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Medicine Sem 1 > Cytology Week 12 > Flashcards

Cytology Week 12 Flashcards

1
Q

What is muscle tissue specialised for

A
  • contractility
  • enabling movement with organ systems
  • Blood flow
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2
Q

What is muscle contraction driven by ?

A
  • Actin microfilaments and associated proteins
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3
Q

What are muscle cells derived from

A

Mesoderm

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4
Q

What does muscle cell differentiation involve

A
  • cell lengthening
  • The synthesis of myofibrillar proteins
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5
Q

Name the 3 types of muscle tissue

A
  • Skeletal muscle
  • Cardiac muscle
  • Smooth muscle
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6
Q

What does skeletal muscle contain ?
Explain the skeletal muscle contractions

A
  • Long multitnucleated cells with cross striations
  • Contractions are quick, forceful and under voluntary control
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7
Q

What is the Sarcoplasm?

A

Muscle cell cytoplasm

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8
Q

What is Sarcoplasmic Reticulum

A

Smooth ER of muscle cells

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9
Q

What is sarcolemma

A

Muscle cell membrane and its external lamina

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10
Q

What is Hypertropy

A

Increase in cell volume due to new myofibrils

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11
Q

What is Hyperplasia

A

Increase in cell production

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12
Q

What does Cardiac muscle contain

A
  • Elongated,often branched cells with cross striations
  • Cells are connected by intercalated discs
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13
Q

Explain Cardiac muscle contractions

A
  • They are involuntary, vigorous,rhythmic
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14
Q

What is smooth muscle cmoposed of

A
  • Fusiform(spindle shaped ) cells without striations
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15
Q

Explain smooth muscle contractions

A
  • Slow and involuntary
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16
Q

What is muscle contraction caused by

A
  • The sliding interaction of myosin(thick) and actin(thin) filaments
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17
Q

Explain the structure of skeletal muscles

A
  • Composed of muscle fibers, long cylindrical cells that are multinucleated
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18
Q

How are straited muscle fibers formed

A
  • During embryonic development, mesenchymal myoblasts fues to form myotubes, which differentiate into striated muscle fibers
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19
Q

Where is Nucei located in skeletal muscle

A
  • Peripherally, under the sarcolemma
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20
Q

What are muscle satellite cells

A
  • A reserve progenitor cell poulation
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21
Q

Name the layers of connective tissue in which skeletal muscle is supported and organized by

A

-Epimysium
-Perimysium
-Endomysium

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22
Q

What is the functional role of connective tissue

A
  • They Transmit the mechanical forces generated by muscle contraction
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23
Q

Explain structure and function of Epimysium

A
  • Dense irregular connective tissue
  • Surronds the entire muscle and carries larger nerves
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24
Q

Explain the structure and function of Perimysium

A
  • Thin connective tissue surrounds muscle fiber bundles
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25
Q

Explain the structure and function of Endomysium

A
  • Delicate recticular fibers and fibroblasts
    -Surround individual muscle fibers , providing a rich capillary network for oxygen supply
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26
Q

What are myofibrils

A

Cylindrical bundles running parallel to the muscle fiber axis

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27
Q

What do sacromeres contain

A
  • Thick mysoin and thin actin filaments
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28
Q

What is thick mysoin filaments composed of and their function

A
  • Composed of myosin molecules with heavy chains forming rodlike tails and heads that bind actin and ATP.
    -Myosin heads facilitate actin binding and energy release for contraction.
29
Q

What does thin actin filamentsa contain

A
  • Contain myosin binding sites
    -Associated with tropomysoin and troponin
30
Q

Waht is the brief function of tropmyosin

A

Stabilises actin

31
Q

Describe the structure of the protein Troponin

A

-It has a complex of 3 subunits
-TnT: Attaches to tropomyosin.
TnC: Binds calcium.
TnI: Regulates actin-myosin binding.

32
Q

Explain what is the I band and A band

A

I Bands: Lighter regions containing only thin filaments.
A Bands: Dark regions with overlapping thick and thin filaments

33
Q

Explain what the H zone and M line is( and what it contains)

A

H Zone: Center of the A band with only thick filaments.
M Line: Bisects the H zone and contains proteins like myomesin and creatine kinase to stabilize thick filaments and regenerate ATP

34
Q

What are the 2 functions of the sarcoplasmic reticulum

A
  • Surrounds myofibrils + functions in calcium sequestration
  • Releases calacium from cisternae via voltage gated calcium channels triggered by membrane depolarization
35
Q

What are transveres tubules

A

-Tubular infoldings of the sarcolemma that penetrate deep into the sarcoplasm

36
Q

What are the 2 functions of transvere tubules

A
  • Encircle each myofibril at the A and I band boundaries of the sarcomere
  • It ensures simultaneous calcium release across the muscle fiber
37
Q

