THE MUSCULAR SYSTEM What do you already know about muscle tissue? What is the definition of an...
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Transcript of THE MUSCULAR SYSTEM What do you already know about muscle tissue? What is the definition of an...
THE MUSCULAR THE MUSCULAR SYSTEMSYSTEM
What do you already know about What do you already know about muscle tissue?muscle tissue?
What is the definition of an organ?What is the definition of an organ?
Types of muscle tissueTypes of muscle tissue
Skeletal muscleSkeletal muscle
Cardiac muscleCardiac muscle
Smooth muscleSmooth muscle
FunctionsFunctions
1.1. Producing body movements by Producing body movements by changing chemical energy into changing chemical energy into mechanical energymechanical energy
2.2. Stabilizing body positionsStabilizing body positions
3.3. Generating heatGenerating heat
4.4. Moving substances Moving substances
Within the bodyWithin the body
Skeletal muscle anatomySkeletal muscle anatomy
Connective tissue around muscle Connective tissue around muscle ((epimysiumepimysium))– Extends to form tendon (dense regular Extends to form tendon (dense regular
connective tissue) – connects muscle to connective tissue) – connects muscle to periosteum of boneperiosteum of bone
Muscles: bundles of Muscles: bundles of fascicles (group of fascicles (group of fibers – cells) fibers – cells) surrounded by surrounded by perimysiumperimysium
Nerves and blood Nerves and blood vesselsvessels– At least 1 capillary At least 1 capillary
per muscle fiberper muscle fiber
Myofibrils= contractile organelles Myofibrils= contractile organelles stripesstripes
Sarcoplasmic reticulum - encircles Sarcoplasmic reticulum - encircles myofibrils= similar to smooth ER; myofibrils= similar to smooth ER; function = stores calciumfunction = stores calcium
Filaments (thin and thick)– inside Filaments (thin and thick)– inside myofibrils; don’t extend length of myofibrils; don’t extend length of fiber; contained in sarcomeresfiber; contained in sarcomeres
Anatomy of muscle fiberAnatomy of muscle fiber
No mitosisNo mitosis
Growth: hypertrophy due to Growth: hypertrophy due to hormones (testosterone, HGH)hormones (testosterone, HGH)
Sarcolemma = cell membraneSarcolemma = cell membrane
Sarcoplasm = cytoplasm Sarcoplasm = cytoplasm (glycogen!!)(glycogen!!)
Myoglobin Myoglobin – a protein– a protein = binds = binds with/release O2 for the mitochondriawith/release O2 for the mitochondria
Mitochondria = many!Mitochondria = many!
Don’t writeDon’t write
Review:Review:– SarcolemmaSarcolemma– SarcoplasmSarcoplasm– Sarcoplasmic reticulumSarcoplasmic reticulum– MyofibrilsMyofibrils– filamentsfilaments
HOW A MUSCLE CONTRACTSHOW A MUSCLE CONTRACTS
http://www.youtube.com/watch?v=ren_IQPOhJc&list=PL7DDED4766451C09D
A neuron connects to a muscle fiber A neuron connects to a muscle fiber [called the neuromuscular junction (NMJ)][called the neuromuscular junction (NMJ)]
Arrival of nerve impulse causes release of Arrival of nerve impulse causes release of acetylcholine (ACh: a neurotransmitter – a acetylcholine (ACh: a neurotransmitter – a chemical).chemical).
ACh diffuses to receptors on muscular ACh diffuses to receptors on muscular membrane (sarcolemma), opening a Namembrane (sarcolemma), opening a Na++ ion channel, causing Naion channel, causing Na++ to enter the to enter the muscle fibermuscle fiber
Muscle contraction contMuscle contraction contCauses muscle action potential due to Causes muscle action potential due to change in membrane potential (b/c of change in membrane potential (b/c of addition of Naaddition of Na++ ) )Sarcoplasmic reticulum releases stored Sarcoplasmic reticulum releases stored CaCa+2 +2 into sarcoplasminto sarcoplasmCauses muscle contraction (sliding Causes muscle contraction (sliding filament mechanism):filament mechanism):– Unblocks actin (thin) so myosin (thick) heads Unblocks actin (thin) so myosin (thick) heads
can bind to themcan bind to them– Filaments slide past one another, shortening Filaments slide past one another, shortening
the musclethe muscle
Sliding filament mechanism
Sliding filament mechanismSliding filament mechanism
Lengths of filaments do not changeLengths of filaments do not change
Sarcomere shortensSarcomere shortens
Causes shortening of muscle fiber Causes shortening of muscle fiber and muscleand muscle
Plants/drugs effect NMJPlants/drugs effect NMJ
Botulinum toxin from bacterium Botulinum toxin from bacterium Clostridium botulinum blocks Clostridium botulinum blocks exocytosis of AChexocytosis of ACh
Curare – plant derivative – used on Curare – plant derivative – used on arrow/blowgun darts. Binds to/blocks arrow/blowgun darts. Binds to/blocks ACh receptorsACh receptors
Muscle physiologyMuscle physiology
Muscles tug on tendons which pull on Muscles tug on tendons which pull on bonesbones
One bone is pulled towards anotherOne bone is pulled towards another
Insertion towards originInsertion towards origin
Most cross a jointMost cross a joint
Muscle groupsMuscle groupsPrime mover and Prime mover and antagonistantagonist
Opposite actionsOpposite actions
Switch rolesSwitch roles
Opposite sides of Opposite sides of bone/jointbone/joint
Lever Lever systemssystems
Most of the bones of the limbs (arms & legs) act as levers. These levers are powered by muscles.A lever is a rigid rod able to rotate about a fixed point known as a fulcrum, formed by the joint. Any force applied to the lever is called the effort.A force that resists the motion of the lever, such as the downward force exerted by a weight on the bar, is called the load or the resistance.The contraction of the muscles is the effort and the part of the body concerned is known as the resistance or load.Bones of the body act as levers (a mechanical device) which create a mechanical advantage of strength or speed.
