of adenine and d-ribose. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Class 5 Antiarrhythmic Drugs triphosphate is the primary energy source required to generate the power Power The probability that a test will correctly reject a false null hypothesis. Statistical Tests and Data Representation strokes causing muscle contraction. There are several different ways this ATP energy is generated, and there are several different types of muscle fibers based on their capacity to use different energy sources.
Adenosine Adenosine A nucleoside that is composed of adenine and d-ribose. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Class 5 Antiarrhythmic Drugs triphosphate concentration in the muscle fiber is only enough to sustain full contraction for 1 to 2 seconds. Therefore, ADP must be rephosphorylated to generate new ATP, allowing the muscle to continue contracting, which requires energy.
There are 3 primary types of skeletal muscle fibers, found in different muscles throughout the body based on their function.
Type I fibers Type I fibers Skeletal muscle fibers characterized by their expression of the type I myosin heavy chain isoforms which have low ATPase activity and effect several other functional properties – shortening velocity, power output, rate of tension redevelopment. Muscle Tissue: Histology: slow-twitch muscle fibers Slow-twitch muscle fibers Skeletal muscle fibers characterized by their expression of the type I myosin heavy chain isoforms which have low ATPase activity and effect several other functional properties – shortening velocity, power output, rate of tension redevelopment. Energy Homeostasis
Type II fibers Type II fibers Skeletal muscle fibers characterized by their expression of the type II myosin heavy chain isoforms which have high ATPase activity and effect several other functional properties – shortening velocity, power output, rate of tension redevelopment. Several fast types have been identified. Muscle Tissue: Histology: fast-twitch muscle fibers Fast-twitch muscle fibers Skeletal muscle fibers characterized by their expression of the type II myosin heavy chain isoforms which have high ATPase activity and effect several other functional properties – shortening velocity, power output, rate of tension redevelopment. Several fast types have been identified. Energy Homeostasis
SO/Type I | FOG/Type IIA | FOG/Type IIB | |
---|---|---|---|
Synonyms | Red | Red | White |
Myosin ATPase activity | Slow | Fast | Fast |
Fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing capacity | High | Moderate | Low |
Oxidative capacity | High | Moderate | Low |
Glycolytic capacity | Low | Moderate | High |
Myoglobin Myoglobin A conjugated protein which is the oxygen-transporting pigment of muscle. It is made up of one globin polypeptide chain and one heme group. Rhabdomyolysis content | High | Moderate | Low |
Mitochondrial volume | High | Moderate | Low |
Capillary density | High | Moderate | Low |