Chapter 10 Flashcards
Muscle tissue
skeletal muscle (voluntary )
cardiac muscle (involuntary )
smooth muscle (function involuntary )
functions of skeletal muscles
- produce skeletal movement
- maintain body position
- support soft tissue
- guard body openings
- maintain body temperature
Organization of Connective Tissues
3 layers of connective tissues:
1. epimysium
2. perimysium
3. Endomysium
Epimysium
wraps skeleton muscles
- exterior collagen layer
- connected to deep fascia
- separates muscle from surrounding tissues
Perimysium
the clear thin skin of a fascicle
- surrounds muscle fiber bundles (fascicles)
- contains blood vessel and nerve supply to fascicles
Endomysium
Surrounds individual muscle cells (muscle fibers)
contains capillaries and nerve fibers contacting muscle cells
contains satellite cells (stem cells) that repair damage
Muscle Attachements
Endomysium, perimysium, and epimysium come together:
- at ends of muscles
- to form connective tissue attachment to bone matrix
- examples. tendon(bundle) or aponeurosis(sheet)
Formation of Skeletal Muscle Fibers
skeletal muscle cells are called fibers
The Sarcolemma
The cell membrane of a muscle cell
Surrounds the sarcoplasm (cytoplasm of muscle fiber)
A change in transmembrane potential begins contractions
Transverse Tubules (T tubules)
Transmit action potential through cell
Allow entire muscle fiber to contract simultaneously
Myofibrils
- Lengthwise subdivisions within muscle fiber
- Made up of bundles of protein filaments (myofilaments)
- Myofilaments are responsible for muscle contraction
Types of Myofilaments
Thin filaments:
- made of protein actin
Thick filaments:
- made of protein myosin
Sarcoplasmic Reticulum
A membranous structure surrounding each myofibril
Helps transmit action potential to myofibril
Similar in structure to smooth endoplasmic reticulum
Sarcomeres (structural components)
The contractile units of muscles
Structural units of myofbrils
form visible patterns within myofibrils
Muscle Striations
A striped or striated pattern within myofibrils:
- alternating dark , thick filaments (a band) and light, thin filaments (I bands)
Sarcomere structure (levels)
- skeletal muscle - surrounded by epimysium
contains: muscle fascicle - muscle fascicle: perimysium
contains: muscle fibers - muscle fiber surrounded by endomysium
contains: myofibrils - myofibril surrounded by sarcoplasmic
- Sacromere contains thick and thin filaments
Skeletal Muscle Contraction
Sliding filament theory:
- thin filament of sarcomere slide toward M line
- between thick filaments
- z lines move closer together
The neuromuscular junction
- is located of neural stimulation
- Action potential (electrical signal)
– travels along neuron
– ends at synaptic terminal
types of skeletal muscle tension (2)
- Isotonic contraction
- Isometric contraction
Isotonic Contraction
Skeletal muscle changes length:
- resulting in motin
If muscle tension resistance:
- muscle shortens (concentric contraction)
if muscle tension < resistance:
- muscle lengthens (eccentric contraction)
Isometric Contraction
Skeletal muscle develops tension, but is prevented by changing length
Note: iso = same, metric = measure
Muscle Relaxation
after contraction, a muscle fiber returns to resting length by:
- elastic forces
- opposing muscle contractions
- gravity
Elastic Forces
- the pull of elastic elements (tendons and ligaments)
- expands the sarcomeres to resting length
Opposing muscle contractions
reverse the direction of the original motion
are the work of opposing skeletal muscle pairs
Gravity
Can take the place of opposing muscle contraction to return a muscle to its resting state
Atp and muscle contraction
Sustained muscle contraction uses a lot of ATP energy
muscles store enemy’s energy to start contraction
muscle fibers must manufacture more ATP as needed
ATP and CP reserves
- Adenosine triphosphate (ATP):
- the active energy molecule
-Creatine phosphate(CP) - the storage molecule for excess ATP energy in resting muscle
ATP Generation
Cells produce ATP in to ways:
- Aerobic metabolism of fatty acids in the mitochondria = as long as it has enough oxygen
- anaerobic glycolysis in the cytoplasm
= When does it produce when you’re out of breath.
