Chapter 7 Davis Flashcards
- The unit of contraction in a muscle fiber
sarcomere
The very large extensor of the thigh
gluteus maximus
Transmits action potential for contraction
sarcolemma
Integrates unconscious muscle sense
cerebellum
State of slight contraction of muscles
muscle tone
Dome-shaped respiratory muscle
diaphragm
Neurotransmitter at neuromuscular junctions
acetylcholine
Releases the energy of A T P
myosin
Why are muscle actions grouped in such pairs?
Muscle actions are grouped in pairs, because a muscle can only pull a bone, not push. A muscle pulls in one direction. Another muscle is needed to pull in the opposite direction.
These are antagonistic functions or pairs of opposites.
Most muscle actions are in pairs:
Flexion—
extension
Most muscle actions are in pairs:
Abduction—
adduction
Most muscle actions are in pairs:
Inversion—
eversion
Most muscle actions are in pairs:
Pronation—
supination
the inability of muscles to contract
Paralysis
In response to a single nerve impulse, a muscle fiber will contract completely (all of the sarcomeres contract) and then relax
Twitch
The functions of the muscular system are to:
- Move the skeleton
- Produce heat
Name the tissues that make up the parts of the muscular system.
The skeletal muscles are made of skeletal muscle tissue, also called striated or voluntary muscle tissue.
Tendons are made of fibrous connective tissue.
The fascia around each muscle is also made of fibrous connective tissue.
Tendons are made of
fibrous connective tissue.
The fascia around each muscle is made of
fibrous connective tissue
The organ systems directly necessary for movement are the:
- Skeletal system
- Nervous system
- Respiratory system
- Circulatory system
The skeletal system is moved by
muscles
The nervous system transmits
electrochemical impulses to muscles.
The respiratory system exchanges O2 and C O2 between
the air and the blood.
The circulatory system transports
O2 to muscles and takes C O2 away.
One muscle is made of thousands of
muscle fibers.
Muscle fibers
contract, shorten, and bring about movement.
Tendons attach muscles to
bone
A tendon merges with
the fascia of the muscle and the periosteum of the bone.
the state of slight contraction present in healthy muscles; regulated by the cerebellum
Muscle Tone
the direct source
A T P
for the resynthesis of A T P
Creatine phosphate
a nitrogenous waste product.
Creatinine
most abundant, stored in muscles
•First broken down to glucose
•Glucose + O2 C O2 + H2O + A T P + heat
Glycogen
What happens to each of the products of cell respiration?
C O2 is exhaled.
Water becomes part of intracellular fluid.
A T P is used for the contraction process.
Heat contributes to body temperature.
Name the cell organelle that is the site of cell respiration.
The mitochondria are the sites of cell respiration.
The brain creates a mental picture:
Unconscious muscle sense is essential for
coordination in the cerebellum
The brain creates a mental picture:
Conscious muscle sense is in
the parietal lobes
knowing where our muscles are without seeing them
Muscle Sense (proprioception)
Stretch receptors (proprioceptors) in muscles detect
stretching, generate impulses.
the outside of the sarcolemma becomes negative relative to the inside.
Depolarization
the sarcolemma has a (+) charge outside and a (negative) charge inside.
Polarization (resting potential)
Electrical charges outside and inside the membrane are created by
the presence and movement of ions.
Sliding Filament Mechanism
Nerve impulse arrives at the axon terminal and
A c h is released.
Sliding Filament Mechanism
A c h A c h receptors on the sarcolemma; N a+ ions enter
the cell.
Sliding Filament Mechanism
The sarcolemma
depolarizes.
Sliding Filament Mechanism
With depolarization: C a+2 ions are released from the _______; C a+2 ions bond to _______.
sarcoplasmic reticulum; troponin-tropomyosin
Sliding Filament Mechanism
Myosin splits
A T P.
Sliding Filament Mechanism
Myosin bridges pull the actin filaments to the
center of the sarcomere.
