Chapter 11 Flashcards
Responsiveness (excitability)
When stimulated by chemical signals, stretch, and other stimuli, muscle cells respond to electrical changes across plasma membrane.
Conductivity
local electrical changes triggers a wave of excitation that travels along muscle fibers
Contractility
Shortens when stimulated
extensiblity
able to stretch
elasticity
comes back to original position after being stretched
The sarcoplasm is filled with microfiber bundles of protein microfilaments called
myofilaments.
The sarcoplasm tunnel like structures that penetrate the cell.
transverse tubules
Transverse tubules penetrate the cell and
carry electric current to the inner cell
Sarcoplasm contains (3)
myofibrils, glycogen, and myoglobin
the sarcoplasm is NOT a modified endoplasmic reticulum
False
Glycogen is used for
storing energy
myoglobin is used for
binding oxygen
A series of dialated calcium storage called the terminal cisternae is called
Sarcoplasmic Reticulum
To make a muscle contract more strongly, the nervous system can activate more motor units. This process is called
Recruitment
The functional unit of a muscle fiber is the
sarcomere
before a muscle fiber can contract the ATP must band to the
myosin head
Before a muscle fiber can contract, Ca2+ must bind to
tropomyosin
Which muscle protein is not intracellular
collagen
Smooth Muscle cell have___whereas skeletal muscle fibers do not.
calmodulin
ACh receptors are found mainly in
junction folds
A person with high VO2 max
experiences less muscle fatigue during exercise than someone with a low VO2
Slow oxidative fibers contains myoglobin, high fatigue resistance, and a high capacity to synthesis APT areobically but does not contain
an abundance of glycogen
The minimum stimulus intensity that will make a muscle contract is called
the treshold
A state of prolonged maximum contraction is called
complete tetnus
Parts of the sarcoplasmic reticulum called ____lie on each side of the T Tubule.
terminal cisternae
Thick myofilaments consist mainly of the protein
acetlycholine
Muscle contains an oxygen binding pigment called
myoglobin
The _____ of skeletal muscle plays a role as dense bodies in smooth muscles,
Z discs
The Autonomic nerve fibers that stimulate single unit smooth muscle in the neurotransmitter is contained in swellings called
varicosities
A state of continual partial muscle contraction is called
muscle tone
_____is an end product of anaerobic fermentation that causes muscle fatigue
Lactic Acid
Each motor unit supplies just one muscle fiber
f A motor neuron may supply 1000 or more muscle fibers; a motor unit consist of one motor neurons and all of the muscle fibers it innervates.
To initiate muscle contraction , calcium ions must bind to the myosin heads.
f Calcium binds to troponin, not to myosin
Slow oxidative fibers are relatively resistant to fatigue.
t
Thin filaments are found in both the A bands and the I bands of striated muscle.
t
Thin filaments do not change length when muscles a contract.
t
Smooth muscle lacks striations because it does not have thick or thin myofilaments.
f Thick and thin filaments are present but are not arranged in a way that produces striations
A muscle must contract to the point of complete tetnus if it is to move an object.
F Under natural conditions, a muscle seldom or never attains complete tetnus.
If no ATP were available to a muscle fiber, the excitation state of muscle action would not occur.
t
For the first 30 minutes of exercise, the body gets most of it’s energy for lactic acid.
f A muscle produces most of it’s ATP during this period of anaerobic fermentation, which generates lactic acid but does not consume it.
Cardiac Muscle and some smooth muscle are autorhythmic, but skeletal muscle is not.
t
5 physiological properties of all muscular tissue.
Responsiveness, conductivity, contractility, extensibility, elasticity
In relaxation, Active transports pumps calcium back to the SR where it binds to
Calsequestron
Thick filaments are made up of what protein?
Myocin
Thin filament are made up of what protein?
Actin
Tropomyosin & troponin are regulatory proteins that..
Act like a switch that starts and stops shortening.
At threshold or higher, a single stimulus thus causes a quick cycle of contraction and relaxation called a
twitch
The timing and strength of a muscle’s contraction can be shown in a chart called a
myogram
What is the function of the troponin & Tropomyosin complex?
Find binding sites for myocin.
