CONTRACTION OF SKELETAL MUSCLE Flashcards
…gives muscle its muscle its striated appearance
The light band(I) and the dark band (A)
The length at which actin finally overlaps the myosin is…
Sarcomeres
Skeletal muscle is composed of fibers that are …um in diameter
10-80um
The small unit of muscle fibers are
sarcomalemma, myofibril,sarcoplasmic reticulum
The true membrane of sarcomalemma is called..
Plasma membrane
…is the cell membrane of muscle fibers
Sarcomalemma
The outer coat of sarcomalemma contains thin polysaccharide that contains…
Thin collagen fibrils
The surface of…fuses with tendon fiber at the end of each muscle fiber
Sarcolemma
Myofibril consist of
Actin and myosin
….are the large protein polymer that is responsible for the actual muscle contraction
Actin and myosin filaments
… interdigitate and cause the myofibril to form light and dark band
Actin and myosin filaments
The light bands and dark band are … respectively
Actin and myosin
Light band are called …. because of..
(I) band because they are isotropic to polarized light
Dark band are called… because they..
(A) because they Anisotropic polarized light
What produces muscle contraction
The interaction btw actin and cross -bridge
The small projection from the side of myosin is …
Cross-bridges
…is a disc composed of filamentous protein that help attach myofibril from one another across the muscle fibers
Z-disc
Actin filaments is attached to…disc which the actin interdigitate with myosin
Z-disc
Skeletal muscle is about ..%of the body while smooth and cardiac muscle are about…%
40 and 1O respectively
The portion of myofibril that lies between two successive Z disc is called
Sarcomeres
As the muscle contracts the sarcomeres reduces by…
2um
…is the filamentous protein with the largest MMW of 3million
Titin protein
The largest filamentous protein is
Titin protein
Titin protein is …in nature
Springy
What’s the function of titin protein
It acts as a framework that holds the myosin and actin together in place so that the contractile machinery if sarcomeres will work
The space between myofibrils that are filled with intracellular fluid is …
Sarcoplasm
Sacroplasm contain large qty of
Potassium, magnesium phosphate, multiple protein enzyme and mitochondria
… supplies the contracting myofibril energy in form of ATP
Mitochondria
The sarcoplasm that surrounds the myofibril contains …that control the muscle contraction
Sarcoplasmic reticulum
How many mechanisms are involved in muscle contraction
8 steps
The neurotransmitter secreted by nerve at each endings on muscle fibers is
Acetylcholine
What is the function of acetylcholine
It acts on a local area of the muscle fibers membrane to open multiple acetylcholine gated channels through protein molecules floating in the membrane
Na ions that diffuses inside the muscle fibers membrane initiate ..
Action potential at the membrane
Opening of acetylcholine gate allows…
The diffusion of Na ions
Where is calcium stored …
Sarcoplasmic reticulum
… depolarizes muscle membrane and causes electric flow through the counter of the muscle
Action potential
The removal of calcium causes myofibril to
Cease
Muscle contraction occurs by… mechanism
Sliding filament mechanism
The interaction of myosin cross-bridges with actin filaments causes the actin filaments to slide.. . among myosin filaments
Inward
… activates the forces btw actin and myosin filaments which causes contraction to begin
Calcium ion
The end of myosin functions as… enzyme
ATPase
ATPase enzyme…ATP which energizes the contraction process
Hydrolysis
The actin filament is made up of
Actin, tropomyosin and troponin
The actin filaments is inhibited by…and activated by…
Troponin -tropomyosin complex
Calcium ions
Ca2+ combines with… causing troponin complex to pull on the tropomyosin molecules
Troponin
Another name for walk along theory is
Ratchet theory
The tilting of the myosin head
Power stroke
Tension…as sarcomeres shortens
Increases
Full tension is achieved at … sarcomeres length
2um
Functions of ATP in muscle contraction
Activate walk along mechanism
Pump ca2+ ion in sarcoplasmic reticulum
Pumping of Na and K ions to maintain ionic movement for the propagation of ATP
3 main sources of energy apart from ATP
Phosphocreatine
Glycogen breakdown to pyruvic and lactic acid
Oxidative metabolism of cellular foodstuff
How long does phosphocreatine, glycogen breakdown and oxidative metabolism of cellular foodstuff maintain contraction respectively
5-8sec,1min and for a long period
2 characteristics of whole muscle contraction are
Isotonic contraction and
Isometric contraction
… contraction occurs when muscle does not shorten during contraction
Isometric contraction
… contraction occurs when the muscle shortens and tension on the muscle remains constant
Isotonic
True isometric contraction cannot be generated in intact body because of the stretch of the stretch of series of elastic components during muscle contraction allowing shortening of the muscle. T) F
T
The elastic element include
Tendon
Sarcolemma end of muscle fibers
Hinged arm of myosin cross-bridges
Characteristics of isotonic contraction depends on..
