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73 Cards in this Set

  • Front
  • Back
Three types of muscle found in the body
skeletal, cardiac, smooth
prefixes that refer to muscles
myo & mys
what determines the concentration of muscles?
the movement of microfilaments
Skeletal muscle characteristics
1. attached by tendons to bones
2. cells are multinucleated
3. Striated
4. voluntary
What do muscle fibers look like?
long cylinders
Another name for muscle fibers
muscle cells
muscle cells are surrounded by what?
connective tissue
Endomysium
encloses a single muscle fiber
Perimysium
Wraps around a fasicle of muscle fibers
Epimysium
covers the entire skeletal muscle
Fascia
On the outside of of the epimysium, continuous with hypodermis and epimysium
Tendons
cord-like structures composed of collagen fibers, often cross a joint due to toughness and small size
Aponeuroses
Sheet-like structures, attach muscles to other muscles or skin. Indirectly attach muscles to bones
Aponeuroses is similar to what?
A tendon but in sheet form
Sites of muscle attatchment
Bones, Cartilages, Connective tissue coverings
Smooth muscle characteristics
1. Lacks striations
2. Spindle-shaped cells
3. Single nucleus
4. Involuntary muscle control
Cardiac muscle characteristics
1. Striations
2. Single nucleus
3. Branching cells
4. Involuntary
5. Joined to other muscle cells at intercalated disks
Skeletal muscle functions
1. Produce movement
2. Maintain posture
3. Stabilize joints
4. Generate heat
Do skeletal muscles push or pull to do work?
They pull and shorten
Microscopic anatomy: Sarcolemma
specialized plasma membrane outside of muscle fiber
Microscopic anatomy: Myofibrils
Long organelles inside muscle cells, fill most of interior space of muscle fibers
Microscopic anatomy: Sarcoplasmic reticulum
specialized smooth endoplasmic reticulum
Endoplasmic reticulum
wrapped around myofibrils
L band
"Light band" contains only thin filaments
A band
"dark band" contain the entire length of the thick filaments
Microscopic anatomy: Sarcomere
contractile unit of a muscle fiber (functional unit of muscle fibers, repeating units like links on a chain)
Myofilaments
thin filament= actin filaments
thick filament= myosin filaments
Myosin Filaments characteristics
Thick filaments, composed of the protein myosin, has ATPase enzymes, myosin filaments have heads
Actin Filaments characteristics
Thin filaments, composed of the protein actin, anchored to the z-disc
ATPase enzyme
can break ATP to release energy to do work
Z-disc
Proteins that connect sarcomeres to other sarcomeres
Sarcoplasmic reticulum
stores and releases calcium, surrounds the myofibrils
Excitability
ability to receive and respond to a stimulus
Contractility
ability to shorten when an adequate stimulus is received
Extensibility
ability of muscle cells to be stretched
Elasticity
ability to recoil and resume resting length after stretching
What stimulates a muscle to contract?
motor neuron (nerve cell)
Motor unit
one motor neuron and all the skeletal muscle cells stimulated by that neuron
Relationship between motor units and motor neurons
Motor neurons are branching to a motor unit
Neuromuscular junction
Association site of axon terminal of the motor neuron and muscle, location where an axon terminal of a neuron interacts with the sarcolemma of a muscle fiber
Axons
long extensions that carry signals
Action Potential
special kind of electrical signal (can be carried by neurons and muscle cells)
Axon terminals
Ends of axons
Synaptic Gap
Gap between nerve and muscle (THEY DO NOT MAKE CONTACT) The area between is filled with interstitial fluid
How many fibers are stimulated during a muscle contraction?
It depends based on how much force is put into the contraction
Graded response
different degrees of muscle shortening
How are graded responses produced?
By changing:
1.The frequency of muscle stimulation
2. The number of muscle cells being stimulated at one time
Use one or fewer motor units
Very small, very fine, precise movements (only in muscles of eyes)
Use many motor units and larger motor units
Large, powerful, less precise movements (ie hamstrings)
Types of graded responses
Twitch, Tetanus, Unfused tetanus, Fused tetanus
Twitch
Single, brief contraction, not a normal muscle function
Tetanus
One contraction is immediately followed by another, the muscle does not completely return to a resting state
Fused (complete) Tetanus
Sustained, continuous contraction
First source of energy to muscles
Stored ATP, only 4-6 seconds of energy provided, ATP bonds are broken to release energy
Unfused (incomplete) Tetanus
Some relaxation occurs between contractions
Second source of energy to muscles
Direct phosphorylation of ADP by creatine phosphate
Third source of energy to muscles
Aerobic respiration or Anaerobic glycolysis
How does Aerobic respiration give the muscles energy?
Glucose is broken down to carbon dioxide and water, releasing ATP
Characteristics of aerobic respiration
Requires Oxygen, Very efficient with high ATP output
How does anaerobic glycolysis provide muscles with energy?
Glucose is broken down to pyruvic acid to produce some ATP
Anaerobic glycolysis characteristics
Does not require oxygen, does require large amounts of glucose. Not efficient but is fast
What type of exercise requires anaerobic glycolysis?
powerful explosive exercise, does not last long so it is reserved for intense short exercise
What type of exercise requires aerobic respiration?
Endurance exercise, ie running and cycling
What happens when a muscle is fatigued?
It can no longer contract even with stimulus
Cause of fatigue
Oxygen deficit
How is muscle fatigue cured?
oxygen must be repaid to get rid of accumulated lactic acid
Types of muscle contractions
Isotonic, Isometric, Eccentric
Isotonic Contractions
The muscle shortens and movement occurs (visible movement), myofilaments are able to slide past each other during contractions
Isometric contraction
Tension in the muscle increases, the muscle is unable to shorten or produce movement, movement will not occur
Eccentric Contraction
Muscle breaking, stopping the muscle from going as fast as it usually would
Muscle tone
Some fibers are always contracted, different muscle fibers at different times, involutary
Sarcoplasmic Reticulum
Looks like a crocheted sweater surrounding myofibrils, they store calcium
Acetylcholine
neurotransmitter in neuromuscular junctions, stimulate muscle cells