8: Muscle Tissue Flashcards
What are the 3 kinds of muscle tissue?
Skeletal, cardiac, smooth
What are the 4 properties of muscle tissue?
Excitability, contractability, elasticity, extensibility
What is unique about cardiac fibers?
“Y” shaped/branched fibers
How many nuclei do cardiac cells have?
Uninucleate or binucleate
What is the name of the structure that joins cardiac cells?
Intercalated discs
What does it mean that cardiac cells are auto-rhythmic?
They can contract without input from the nervous system
Where is smooth muscle found?
Walls of visceral organs and walls of arteries
What is the shape of smooth muscle cells?
Fusiform
How many nuclei do smooth muscle cells have?
Uninucleate
Which muscle cells are striated/not striated?
Cardiac and skeletal are striated, smooth is not
What muscle type is fatigue resistant?
Smooth
What is the shape of skeletal muscle cells?
Large cylindrical shape
How many nuclei do skeletal muscle cells have?
Multinucleated
Skeletal muscle cells are formed from the fusion of what cells?
Myoblasts
What are the 6 functions of skeletal muscle?
Movement,
Maintenance of posture,
Temperature regulation,
Storage and movement of materials,
Support and protection abdominal organs,
Joint stabilization
What bodily functions are performed with skeletal muscle?
Swallowing, urination, and defecation
What type of muscle is vascular?
Skeletal
What is mysia and the three layers of it?
Layers of connective tissue is skeletal muscle
1. Epimysium
2. Perimysium
3. Endomysium
What is the structure of epimysium?
Dense, irregular connective tissue
What layer of the mysia is most superficial and covers a muscle?
Epimysium
What is a bundle of skeletal muscle fibers called?
Fascicle
What layer of the mysia forms the fascicles?
Perimysium
What is the structure of the endomysium?
Collagen and reticular fibers
What layer of the mysia wraps the myofibers?
Endomysium
What layer of the mysia contains extracellular fluid and nutrients to support the muscle fiber?
Endomysium
What structure wraps muscle groups?
Deep fascia
What does the collagen of a tendon intertwine with to attach to a muscle?
The collagen of the three layers of the mysia
What is a broad, tendon-like sheet that mysia may fuse to called?
Aponeurosis
What are myofibrils composed of?
Chains of sarcomeres
What does the fusion of myoblasts allow for?
Multiple codes of genes in a cell, permitting the production of large amounts of proteins and enzymes
What is the plasma membrane of muscle fibers called?
Sarcolemma
What is the cytoplasm of muscle fibers called?
Sarcoplasm
What are the functional units of skeletal muscles called?
Sarcomeres
What is the name of the specialized smooth endoplasmic reticulum of skeletal muscle cells? What does it store/release/retrieve?
Sarcoplasmic reticulum
Ca++ ions
What are linked together to form a myofibril?
Sarcomeres
What is a z-line/z-disc?
Structure that sits between the sarcomeres of a myofibril
What is the thick filament of a sarcomere composed of?
Myosin
What are the thin filaments of a sarcomere composed of?
Actin
Which filament (thick or thin) is anchored directly to the z-disc?
Thin filament
What winds around the chains of the actin filament and covers the myosin-binding sites to prevent actin from binding to myosin?
Tropomyosin
What extension of the nervous system controls the muscles?
Motor neurons
What is the name of the site where a motor neuron meets a muscle cell?
Neuromuscular junction
How many skeletal muscle fibers are innervated?
All of them
When an action potential is received from a motor neuron, across what structure does it propagate?
Sarcolemma
What do t-tubules stand for and do?
Transverse tubules
These ensure that the electrical impulse is carried into the muscle cell, to the sarcoplasmic reticulum
What is the part of the sarcoplasmic reticulum that is near the t-tubules?
Terminal cisternae
What is the name of the portion of the t-tubule with terminal cisternae on either side?
Triad
What are skeletal muscle cells commonly referred to?
Muscle fibers or Myofibers
What are the steps of sarcomere contraction?
- Signal from motor neuron
- Local membrane initiates action potential that spreads across sarcolemma and t-tubules
- Ca++ ions release from the terminal cisternae which diffuses across the sarcoplasmic reticulum
- Ca++ binds to troponin, causing tropomyosin to slide away from the binding sites on actin strands
- Myosin heads bind to actin
- Thin filaments are pulled my myosin heads to the center of sarcomere
What are the steps of muscle relaxation?
- Signaling from the motor neuron ends
- Electrical impulses on the sarcolemma and t-tubules dissipate
- Ca++ ions pumped back into the sarcoplasmic reticulum
- Tropomyosin reshields the binding sites on the actin strand and the thin filaments return to their original position
How can a muscle stop contracting even when an electrical impulse is present?
It runs out of ATP
