Muscular Tissue (L1 & C7) Flashcards
Name the 4 types of cells that can contract
Muscle cells/Fibers
Pericytes
Myoepithelial cells
Myofibroblasts
Name the muscular tissues that are striated
Cardiac
Skeletal
Name the muscular tissue that is not striated
Smooth
Name the muscular tissues that are voluntary
Skeletal
Name the muscular tissues that are involuntary
Smooth
Cardiac
State the function of myofibroblasts
Secrete Collagen and contract
State the structure and location of pericytes
Structure:
Smooth muscle-like
Location:
Surrounding blood vessels
State the location of myoepithelial cells
Around certain glands
State the other names for a muscle cell
Muscle fiber / Myofiber
State the other name for a muscle cell’s cytoplasm
Sarcoplasm
State the other name for smooth ER in a muscle cell
Sarcoplasmic reticulum
State the other name for the cell membrane of the muscle cell
Sarcolemma
What are the contents of the Sarcoplasm that allow the muscle to perform its function
Myofibrils
Myoglobin
Mitochondria
Sarcoplasmic reticulum
State the structure of a skeletal muscle cell
Long thin cylinder
State the contents of cell inclusions in a skeletal muscle
Myoglobin and glycogen
State the structure and function of myoglobin
Structure:
Globular protein similar to haemoglobin
Contains iron atom
Function:
Store oxygen
Myofibrils are made of
Overlapping Myofilaments - Actin and myosin
What is the functional unit of a muscle
Sarcomere
State the structure of a sarcomere
- The region between 2 successive Z lines
- Bisected by the M line
- Dark Central A Band with a pale area called H band
- 1/2 Light Peripheral I Band on each side
What is the A band made of?
Overlapping Myosin (Thick) and actin (thin) myofilaments
What is the H band made of?
Myosin myofilaments only
What are the I bands made of?
Actin myofilaments only
Why is the A band called so?
It is Anisotropic
Why is the I band called so?
It is Isotropic
The arrangement of myofilaments in a sarcomere cross section is a central myosin molecule surrounded by actin molecules in a _____________ arrangement
1/ Pyramidal
2/ Diamond
3/ Pentagonal
4/ Hexagonal
Hexagonal
State the structure of Actin Molecules
- Thin (5nm)
- Made of F-protein
- F-protein is made of G-proteins
State the 2 proteins closely associated with Actin with their function
Troponin (T,C,I) and Tropomyosin
Function:
Responds to Ca2+ concentration in the sarcoplasm to allow or prevent cross-bridge formation
State the structure of Myosin Molecules
- Thick (15nm)
- Polarized
- 2 globular heads attached to a tail
- Heads contain ATPase
What is the function of ATPase in Myosin
Enables binding of myosin to actin for the power stroke
State the structure of T-Tubules
Invaginations of the sarcolemma
State the structure of a Triad
1 T-Tubule with a terminal cisterna of sarcoplasmic reticulum on each sides
How many Triads are in each sarcomere?
2
What happens to the sarcomere when it contracts
Z lines move toward M line
H band disappears
Sarcomere shortens and in turn myofibrils
State the different muscle accessory proteins
Titin Nebulin alpha-actinin Tropomodulin Dystrophin
State the function of Titin
- Large protein connecting M and Z lines to maintain sarcomere length.
- It’s elastic contributing to passive elasticity of muscle
State the function of Nebulin
Large protein spanning actin’s length to attach it to Z line
State the function of alpha-actinin
Attaches actin, titin and nebulin to Z line
State the function of Tropomodulin
Attaches to free end of actin to regulate its length
State the function of Dystrophin
Attaches to sarcolemma and cytoskeleton to maintain sarcomere during contraction
What is Myotonia and what are it’s causes?
Neuromuscular condition where muscle is slow to relax after voluntary contraction
Occurs due to exposure to cold
What is Myotonia Congenita?
Genetic condition causing muscle stiffness due to prolonged contractions
What is the structure that is nonfunctional in myotonic muscular dystrophy?
Voltage gated Cl- channels in the sarcolemma
How is myotonia congenita diagnosed and treated?
