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58 Cards in this Set
- Front
- Back
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This fascia covers the entire skeletal muscle.
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Epimysium.
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This fascia covers each fascicle (bundle of muscle fibers).
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Perimysium.
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This surrounds each individual cell/fiber.
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Endomysium.
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A muscle fiber comes from what embryonic tissue?
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Mesenchyme. The Myoblasts.
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Why are muscle fibers multinucleate?
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Irregularly shaped cells line up and fuse into a single cell.
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Where do we find the nuclei in skeletal muscle fibers?
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They are always peripheral.
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In skeletal muscles, the light bands are?
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I bands.
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In skeletal muscles, the dark bands are?
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A bands.
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What is the plasma membrane of the muscle cell called?
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Sarcolemma.
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What bisects the I-bands?
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Z-discs.
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A sarcomere is defined as...
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...the area from one Z-disc to the next Z-disc.
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Down the middle of the A-band is a lighter band called what?
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The H-band.
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This runs down the middle of the H-band.
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The M-line.
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What does the M-line do?
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It holds the myosin in place.
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This acts as an ATPase in muscle cells?
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Heavy meromyosin.
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What makes up the thick filaments?
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Myosin.
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The A-band is the span of this.
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The thick filaments.
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The M-line is made of this.
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Creatine Phosphate.
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This makes up the backbone of the thick filaments.
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Light meromyosin.
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This is the 'club-head' sticking out from the thick filament.
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Heavy meromyosin.
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Thin filaments are made of what?
What shape are they in? |
Actin, with tropomyosin around the outside. At 40 nm intervals there are molecules of troponin.
Helical. |
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What is the function of tropomyosin?
Where is it bound? |
It is bound directly on the actin. Tropomyosin covers the site where actin can interact with the heavy meromyosin (thick filaments).
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What is the function of troponin?
Where is it bound? |
It is bound directly to tropomyosin. It interacts with released Calcium and moves the tropomyosin out of the way so that actin can crossbridge with heavy meromyosin (thick filaments).
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Where is calcium sequestered?
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In Smooth ER.
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Where are T-tubules located?
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Between A-bands and I-bands.
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During contraction:
What happens to A-bands? I-bands? H-band? Thin filaments? |
A-bands remain unchanged.
I-bands get smaller. H-bands get smaller. Thin filaments pile up and accentuate the M-line. |
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When muscles are streched:
What happens to A-bands? I-bands? H-band? M-line? |
A-bands stay the same.
I-bands get wider. H-bands get wider. M-line stays the same. |
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Grossly:
What are some characteristics of dark meat? |
Contains myoglobin.
Sometimes called red muscle. High frequency against low resistance. |
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Grossly:
What are some characteristics of light meat? |
Works against heavy resistance, but low repetition.
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This is the main hormone responsible for creating muscle.
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Testosterone.
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How are cardiac muscle cells different from skeletal muscle cells?
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1. Held together end to end by intercalated discs
2. Nuclei are found in the center of the cells 3. Branched cardiac fibers. 4. T-tubules are found at the Z-line instead of the A/I junction. 5. No satellite cells (no regeneration) |
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What pigment builds up in cardiac muscle cells as we age?
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Lipofuscin. It doesn't seem to affect cells in any way.
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Where is the nucleus located in smooth muscle fibers?
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In the center.
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What is stronger, skeletal or smooth muscle?
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Smooth.
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How are smooth muscle fibers different from skeletal muscle fibers?
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1. Lack striations.
2. Centered nucleus (single). 3. Does not have T-tubules or Sarcoplasmic Reticulum. |
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What are some functions of the skin?
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1. Protection (mechanical, sunlight, dehydration, micobes)
2. Temperature regulation 3. Sensory contact 4. Excretion through sweat glands 5. Modified special structures (hair and nails) 6. Flexuous container of the body |
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What is the embryological origin of the skin?
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Ectoderm (epidermis and appendages)
Mesoderm (dermis) |
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What is a tell-tale sign of thick skin?
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It has no hair and not much pigment.
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From where does the epidermis come from?
What is it made from? |
From the ectoderm.
Stratified squamous epithelium. It is known as the keratinizing layer. |
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From Basement membrane out, name the 4 layers in the Epidermis.
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1. Stratum Malpighi (also contains the stratum germinativum and stratum spinosum)
2. Stratum granulosum 3. Stratum lucidum 4. stratum disjunctum (corneum) |
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Stratum malpighi:
What type of cells? How are they attached to the BM? |
They are Cuboidal cells.
Attached to the BM by hemidesmosomes. |
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Stratum germinativum:
Will become what type of cells? Division? |
Committed stem cells to keratinocytes.
Capable of continuous division. One stays put, the other migrates up. |
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Stratum spinosum:
Surface? Joined to immediate neighbors how? What do they produce when they reach the upper-most layer? |
Have numerous processes on surface.
Joined to immediate neighbors by desmosomes (2300 per cell). Very tight bond. When they reach the upper-most layer, they create a Membrane coating granule --> coats surface making skin waterproof. |
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Stratum granulosum:
Presence of what? |
Basophilic granules.
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Stratum lucidum:
Cells appearance? |
Shiny appearance. Wavy band of shiny material running horizontally.
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Stratum disjunctum (corneum):
Cells? How many layers? Desmosome linkages? |
Dead cells.
There can be huge numbers of layers. Desmosome linkages are broken up as cells are migrating up. |
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In cell's journey upwards, these accumulate.
These begin to disappear. |
Keratin filaments accumulate.
Organelles begin to disappear and nucleus breaks down. |
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Thin skin may have these layers reduced or missing?
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Granulosum & Lucidum: May be absent.
Corneum (disjunctum): May be thin. |
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In the thin skin:
Melanocytes are found where? What do melanocytes produce? |
In the stratum malpighi.
Melanin in melanosome (organelle). |
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How is melanin produced?
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Tyrosine converted to DOPA,
DOPA converted to melanin. |
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What is skin color based on?
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1. Melanin production (not # of melanocytes)
2. Blood showing through skin 3. Carotene (precursor of Vitamin A) |
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These cells are important in the immune system in skin.
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Langerhans cells:
--Most peripheral sentinals for allergic/immune responses --Can encounter topical antigens and send messages to immune system --Not readily seen in normal sections |
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Merkel cells:
Function? |
Critical in the innervation of epidermis.
Send out 'homing signal' to nerve axons during embryonic development Important in ultimate inneration of the skin. |
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Dermis:
What? Where? |
Dense irregular collagenous connective tissue.
Loose, right under epithelium. |
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What is the hypodermis and what are its contents?
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It is loose connective tissue which frequently has a lot of fat cells in it.
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Sebaceous glands:
Associated with what? What type of secretion? |
They are associated with hair follicles.
Holocrine secretions. Secreted form is called sebum. |
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Eccrine sweat glands:
What type of sweat? Lots of this organelle. |
Thin, watery sweat.
Mitochondria. |
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Apocrine sweat glands:
When do they become active? What type of sweat? Where? |
Present at birth but don't activate until puberty (except those that make ear-wax).
Thick, turbid sweat. Odorless upon secretion but a good growth medium for bacteria (they metabolize it to make odor). Armpits, around naval and anus. Mammary glands are modified apocrine sweat glands. |
