Chapter 10 Muscular tissue Flashcards
What are three types of muscle tissue?
- Skeletal
- Cardiac
- Smooth
What are the functions of muscle tissue?
- produce movement
- stabilizing body positions
- storing and mobilizing substance within the body
- generate heat
What are some properties of muscular tissue?
- Electrical excitability
- contractility
- extensibility
- elasticity
What are three types of fascia?
- epimysium
- perimysium
- endomysium
What are two types of sacrolemma?
- Sarcoplasm
- Sarcoplasmic reticulum
What are two types of contractile muscle proteins?
Myosin and actin
What are muscle fascicle?
Bundle of muscle fibers wrapped in perimysium
What are muscular fibers
Long cylindrical cell covered by endomysium and sarcolemma; contains sarcoplasm, myofibrils, many peripherally located nuclei, mitochondria, t tubules, sarcoplasmic reticulum and terminal cisterns. Striated appearance
What is a myofibril?
Threadlike contractile elements within muscle fiber that extend entire length of fiber; composed of filaments
What is a filament?
Contractile proteins within myofibrils that are two types: thick filaments composed of myosin and thin filaments composed of actin, tropomyosin, and troponin; sliding of thin filaments past thick filaments produces muscle shortening
What are z discs?
Narrow, plated- shaped regions of dense material that separate one sarcomere from the next
What is an A Band?
Dark, middle part of sarcomere that extends entire length of thick filaments and includes those parts of thin filaments that overlap thick filaments
What is an I band?
Lighter, less dense areas of sarcomere that contains remainder of thin filaments but no thick filaments, A Z disc passes through center of each I band
What is the H band?
Narrow region in center of each A band that contains thick filaments but no thin filaments
What is a M line?
Region in center of H zone that contains proteins that hold thick filaments together at center of sarcomere
What is the sliding filament mechanism?
- Myosin pulls on actin, causing the thing filament to slide inward
- Z disc move towards each other and the sarcomere shortens
- Thanks to structural proteins, there is a transmission of force throughout the entire muscle, resulting in muscle contraction
What is the excitation- contraction coupling?
This concept connects the events of a muscle action potential with the sliding filament mechanism
What is the length- tension relationship?
The force of a muscle contraction depends on the length of the sarcomeres in a muscle prior to contraction
What are the three ways to produce ATP?
- Creatine phosphate
- Anaerobic glycolysis
- Aerobic respiration
How does creatine phosphate (CP work)
Creatine kinase catalyzes the transfer of a phosphate group from CP to ADP to rapidly yield ATP
How does Anaerobic Glycolysis work?
When CP stores are depleted, glucose is converted into pyruvic acid to generate ATP
How does Aerobic respiration work?
Under aerobic conditions, pyruvic acid can enter the mitochondria and undergo a series of oxygen-requiring reactions to generate large amounts of ATP
What is Muscle fatigue?
The inability to maintain force of contraction after prolonged activity
The onset of fatigue is due to what four things?
- Inadequate release of Ca2+ from ST
- Depletion of CP, oxygen, and nutrients
- Build up of lactic acid and ADP
- Insufficient release of ACh at NMJ
Why do you continue to breathe heavily for a period of time after stopping exercise?
- To pay back your oxygen debt
- Replenishing CP stores
- Converting lactate into pyruvate
- Reloading O2 onto myoglobin
The strength of a muscle contraction depends on what?
How many motor units are activated
A motor unit consists of what?
A somatic motor neuron and the muscle fibers it innervates
Activating only a few motor units will generally result in what?
A weak muscle contraction
Activating many motor units will generally result in what?
A strong muscle contraction
What is motor unit recruitment?
The process in which the number of active motor units increases
During muscle recruitment what is recruited first?
Weak motor units are recruited first, followed by stronger motor units
Motor units contract alternatively to do what?
Sustain contractions for longer periods of time
What is muscle tone?
The small amount of tension that skeletal muscles exhibit even at rest
Tone is established by what?
Alternating, involuntary activation of small groups of motor units in a muscle
What is isotonic?
When Tension is constant while muscle length changes
How are two ways we can achieve isotonic?
- Concentric
- Eccentric
What is isometric?
Muscle contracts but does not change length
