Muscle Physiology: The Actions of the Sarcomere.
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Transcript of Muscle Physiology: The Actions of the Sarcomere.
Muscle Physiology:The Actions of the Sarcomere.
Cardiac MuscleCharacteristics Intercalated
disks Striated Involuntary Located in heart
Skeletal Muscle
Characteristics Many nuclei per
cell Striated Voluntary Located along
bones
NonstriatedInvoluntaryLocated in digestive tract
Smooth Muscle
Functions of Muscles
Movement: results from muscle contraction, enables you to respond quickly
Maintains Posture and Joint Stability: allows you to sit upright; stabilize joints of the body
Support Soft Tissue: abdominal muscles protect underlying digestive organs.
Guard Entrances and ExitsGenerate Heat: heat is generated as they work…FRICTION
Maintains body temperature Skeletal muscles create the most heat
Characteristics of Muscle Tissue
Excitability: ability to receive and respond to stimuli…
Contractibility: ability to shorten quickly and with force…
Extensibility: ability to be stretched or extended beyond their resting state…
Elasticity: ability of a muscle fiber to recoil and resume its resting length
Organization of Muscle
Muscles are composed of groups of fibers called fasicles.Fibers are the muscle cells inside all muscle.Tendons are bands of collagen fiber that attach muscle to bone.
Sarcomere: the contracting unit
Skeletal Muscle Striations
Z line
I band
H band
A band
Organization from the muscle fiber to the sarcomere.
Cross sectional view of Sarcomere.
Differences are detected in the sizes of the myofilaments
Myosin is the thicker fiber.
Actin is the thinner fiber.
Striations are seen because of sarcomere bands.
.
Muscle fiber structure
Muscle cellSarcolemmaSarcoplasmSarcoplasmic reticulumT tubulemitochondria
Structure of Muscle Tissue
Sliding Filament Theory
Sliding Filament TheoryActin slides over myosin shortening the
sacromere between the Z lines
Chain of Events during Muscle Contraction! 1. Cross Bridge Attachment2. Power Stroke 3. Cross Bridge Detachment4. Cocking (Recoil) of Myosin Head
What happens at the sarcomere?
Players for the power stroke
Cross bridge attachmentPower strokesCross bridge detachment“Cocking” of the myosin head
Power stroke
Motor Unit: A motor neuron and all the muscle fibers it stimulates.
Diagram of a Muscle Twitch
Increase in muscle tension due to continued stimulation.
Muscle that reaches peak tension during rapid cycles of contraction and relaxation.
Complete tetanus = relaxation state is eliminated.
Label the following!
Aerobic Muscle Metabolism
GlycolysisAerobic Respiration Krebs Cycle ETC
Anaerobic Muscle Metabolism
Oxygen Debt
Lactic Acid Fermentation
Muscle Fatigue
Creatine Phosphate
Red (slow) twitch fibers
AerobicSlow-acting ATPases (enzymes that break down ATP) Large amounts of myoglobinRed color to cellAbundant supply of mitochondriaFatigue resistant-as long as O2 is availableHigh endurance (jogging, swimming, soccer)
White (fast) twitch fibers
Large pale cells with twice the diameter of red fibersVery little myoglobinContain fast-acting ATPases and contract rapidlyContain few mitochondria, but large glycogen storesDepend on anaerobic resp. to make ATP, therefore fatigues easilyLow endurance, much power….sprints
Pink (intermediate) twitch fibers
Mixture of red and white fibersAerobic mechanisms and fatigue resistantContain fast-acting ATPasesHigh myoglobin content