Define term: Energy
Capacity to do work
Define Term: Potential Energy
Energy stored by matter due to its position
Define Term: Kinetic Energy
energy associated with matter in motion
Define Term: Chemical Energy
a form of potential energy stored in the bonds of compounds and molecules
Define Term: Exergonic Reaction
chemical reactions that release more energy than they absorb
Define Term: Endergonic Reaction
chemical reactions that absorb more energy than they release
Define Term: Cellular Respiration
the process by which glucose provides the energy to make ATP. Cellular repiration as two phases: anaerobic and aerobic. In the anaerobic phase, glucose is partially broken down into pyruvie aold by a series of reactions that do not require energy. In the aerobic phase, glucose is completely broken down to CO2 and H2O. Oxygen is required for this process.
Understand how different joints mimic different types of levers [NEED TO INCLUDE DIFFERENT LEVEL SLIDES]
Bnes at as levers, a ridgid structure that can move around a fixed point (the fulcrum). The joint functions as the fulcrum of the lever. Two forces come into play: 1) Effort which cases movement and 2) Load or resistance which opposes movement.
Understand how the muscle uses ATP to produce energy necessary for muscle contraction.
Muscle stores energy in ATP in mitochondria (in 3rd phosphate bond). Myosin head (myosin = thick filament) has an ATP-binding site and an ATPase (enzyme that converts ATP to ADP). Energy provided results in change of position of head (breaks the crossbridges) ATP is thus required for both formation of crossbridges and detachment of crossbridges.
Understand how energy obtained from glucose is stored in the covalent bonds of ATP ready for future use.
The process by which glucose provides the energy to make ATP is called cellular respiration. Cellular respiration has two phases: anaerobic and aerobic. In the Anaerobic phase, glucose is partially broken down into pyruvic acid by a series of reactions that do not require energy. In the aerobic phase, glucose is completely broken down to CO2 and H2O. Oxygen is required for this process.
How the distinguising histological features and functions of the three muscle types: Skeletal
-Long striated fibers -Peripheral Nuclei -Voluntary Control -Usually attached to bones via tendons -Important in motion, posture, heat production, and protection
How the distinguising histological features and functions of the three muscle types: Cardiac
-Branched, striated fibers -Involuntary Control -Centrally located nuclei -Pound in heart wall -Pumps blood to all parts of the body
How the distinguising histological features and functions of the three muscle types: Smooth
-Spindle-shaped, non-striated with centrally located nuclei -Involuntary Control -Walls of internal organs such as blood vessels, GI tract, airways to lungs. Gall bladder, urinary bladder, uterus. -Motion, e.g. contriction of blood vessels, movement of food through GI, contraction of bladder, uterus
Understand how muscle achieves each of the following functions: Producing body movement
relies on integrated functioning of bones, joints, muscles and nervous system. Muscle contractions on bones create movement.
Understand how muscle achieves each of the following functions: Stabilizing body positions
Skeletal muscles stabilize joints and help maintain body positions. Postural muscles contract continually when you are awake.
Understand how muscle achieves each of the following functions: Storing and moving substances within body
-Smooth muscle allows for continual contraction of ringlike bands of muscle (sphincters), e.g. storage of food in stomach - Contraction and relaxation of smooth muslce walls of blood vessels allows for storage of blood.
Understand how muscle achieves each of the following functions: Generating heat
As muscle contracts it generates heat in a process known as thermogenesis -- this heat is used to maintain normal body temperature. Involuntary contractions of skeletal muscle (shivering) can generate more heat.
What are the properties of musle tissue?
Excitability, contractibility, extensibility, elasticity
Define Term: Fascia
means a broad band of connective tissue that surrounds muscle or other organs
Define Term: Epimysium
Three distinct layers of connective tissue surround and protect skeletal muscle. The epimysium is the layer that encircles the entire muscle.
Define Term: Perimysium
Three distinct layers of connective tissue surround and protect skeletal muscle. The perimysium sorrounds groups of 10-100 or more muscle fibers. This separates them into bundles called fascicles.
Define Term: Endomysium
Three distinct layers of connective tissue surround and protect skeletal muscle. The Endomysium separates individual muscle fibers within fascicles.
Define Term: Fascicle
Bundles of approx 10-100 or more muscle fibers within a muscle, surrounded by the Perimysium. Some Fasicles large enough to be seen with the naked eye.
Define Term: Tendon
Epimysium, perimysium, and endomysium are continuous with the connective tissue that connects muscles to other organs. When they extend in long parallel bundles to attach a muscle to a bone, they are called a tendon.
