Chapter 14: Muscle Tissue and Organization Flashcards
What are the 4 properties of muscle?
- Excitability: responds to external stimuli w/ electrical changes
- Contractility: tension may lead to shortening
- Elasticity: returns to resting length when tension ceases
- Extensibility: stretched by other muscles
List the 5 functions of muscle.
- Body movement
- Maintenance of posture
- Protection and support
- Sphincters control passage of materials
- Temperature regulation
In the skeletal muscle structure, what dense irregular connective tissues make up the skeletal muscle and fascicle?
Skeletal muscle= epimysium
Fascicle= perimysium
The endomysium is (___) connective tissue and makes up what skeletal muscle structure?
Areolar connective tissue
- endomysium= muscle fiber (cell)
Identify the highlighted structures.
- Tendons
- Epimysium
- Perimysium
- Endomysium
What is the sarcolemma?
The plasma membrane
What structure is being described:
- extensions of sarcolemma deep into the cell
- allow for conduction of electrical signals
- increases surface area
T-tubules
The sarcoplasmic reticulum has blind ended sacs called the (____) that stores calcium ions.
Terminal Cisterna
Why is calcium important?
It allows for muscle contraction
Identify the highlighted structures.
orange: sarcolemma
pink: sarcoplasma
red/purple: myofibrils
yellow: myofilaments
dark blue: sarcoplasmic reticulum
blue: terminal cisterna
green: transverse tubules (T-tubules)
yellow: Triad
Where is the sarcolemma, T-tubule, and terminal cisternae located on this image?
- Sarcolemma
- T-tubule
- terminal cisterna
What makes up the triad.
- Terminal cisterna
- t-tubule
- Terminal cisterna
The myofibrils are enclosed in which specific structure?
A. sarcoplasmic reticulum
B. sarcolemma
C. myosin
D. actin
A. sarcoplasmic reticulum
The thick myofilmaents are called:
myosin
The thin myofilaments are called (____) and the two types are called:
actin
- f-actin
- g-actin
Label tropomyosin and troponin. Describe what Ca2+ binds to during which process.
Green: tropomyosin
- the actin cross-bridge is blocked by tropomyosin
Blue: troponin
- Ca2+ binds to troponin and undergoes conformational change
- tropomyosin unblocks actin for muscle contraction
The sarcomeres are the contractile unit of a myofibril and contain what special characteristic?
striations
Label the M line, H zone, A band, and sarcomere. Give a description of each.
Sarcomere: contractile unit
M line: protein structure; attachment for thick filaments
H zone: only thick filaments
A band: thick filaments and parts of the thin filaments
Label the I bands, Titin, and Z discs. Give a description of each.
I bands: only thin filaments
Titin: very elastic protein; muscle stretched beyond resting
Z disc: protein structure; anchors thin filaments
When the sarcomere shortens, what action is this called?
Contraction
What 3 things make up the motor unit?
- motor neuron
- Muscle fibers
- Neuromuscular junction
Label this structure and describe its two types.
Motor unit
1. small motor units
- less power, precise control
- controlling two or three muscle fibers (eye/hand)
2. large motor unit
- more power, less precise
- controlling 2000 muscle fibers (thigh)
What is the precise location the neuron innervates the muscle fiber?
Neuromuscular junction (NMJ)
Label the following:
- neuromuscular junction
- synaptic cleft
- synaptic knob
- motor end plate
Labeled
Which specific region is between the neuron and muscle?
A. motor end plate
B. synaptic knob
C. synaptic cleft
C. synaptic cleft
This structure has voltage-gated Ca2+ ion channels, synaptic vesicles that release acetylcholine, and is the extended tip of the motor neuron. Name this structure.
Synaptic knob
What kind of receptor and pump is located on the motor end plate?
- ACh receptors
- Na+/K+ pump
What are the 3 steps of skeletal muscle contraction according to this image.
- Neuromuscular junction: excitation of a skeletal muscle fiber
- Sarcolemma, T-tubules, and sarcoplasmic reticulum: excitation-contraction coupling
- Sarcomere: crossbridge cycling
List three steps that occur at the neuromuscular junction.
1a. Nerve signal triggers influx of Ca2+ at synaptic knob
- Ca2+ binds to proteins in synaptic vescicles
1b. Ca2+ binding causes synaptic vesicles to merge with synaptic knob membrane
- ACh is released from the vesicles
1c. ACh diffuses across synaptic cleft and binds to receptors on motor end plate
List three steps that occur at the sarcolemma, t-tubules, and sarcoplasmic reticulum.
2a. Binding of ACh to receptors on motor endplate triggers chemically-gated ion channels to open
- Na+ influx, K+ efflux
- membrane potential changes as Na+ enters = EEP (end plate potential)
2b. EEP initiates an action potential along t-tubules
- Na+ channels open= depolarization
- K+ channels open = repolarization
2c. Ca2+ release from channels in terminal cisternae due to action potential
- Ca2+ diffuses out of the terminal cisternae into sarcoplasmic reticulum
What are the types of muscle contraction?
- Isometric contraction
- Isotonic contraction
Which isotonic contraction shortens as it contracts? Which one lengthens?
Concentric: shortens as contracts
Eccentric: lengthens as it contracts
List the three types of muscle fibers (twitches) and their oxygen state.
- Slow (Type I, oxidative)
- Intermediate (Type IIa, fast oxidative)
- Fast (Type IIb, fast anaerobic)
List 5 characteristics of slow twitch muscle fibers.
- slow, less powerful contractions
- smallest diameter
- aerobic
- abundant myoglobin
- oxygen reserve
- red color - very fatigue resistant (marathon runners: thighs)
List 5 characteristics of fast twitch muscle fibers.
- fast, powerful contractions
- largest diameter
- anaerobic
- no myoglobin
- white color - fatigue easily (sprinters, hand/eye muscles)
Recall the 11 steps of muscle contraction starting with the electrical impulse and ending with ATP binding to myosin.
Steps 1-11.
