Muscle Tissue Flashcards
How many nuclei do Skeletal, Cardiac, and Smooth muscle have?
- Skeletal - multi
- Cardiac - 1-2
- Smooth - 1
What type of muscle exhibits structural branching?
Cardiac
What is a syncytium? How do skeletal muscle cells exhibit this characteristic?
- Many muscle cells acting as 1 unit
- All the muscle fibers contract at once…causes the whole muscles to contract.
T/F
Cardiac muscle is regenerative
FALSE
Cardiac muscle is not regenerative…skeletal muscle is regenerative.
What are the 3 layers of CT surrounding muscle?
Epimysium
Perimysium
Endomysium
[] is the outer most layer of CT around the entire muscle.
What type of CT is this?
- Epimysium
- Densre Irregular CT
What type of CT fibers would you find in the epimysium?
Collage, elastic, Reticular
[] divides the muscle into smaller functional units called fascicles
Perimysium
What layer of CT surrounds each individual muscle fiber?
What type of CT fibers would you find in this layer?
- Endomysium
- Collagen & Reticular Fibers
What are the 3 types of muscle fibers?
Type I - Slow Oxidative Fibers
Type IIa - Fast Oxidative, Glycolytic Fibers
Type IIb - Fast, Glycolytic Fibers
Type I - [] Oxidative Fibers
- [] twitch muscles
- [] myoglobin
- [] mitochondira
- Speed of Myosin ATPase = []
- Found in muscles for running, or []
Type I - Slow Oxidative Fiber
- Slow twitch
- Large amounts of myoglobin
- Many mitochondria
- Slowest ATPase
- Posture
Type IIa - [] [], Glycolytic Fibers
- [] twitch muscles
- In vivo color - []
- [] amounts of myoglobin
- [] mitochondira
- [] Glycogen
- Speed of Myosin ATPase = []
- [] resistance due to the the ability to use [] respiration and []
Type IIa - Fast Oxidative, Glycolytic Fibers
- Fast twitch muscles
- In vivo color - pink
- Large amounts of myoglobin
- Many mitochondira
- Alot of Glycogen
- Speed of Myosin ATPase = moderately fast I guess
- Fatigue resistance due to the the ability to use Cellular Respiration and Glycolysis
Type IIb - [] Fibers
- [] twitch muscles
- Size of Fiber -
- In vivo color - []
- [] myoglobin and mitochondria
- [] Glycogen content and [] activity
- Speed of Myosin ATPase = []
- [] prone
- Adapted for [] contractions and precise movements
Type IIb - Glycolytic Fibers
- Fast twitch muscles
- Size of Fiber - Large
- In vivo color - white, light pink
- Less myoglobin and mitochondria
- High Glycogen content and anaerobic activity
- Speed of Myosin ATPase = Fastest!
- fatigue prone
- Adapted for rapid contractions and precise movements
- The functional/contractile apparti of skeletal muscle and cardiac muscle is the []…
- The structural and functional subunit of the myofiber is the…[]
- Sarcomere
- Myofibril
Which specific myosin is the “thin filament” in a sarcomere?
Psyche!
Myosin is not the thin filament…you should know that.
Myosin II is the thick filament.
What 4 things can you find on the head of a Myosin II?
2 Light chains (regulatory and ATPase regulating)
1 ATPase
1 actin binding site
Where is titin found in the sarcomere? What does it do?
- It is found in the Z-line
- It anchors myosin to the Z-lines.
What protein anchors actin to the Z-line?
Alpha-actinin
- What type of protein is Nebulin?
- Where does it lie in the sarcomere?
- inelastic protein
- lies parallel to actin and assist in stabilizing alpha-actinin/actin interaction at the Z-line
[] is associated with the free end of actin, and “caps” actin to regulate its length
Tropomodulin
What 2 proteins are myosin binding proteins and hold myosing filaments “in register” at the M line?
Myomesin
C-protein
What are the 3 Extra Sarcomeric Accessory Proteins and what do they do?
- Costamere - sub-membrane Z-line associated protein structure that connects the sarcomere of the muscle to the cell membrane
- Dystrophin - links actin to laminin in the basal lamina
- Desmin - surrounds sarcomere at the Z-line attaching them to the sarcolemm
T-tubules align at the [] - [] junction perpendicular to fibrils
A-I Junction
So it helps to place the Ca2+ right at the myosin/actin junction for contraction.
T/F
Each muscle fiber has only one motor end-plate?
True!
Muscle Spindle
- Basically sense []
- Contains both [] and [] nerves
- Stretch Reflex - what is it?
- Loacated within the []
- basically it senses stretching
- Contains both afferent and efferent fibers
- Stretch Reflex - Stretch on the muscl ecauses a reflex contraction
- Located within the muscle
Golgi Tendon Organ (GTO)
- Monitors [] developed in muscle
- Consists of [] fibers only
- Prevents damage during [] for generation
- How?
- Tension
- Afferent
- Excessive
- Stimulation of the GTO results in reflex relaxation of muscle via interneuronal inhibition of alpha-motoneurons
Regular muscle cells outside of a muscle spindle are called what?