Aerobic Metabolism
Is primary energy source of resting muscles
break down fatty acids
Produces 34 ATP molecules per glucose molecule
Anaerobic Glycolysis
- Is the primary energy source for peak muscular activity
- produces 2 ATP molecules per molecule of glucose
- breaks down glucose from glycogen stored in skeletal muscles
Energy Use and Muscle Activity
At peak exertion:
- muscles lack oxygen to support mitochondria
- muscles rely on glycolysis for ATP
- pyruvic acid builds up, is converted to lactic acid
Results of Muscle Fatigue
- Depletion of metabolic reserves
- Damage to sarcolemma and sarcoplasmic reticulum
- Low pH (lactic acid)
- Muscle exhaustion and pain
Muscle Performance
Power:
- the maximum amount of tension produced
Endurance:
- the amount of activity can be sustained
Power and endurance depend on:
- the types of muscle fibers
- physical conditioning
what are the 3 skeletal muscle fibers?
- Fast fibers
- Slow fibers
- Intermediate fibers
Fast Fibers
- contract very quickly
- Have large diameter, large glycogen reserves, few mitochondria
- Have strong contractions, fatigue quickly
explosive muscle but fatigue quickly
Slow Fibers
Are slow to contract, slow to fatigue
have small diameter, more mitochondria
have high oxygen supply
Contain myoglobin (red pigment, binds oxygen)
Intermediate Fibers
are mid-sized
have low myoglobin
have more capillaries than fast fiber, slower to fatigue
Muscles and Fiber Types
- White muscle: mostly fast fibers and pale (ex. chicken breast)
- Red muscle: mostly slow fibers - dark (ex. chicken legs)
Most human muscles: - mixed fibers
- pink
Muscle Hypertrophy
Muscle growth from heavy training:
- increase diameter of muscle fibers
- increases number if myofibrils
- increases mitochondria, glycogen reserves
Muscle Atrophy
lack of muscle activity:
- reduces muscle size, tone, and power
Anaerobic Endurance
anaerobic activities (ex. 50 meter dah, weightlifting);
- use fast fibers
- fatigue quickly with strenuous acitivty
Improved by: frequent, brief, intensive workouts
- hypertrophy
Aerobic Endurance
Aerobic activities(prolonged activity):
- support by mitochondria
- require oxygen and nutrients
Improved by:
- repetitive training (neural responses)
- cardiovascular training
Muscle Terminology Based on Function
Agonist= prime mover
- produces a particular movement
Antagonist
- opposes movement of a particular agonist(opposite of agonist)
agnost to antagonist
biceps brachii vs Tricepts brachii
Pectoralis major vs. Latissimus Dorsi
Hamstrings vs quadriceps
Trapezius vs Sternocleidomastroid
Muscle Terminology Based on Function
Synergist:
- a smaller muscle that assists a larger agonist = prime mover
- helps start motion or stabilize noggin of agnostic (fixator)
Muscle Opposition
Agonists and antagonists workin pairs:
- when 1 contracts, the other stretches
- flexors-extensors, abductors-adductors
6 muscles groups of the head and neck
- muscles of facial expression: skull
- extrinsic eye muscles: surface of orbit - control of eye
3.Muscles of mastication: move the mandible - muscles of the tongue: names end in glossus
- Muscles of the pharynx: begin swallowing process
- Anterior muscles of the neck: - Control position of larynx - depress the man
- support tongue and pharynx
Extrinsic Eye Muscles
also called extra ocular muscles
superior oblique
superior rectus
lateral rectus
inferior rectus
inferior oblique
3 Muscles of Mastication = chewing
Masseter = most of work
- The strongest jaw muscle
Temporalis:
- helps lift the mandible
Pterygoid muscles:
- Position mandible for chewing
