A&P exam 3 Flashcards
Lectures 6.3-10.1
major tissue type
typically shortens to create movement
muscle
point of muscle attachment that does not move the structure
origin
point of muscle attachment where muscle moves the structure
insertion
Muscles located on the anterior forearm
flexors
muscles located on the posterior forearm
extensors
muscles of the shoulder
rotator cuff
muscles of the anterior thigh
quadriceps
muscles of the posterior thigh
hamstrings
muscles of the medial thigh
adductor
group of muscles in the lower back
erector spinae
What are the levels of muscle organization in order from largest to smallest?
muscle body (epimysium)
muscle fascicles (perimysium)
muscle fibers (endomysium) => cell
myofibrils => organelle
sarcomeres
actin and myosin
What’s the name of the connective tissue surrounding muscle fascicles?
perimysium
What are the units that make up a myofibril?
sarcomeres
What causes sarcomere shortening?
increased overlap of actin and myosin (slides past) [action potential]
Are the thick filaments actin or myosin?
myosin
Are the dark areas in striated muscle A bands or I bands?
A band= myosin
What shape of muscle provides the greatest strength?
convergent or pennate
Which type of muscle is not striated?
smooth
How is a membrane potential created/maintained?
- stimulus causes some Na channels to open
- threshold is reached, ligand-gated Na channels open, depolarization occurs
- Na channels close and K channels open, repolarization occurs
- Voltage overshoots, K channels close, voltage returns to normal
What is the normal voltage for a resting potential?
-
What happens to voltage during an action potential?
becomes positive briefly
What happens to potassium channels during hyperpolarization?
they close
What is notable about the absolute refractory period?
no new action potentials can start regardless of stimulus
What is a T-tubule?
transverse tubules, alleyways in sarcolemma that stretch towards myofibrils
Where can one find the sarcoplasmic reticulum?
adjacent to t-tubules
What ion is released from the sarcoplasmic reticulum?
Ca2+
What part of the sarcomere rotates during contraction?
actin
What neurotransmitter is used to initiate contraction?
acetylcholine
What is muscle recruitment?
number of motor units
Which would you expect to have more motor units–muscle of the hand or the back?
back
If a person picks up a ball off the ground, what kind of contraction happened?
isotonic
Factors in contraction force and muscle fatigue
number of motor units, diameter of fibers, frequency of stimulation, length of muscle fiber
Isotonic vs isometric contraction
isotonic: shortens muscle, moves objects
isometric: pulling of the muscle that does not shorten it
Fast vs Slow twitch fibers
slow: more mitochondria, aerobic, myoglobin, duration
fast: anaerobic, short and intense use
Where would you expect muscle that makes the most use of aerobic respiration?
back
What molecules can be used to supply muscle with energy once its initial ATP has been used up?
creatine, glucose
What causes rigor mortis?
Since ATP is no longer present, there is nothing to make the muscles relax until myofilaments decay
smooth muscle
- unconscious control
- no myofibrils
- activation: neurons or hormones (Ca+)
- structure: sigmoidal shape, network of actin and myosin, gap junctions, random nuclei, no striations
skeletal muscle
- conscious control
- activation: neurons
- structure: striated, elongated nuclei pushed to sides
cardiac muscle
- unconscious control
- activation: neurons
- structure: intercalated disks, striated, split cells, random nuclei
Location of smooth muscles
internal organs
What do gap junctions allow smooth muscle to do?
allows action potential to travel to adjacent cells