Extrafusal muscle fibers
(INtrafusal muscle fibers are within the spindle
What are the 2 types of intrafusal fibers?
- Nuclear chain fiber
- connect to efferent nerves
- Nuclear bag fiber - found within the center of a muscle spindle
- Connect to afferent nerves
What are the 2 types of nerve endings found on a muscle spindle?
- Annulospiral endings - respond to the rate of stretching)
- Flower Spray Endings - respond to the duration of stretching
What type of cell does skeletal muscle originate from?
What regulatory protein negatively controls muscle growth and differentiation?
Myoblast
Myostatin
Inhibition of [] causes excess muscle growth
myostatin
How do myoblasts differentiate from the embryo and end up as muscle cells? (Step-by-Step)
- Mesodermal progenitor Cells –>
- Myoblasts –>
- Multinucleate Myotube –>
- Muscle Fiber –>
What are the 2 mechanisms for cell repair? What are the cell types used for repair in each?
- Injury but External Lamina is Intact
- satellite cells become activated after injury and divide and differentiate into myoblasts. Then, myoblasts fuse within external lamina and become myotubes
- Injury by External Lamina is not intact
- Fibroblast repairs injury and it becomes scar tissue
T/F
Nebulin causes satellite cells to activate and repair skeletal muscle?
FALSE
- Yes, satellite cells repair, only, skeletal muscle….but cytokins cause the satellite cells to activate.
The sarcoplasm of cardiac muscles contain more [], [], and [] than skeletal muscle becuase its always contraction.
Glycogen, lipid, mitochondria
[] [] joins cardiac muscles and provides mechanical and electrical coupling…
intercalated discs
What is the sarcoplasmic cone in cardio myocytes?
- area around the nucleus in cardiac cells that is especially enriched with mitochondria and glycogen granules.
- It shows up as a “white cone” around the nucleus in staining.
What are the 2 transverse portions of the intercalated discs?
- Fasciae Adherentes
- analogous to zonulae adherens of epithelia to which actin filaments attach
- anchors thin filaments in sarcomeres
- Maculae Adherentes
- Desmosomes
- Bind cells to prevent separation during contraction
What are the 2 portions of an intercalated disc?
- Transverse Portion
- Fasciae Adherentes
- Maculae Adherentes
- Lateral Portion = gap junction
Which is stronger in the intercalated disc…
Transverse Portion
Lateral Portion (Gap Junction)
Transverse portion cuz it has desmosomes.
T/F
Cardiac muscle has SMALLER T-tubules than those in skeletal muscle and are lined with an internal lamina?
FALSE
- Cardiac muscles t-tubules are LARGER
- They are lined with an external lamina
T/F
In cardiac muscle, the T-tubes and SR form a dyad that lines up at the A-I junction, like in skeletal muscle
FALSE
- Cardiacs muscles do form a dyad, instead of a triad.
- However, these are located at the Z-lines, not AI-junction.
Atrial Granules:
- Found in muscle cells of the []
- What 2 polypeptide hormones are found in these granules?
- What doe these hormones function as? and what is their purpose?
- Atrium
-
Atrial Natriuretic Factor (ANF) and Brain Natriuretic Factor (BNF)
- These detect too much blood volume and signal the kidney to urinate more to reduce our blood volume!
Purkinje Fibers:
- modified [] muscle cells located in the [] [] of []
- [] than ordinary cardiac muscle cells
- lower content of [] & higher content of []
- modified cardiac muscle cells located in the atrioventricular bundle of His
- Larger than ordinary cardiac muscle cells
- lower content of myofibrils & higher content of glycogen
How do smooth muscles connect to each other electrically?
Gap Junctions
T/F
Smooth muscle secrete a ground substance matrix?
False
Smooth muscle can secrete a CT matrix of collagen.
What anchors thin filaments in smooth muscle?
Dense Bodies or Dense Plaques
T/F
In smooth muscles, most of the cytoplasmic organelles are mainly confined to conical regions a the ends of the centrally locted nucleus?
True!
Thin filament in Smooth Muscle:
- contains [] - the primary substance
- Also contains troponin just like skeletal muscle…
- Contains [] and [] that bind to actin and block the [] binding site on actin
- Actin
- FALSE! - smooth muscle does not contain troponin. It has tropomyosin though.
- Caldesmon and Calponin; block myosin binding site on actin
Dense bodies in smooth muscle are functionally comparable to skeletal muscle [] - []
Z-Discs
What filaments attaches to the dense plaques in smooth muscle?
- Thin filament - actin
- Intermediate Filaments
- Vimentin
- Desmin
What are the 2 contractile non-muscle cells?
Myoepithelial Cells
Myofibroblasts
Myoepithelial Cells
- [] to assist in the expression of glandular material
- Located between the epithelium and [] lamina of certain types of glands
- In mammary glands - contraction is initiated by []
- In lacrimal glands - contraction is initiated by []
- Contract
- basal lamina
- oxytocin
- acetylcholine
T/F
Myoepithelium cells may contribute to wound healing contracting to decrease size of defect….
False
Myofibroblasts may do this.
