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Biology 108 > Chapter 6 Muscular System > Flashcards

Chapter 6 Muscular System Flashcards

1
Q

Muscles

A

Responsible for all types of body movement

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2
Q

3 types of muscle

A

Skeletal

Cardiac

Smooth

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3
Q

Muscle charactoristics

A

skeletal and smooth are elongated

contraction is due to movement of microfilaments

myo and mys refers to muscle

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4
Q

Skeletal Muscle

A

attached by tendons

cells are multinucleated striated,

have visible banding voluntary

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5
Q

connective tissue wrappings

A

cells surrounded and bundled by connective tissue

Endomysium

Perimysium

Epimysium

Fascia

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6
Q

Endomysium

A

encloses a single muscle finber

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7
Q

Perimysium

A

wraps around a fascicle (bundle) of muscle fiber

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8
Q

Epimysium

A

covers entire skeletal muscle

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9
Q

Fascia

A

on the outside of the epimysium

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10
Q

Skeletal muscle attachments

A

epimysium blends into tendons

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11
Q

Tendons

A

cord like structures that connect muscle to bone

mostly collogen fibers

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12
Q

Smooth muscle chacteristics

A

lack striations

spindle shaped cells

singel nucleus

involuntary

mainly in wall of hollow organs

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13
Q

Cardiac muscle characteristics

A

Striations

usually single nucleus branching cells

joined by intercalated disc

involuntary

found only in heart

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14
Q

Muscle functions

A

produce movement

maintain posture

stabilize joints

generate heat

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15
Q

Skeletal muscle fiber

A

thin elongated cylindrical cell with rounded ends

extends length of muscle

sarcolemma

transverse tubules

myofibrils

sarcoplasmic reticulum

striation pattern

sarcomere

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16
Q

Sarcolemma

A

plasma membrane

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17
Q

transverse tubules

A

invaginations of sarcolemma

entend all through fiber

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18
Q

myofibrils

A

bundle of contractile proteins

think filament-myosin

thin filament-actin

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19
Q

sarcoplacsmic reticulum

A

modified ER

sacs and tubes that surround each myofibril

stores Ca+2

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20
Q

striation pattern

A

due to arrangement of thin and thick fibers

A band: dark think filament

I band: thin filament anchored to Z lines

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21
Q

Sarcomere

A

contractile unit of muscle

segment of myofirbril between 2 Z lines

22
Q

Sarcomere organization

myosin

A

myosin

2 twisted proteins with globular heads (cross bridges) projecting outwards

myosin cross bridge head has ATPase enzymes

energy released cocks myosin head to prepare for binding wtih actin

23
Q

thick filaments

A

composed of many myosin molecules

located in center of sarcomere

24
Q

Actin

A

double stranded helical molecule

each actin monomer has binding site for myosin

troponin and tropomyosin are regulatory proteins found on thin filament

25
Q

thin filament

A

actin is the main protein

anchored to the Z disc

26
Q

H zone

A

region in the center of “A” band that contains only myosin at rest

27
Q

M line

A

proteins that hold myosin molecules in place

28
Q

Excitability

A

ability to receive and respond to a stimulus

29
Q

Contractabillity

A

ability to shorten when an adequate stimulus is received

30
Q

Extensibility

A

ability of muscle cells to be stretched

31
Q

Elasticity

A

ability to recoil and resume resting length after stretching

32
Q

muscle contraction

A

skeletal muscles must be stimulated by a motor neuron to contract

33
Q

Motor unit

A

one motor neuron

all of skeletal muscles cells are stimulated by that neuron

34
Q

Neuromuscular Junction

A

connection between axon terminal of the motor neuron and muscle

35
Q

Motor Neuron

A

Axon terminal contains the synaptic vesicles

vesicles contain neurotransmitters

transmitters are chemicals taht transmit signal from neuron to next cell

36
Q

Motor End Plate

A

folded region of the sarcolemma under the axon terminal

contains Ach receptors

37
Q

Synaptic Cleft

A

gap between nerve and muscle

filled with interstitial fluid

38
Q

transmission of Nerve Impulse to Muscle

A

Nerve impulse reaches axon terminals of motor neuron

synaptic vesicles release acetylcholine (ACh)

ACh diffuses across cleft and binds to receptors on motor end plate

sarcolemma becomes permeable to Na+

Na+ rushes into the cell generating an action potential

action potential travels on sarcolemma and stimulates muscle fiber to contract

39
Q

sliding filament theory

A

muscle contraction involves the shortening of all the sarcomeres within a muscle fiber

40
Q

sliding filament theory

A

myosin pulls the thin filaments intothe center of the sarcomere

thin filaments slide past the think filaments

41
Q

Main events in skeletal muscle contraction

A

once stimulated an action potential travels along sarcolemma down t-tublules

causes SR to release Ca+2

Ca+2 binds to troponin

troponin and tropomyosin move exposing binding site for myosin on actin

myosin cross bridge binds to actin

phosphate and SDP are released from cross bridge

myosin cross bridge changes and pulls actin in (power stroke)

new ATP binds to myosin and cross bridge detaches from actin

ATP is hydrolysed and energy is used to “cock” myosin head so it is ready to bind with actin

cross bridge cycle continues if ATP and Ca+2 are present

42
Q

Skeletal muscle Relaxation

A

ACh is degraded

muscle fiber is no longer stimulated

Ca+2 is pumped back into the SR

new ATP causes cross bridge to detach from actin

Troponin-tropomyosin move so tropomyosin covers myosin binding site on actin

muscle fiber relaxes

ATP is hydrolysed and energy is used to “cock” myosin cross bridge

ready for further stimulation

43
Q

Contraction of Skeletal muscle

A

All or None

not all fibers may be stimulated during same interval

different combinations may give different responses

graded responses different degrees of contraction strength

44
Q

contractoin graded responses

A

frequency of stimulation

number of motor units being stimulated at one time

45
Q

Energy for contraction

A

stored ATP

only 4-6 secons is stored

other pathways to produce ATP

46
Q

Direct Phosphorylation of ADP

A

muscle cells store CP (high energy molecule)

CP supplies are exhausted in less than 15 seconds

47
Q

Anerobic glycolysis and lactic acid formation

A

occurs when O2 is limited or absent

produces 2 ATP and lactic acid

not as efficient but fast

about 40 seconds of energy

48
Q

Aerobic Respiration

A

Main source of ATP

can provide hours of energy

49
Q

Cell oxygen source

A

blood

hemoglobin in RBC carries oxygen from lungs

Myoglobin

found in skeletal muscle

temporary storage site for oxygen

50
Q

muscle fatigue

A

Muscle unable to contract even with a stimulus

51
Q

muscle fatigue causes

A

build up of lactic acid

lack of ATP

depletion of muscle glycogen stores

lack of acetylcholine

Biology 108 (38 decks)

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