Desribe the structure of the Triad

A
  • Composed of one T tubule and 2 adjacent terminal cisternae of the sarcoplasmic reticulum
38
Q

What is the sliding Filament Model

A
  • That muscle contraction occurs when thin actin and thick mysoin filaments slide pass each other
  • The filaments dont change length and the sacromere shortens
39
Q

Explain the initiation of muscle contraction

A
  • A neural signal reaches the neuromuscular junction and travels along the T tubules to the sarcoplasmic reticulum , triggering the release of calcium ions
40
Q

Explain the Troponin and Tropmyosin complex when the muscle is in resting

A

The complex blocks myosin-binding sites on actin

41
Q

What happens when the release of calcium is triggered by the neural signal

A

The Released calcium binds to troponin , causing a shape change that moves tropmyosin and exposes the myosin binding sites on actin.

42
Q

How is a cross bridge formed

A

When the myosin heads bind to actin, forming cross bridges

43
Q

What is required for the attach pivot death cycle

A
  • ATP
  • Calcium
44
Q

Explain the process of Relxation in Muscle contraction

A

-Neural impulses stop , leading to reduced free calcium levels
- Tropomysoin re blocks myosin binding site on actin

45
Q

What does the myelinated motor nerve branch into

A

-Branches into unmyelinated twigs within the perimysium and endomysium

46
Q

What are the components of a Neuromuscular junction

A

-Axon terminal
-Synaotic cleft
- Post synaptic sarcolemma

47
Q

What does the Axon terminal contain

A

Mitochondria and synaptic vessels with acetylcholine

48
Q

What is the synaptic cleft

A
  • Gap between the Axon terminal and muscle fiber
49
Q

Explain the process of muscle contraction

A
  • Nerve action potential triggers the release of acetylcholine into the synaptic cleft
  • Acetylcholine binds to receptors , opening cation channels and depolarising the sarcolemma.
    -An action potential then propagates along the sarcolemma and T tubules
  • Then Depolarisation at triads trigger caloric release from the sarcoplasmic reticulum, initiating the contraction cycle
50
Q

Explain the precision of small muscles

A

They have precise control

51
Q

Explain the precision of Large muscles

A

They have coarser movements

52
Q

What is the All or None response in muscles

A

Where individual fiberw contract fully or not at all .

53
Q

What is Rigor Mortis

A
  • When in the absence of ATP, actin-myosin cross bridges stabilize, causing muscle rigidity
54
Q

What does a motor unit consist of

A
  • A motor untit consits of one motor neuron and all the muscle fibers it innervates
55
Q

Where are Golgi Tendons found

A

Found at the myotendinous junctions

56
Q

What is the structure of Golgi Tendon organs

A
  • They are small,encapsulated structures, with sensory axons embedded among collagen bundles
57
Q

What is the function of Golgi Tendons

A
  • Detct changes in tension within tendons caused by muscle contraction
58
Q

What is the function of proprioceptors

A
  • They provide the CNS with information about the musculoskeletal system , aiding in posture and movement regulation
59
Q

Where are muscle spindles found?

A

-They are found amongs muscle fascicles

60
Q

What is the Function of muscle spindles

A
  • Relay information to the spinal cord through sensory nerve axons
61
Q

What is Duchenne Muscualr Dystrophy caused by

A
  • Cuased by mutation in the dystophin gene, leading to defective cytoskeletion-ECM linkages
62
Q

What is Myasthenia Gravis

A
  • An autoimmune disorder where circulating antibodies target proteins in the acetycholine receptors
63
Q

Different types of fibers can be identified on the basis of their….

A
  1. Rate of ocntraction(fast or slow fibers)
    2.ATP synthesis pathway (oxidative phosphorylation or glycolysis).
64
Q

Name the types of Skeletal Muscle fibers

A
  • Slow Oxidative fibers
    -Fast glycolytic fibers
    -Fast oxidative-Glycotic Fibers
65
Q

Explain slow oxidative fibers
-What they are adapted for
-What they contain
- Explain their endurance and fatigue

A
  • Adapted for slow contractions
    -Rich in mitochondria, capillaries, and myoglobin, making them dark/red in color.
    -High endurance, fatigue resistant
66
Q

Explain Fast Glycolytic Fibers
-What it is specialised for
-What it contains
-Its endurance/fatigue

A

-Specialized for rapid, short-term contractions.
-Few mitochondria and capillaries; rely on anaerobic glycolysis, leading to white color.
- Fatigue quickly due to lactic build up

67
Q

Explain compact ( cortical )bones + location

A
  • They are dense and located near the surface of the bones
68
Q

Explain where Cancellous (Trabecular Bone) are located

A
  • Deeper within the interconnecting cavities

Medicine Sem 1 (33 decks)

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