Skeletal muscle attaches by what and characteristics of it
tendons and aponeuroses
striated and voluntary
Cardiac muscle epithelial characteristics
striated and involuntary
Smooth muscle location and characteristics
hollow organs and non striated and involuntary
Functions of muscle tissue (5)
- body movement
- body position
- move substances within the body
- generation of heat
- moves nutrients
Properties of what tissue?
-electrical excitability
Skeletal tissue
ability to respond to certain stimuli by making AP’s
Properties of what tissue?
Contractility
Skeletal
ability to shorten and thicken generating force to do work
Properties of what tissue?
Extensibility
Skeletal
stretch without damage
Properties of what tissue?
elasticity
skeletal
able to return to normal shape after being stretched
Which tissue is multi-nucleated?
Skeletal
Define Fascia
fibrous CT that covers each organ, muscle, bone, blood vessels
Types of Fascia
Superficial and Deep
Superficial Fascia aka
contains what kind of fibers?
function
subcutaneous
yellow and white fibers
separates muscle from sin, lines body wall, stores fat, and protects muscle from trauma
Deep Fascia Function
covers, divides, and protects muscles with similar functions
Where are trigger points located ?
latent vs active
Usually occurs where?
Deep Fascia
latent-hurts when touched
active-hurts all the time
Belly of the muscle
Cardiac Vs Skeletal
Cardiac has own internal activation system (intrinsic) called pacemaker cells
Smooth is not attached to skeleton
What is Calmaudin?
Smooth muscles troponin
Which systems are actin based ?
Myosin Based?
Actin-Cardiac and Skeletal
Myosin-Smooth
What exists between the fascicles and their perimysium?
Areolar CT and adipose
What surrounds each muscle cell ?
What cells are here?
Endomysium
Myosatellite cells which repair damage
Myotubes are formed by what
Whats produced here?
By mypblasts fusing together which are triangular cells
Actin and Myosin are produced in cytoplasm of myotubes
How is a myocyte/myofiber formed?
Myoblasts coming together by aligning with myotubes and myofibrils
Outer covering of skeletal muscle cell is called?
Sarcolemma
What are t-tubules?
Function?
Invagination of sarcolemma
To transmit the AP from sarcolemma to inside of muscle cell which then contracts simultaneously
What is the Sarcoplasm?
Whats in it?
Muscle cell cytoplasm
Contains glycogen for energy production and hemoglobin for oxygen storage
What are myofibrils?
Thick and thin filament s and contain contractile elements
Where is the SR?
Stores what?
Surround each myofibril
Stores CA2+
Where EXACTLY is Ca2+ stored?
Where is most of the Ca2+ at rest?
Where is it released?
Terminal cisternae of the SR
Cisternae
Released into the sarcoplasm
Muscular atrophy vs hypertrophy
Atrophy- decrease in muscle mass
Hypertrophy-increase
Thick vs thin filament names
Think-Myosin
Thin-Actin
A band consists of what ?
primarily thick filaments-mysoin
I bands consist of what?
think filaments only- Actin
Z disc passes through where?
through I band (center)
Where is the H zone located?
Center of A band, region of non overlap & thick filaments only
What is mieromysin?
2 pairs of light chains and 2 pairs of heavy chains
Thick lines are anchored to Z line by what ?
Adjacent filaments?
Titin
two proteins, more called myomysin
Actin strands are made of?
2 strands of fibrous actin (F actin) which is made from 200 small globular units called G actin
Function of Tropomyosin
prevents interaction of actin and myosin
Troponin Function
Binds G actin to tropomyin
How is Actin bound to Z discs?
Nebulin
What are regulatory proteins and what are their functions?
Troponin and tropomyosin
Keep thick and them in proper alignment and give myofibril elasticity
Function of myomesin?
anchors actin to adjacent filaments on M line
What gets smaller during the sliding filament theory?
H and I
Z bands are moved closer together
What is a allosteric change?
Calcium binding to troponin causing it to change shape
What is a rigor complex?
How is it broken?
Head pulling the attached actin to and z lie toward the sarcomere
Broken by ATP connecting to myosin head
What is a triad?
2 terminal cisternae and 1 t-tubule
Duration of contraction depends on what?
Amount of ATP available
Duration of stimulus
Free Ca 2+ in sarcoplasm
Where does he NMJ occur?
