Quiz #3: Muscle Flashcards
What are the three types of muscle tissue? Name the types of contractions and where they are located.
- Skeletal: Voluntary Movements, anything you can move
- Cardiac: Involuntary/Strong, found in the heart
- Smooth: Involuntary/Weak, found in hollow tubes (respiratory tract, digestive tract, Fallopian tubes, vas deferens…)
What is the basic function of muscle?
-Contactility
-Achieved due to actin protein filament with Myosin
All cells have actin and myosin (True/False)
-True
-Although concentrations are higher around muscles, all cells have actin and myosin.
Myosin is a motor protein that has a similar function to _________
Kinesin
The contraction of muscle is important for numerous functions including:
-Locomotion
-General body movements
-Blood circulation
-Peristalis
-Involuntary functions of the body:
(Transport of sperm/ovum, heart pumping, maintenence of blood pressure and function of sphincters)
What is the difference between G-actin and F-actin?
G-Actin: Single strand
F-Actin: Two strands wrapping around each other to form a micro filament
(Each actin filament has two strands)
Why are myosin and actin important in cytokinesis (end of meiosis)?
Formation of the contractile ring
What are some differences between rER and sER?
-Prescence of ribosomes: sER has none
-Structure: sER is more tubular/saccular
What is the function of sER in muscle?
Storage and release of calcium ions
(activate the contractile mechanism)
Name the cellular organelles of a muscle cell and their definitions
-Sarcoplasm: Cytoplasm of a muscle cell
-Sarcoplasmic Reticulum: Smooth ER
-Sarcolemma: Plasma membrane of the muscle cell
Actin and Myosin play a time in forming the contractile ring when the 2 daughter cells separate at the end of cell division (True or False)
True
Functions of Muscle Cells
-Storage and release of calcium ions
-Activate the contractile mechanism
Cellular Organelles of a muscle cell
-Sarcoplasm: Cytoplasm of a muscle cell
-Sarcoplasmic Reticulum: Smooth ER
-Sarcolemma: Plasma membrane of the muscle cell
Characteristics of Skeletal Muscle
-Multinucleated (Located Peripherally below the sarcolemma)
-Striated (Very evident)
-1 multinucleated cell
-Voluntary (all or none)
-Contraction is quite strong
-Cylindrical Shape
What is the regeneration capacity of skeletal muscle and how does it regenerate?
Limited; Regeneration done through Satellite Cells
Where is skeletal muscle found in the body?
Skeletal muscle, tongue, eyes, diaphragm
Characteristics of Cardiac Muscle
-Cylindrical (Branched)
-Mononucleated (surrounded by glycogen inclusion bodies)
-Strong Involuntary contractions
-Glycogen used for energy
-Cell connections made via intercalated discs (making cells striated)
-Many mononucleated cells attached end to end
-Automomous innervation (All or None)
What is the regeneration capacity of cardiac muscle?
Limited
Where is cardiac muscle found?
Heart only
Characteristics of Smooth Muscle
-Spindled (fusiform) shaped
-Lack Striations
-Not to strong, involuntary contractions (partial)
-Many spindle cells bound to one another via cell junctions
What is the capacity of smooth muscle to regenerate?
Greatest capacity to regenerate (Mitosis of muscle cells)
Where does skeletal muscle originate and what do they differentiate into?
Embryonic mesenchyme; First differentiate into myoblasts
How does skeletal muscle form one multinucleated cell?
Many myoblasts fuse with each other then later develops into a striated muscle fiber
Where are satellite cells found and what is their function?
-“left out” cells found attached to muscle cells outside the sarcolemma
-Muscle Repair (Cell division/forming new cells)
Characteristics of Epimysium
-Dense layer of CT that covers the whole muscle
-Present just under the deep fascia
-Connects bone to muscle
Characteristics of the Perimysium
-Dense layer of connective tissue that covers fascicles
-Thinner than Epimysium but still dense CT
Characteristics of Endomysium
-Covers each muscle fiber
-Both endomysium layers contain collage type 1, collagen type 3 and fibroblasts
What kind of nucleus does a fibroblast have?
Pachychromaric nucleus (dormant cell)
What kind of nucleus does a skeletal muscle have?
Leptochromatic nucleus (Active cell)
What is the A-Band made of?
Myosin protein
What is the I-Band made of?
Actin
What is each myofiber made up of?
5-6 myofibrils
What is the contractile unit of a muscle fiber?
Sarcomere
Where does a sarcomere span?
From z-disc to z-disc
What is a thick filament?
Myosin
What is a thin filament?
Actin
What two regulatory proteins are associated with F-actin?
Troponin and Tropomyosin
What three things combine together to make the thin filament?
F-actin + tropomyosin + troponin
What is Tropomyosin and what is it’s purpose?
-Wraps around the twisted F-actin/lies in the groove between 2 f-actin fibers
-keeps the myosin binding sites of actin covered when not in action
What is the structure of Troponin and what does it do?
-1 protein and 3 subunits
-Binds to Tropomyosin
What are the three subunits of Troponin and what is their purpose?
-TnT: Binds to Tropomyosin
-TnC: Binds to Ca++
-TnI: Actin and Myosin interactions
What is the structure of myosin?
Made of 2 tails twisted around each other and 2 globular heads
What does ATP break down in order to make a contraction
ADP + Pi