Sliding Filament Mechanism
All of the sarcomeres in a muscle fiber
shorten.
Sliding Filament Mechanism
The sarcolemma
repolarizes.
Sliding Filament Mechanism
Cholinesterase inactivates
A c h.
Sliding Filament Mechanism
Subsequent nerve impulses:
prolong contraction.
Sliding Filament Mechanism
No further impulses:
the muscle fiber relaxes.
The origin of a muscle is the
More stationary bone
The insertion of a muscle is the
More movable bone
have opposite functions. A muscle pulls when it contracts but exerts no force when it relaxes and it cannot push. When one muscle pulls a bone in one direction, another muscle is needed to pull the bone in the other direction
Antagonistic muscles
have the same function and alternate as the prime mover depending on the position of the bone to be moved. also stabilize a joint to make a more precise movement possible.
Synergistic muscles
generate the impulses necessary for contraction of skeletal muscles. The cerebellum regulates coordination.
The frontal lobes of the cerebrum
A muscle can only
pull a bone
helps maintain posture, produces 25% of body heat (at rest), and improves coordination.
Good muscle tone
involves contraction with movement; improves tone and strength and improves cardiovascular and respiratory efficiency (aerobic exercise).
Isotonic exercise
Isotonic exercise:
Concentric contraction —
muscle exerts force while shortening.
Isotonic exercise:
Eccentric contraction-
muscle exerts force while returning to its original length.
involves contraction without move-ment; improves tone and strength but is not aerobic.
Isometric exercise
Exercise stimulates skeletal muscle cells to secrete the hormone irisin, which converts fat-storing white adipocytes to thermogenic brown or beige adipocytes.
Important information
Hemoglobin in R B C’s carries
Oxygen to muscles
Myoglobin in muscle cells stores
Oxygen in muscles
Lactic acid is formed in place of C O2 and H2O:
which lowers cellular pH and contributes to fatigue.
Oxygen debt (recovery oxygen uptake):
Muscle fibers run out of oxygen during strenuous exercise
Neuromuscular junction: axon terminal and sarcolemma:
the synapse is the space between them.
The axon terminal contains
acetylcholine (a neurotransmitter)
the sarcolemma contains
cholinesterase (an inactivator)
Sarcomeres are the
contracting units of a muscle fiber.
Myosin and actin filaments are the
contracting proteins of sarcomeres.
Troponin and tropomyosin are proteins that inhibit
the sliding of myosin and actin when the muscle fiber is relaxed
The sarcoplasmic reticulum surrounds the sarcomeres and is a reservoir for
calcium
(Polarization)
N a+ ions are more abundant
outside the cell
(Polarization)
K+ ions are more abundant
inside the cell
(Polarization)
The sodium and potassium pumps maintain these relative concentrations on
either side of the sarcolemma
. is the exit of K+ ions and the restoration of a positive (+) charge outside.
Repolarization
T tubules are
Folds up of the sarcolemma
makes the sarcolemma permeable to N a+
A c h
a sustained contraction brought about by continuous nerve impulses; all our movements involves it.
Tetanus
Muscles that do not receive nerve impulses are unable to contract and will atrophy.
Paralysis
Paralysis may be the result of
nerve damage, spinal cord damage, or brain damage.
The end of a motor neuron; contains vesicles of acetylcholine that are opened by the arrival of a nerve impulse
Axon terminal
The enzyme that inactivates acetylcholine; prevents continued depolarization and contraction
Cholinesterase
The neurotransmitter released by the axon terminal; it diffuses across the synaptic cleft, bonds to the ACh receptors, and brings about depolarization of the sarcolemma with an influx of Na* ions
Acetylcholine (ACh)
The space between the axon terminal and the sarcolemma
Synaptic cleft
Proteins of the sarcolemma that are channels for Na+ ions; are opened by acetylcholine
Acetylcholine receptors
The cell membrane of the muscle fiber; has receptors for acetylcholine
Sarcolemma
