Notes in 2- S, S, C - Muscle

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Published	02/10/2024	{{c1::Skeletal}} muscle fibers are large, multinucleated cells 'fused together', striated.- attached to the bones of skeleton to enable control of mov…
Published	02/10/2024	Skeletal muscle multinucleate cells merge together to form a {{c1::muscle fibre}}.This process happens in utero from precursor cells called …
Published	02/10/2024	Skeletal muscle fibers are the largest cells in the body, created by the fusion of many individual embryonic cells in utero called {{c1::mononucleated…
Published	02/10/2024	{{c1::Satellite cells}} are commited stem cells that become active and differentiate into muscle when needed for muscle growth and repair.When injured…
Published	02/10/2024	Muscles are bundles of fibres encased in connective tissue sheaths and filled with nerves and blood vessels, they are connected to the skeletal system…
Published	02/10/2024	Skeletal muscle → Muscle fascicle → Muscle fibers → MyofibrilsMyofibrils are composed of thick and thin filaments which form a structure called {{c1::…
Published	02/10/2024	Sarcomeres are made up of thin actin filaments and thick myosin filaments.They are arranged in specific 3d structureActin filaments are arranged in a …
Published	02/10/2024	{{c1::Titin}} is a spring-like protein that spans the sarcomere from one Z disk to the neighboring M line.Functions:1- Stabilizes the position of the …
Published	02/10/2024	When the sarcomere shortens i.e. the actin and myosin slide past one another, the muscle contracts.I band is small during contractionWhen the sar…
Published	02/10/2024	According to the sliding filament theory, tension generated in a muscle fiber is {{c1::directly proportional}} to the number of high-force c…
Published	02/10/2024	Describe the structure and ultrastructure of skeletal muscle
Published	02/10/2024	{{c1::Troponin}} is a calcium-binding protein complex that controls the positioning of an elongated protein polymer called TropomyosinIn resting skele…
Published	02/10/2024	The cross-bridge cycle:[1] {{c1::ATP binds and myosin detaches}}• ATP binding decreases the actin-binding affinity of myosin[2] {{c1::ATP Hydrolysis p…
Published	02/10/2024	Describe the cross-bridge cycle in skeletal muscle
Published	02/10/2024	{{c1::Excitation-Contraction coupling}} is the process in which muscle action potentials are translated into calcium signals. The calcium signals in t…
Published	02/10/2024	The {{c1::Sarcoplasmic reticulum}} is the place where Ca2+ is stored around the myofibrils.
Published	02/10/2024	{{c1::Transverse tubules (T-tubules)}} are an extension of the cell membrane (sarcolemma) that allow rapid conduction of the action potential which co…
Published	02/10/2024	The {{c1::Relaxation Phase}} happens when:1- Sarcoplasmic Ca2+-ATPase pumps Ca2+ back into the sarcoplasmic reticulum.2- Decrease in [Ca2+] cause…
Published	02/10/2024	Describe the processes of: Neuromuscular Junction (NMJ) - Excitation-Contraction Coupling - Relaxation Phase
Published	02/10/2024	{{c1::Motor units}} are composed of motor neurons + motor fibres.There are hundreds of them in muscles, they allow graded twitches, from minimal all t…
Published	02/10/2024	{{c1::Tension}} is the force that a muscle exerts{{c1::Load}} is the force that is exerted on a muscle{{c1::Isometric contraction}} is a contraction w…
Published	02/10/2024	A {{c1::Twitch contraction}} is a single contraction and relaxation cycle produced by a single action potential within the muscle fiber.{{c2::Latent p…
Published	02/10/2024	Muscle fibers have different contraction times (10-100 ms) and the length of the contraction time depends on how quickly they release {{c1::[Ca2+]}}
Published	02/10/2024	As the load exerted on the muscle increases, contraction velocity and distance shortened {{c1::decreases}}.
Published	02/10/2024	A typical muscle action potential lasts between 1 to 2 msec, while the muscle contraction may last up to 100 msec.How does summation work in action po…
Published	02/10/2024	{{c1::Tetanus/Tetanic contraction}} is a type of contraction where action potentials continue to stimulate the muscle fiber repeatedly at short interv…
Published	02/10/2024	Why is tetanic tension greater than twitch tension?
Published	02/10/2024	Length-Tension Relationship:{{c1::Less overlap}} of filaments = can't bind so less tension{{c1::Too much overlap}} of filaments = interfere with each …
Published	02/10/2024	Movement around a limb requires 2 antagonistic groups of muscles called a {{c1::flexor}} and an {{c1::extensor}}.These muscles are arranged in lever s…
Published	02/10/2024	How is ATP used in skeletal muscles?