Define Term: Aponeurosis
A tendon that extends in a broad flat layer. E.g. how the occipitofrontalis muscles attach to the skull.
Define Term: Muscle fiber
Muscle cells are called muscle fibers. Mutlinucleat and formed from many myoblasts.
Define Term: Myoblast
Embryonic cells called myoblasts fuse to form muscle fibers.
Define Term: Satellite cell
some myoblast-derived cells called satelite cells remain in the adult, and can accomplish some muscle regeneration, though the number of muscle fibers in set before you are born.
Define Term: Sacolemma
the plasma membrane of the muscle fiber
Define Term: Transverse tubule
tiny structures of the sarcolemma (plasma membrane in muscle), which tunnel in from the surface toward the center of the cell
Define Term: Triad
a group consisting on a T-Tubule and the terminal cisternae of the two adjastent sarcoplasmic reticulums
Define Term: Sarcoplasm
the cytoplasm of muscle cells
Define Term: Myoglobin
An oxygen-binding protein found only in the sarcoplasm of skeletal muscle
Define Term: Myofibril
-Small structures that run through the sarcoplasm of muscle fibers. -Specialized contractile organelles of muscle fibers
Define Term: Sarcoplasmic reticulum
the endoplasmic reticulum of muscle fibers. abundant and encircles each myofibril
How are mutlinucleated muscle fibers formed?
fusion of myoblasts
Know the organization and components of thin and thick filaments.
Thick filaments are composed on Myosin. Thin filaments are mainly composed of Actin, but also contain two regulatory proteins -- tropomyosin and troponin. Individual actin molcules form a twisted helical filament.
Know the organization of a sarcomere
One sacromere goes from Z disc to Z disc, with the M line at the center. Thin filaments are on both sides of the thick filaments. The I band is the zone of thin filament before the thick filament. the H zone is the zone of thick filament and no thin filament (both H zone and I band shrink during contraction). A band is length of thick filament (length of thin and thick filaments remain the same during contraction.
Know the structure of actin and myosin
Mysoin is composed of a head and tail component Myosin molecules look like two golf clubs with the long ends twisted together. Individual actin molcules form a twisted helical filament, with myosin binding heads of actin attached to tropomyosin. Actin molecules look like little balls.
Know the function of myosin
-Myosin is a "motor protein" - a protein capable of pushing or pulling cellular structures. -Movement requires ATP, and chemical energy is converted to mechanical energy.
Know the function of actin
Each actin molecule has a mysoin binding site which binds to the myosin head to create crossbriges. Myosin binding sites are covoered by tropomyosin until calcium binds to troponin to pull the tropomyosin away.
Know the function of titin
A large protein that anchors thick filaments to the Z discs and M line, stabilizing the location of the thick filament
Know the function of nebulin
A large protein that anchors actin filaments to the Z discs
Know the function of dystrophin
A cytoskeletal protein that anchors thin filamnets to membrane proteins of the sarcolemma
Know the steps in the the sliding filament mechanism of muscle contraction
Lengths of thin and thick filaments are the same in both contraction and relaxation. Muscle shortens during contraction because thick and thin filaments slide over each other. Contraction analogouos to running on a treadmill - crossbridge is foot striking the treadmill, moving the actin (belt) backward toward the M line.
Understand the roles of ATP, calcium, and the troponin/tropomyosin complex
Calcium ions released into the sacroplasm from the sarcoplasmic reticulum bind with troponin which moves the troponin-tropomyosin complex away from the myosin-binding site on the actin. Mysoin requires energy from ATP in order to break crossbridges. Myosin head has an ATP-binding site and an ATPase. Required fro formation and detachment of crossbridges.
Understand the meaning of the term: crossbridge"and "excitation contraction coupling"
Crossbridge: when mysoin heads bind to actin
What is rigor mortis?
When muscles contract after death.
Describe what happens in rigor mortis
-After death, cellular membranes become leacky. -Calcium ions leak out of sacroplasmic reticulum -Mysosin binding sites are exposed on actin and crossbridges form. -However, no more ATP is being made to break the crossbridges, so muscles go into a state of contraction until lysosomal enzymes break down the crossbridges.
What are the nerves that stimulate skeletal muscle at the neuromuscular junction called?
somatic motor neurons
Where are the cell bodies of neurons located?
in the brain and spinal cord
Define Term: Synapse
region where communication occurs between two neurons or between a neuron and a target cell.
