Muscle Flashcards
Muscle cells are also known as
Myocytes and myofibers
Muscle cells are what shape and originate from
spindle shaped
Mesoderm
Sarcoplasm
Cytoplasm of muscle cells that contain glycogen and myoglobin
Sarcolemma
Plasma membrane of muscle cells
Sarcoplasmic reticulum
Highly specialized Smooth ER of a muscle cell
Regulates Ca flow
Cardiac muscle cells are arranged in
Fibers
are tubular branching
Smooth muscle
Fusiform
spindle shaped
What type of muscle have striations
Cardiac and skeletal
What type of muscle makes up to 50% of body weight
Skeletal muscle
Myocytes of skeletal muscle contain what
Multiple and peripherally located muscles
Striations of myocytes in skeletal muscles are seen when cut in how
Longitudinal section
Skeletal muscle contracts
Fast
Voluntary
Where are the skeletal muscles (4)
Voluntary sphincter in GIT and urinary system
Muscles in esophagus
Tongue
Development of skeletal muscle
Mesenchymal cells align and fuse together forming multinucleated tubes called myotubules
Myotubules differentiate forming functional myofilaments and the nuclei are displaced against PM
What are satellite cells
In the development of skeletal muscles cells, some cells do not differentiate and remain as mesenchymal cells, they function in muscle repair
What surrounds a skeletal muscle
Irregular CT called perimysium
In the skeletal muscle, a whole muscle cell can be made up to many smaller bundles known as and are surrounded by
Fascicles
Perimysium
Myofibers contain cylindrical bundles of? which in turn contain many smaller bundles of
Myofibrils
Myofilaments
Myofibers
Cylindrical multinucleated cells
What is the contractile element in skeletal muscles
Myofibrils
Myofibrils are composed of
Repeating sections of myofilaments known as thin and thick myofilaments
Thick filaments
Myosin
Thin filaments
Actin
What is the contractile or functional unit of a myocyte
Sarcomere
Which band is darker and contains the thick and thin myofilament overlapping
A band
A band is composed of
Myosin
I band is? and composed of
Pale
Actin filaments
Striations are due to the presence of what type of myofilaments
A: Dark
I: Pale
Each band is bisected by a protein disc known as
Z line
T or F
During contraction of skeletal muscle, the actin filaments slide under the myosin filaments which elongates the I band
False
Slide over and shortens the I band
What other proteins hold actin and myosin in position in myofibril (3)
Desmin
Tropomyosin
Troponin
Thin filament has (4)
G actin
Tropomyosin
Troponin
Actin monomers
Muscle contraction (5)
Ca binds to troponin C
Conformational change in tropomyosin exposes the myosin binding site on ACTIN
Myosin heads bind to actin (ATP turns into ADP which moves the myosin head)
Bound thin filaments slide over thick filaments
Shortening of entire muscle fiber
T or F
ATP is the main character in movement of myosin heads
FALSE
ADP
What are t tubules
Deep invagination of sarcolemma only found in skeletal and cardiac muscles
T or F
T tubules are not present in smooth muscle cells
TRUE
What do t tubules do
Allow depolarization of membrane to quickly penetrate to the interior of the cell allowing Ca release from sarcoplasmic reticulum
Who stores and releases Ca ions to initiate contraction
Sarcoplasmic Reticulum
Type 1 skeletal muscle is also known as
Red muscle
Type one skeletal muscle are rich in
Myoglobin that’s why they are darker
T or F
Type 1 skeletal muscle have a fast twitch
FALSE
SLOW
Examples of type 1 skeletal muscles
Postural muscles of mammals and pectoral muscles of migrating birds
Type 2 skeletal muscle are also known as
WHITE
T or F
Type 2 muscle cells have fast twitch
TRUE
What can you say about the nucleus in cardiac cells
Single cell with central nuclei
Where are the intercalated discs present
In cardiac muscle cells
T or F
Cardiac muscle doesn’t have SR
False
What are the intercalated discs for
To attach cardiac muscle cells together so they function as a syncytium
Intercalated discs consist of (2)
Transverse and longitudinal elements
Transverse elements of intercalated discs (3)
Anchor
Desmosome
Serve as strong attachment
Longitudinal elements of cardiac muscle (3)
Communication
Gap junctions
Propagate electric impulse
Conductile cardiac muscle cells are
Purkinje fibers (pale pink)
Purkinje cells
Neuronal cell bodies in middle layer of cerebral cortex
Characterized by a large, globose body and massive, branching dendrites but a single slender axon
Nuclei in smooth muscle
Single centrally
T or F
There are more striations and myofibrils in smooth muscle than skeletal muscle
False
There are no striations in smooth muscle nor myofibrils
What are the anchor for myofilaments in the smooth muscle
Dense bodies
Contraction in smooth muscle
Involuntary
Single smooth muscle is found where
Visceral organs
Where is the multiunit smooth muscle found
Iris of eye
Contraction of Multiunit sm.
Precise with individual innervations
Peristalsis
Wave-like contractions
Vascular dynamics
Contraction alters blood flow and important in blood pressure
Propulsion is in
Urinary bladder and uterus
Functions of the Smooth muscle cells
Peristalsis
Vascular dynamics
Propulsion
Secretion
Tunica muscularis is
wall of luminal organs
Myoepithelial cells are found as
Basket like cells
Location of myoepithelial cells
Salivary, mammary and lacrimal glands
Enclose clusters of glandular cells
What type of muscle lacks the ability to regenerate
Cardiac muscle
In a muscle type, repair is completed by
Scar formation
