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biology > Muscles > Flashcards

Muscles Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are the types of muscle and where are they found

A

Cardiac–in heart

Smooth - in walls of blood vessels and gut

Skeletal- attached to bone moving body

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2
Q

Describe the structure of a muscle

A 
Whole muscle
Bundles of muscle fibres
Muscle fibre
Myofibril
Sarcomere
Actin and myosin
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3
Q

How are cells arranged in a muscle

A

Cells fused together in a long line

Myofibril run through the middle of the cells

Share cytoplasm (sarcoplasm) cell membrane (sarcollema) and endoplasmic reticulum (sarcoplasm reticulum) and nuclei

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4
Q

What is the advantage of the cell arangemnet in a muscle

A

Junctions would be a point of weakness so makes muscle stronger

Parralell Myofibril make them stronger

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5
Q

What is the function of the sarcoplasm reticulum

A

Store Ca2?+ for release for muscle contraction

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6
Q

What two proteins make up Myofibril

A

Actin and myosin

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7
Q

How is actin arranged

A

Actin molecules are soluble proteins arranged in a helix shape

Tropomysin follows shape of actin

Troponin attaches to Tropomysin

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8
Q

How is actin arranged

A

Actin molecules are soluble proteins arranged in a helix shape

Tropomysin follows shape of actin

Troponin attaches to Tropomysin

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9
Q

What is Tropomysin

A

Blocks actin mysoin binding sites

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10
Q

What is Troponin

A

Ca2+ binding site on Tropomysin

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11
Q

Describe the structure of myosin

A

Made of many parallel fibres of myosin made of insoluble tail and soluble head that stick out

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12
Q

Name the sections on a Sarcomere

A

Z line- middle of I band

I band - only actin

A band- actin and mysoin overlap

H zone- only myosin

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13
Q

What is a neuromuscular junction

A

Where a motor neurone meets a muscle fibre

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14
Q

Describe and explain the distribution of neuromuscular junctions across the muscle fibre

A

Regular intervals

Rapid and Simultaneous contraction

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15
Q

What is a motor unit

A

All muscle fibres supplied by one motor neurone acts a one unit

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16
Q

What is the advantage of having motor units

A

Allows control of force exerted (more units stimulted= more force)

17
Q

How is the sarcollema de polarised

A

Ap reaches the neuromuscular junction

Ca2+ voltage channels open allowing ca2+ to diffuse in.

Cause vesicles containing neurotransmitter to diffuse towards and fuse with postsynatic membrane, exocytosis

Acetylcholine diffuses across Synaptic left binding to Na+ receptors on sarcolemma.

Channels open Na+ Diffuse in = de polarisation

18
Q

Why is it important for acetyl choline to be broken down

A

To prevent over stimulation

19
Q

What are the similarities if a neuromuscular junction with a cholinergic synapse

A

Use acetyl choline through diffusion

Bind to na receptors causing them to open

Enzymes used to breakdown acetylcholine

Na/k pump used to repolarised

20
Q

What are the differences between neuromuscular junctions and cholinergic Synapses

A

Neuromuscular:
Only exhibitory not inhibitory
Only motor neurone not any other type
End of AP pathway

21
Q

What are the two types of muscle fibres

A

Slow and fast twitch

22
Q

Describe slow twitch fibres

A

Weak contractions over a long period of time

23
Q

How are slow twitch fibres adapted and for what

A

Adapted for endurance and aerobic Respiration

Low glycogen storage
Large myoglobin supply (oxygen store)
Good blood supply
Many mitochondria

24
Q

What are fast twitch fibres

A

Contract very rapid, powerfully for short amount of time

25
Q

How and what are fast twitch fibres adapted for

A

Anaerobic Respiration, intense exercise

Large glycogen storage (high rate resp because anaerobic = not efficient)

Large phosphocreatin supply

Thicker and more numerous myosin filaments

Large conc of enzymes involved in anaerobic Respiration

26
Q

By what mechanism do muscled contract

A

Sliding filament theory

27
Q

What is the evidence for the sliding filament theory

A

A band stays same length (so filaments don’t shorten)

I band and H zone decrease causing overlap of filaments

28
Q

How are muscles stimulated

A

Ap reaches neuromuscular junctions causing voltage gated Ca2+ channels to open so ions diffuse in

Vesicles with acetylcholine diffuse and fuse with presynaptic membrane. Exocytosis

Acetylcholine diffuses across the syntactic cleft

Binds to Na+ channels on sarcolemma opening them. Ions diffuse in de polarising membrane.

29
Q

How do muscles contract (starting from de polarisation of sarcollema)

A

Ap travels down t tubules to sarcoplasm reticulum

Ca2+ channels open and ions are released from sarcoplasmic reticulum into cytoplasm.

Ca2+ binds to Troponin causing Tropomyosin to change shape revealing binding sites for myosin on actin

Actin myosin Cross Bridge forms

ADP and pi released = power stroke= slide actin filament

ATP attaches and is hydrolysed= myosin head detaches and is recocked to original position

30
Q

What is the function of the sarcoplasmic reticulum in muscle contraction

A

Actively transports calcium ions fro cytoplasm for release via diffusion for muscle contraction.

31
Q

What is the function of calcium ions in muscle contraction

A

Bind to Troponin changing shape of Tropomyosin allowing actin myosin Cross Bridges to form

Activates ATP Hydrolyse for recock

32
Q

How are muscles relaxed

A

No ap= calcium ion channels close and ions actively transported back in

Less ions = Tropomyosin changes to original shape = blocks binding sites

No actin myosin Cross Bridges so no sliding of filaments

Antagonistic muscle pulls filaments apart

33
Q

How are muscles relaxed

A

No ap= calcium ion channels close and ions actively transported back in

Less ions = Tropomyosin changes to original shape = blocks binding sites

No actin myosin Cross Bridges so no sliding of filaments

Antagonistic muscle pulls filaments apart

34
Q

What role does ATP play in muscle stimulation

A

Allows recock of myosin head

Allows ca2+ to be actively Transported into to sarcoplasmic reticulum again for muscle relaxation

Used to repolarise sarcollema

biology (28 decks)

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