Define Term: Synaptic Cleft
gap between the two cells at a synapse (between the synaptic end bulb and the motor end plate)
Define Term: Synaptic end bulb
the part of the motor nuron axon that terminates on the muscle
Define Term: Synaptic Vesicle
The synaptic end bulb contains hundreds of membrane bound secretory vesicles, containing the neurotransmitter acetylcholine (ACh)
Define Term: Neurotransmitter
A neurotransmitter is a chemical messenger that carries, boosts and modulates signals between neurons and other cells in the body. In most cases, a neurotransmitter is released from the axon terminal after an action potential has reached the synapse.
Define Term: Motor End plate
the region of the sarcolemma opposite the synaptic end bulb.
Define Term: Acetylcholine Receptor
receptors on the sarcolemma of the motor end plate. Ligand-gated ion channels. When acetylcholine binds to the receptor, a channel opens that allows sodium ions to flow into the cell down and electrochemical gradient, which triggers a muscle action potential.
Define Term: Nerve Impulse
nerve action potential. An electical signal that travels along the surface of a neuron. An action potential begins due to the movement of ions through ion channels in the plasma membrane of the neuron. At the neuromuscular junction, the nerve action potential is converted to a muscle action potential.
Define Term: Exocytosis
A process of cellular secretion or excretion in which substances contained in vesicles are discharged from the cell by fusion of the vesicular membrane with the outer cell membrane.
Define Term: Acetylcholinesterase
The enzyme that removes Acetylcholine from the synaptic space.
What is the neurotransmitter that is released at the NMJ?
What are acetylcholine receptors?
These receptors are ligand gated ion channels (acetylcholine is the ligand -- the substance that binds to active the receptor)
Once opened, what ions flow through the channel of the acetylcholine receptor?
What enables the flow of ions through the acetylcholine receptor?
acetylcholine binding to the acetylcholine receptors
What happens when the ions introduced through the acetylcholine receptor reach the intracellular surface of the sarcolemma?
Sodium enters and flows down its concentration gradient. -Na+ influx down its electrochemical gradient makes the inside membrane of the muscle fiber more positively charged -this triggers a muscle action potential -the action potential is propagated from the sarcolemma to the T-tubule system and causes the sacroplasmic reticulum to release stored calcium
What is the muscle action potential?
The muscle action potential is an electrical signal generated by the entry of sodium ions through the acetylcholine receptors
Explain how the electrical signal is transmitted rapidly to the sarcoplasmic reticulum via the T-tubules.
T-tubules form triads with the terminal cisternae of the two adjacent sacroplasmic reticulums in order to relay the electrical signal quickly
Define Term: T-tubule
Transverse tubule -- indentation of the sarcolemma. T-tubule system: T-tubules in association with the sarcoplasmic reticulum of adjacent sarcomeres.
Define Term: Triad
a T-tubule and the terminal cisternae of the sarcoplasmic reticulum of the two adjacent sarcomeres.
Define Term: Terminal Cisternae of the sacroplasmic reticulum
Terminal cisternae are enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules
Define Term: Calsequestrin
potein that binds to calcium inside the sarcoplasmic reticulum to allow for storage of high concentrations of calcium ions.
From where are the calcium ions released to initiate contraction?
Know the mechanisms of action and applications of botulinum toxin:
-Blocks exocytosis of synaptic vesicles at NMJ. -Result is that ACh is not released and muscle contraction does not occur -Used clinically as botox
What is electromyography?
test that measures muscle action potentials (muscle electrical activity) in resting and contracting muscles.
What are some uses of electromyography?
helps determine if muscle weakness is due to a malfunction in the muscle or a malfunction in the nerves supplying the muscle at NMJs. Useful in diagnosis of diseases such as muscular dystrophy.
Describe how muscle can generate ATP from creatin phosphate
When muscles relax, they create more ATP than they need while resting. Excess ATP is used to synthesize creatine phosphate. Creatine phosphate is an energy rich molecule only found in muscle fibers. When high muscle metabolism begins during exercise, the phospate group from creatine phosphate is ternsferred back to ADP to quickly generate more ATP.
Describe how muscle can generate ATP from anaerobic cellular respiration
Muscle glycogen is broken down into glucose or glucose is taken from blood. Gycolysis creates two molecules of ATP and 2 molucules of Pyruvic acid, which is then broken down into 2 molecules of lactic acid which is released into the blood [READ THIS TEXTBOOK SECTION]
Describe how muscle can generate ATP from aerobic cellular respiration
Requires oxygen to produce ATP in mitochondria. Mitochondria takes in: -fatty acids liberated from adipose cells -Pyruvic acid from glycolysis -Oxygen from hemoglobin in blood or from myoglobin in muscle fibers -Amino acids from protein breakdwon Mictochondria releases: -Heat -ATP -CO2 -H20
What is muscle fatigue?