Muscle contractionMuscle contraction
Muscle fibers: all-or-noneMuscle fibers: all-or-none
Strength of muscle contraction: Strength of muscle contraction: depends on # of contracting fibersdepends on # of contracting fibers
Affects energy usageAffects energy usage
Providing energyProviding energyATP broken down during contractionATP broken down during contractionStore little ATP, must produce itStore little ATP, must produce it3 ways:3 ways:– Aerobic respiration: slow, requires O2, lots Aerobic respiration: slow, requires O2, lots
ATPATP– Anaerobic glycolysis and lactic acid Anaerobic glycolysis and lactic acid
formation: faster, no O2 needed, less ATPformation: faster, no O2 needed, less ATP– Creatine phosphate and ADP: CP not found Creatine phosphate and ADP: CP not found
in other cells, very fast, doesn’t lastin other cells, very fast, doesn’t last
Muscle fatigueMuscle fatigueno contraction no contraction even with even with stimulation - occurs stimulation - occurs from from oxygen debt oxygen debt (lactic acid builds (lactic acid builds up and ATP runs up and ATP runs low)low)
Types of muscle contractionsTypes of muscle contractions
Isotonic: with movementIsotonic: with movement
Isometric: muscle against immovable Isometric: muscle against immovable (or almost) object(or almost) object
Effect of exerciseEffect of exercise
Aerobic (endurance): results in Aerobic (endurance): results in muscles with resistance to fatigue. muscles with resistance to fatigue.
Resistance (isometric) training: Resistance (isometric) training: enlarged musclesenlarged muscles
In review……… In review……… (don’t write)(don’t write)
Lifting weights is an example of resistance Lifting weights is an example of resistance or endurance training?or endurance training?
The reaction of creatine phosphate and The reaction of creatine phosphate and ADP generates ATP quickly or slowly?ADP generates ATP quickly or slowly?
The ability of your body to use oxygen to The ability of your body to use oxygen to produce ATP is _____ respiration.produce ATP is _____ respiration.
True or False: The strength of a muscle True or False: The strength of a muscle contraction is determined by the amount contraction is determined by the amount of muscle fibers that are contracting.of muscle fibers that are contracting.
Don’t writeDon’t write
The strength of a muscle contraction The strength of a muscle contraction depends on what?depends on what?
What is the relationship between the What is the relationship between the strength of a muscle contraction and strength of a muscle contraction and energy usage?energy usage?
Muscle fatigue is due to ____ debtMuscle fatigue is due to ____ debt
exampleexample
Running a 100 yd dash in 12 seconds Running a 100 yd dash in 12 seconds requires 6L of oxygen.requires 6L of oxygen.
But the max amount that could be But the max amount that could be delivered and used by your muscles delivered and used by your muscles (VO2 max) would be 1.2 L(VO2 max) would be 1.2 L
Oxygen debt?Oxygen debt?
= 4.8L= 4.8L
THE THE POINTPOINT
The more oxygen your body can take The more oxygen your body can take in and use determines your in and use determines your enduranceendurance
DON’T WRITEDON’T WRITE
Why are some Why are some people better at people better at endurance endurance activities?activities?
Why are some Why are some people FAST?people FAST?
Is it genetic? Is it Is it genetic? Is it training?training?
Types of muscle fibersTypes of muscle fibers1. Slow oxidative fibers1. Slow oxidative fibers– Little power (small in diameter); fatigue Little power (small in diameter); fatigue
resistant; many mitochondria. Adapted for resistant; many mitochondria. Adapted for maintaining posture & endurance activitiesmaintaining posture & endurance activities
2. Fast oxidative-glycolytic fibers2. Fast oxidative-glycolytic fibers– Intermediate in diameter, faster than #1 but Intermediate in diameter, faster than #1 but
briefer in duration. Adapted for: briefer in duration. Adapted for: walking/sprintingwalking/sprinting
3. Fast glycolytic fibers3. Fast glycolytic fibers– Large diameter (contract strongly/quickly); tire Large diameter (contract strongly/quickly); tire
quickly; large amount lactic acid build upquickly; large amount lactic acid build up– Short, rapid, intense movementShort, rapid, intense movement– Adapted for intense anaerobic movements of Adapted for intense anaerobic movements of
short duration: weight lifting/throwing a ballshort duration: weight lifting/throwing a ball
muscle fibers in musclesmuscle fibers in muscles
Muscle are a combo of different Muscle are a combo of different fibersfibers
Proportion of fibers is Proportion of fibers is individualindividual