Load against muscle contraction
Inertia of the load
Types of muscle fibers are
Fast fibers
Slow fibers
Each muscle is composed of…type of fiber
Both
Another name for slow fibers and fast fibre respectively
Type 1/red muscle
Type 2/white fibers
…fiber is characterized by large amount of myoglobin,smaller nerve fiber, high capillarity and large number of mitochondria
Slow fibers
What gives muscle its reddish appearance
Myoglobin
…fiber has extensive sarcoplasmic reticulum for rapid release of ca2+,larger with large amount of glycolytic enzyme, lower capillarity with few mitochondria
Fast fibers
Fast fibers have fewer mitochondria because… metabolism is of secondary importance
Oxidative
… fibers contains glycolytic enzyme
Fast
…is each motor neuron that leaves the spinal cord and innervates multiple muscle fibers
Motor unit
…is the addition of individual twitch contraction to increase the intensity of overall muscle contraction
Force summation
…is a single sudden contraction that lasts for a fraction of seconds
Twitch
Two ways summation occurs are
Multiple motor unit summation
Frequency summation and tentanization
What is multiple motor
It is when the CNS sends a weak signal to contract muscle ,the motor unit in the muscles contains the smallest and fewest muscle fibers stimulated in preference to the larger motor units
Increase in the total mass of muscle
Muscle hypertrophy
The enzyme that increases in muscle hypertrophy is known as
Glycolytic enzyme
The decrease in the mass of a muscle is
Muscle atrophy
Increase in fiber number is …
Hyperplasia of muscle fibers
…occurs as a result of linear splitting enlarged fibers
Hyperplasia
Destroyed nerve fiber are replaced by…
Fibrous and fatty tissue
The continuous shortening of fibrous tissue for many months is known as
Contracture
What is denervation
It is the lose of nerve supply
Recovery of muscle contraction in poliomyelitis is caused by …
Macro motor unit
Several hours after death,all muscles go into a state of contracture called
Rigor mortis
A state of muscle rigidity without action potential is known as
Rigor mortis
Rigor mortis is as a result of
Loss of ATP
A body remains rigor until …takes place
Autolysis
Drugs that inactivate acetylcholinestrase are
Psyostigmine
Neostigmine and
Diflos
Drug that blocks the neuromuscular transmission
Curaciform
Drugs that have the same action as acetylcholine are
Methocholine
Carbachol
Nicotine
…is used by military as a powerful nerve gas poison
Diflos
Myasthenia gravis cause
Paralysis
The pathogen myasthenia gravis is a … disease
Autoimmune disease
The patient suffering from paralysis dies mostly of
Respiratory paralysis
Two types of smooth muscle are
Multi-unit smooth muscle
Single unit smooth muscle
The unique characteristics of multi-unit smooth muscle are
They contract independent of others
They are control by nerve signal
Multi-unit smooth muscle are innervated by… nerve endings
Single
Examples of smooth muscle fibers are
Ciliary of the eyes
Iris
Piloerector
Another name for single unit smooth muscle are
Visceral
Syncytial or
Unitary smooth muscle
They are called single unit smooth muscle because
Hundreds of millions of muscle fibers contract as a single unit
The cell membrane of single unit smooth muscle are joined together by … junction
Gap
The type of muscle mostly found in hollow are
Single unit smooth muscle
Single unit smooth muscle in blood vessel…and …, they propel contents of…and expel the content of…
Regulate blood vessel diameter and part of respiratory system
Gut walls,bile, ureter and uterus
Uretus and urinary bladder
Physical basis for smooth muscle contraction are
Actin filaments attached to dense bodies
Myosin filaments interspersed among the actin filaments
Contractile unit