Diagnosis:
Muscle Biopsy
Electrodiagnosis
Genetic Testing
Treatment:
No permanent cure
Physiotherapy and rehabilitation improve muscle action
State the features of Red muscle fibers regarding
1/ Myoglobin and mitochondria content 2/ Blood supply 3/ Enzymes (ATPase and oxidative) 4/ ATP Generation Method 5/ Contraction Speed 6/ Fatigue
1/ Myoglobin and mitochondria content - High
2/ Blood supply - Extensive
3/ Enzymes
ATPase - Low
Oxidative - High
4/ ATP Generation Method - Oxidative phosphorylation
5/ Contraction Speed - Slow and repetitive
6/ Fatigue - Not easily fatigued
State the features of white muscle fibres regarding
1/ Myoglobin and mitochondria content 2/ Blood supply 3/ Enzymes (ATPase and oxidative) 4/ ATP Generation Method 5/ Contraction Speed 6/ Fatigue
1/ Myoglobin and mitochondria content - Low 2/ Blood supply - Low 3/ Enzymes ATPase - High Oxidative - Low 4/ ATP Generation Method - Anaerobic Glycolysis 5/ Contraction Speed - Fast 6/ Fatigued - Easily
State the features of Intermediate muscle fibers regarding
1/ Myoglobin and mitochondria content 2/ Blood supply 3/ Enzymes (ATPase and oxidative) 4/ ATP Generation Method 5/ Contraction Speed 6/ Fatigue
1/ Myoglobin and mitochondria content - Intermediate
2/ Blood supply - Intermediate
3/ Enzymes (ATPase and oxidative) - Intermediate
4/ ATP Generation Method - Both
5/ Contraction Speed - Fast
6/ Fatigue - Not easily
True or false
All skeletal muscles contain all types of muscle Fibers
True
Marathon runners have predominance of __________ muscle fibers
Intermediate (Type IIA)
Red muscle fibers are also called
Type I
Intermediate muscle fibers are also called
Type IIA
White muscle fibers are also called
Type IIB
Weight lifters have predominance of ___________ muscle fibers
White (Type IIB)
Muscle composition is changed by
Training
Vessels and nerves enter muscles by
Neurovascular bundle
Which of the following is absent in the endomysium?
1/ Capillaries
2/ Nerve Endings
3/ Lymphatics
Lymphatics
Lymphatics are present in all connective tissue components of the muscle except
Endomysium
Presence of skeletal muscle inclusions in electronmicropgraphs is a feature of
Nemaline Rod myopathy
A symptom of Nemaline Rod myopathy is
Mild to severe muscle weakness
Nemaline Rod myopathy is caused by
Mutations of genes coding proteins of thin myofilaments
Patients with Nemaline Rod myopathy have predominance of Type ______ fibers
Type I (Red)
A common site of injury in muscles
Muscle-Tendon Junction
State the structure of Muscle-Tendon Junctions
Extensions of myofibrils with projections of adjacent tendon
Single unaccustomed muscle exercise causes
Delayed onset muscle soreness
What are the symptoms of delayed muscle onset soreness?
Stiffness, pain and soreness
Where does delayed muscle onset soreness begin
Muscle-Tendon Junction
What are the causes of the symptoms of delayed muscle onset soreness
- Sarcolemmal Tear
- Cytoskeleton disarray
- Myofilament disruption
- Z Band streaming
- Acute Inflammation of endomysium causing stimulation of pain receptors (nocireceptors)
State the function Myo-satellite cells
- Reserving Stem cells
- Resting myoblasts
- Repair and regeneration of muscles
Myo-satellite cells are predominant in which type of muscles?
Slow twitch
Dense CT surrounding the entire muscle is called?
Epimysium
Septa that extend from the Epimysium to divide a muscle into fascicles is called?
Perimysium
Loose CT surrounding a single muscle fiber is called?
Endomysium
Muscle fibers and satellite cells are surrounded by
Basal Lamina
The external lamina of a muscle is made of
Reticular fibres and glycoproteins
Capillaries supplying muscles run along which axis of the muscle?
Longitudinal
What is the cause of Duchenne muscle dystrophy?
Mutation in gene on short arm of X chromosome.
This gene codes for the protein dystrophin
What are the symptoms of Duchenne muscle dystrophy?
Progressive wasting and weakness of muscles
Progressive Heart weakness
Duchenne muscle dystrophy is more common in which gender?
Males
The functional unit of a muscle is
Sarcomere
Muscle fibers have pleomorphic ____________
Mitochondria
The site of excitation-contraction coupling in a sarcomere is
Triad
State the location of T tubules
Junctions of A and I bands
State the function of T-tubules
Conduct electrical impulse from the sarcolemma to deeper part of the muscle fiber
State the location of Triads
Junction of A-I band
State the function of Triads
Regulate Ca2+ concentration in sarcoplasm by releasing or sequestering it