• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/48

Click to flip

48 Cards in this Set

  • Front
  • Back
What are the three muscle types?
1) skeletal
2) cardiac
3) smooth
Histology of skeletal muscles
- Longitudinal section: long, multinucleated, nucleus at edge just under sarcolemma, may appear to be different sizes according to section, striated
- Cross: do not see striations, oval, nuclei at edge, visible sarcolemma and sarcoplasm
Histology of cardiac muscles
- Longitudinal: long, looks cylindrical but is individual cells with central nuclei, intercalated disks, striated
-Cross: central nuclei, striations not apparent
Histology of smooth muscles
- Longitudinal: appear in sheets, central nuclei, tapered cells, no striations
- Cross: central nuclei (may/may not see), ovalish in varying size according to section
What is the motor unit of a skeletal muscle comprised of?
- neuron
- axon
- all the muscle fibers it innervates
What are the connective tissues of skeletal muscle?
- endomysium: delicate, loose connective tissue around each muscle fiber
- perimysium: surrounds bundles of muscle fibers (fascicles)
- Epimysium: dense connective tissue surrounds muscle
What is the importance of external lamina/basement membrane in regeneration?
- as long as the lamina is fairly intact satellite cells can regenerate damaged muscles
What are the 3 types of fibers?
1) Red (type I)
2) White (type IIb)
3) Intermediate fibers (type IIa)
Red fibers (type I)
- high mitochondria
- strong NADH/succinic dehydrogenase enzyme activity
- slow-twitch
- resist fatigue
- less muscle tension
- continuous activity
White fibers (type IIb)
- low mitochondria
- weak NADH/succinic dehydrogenase reaction
- fast twitch
- fatigue easily
- generate a lot of tension
Intermediate fibers (type IIa)
- in between red and white fibers
Organization of skeletal muscle
- muscle fibers contain many myofibrils
- myofibrils are made up of myosin and actin (myofilaments)
- myofilaments are arranged in specific patters in sarcomeres
A band of myofilaments
-overlapping area of actin and myosin
- middle of sarcomere
- stains dark
H band of myofilaments
- only myosin
- bisects A band
M line of myofilaments
- myosin and network protein
- bisects H band
I band of myofilaments
- only actin
- half is part of sarcomere (the other half is part of a different sarcomere)
Z band of myofilaments
- bisects the I band
- Z band to Z band is the sarcomere
What are the 3 subunits of troponin?
C: calcium binding
I: inhibitor
T: troppomyosin binding
Where is tropomyosin located?
- on top of globular actin chain
What configuration is troponin/tropomyosin in when muscle is relaxed?
- T subunit of Troponin is bound to tropomyosin
- tropomyosin is on top of actin
- myosin head cannot bind to actin
What happens during a muscle contraction?
- Ca influx through the sarcoplasmic reticulum and T-tubulues (tria)
- Ca binds to C subunit and induces conformation change
- Myosin able to attach to actin, moves through ATP
What happens in the transport of a Nerve Impulse in muscle contraction?
- Nerve impulse arrives at motor end plate by motor neuron
- Axon sent to skeletal muscle (branches to several fibers)
- Action potential depolarizes membrane
- Action potential generated in the muscle cell (continues downwards b/c T-tubules)
- Ca released from sarcoplasmic reticulum
- Ca activate contractile proteins (actin/myosin)
- Ca returned to sarcoplasmic reticulum
What is the muscle spindle?
- receptor unit in muscle that contains special muscle fibers and neuron terminals surrounded by a capsule
- responds to stretch and controls muscle coordination
- provides information on muscle length
What are the two types of special muscle fibers within a muscle spindle?
- Nuclear bag fibers
- Nuclear chain fibers
What is the golgi tendon organs
- encapsulated nerve endings in the tendon that respond to stretch
- only contain afferent neurons
- provides information on tension development
What are intercalated discs in cardiac muscle?
- end to end junctions between each cell
What are the 3 types of intercalated discs in cardiac muscle?
1) Fascia adherents: sheets
2) Macula adherents: desmosomes
3) Gap junctions: allows electrical passing
What comprises a fiber in cardiac muscle?
- many mononucleated cells
What are some specialized features of cardiac muscle?
- cells branch
- mitochondria are very large (could be length of a sarcomere)
- Sarcoplasmic reticulum is well developed and organized into diads at the Z line
- central nuclei, could be binucleated
- cannot regenerate (creates connective tissue)
- Heart will beat without innervation (intrinsic conducting system)
How are the contractile proteins of smooth muscles different?
- not very organized
- they are anchored at the edges of the cell, called dense bodies
- thin filaments (actin) are attached to the dense bodies that contain the actin binding proteins: alpha-actinin and desmin
What do dense bodies contain?
-vinculin
-talin
-desmin
What shape do smooth muscle cells have?
- spindle shaped with a central nuclei that form to cell shape
What supplies the energy for contraction in smooth muscle?
- mitochondria,usually around the nucleus
How does the contraction signal spread in smooth muscle?
- through gap junctions (nexus junctions)
- cells function together
What are the invaginations in smooth muscle called that control the entry of Ca?
- caveoli
What do smooth muscle contractions result from?
- mechanical impulses
- electrical depolarization
- biochemical stimuli
Where is smooth muscle found?
- hollow visceral organs
- blood vessel walls
Can smooth muscle replace damaged cells?
- yes through mitosis
Where is the T-tubule located in skeletal muscles, describe its composition.
- A/I junction
- Triad: contains 2 terminal cisternae (where sarcoplasmic reticulum joins) and 1 T-tubule (invagination of plasma membrane)
Where are satellite cells of skeletal muscle located? what do they do?
- between plasma membrane and basement membrane
- dormant stem cells that can proliferate after injury to produce myoblasts
What parts of the sarcomere shorten during contraction?
- I and H bands
What is the motor end plate/neuromuscular junction of skeletal muscle
- axonal ending of motor neuron
- receptor region of striated muscle fibers that receives innervation
What is the primary cleft in skeletal muscle?
- a shallow depression in the muscle cells where the axon terminal lies
What are secondary or subneural clefts in skeletal muscle?
- narrow folds formed by the sarcolemma
- increase receptor surface area of the muscle
- presence of basement membrane does not interfere with synaptic transmission
What is the arrangement of nuclei from nuclear bag fibers within a muscle spindle? (skeletal muscle)
- nuclei aggregate in the expanded middle region of the spindle
What is the arrangement of nuclei from nuclear chain fibers within a muscle spindle? (skeletal muscle)
- nuclei are arranged linearly
How are the T-tubules organized in cardiac muscle?
- diads foudn at the Z line
Is the T-tubule system found in smooth muscles?
No, have caveoli to control Ca entrance