Published	02/10/2024	The rate of muscle fatigue depends on:1- {{c1::Fibre type}}2- {{c1::Length of contraction}}3- {{c1::Fitness of individual}}
Published	02/10/2024	{{c1::Muscle Fatigue}} is a safety mechanism that prevents muscle from using up vast amounts of ATP, which would cause rigor (i.e. muscles would not b…
Published	02/10/2024	What are the factors causing fatigue?• During high intensity, short-term exercise e.g. sprinting:1- Conduction failure due to {{c1::accumulation …
Published	02/10/2024	What are the factors causing fatigue during high intensity, short-term exercise e.g. sprinting?
Published	02/10/2024	What are the factors causing fatigue during low intensity, long-term exercise e.g. marathon running?
Published	02/10/2024	{{c1::Central command fatigue}} is a type of psychological fatigue where the cerebral cortex cannot excite motor neurons anymore because of loss of 'w…
Published	02/10/2024	Classification of Skeletal Muscle Fibre was based on:1- Whether fibres are fast or slow-shortening2- Oxidative (aerobic) or Glycolytic (anaerobic…
Published	02/10/2024	Oxidative fibers are a type of muscle fiber with:1- ↑ mitochondria → ↑ oxidative phosphorylation2- ↑ vascularisation to deliver more O2 and nutri…
Published	02/10/2024	Glycolytic fibers are a type of muscle fiber with:1- Few mitochondria2- ↑ glycolytic enzymes (for glycolysis) and glycogen3- Lower blood supply (…
Published	02/10/2024	Oxidative fibers vs Glycolytic fibersWhat are the differences?
Published	02/10/2024	There are three types of muscle fibers according to fatigue resistance: [1] {{c1::Slow oxidative (I)}} → resist fatigue (reliant on oxy…
Published	02/10/2024	{{c1::Recruitment}} is the process of increasing the number of active motor units.The more load you carry, the more motor units are needed to be activ…
Published	02/10/2024	Neural control of muscle tension depends on:1- {{c1::Frequency}} of action potentials sent to motor units2- {{c1::Recruitment}} of motor units (how ma…
Published	02/10/2024	{{c1::Denervation atrophy}} is when the nerves/NMJs supplying a muscle fiber are destroyed, which causes a gradual deterioration of the muscle.Because…
Published	02/10/2024	Exercise type adapts and determines the type of muscle fibers that you have e.g.{{c1::Aerobic}} exercise e.g. marathon running, leads to more slow/fas…
Published	02/10/2024	Compare (Similarities/Differences) between smooth and skeletal muscle fibres
Published	02/10/2024	Smooth muscle X-bridge cycle:[1] ↑ [Ca2+][2] Ca2+ binds to calmodulin forming a Ca2+-Calmodulin complex[3] Ca2+-Calmodulin activat…
Published	02/10/2024	Explain the process of X-bridge contraction cycle and Relaxation in smooth muscle cells
Published	02/10/2024	In skeletal muscles, Ca2+ binds to {{c1::Troponin}} to initiate contraction.In smooth muscles, Ca2+ binds to {{c1::Calmodulin}} to initiate …
Published	02/10/2024	In smooth muscle, {{c1::phosphorylation}} and {{c1::dephosphorylation}} of the myosin light chain controls contraction and relaxation.This process is …
Published	02/10/2024	Why do some types of smooth muscle, e.g. blood vessels, have a persistent stimulation and ↑ [Ca2+] all the time?
Published	02/10/2024	How do some types of smooth muscle maintain tension for a long time using low ATP consumption? e.g. blood vessels
Published	02/10/2024	In Smooth muscles, Ca2+ comes from the {{c1::sarcoplasmic reticulum}} and the {{c1::ECF}}• Contains less Ca2+ than Skeletal muscle, it …
Published	02/10/2024	{{c1::Latch state}} is a significant factor in the ability of smooth muscle to sustain contraction without fatiguing.When dephosphorylated myosin rema…
Published	02/10/2024	Skeletal muscle, - Faster than smooth muscles- One AP releases enough Ca2+ to saturate all troponin sites.- Can have a base-line tone but qu…
Published	02/10/2024	What are the factors affecting contractile activity in smooth muscles?1– Spontaneous electrical activity in muscle membranes = pacemaker activity, e.g…
Published	02/10/2024	Types of Smooth muscle:[1] {{c1::Single units}} (GIT, uterus, small blood vessels)– Many cells linked by gap junctions (Signals travel between ce…
Published	02/10/2024	What are the factors affecting contractile activity in smooth muscles?
Published	02/10/2024	What's the importance of Nitric Oxide in the cardiovascular system?
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