Download MUSCLE REVIEW

MUSCLE REVIEW - TEST
4 functions of muscles

Functions of Skeletal Muscle
movement
 Produce _________
 Maintain _______
posture
joints
 Stabilize _____
 Generate _____
heat
Prefixes

All muscles share some terminology
myo
Prefix _____refers
to muscle
 Prefix mys
____ refers to muscle
sarco refers to flesh
 Prefix ______

Tendon/Aponeurosis
Tendons epimysium blend into a cordlike structure
________;
connecting muscles to bones
sheetlike
 Aponeurosis: ________

3 types of muscle tissue
Types of muscle tissue:
1. Skeletal muscle tissue
• Associated with & attached to the skeleton
• Under our conscious (voluntary) control
• Microscopically the tissue appears striated
• Cells are long, cylindrical & multinucleate
3 types of muscle tissue
Types of muscle tissue:
2. Cardiac muscle tissue
• Makes up myocardium of heart
• Unconsciously (involuntarily) controlled
• Microscopically appears striated
• Cells are short, branching & have a single nucleus
• Cells connect to each other at intercalated discs
3 types of muscle tissue
Types of muscle tissue:
3. Smooth (visceral) muscle tissue
• Makes up walls of organs & blood vessels
• Tissue is non-striated & involuntary
• Cells are short, spindle-shaped & have a single nucleus
• Tissue is extremely extensible, while still retaining ability to
contract
Coverings of muscles

Endomysium
__________; connective tissue that encloses each muscle
fiber
Perimysium connective tissue that wraps into a bundle
 ___________;
fascicle
called a ______
Epimysium many fascicles bound together
 __________;
Sarcomere/Sarcolemma/Sarcoplasm
• Sarcomere - Contractile unit of the muscle from Z-Line to ZLine
• Sarcolemma – acts as the plasma membrane for the muscle;
is sensitive at the motor unit
• Sarcoplasm – acts as the cytoplasm of a muscle cell
Sarcomere arrangement
• (a) Relaxed position
• (b) Contracted state
• Note the difference in the
muscle as it shorten (contracts)
• Also realize the myofilaments do
not change their size or shape
Sarcoplasmic Reticulum/T-tubules, striations
• Sarcoplasmic Reticulum – stores and releases Calcium in the
muscle
• T-tubules – (transverse) is a passageway for the Action
Potential to travel to the SR
• Striations – striped appearance due to alternating dark and
light bands
A & P of NMJ
• http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0009swf_function_of_th.swf
A & P of NMJ
Action potential
Ca2+
1
• Motor Neuron meets with the
muscle forming a motor unit
• Synaptic cleft – gap between
motor neuron and muscle
• Motor end plate (MEP) – found
on the sarcolemma
Synaptic
vesicle
Voltage-gated
Ca2+ channel
Presynaptic
terminal
Synaptic cleft
2
3
Acetylcholine
Postsynaptic
membrane
Na+
Acetylcholine bound
to receptor site opens
ligand-gated Na+
44
channel
H-Zone, Z-line
Chemicals involved in contraction:
• ACh – acetylcholine ( a neurotransmitter)
• AChE – acetylcholinesterase (an enzyme) to help with the
reabsorption of ACh
• Na – Sodium causes depolarization of the sarcolemma once
ACh sufficiently stimulates the muscle to produce an AP
• K – Potassium is intracellular and gets pumped out during
depolarization
• Ca – Calcium is vitally important in the neuron to cause
vesicle exocytosis and in the muscle as it binds to troponin
Proteins involved in contraction:
• Troponin – Calcium binds to it as it is released from the SR
• Tropomyosin – exposes the binding sites once troponin
produces a change in positioning
• Binding sites – (active sites) myosin heads form cross-bridges
to link the myosin to the actin to produce the sliding phase
(AP) Action potential (propagation)
• An AP gets generated either in the motor neuron by the
brain and spinal cord or it is formed by the inward rush of
Sodium into the muscle
• The T-tubules are the connection between the sarcolemma
and the SR
Nerve Impulse Transmission
•POLARIZED – when the plasma membrane
(sarcolemma) is resting or inactive. The
membrane is relatively impermeable to
both sodium and potassium.
Fewer positive (+) ions are on the inside (intracellular) than
there are on the outside (extracellular)
Na+ (Sodium) is extracellular; K+ (Potassium) is
intracellular
Note: as long as the inside remains more negative as
compared to the outside, then the muscle will remain
inactive
Nerve Impulse Transmission
DEPOLARIZATION – the inward rush of Sodium
ions into the cell changes the polarity (+ -)
• The inside is now more positive, the outside
more negative which generates an Action
Potential (AP)
• Na+ (Sodium) is now intracellular due to change
in permeability; K+ are allowed to diffuse out
• Note: the nerve impulse is an all-or-none
response – either it affects the entire muscle or
not at all as it spreads (propagates)
Nerve Impulse Transmission
• REPOLARIZATION – restores the muscle to a resting or
polarized state due to the outflow of positive ions.
• The electrical conditions are restored to a polarized state
via the NaK pump.
• Na+ is now extracellular, K+ becomes intracellular
• Note: until repolarization occurs, a neuron cannot
conduct another impulse
Energy Factors
• ATP
• ADP + Pi
• Phosphorylation of ADP by
Creatine Phosphate
 Fastest mechanism for
regenerating ATP
 Creatine phosphate found only in
muscle cells
 Supply is quickly exhausted
(about 15-20 seconds)
Aerobic vs. Anaerobic
• Aerobic – requires oxygen
• Anaerobic – does not require oxygen
• Glucose – energy source as it is broken down to pyruvic acid to
gain ATP; also requires oxygen to continue
• Oxygen – body produces lactic acid which leads to fatigue as
levels decrease
• Lactic acid – leads to muscle fatigue as levels increase due to
low levels of oxygen
Aerobic respiration
• Glucose is broken down to
carbon dioxide and water,
releasing energy (ATP)
• This is a slower reaction that
requires continuous oxygen
• A series of metabolic pathways
occur in the mitochondria
Anaerobic respiration
• Anaerobic glycolysis and lactic
acid formation
– Reaction that breaks down
glucose without oxygen
– Glucose is broken down to
pyruvic acid to produce some
ATP
– Pyruvic acid is converted to
lactic acid
Oxygen debt
• Body replaces the “borrowed” oxygen during rapid breathing
once bout of exercise is suspended.
• When the demand for oxygen is too great than what the body
can supply, then the body changes over to the anaerobic type.
Isotonic/Isometric
Isotonic contractions
Myofilaments are able to slide past each other during contractions
The muscle shortens
Isometric contractions
Tension in the muscles increases
The muscle is unable to shorten
Fast twitch/Slow twitch fibers
• Fast Twitch – are white due to low oxygen levels; rely on short,
powerful bursts of activity; have smaller mitochondria
• Slow Twitch – are red due to larger mitochondria and oxygen
levels; are for duration and distance
• Both are genetic – you have what you have
Muscle Movements
Muscle Movements
Muscle Movements