Muscle Physiology Flashcards
Types of muscle tissue
Skeletal
Cardiac
Smooth
Highly specialized cells for the func of contraction
Muscle cells
Muscles contract for
Movt
Opposes gravity or forces
Propulsion of contents of hollow organs
Skeletal Muscle cells are innervated by
Somatic motor neuron
Smooth and cardiac muscles get signals to contract from
Autonomic nervous system
Responsible for movt of internal organs
Smooth muscle
Can contract spontaneously
Can regulate itself
Cardiac muscle
Smooth muscles..
Smooth mucles are
- spindle shaped
- homogenous with no striations
- single and centrally placed nucleus
- involuntary
- Innervated by ANS
- Visceral smooth muscle
Describe Cardiac muscle
Latticework appearance Striated Myofibrils interdigitate during contraction Presence of intercalated disks Have SYNCTIAL INTERCONNECTIONS bet cells
Contain myofilaments - actin and myosin
Myofibril
Contractile organelle. Most abundant part of the muscle tissue. Responsible for actual contraction
Myofibril
Describe skeletal muscle
Striated
Voluntary
Multinucleated
It is the intracellular fluid between myofibrils
Sarcoplasm
Cell membrane of muscles
Sarcolemma
Cytoplasm of muscles
Sarcoplasm
Er of muscles
Sarcoplasmic reticulum
What are t tubules or transverse tubules
Located beside sarcoplasmic reticulum
Impt in distributing command to contract in skeletal fibers
Aids in allowing action potential at the cell surface to move rapidly
Made up of grps of muscle fiber
Muscle bundle
Consists of myofilaments arranged in sarcomere
Myofibrils
Smallest func unit of muscle fibril
Sarcomere
Actin molecules
Pear shaped arranged in strands of beads
Myosin molecules
Has a rod shaped tail and globular head
Myofibrils are made up of _ sarcomere
10000 sarcomere
Myosin
Thick filaments
A bands
Found at center
Actin
Thin filaments
I bands
Found at periphery
Center of thin filaments
Anchors thin filaments
Z line
Area of A bands w/o an actin filament
H zone
Line anchoring center of A band
M line
1 sarcomere =
Z line to z line
Sliding filament theory
When a sarcomere contracts, thin filaments are sliding along the center of the sarcomere alongside the thick filaments, decreasing the H ZONE
Types of muscle contraction
Simple twitch
Isometric
Isotonic
Stages of a twitch
Diff phases of contraction
Latent phase
Contraction phase
Relaxation phase
Diff forms of stimulus
Thermal
Mechanical
Electrical
Chemical
Diff degress of stimulus
Sub threshold
Threshold
Maximal
Supramaximal
2 types of muscle fibers
Slow fibers
Fast fibers
Characteristics of muscle contraction
- All or none principle
- Exhibits gradation
- Shows asynchronous contraction
- Exhibits muscle tone
Factors in exhibiting gradation
Strength Stretch Load Treppe Rate of frequency of stimulation
2 types of tetanus
Incomplete
Complete
Difference of isometric and isotonic
Isometric - tension rises but the length of muscle contraction is CONSTANT. Maintains position of body
Isotonic - tension builds until it extend the amount of resistance. Muscle shortens. Movt of arms hands fingers
Any agent act or influence producing functional or trophic reactions in a receptor or irritable tissue
Stimulus
Shows a period of contraction followed by a period of relaxation
Simple twitch
Describe the latent phase
Latent - begins at stimulation. Lasts about 10ms. Action potential is still sweeping across the membrane. No tension.
Describe contraction phase
Tension rises to a peak
Cross bridging occurs
40 ms
Relaxation phase
Muscle tension returns to resting levels
Detachment of cross bridges
50ms
Degree that does not produce a response
Sub threshold
Strength of stimulus that causes excitation
Threshold
More muscle fibers contracting at the same time
Maximal
All muscles contracting at the same time until it is close to fatigue
Supramaximal
Describe slow fibers
Red muscle
High myoglobin content
100ms twitch duration
Long muscles of the back
Describe fast fibers
Pale or white muscles Low myoglobin content Twitch duration 7ms Muscles that produce fine movt Less resistance to fatigue Muscles in hand, extracellular muscle
Response of muscle fiber to the stimulus is maximal
All or none principle
^ strength or intensity of stimulus
^ height
^ load
⬇️ height
What is TREPPE
Staircase effect
Repeated stimulation after the resting phase and the peak tension will rise in stages
Inc speed of stimulation causes
Tetanus
Fusion of contraction
Tetanus
Diff incomplete and complete
Incomplete- rate increases further. Tension production rises to a peak and periods of relaxation will be very brief
Complete- freq of s. Is so high that the relaxation phase is completely eliminated
Inability of the motor unit to respond to a workload
No excitation will be produced
Fatigue
While one motor unit is contracting the other is resting
Shows asynchronous contraction
Firmness of the muscle
Flaccid denervated muscle (no nerve, no firmness)
Exhibits muscle tone