The inability of muscle to maintian force of contraction after prolonged exercise
What are some possible reasons for muscle fatigue?
-Inadequate release of calcium from SR -Depletion of Creatine Phosphate -Insufficient Oxygen -Depletion of Nutriets -Build up of lactic acid
Define Term: Oxygen debt
during exercise, breathing rate, heart rate, and blood flow increase Continues after exercise to replace oxygen dept Oxygen dept is required to restore metabolism to resting state in 3 ways: 1) to convert lactic acid back into glycogen stores in liver 2) to resynthesize creatine phosphate and ATP in muscle fibers 3) to replace oxygen removed from myoglobin
Define Term: Motor Unit
a somatic motor neuron and the group of muscle fibers it stimulates
Define Term: Twitch contraction
the brief response of all muscles in a motor unit to a single action potential.
Define Term: Aerobic Exercise
Aerobic exercise - regular repeated exercise, e.g. jogging, cycling - increate supply of oxygen rich blood to muscle. Aerobic exercise builds endurance.
Define Term: Anaerobic Exercise
anaerobic activities, e.g. weight lifting, rely more on anaerobic production of ATP. Strength training increases the synthesis of muscle proteins.
Define Term: Concentric isotonic contraction
Isotonic contractions: tension (force of contraction) in muscle remains almost constant while the muscle changes length. Concentric isotonic contraction: tension generated great enough to overcome resistance and move an object
Define Term: Eccentric isotonic contraction
Isotonic contractions: tension (force of contraction) in muscle remains almost constant while the muscle changes length. Eccentric isotonic contractions: length of muscle increases during contraction
Define Term: Isometric contraction
the tension generated is not enough to exceed the resistance of an object object stays in place and length of muscle does not change important for maintaining posture
How is normal metabolism restored by continued oxygen consumption after exercise?
Oxygen dept is required to restore metabolism to resting state in 3 ways: 1) to convert lactic acid back into glycogen stores in liver 2) to resynthesize creatine phosphate and ATP in muscle fibers 3) to replace oxygen removed from myoglobin
Describe the appearance and function of each type of muscle fiber: Slow oxidative
darkest in appearance. more aerobic respiration (more mitochondria) Better for endurance, e.g. cross country running
Describe the appearance and function of each type of muscle fiber: fast oxidative-glycolytic
darker than fast glycolytic and lighter than slow oxidative in appearance. some anaerobic and some aerobic respiration.
Describe the appearance and function of each type of muscle fiber: Fast glycolytic
lightest in appearance. more Anaerobic resipration (fewer mitochondria) Intense activities (e.g. weight lifting) requires a greater proportion of fast glycolytic fiber
What do anabolic steroid do to muscle mass?
increate muscle size
What do anabolic steroids do to general health?
increase risk of heart disease, liver and kidney damage, and sex horomore-related problems
Define Term: Myopathy
in neuromuscular diseases, the term myopathy indicates that the problem is with the skeletal muscle.
Define Term: Neuromuscular disease
diseases that can occur as a result of problems of the somatic motor neurons. The neuromuscular junctions or the muscle fibers themselves.
Explain the symptoms and causes of Myasthenia Gravis
-An autoimmune disease. -Chronic damage to NMJ. -Antobodies are produced that bind to ACh receptors, decreasing the number of receptors available for ACh binding. -Muscles become weak and fatigue easily. -Intially treated with anti-cholinesterase drugs that inhibit acetylcholinesterase.
Explain the Symptons and causes of Muscular Dystrophy
-Refers to a group of diseases in which muscle is destroyed. -In Duchenne Muscular Dystrophy, there is a mutation in the gene that encodes for dystrophin (a protein that anchors thin filaments to the sarcolemma). -Without dystrophin, muscle fibers are easily ruptured
Understand the meaning of the term: excitation-contraction coupling
DEFINITION:The combined events that connect the action potential (excitation) to the muscle contraction. In a relaxed state, intracellular [Ca2] in the sacroplasm is low. Calcium ions are stored in high concentration in the sarcoplasmic reticulum. When an action potential is generated at a neuromuscular juntion, it moves from the sarcoplasmic reticulum along the T-tubules to the membrane of the sarcoplasmic reticulum. This causes the release of calcium ions from the sacroplasmic reticulum into the sacroplasm through calcium release channels.
Know the mechanisms of action and applications of curare.
binds to and clocks ACh receptors (a receptor antagonist) receptor ion channels do not open, so a muscle action potential is not triggered. Used surgically to relax muscles during surgery