Calmodulin activates
Myocin light chain kinases
Ability to contract rhythmically and independently
autorhythmic
Calmodulin activates an enzyme called____, which adds a phosphate group to a small regulatory protein on the myosin head.
myosin light-chain kinase
Plasticity
Ability to adjust its tension to the degree of stretching; exhibited in smooth muscle.
Binds protein to Z discs
Elastic filaments
Distension of the esophagus with food or the colon with feces, for example, evokes a wave of contraction called
peristalsis
Z discs pulling together pulling on the sarcolemma results in
Muscle cells shortening
A collective term for several hereditary diseases in which the muscles degenerate, weaken, and are gradually replaced by fat and fibrous scar tissue.
Muscular Dystrophy
A sex-linked recessive trait affecting about 1 out of every 3,500 live-born boys; most common form of disease.
Duchenne muscular dystrophy
Pesticides contain______ that bind to acetylcholinesterase and prevent it from degrading to ACh.
Cholinestrase inhibitors
A less severe form of muscular dystrophy that is an autosomal dominant trait that begins in adolescence and affects both sexes.
facioscapulohumeral muscular dystrophy (MD)
Prevention of the degrading of ACh causes
Spastic paralysis are possible suffocation.
A spastic paralysis caused by toxin of clostridium bacteria is called
Tetanus or lock jaw
Usually occurs in women between ages of 20 and 40; an autoimmune disease in which antibodiesattack the neuromuscular junctions and bind ACh receptors together in clusters, muscle fibers then removes the clusters from the sarcolemma by endocytosis, resulting the muscle fibers to become less sensitive to ACh. Effects appaer in facial muscles like drooping eyelids and double vision.
Myasthenia gravis
Limp muscles unable to contract caused by______ that competes with ACh.
Flaccid paralysis
Some myoblasts remain as unspecialized ______ between the muscle fiber and endomysium; these play an important role in the regeneration of damaged skeletal muscle.
Satellite Cells
Both the sarcolemma and that part of the basal lamina in the cleft contain ______; an enzyme that breaks down ACh after the ACh has stimulated the muscle cell (thus, it is important in turning off muscle contraction and allowing the muscle to relax).
acetylcholinesterase (AChE)
_____transfers Pi from one ADP to another, converting the latter into ATP.
Myokinase
_____obtains Pi from a phosphate-storage molecule, _____, and donates it to ADP to make ATP; fast-acting system that helps maintain ATP level while other ATP-generating mechanisms are being activated.
Creatine kinase; creatine phosphate (CP)
ATP and CP; collectively called the _____, provide nearly all the energy used for short bursts of intense activity.
Phosphagen system
The pathway from glycogen to lactic acid, called the _____, produces enough ATP for 30 to 40 seconds of maximum activity.
Glycogen-lactic acid system
The hardening of the muscles and stiffening of the body that begins 3 to 4 hours after death.
Rigor mortis
Skeletal muscles have T tubules, smooth muscles do not.
t
The point where a nerve fiber meets any target cell
synapse
When the target cell is a muscle fiber, the synapse is also called
neuromuscular juction (NMJ) or motor end plate
_____, 1 nm in diameter, are made of a huge springy coil called
Elastic filaments; titin
Notice that you breathe heavily not only during strnuous exercise but also for several minutes afterward; this is to meet a metabolic demand called excess postexercise oxygen consumption (EPOC), also known by an older polarized term,
Oxygen debt
Not present in skeletal muscle, present in intercalated discs of cardiac muscle, present in single-unit smooth muscle.
Gap junctions
Present in cardiac and skeletal muscle.
Striations
Skeletal muscle receives Ca2+ in sarcoplasmic reticulum.
t
Cardiac muscle receives Ca2+ in sarcoplasmic reticulum and extracellular fluid.
t
Smooth muscle receives Ca2+ in extracellular fluid.
t
A functional connection between the distal end of a nerve fiber and the middle of a muscle fiber.
NMJ
In the Excitation-contraction coupling; changes shape and exposes the active sites on the actin filaments; makes available the active sites for binding to myosin heads.
Troponin-tropomyosin complex
Abundant and large in slow-twitch (slow oxidative) muscle fibers, fewer and smaller in fast-twitch (fast oxidative) muscle fibers.
Mitochondria