Neurotransmitter found here?
Somatic motor neuron & skeletal muscle fiber
Ach
Where are neurotransmitters stored?
Synaptic vesicles
Sources for ATP production in muscle cells (3)
Creatine phosphate, anaerobic & aerobic
Where is most of ATP energy stored?
Phosphate bond of Creatine Phosphate
C-P is unique to what kind of tissue?
Can also be obtained from?
Muscle
Milk,meat & fish
Excess ATP from relaxed muscles
synthesis of liver and kidney
C-P and Ach amount of time for muscle contraction
15 second max- short distance bursts of energy
Anaerobic Cellular Respiration
Starts where and completes where?
Max muscle activity time
starts in cytoplasm which is anaerobic and ends in mitochondria which is aerobic
30-40 seconds
exergonic
Aerobic Cellular Respiration
ATP production in mitochondria-complete oxidation of glucose (cellular respiration), fatty acids & amino acids
exergonic
Mitochondrial ATP is dependent on what?
Availability of O2 delivered to blood by muscle cells depends on rate they can use it at
Aerobic respiration accounts for how much of ATP needed for muscular endurance?
90% for endurance lasting over 10 minutes
Muscle Fatigue (6) contributors
Depletion of C-P Build up of lactic acid Insufficient O2 or glycogen Decline of Ca2+ in sarcoplasm Insufficent release of Ach at NMJ
Muscle fatigue definiton
More pyruvic acid used than produced by mitochondria
Oxygen Debt caused by
Prolonged strenuous activity , considerable ATP production by mechanisms that don’t require oxygen
What happens to the excess ATP in Oxygen debt?
Decreases the accumulation of lactic acid by converting it back to pyruvic acid
Definition of Oxygen Debt
amount of oxygen the mitochondria would have used in order to produce that same amount of extra ATP
At rest what are mitochondria doing?
Producing ATP and using O2 , so in muscles they are producing more ATP than needed.
Tension depends on what?
depends on number of muscle fibers are contracting in unison
Muscle tone
Increasing metabolic energy even at rest
Twitch contraction
response of all fibers in a motor unit to a single stimulus or AP
3 phases of twitch response
Latent-instant stimulation , SR is releasing the stored Ca2+
Contraction-start on contraction, until forming rigor complexes
Relaxation-max contraction to max relaxation
Refractory Period
time where muscle will not respond to a second stimulus
If a stimulus is applied to a muscle after the refractory period
Will respond to a second stimulus by having a second AP
Second stimulus but has relaxed
Contracted state will be prolonged-tetanus
Wave Summation
Second stimulus before contraction muscle has completely relaxed, so contraction is prolonged
If greater than 50 - summation of twitches
Incomplete (Unfused) Tetanus
sustained muscle contraction in response to multiple stimuli 20-30 sec. permits partial relaxation between stimuli
Complete (fused) Tetanus
sustained contraction in response to multiple stimuli 80-100 sec that doesn’t allow partial relaxation between stimulus
Recruitment(multiple motor unit summation)
increasing number of active motor units
- delays fatigue so contraction can be sustained
- produces smooth muscular contraction and not jerky movements
Muscle Tone
state of maintained partial contraction , essential for things like maintain posture
Isotonic Contractions
tension does not change and muscles shorten and lengthen to move a weight.
Isometric Contractions
muscles do not shorten or lengthen and no movement occurs, however, tension increases; maintains body posture and supports objects in a fixed position.
What isn’t in the sarcoplasm?
myofibrils
Thin & intermediate filaments are attached to ?
Dense bodies, help transmit from cell to cell
Why is duration of contraction and relaxation of smooth muscle longer?
Longer than skeletal because of slower movement of Ca2_ ions
The sliding of thick and thin filaments generates tension on?
intermediate filaments which attach to dense bodies of sarcolemma and corkscrew
How is smooth muscle tone attained?
prolonged presence of calcium ions in cytosol: state of cont partial contraction.Calmodulin helps with corkscrew
Neuromuscular diseases are from?
Myopathy?
- somatic motor neurons
- neuromuscular junction
- muscle fibers
disease in disorder of skeletal muscle tissue
Myasthenia gravis
autoimmune disorder
muscular weakness and antibodies directed against Ach receptor
Duchenne Muscular dystrophies form of ?
muscular dystrophies
inherited
degeneration of individual muscle fibers