BIO 360 - Exam 3 - Chapter 12 Summary Questions Flashcards

1
Q

______ generate motion, force, and heat.

A

Muscles

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2
Q

The three types of muscle are:

A

skeletal muscle, cardiac muscle, and smooth muscle. Skeletal and cardiac muscles are striated muscles.

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3
Q

Skeletal muscles are controlled by ______ ______ neurons. Cardiac and smooth muscle are controlled by a_____ i______, p______ s______, and h______.
Some smooth and cardiac muscles are ______ and contract spontaneously.

A

somatic motor / autonomic innervation, paracrine signals, and hormones / auto-rhythmic

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4
Q

Skeletal muscles are usually attached to bones by tendons. The ______ is the end of the muscle attached closest to the trunk or to the more stationary bone. The ______ is the more distal or mobile attachment.

A

origin / insertion

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5
Q

At a flexible joint, muscle contraction moves the skeleton. ______ bring bones closer together; ______ move bones away from each other. Flexor-extensor pairs are examples of ______ muscle groups.

A

Flexors / extensors / antagonistic

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6
Q

A skeletal muscle is a collection of ______ ______, large cells with many nuclei.

A

muscle fibers

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7
Q

______ allow action potentials to move rapidly into the interior of the fiber and release calcium from the s______ r______.

A

T-tubules / sarcoplasmic reticulum

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8
Q

______ are intracellular bundles of contractile and elastic proteins. ______ filaments are made of ______. ______ filaments are made mostly of ______. _____ and ______ hold thick and thin filaments in position.

A

Myofibrils / Thick filaments / myosin / Thin filaments / actin / Titan / nebulin

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9
Q

Myosin binds to actin, creating ______ between the thick and thin filaments.

A

crossbridges

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10
Q

A ______ is the contractile unit of a myofibril. It is composed of two ______ and the filaments between them. The sarcomere is divided into ______ (thin filaments only), an ______ that runs the length of a thick filament, and a central ______ occupied by thick filaments only. The ______ and Z disks represent attachment sites for myosin and actin, respectively.

A

sarcomere / Z disks / I bands / A band / H zone / M line

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11
Q

The force created by a contracting muscle is called ______ ______. The ______ is a weight or force that opposes contraction of a muscle.

A

muscle tension / load

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12
Q

The _________________________________ states that during contraction, overlapping thick and thin filaments slide past each other in an energy-dependent manner as a result of actin-myosin crossbridge movement.

A

sliding filament theory of contraction

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13
Q

In relaxed muscle, ______ partially blocks the myosin-binding site on actin. To initiate contraction, ______ binds to ______. This unblocks the myosin-binding sites and allows myosin to complete its power stroke.

A

tropomyosin / Ca2+ / troponin

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14
Q

During relaxation, the sarcoplasmic reticulum uses a ________
to pump _______ back into its lumen.

A

Ca2+ - ATPase / Ca2+

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15
Q

Myosin converts energy from ATP into motion. ______ ______ hydrolyzes ATP to ADP and ______.

A

Myosin ATPase / Pi

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16
Q

When myosin releases ______ the myosin head moves in the ______ ______. At the end of the power stroke, myosin releases ADP. The cycle ends in the ______ ______, with myosin tightly bound to actin.

A

Pi / power stroke / rigor state

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17
Q

In ______ - ______ ______, a somatic motor neuron releases ACh, which initiates a skeletal muscle action potential that leads to contraction.

A

excitation-contraction coupling

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18
Q

Relaxation occurs when ______ is pumped back into the SR by a ______.

A

Ca2+ / Ca2+-ATPase

19
Q

A single contraction-relaxation cycle is known as a ______. The ______ ______ between the end of the muscle action potential and the beginning of muscle tension development represents the time required for Ca2+ release and binding to troponin.

A

twitch / latent period

20
Q

Muscle fibers store energy for contraction in ______ . Anaerobic metabolism of glucose is a rapid source of ATP but is not efficient. Aerobic metabolism is very efficient but requires an adequate supply of oxygen to the muscles.

A

phosphocreatine

21
Q

______ ______is a reversible condition in which a muscle is no longer able to generate or sustain the expected power output. Fatigue has multiple causes.

A

Muscle fatigue

22
Q

Skeletal muscle fibers can be classified on the basis of their speed of contraction and resistance to fatigue into?

Oxidative fibers are the most fatigue resistant.

A

slow-twitch (oxidative) fibers, fast-twitch oxidative-glycolytic fibers, and fast-twitch glycolytic fibers.

23
Q

______ is an oxygen-binding pigment that transfers oxygen to the interior of the muscle fiber.

A

Myoglobin

24
Q

The tension of a skeletal muscle contraction is determined by the ______ of the ______ before contraction begins.

A

length / sarcomeres

25
Q

Increasing the stimulus frequency causes summation of twitches with an increase of tension. A state of maximal contraction is known as ______.

A

tetanus

26
Q

A ______ ______ is composed of a group of muscle fibers and the somatic motor neuron that controls them. The number of muscle fibers in a motor unit varies, but all fibers in a single motor unit are of the same fiber type.

A

motor unit

27
Q

The force of contraction within a skeletal muscle can be increased by ______ of additional motor units.

A

recruitment

28
Q

An ______ contraction creates force as the muscle shortens and moves a load. An ______ contraction creates force without moving a load. Lengthening contractions create force while the muscle lengthens.

A

isotonic / isometric

29
Q

Isometric contractions occur because s______ e______ e______ allow the fibers to maintain constant length even though the sarcomeres are shortening and creating tension.

A

series elastic elements

30
Q

The body uses its bones and joints as ______ and ______. Most lever-fulcrum systems in the body maximize the distance and speed that a load can be moved but also require that muscles do more work than they would without the lever.

A

levers and fulcrums

31
Q

Contraction speed is a function of muscle fiber type and load. Contraction is fastest when the load on the muscle is ______.

A

zero

32
Q

XXXXXXXXXXXXXXXXXXXXXXXXXXXXX

A

XXXXXXXXXXXXXXXXXXXXXXXXXXXXX

33
Q

______ muscle is slower than ______ muscle but can sustain contractions for longer without fatiguing.

A

Smooth / skeletal

34
Q

______ muscles are usually relaxed or cycle through contractions. ______ ______ muscle is usually contracted.

A

Phasic / Tonic smooth

35
Q

______-______ ______muscle contracts as a single unit when depolarizations pass from cell to cell through gap junctions.

In ______ ______ muscle, individual muscle fibers are stimulated independently.

A

Single-unit smooth / multiunit smooth

36
Q

Smooth muscle has less ______ than skeletal muscle. Each myosin is associated with about 12–15 actin molecules. Smooth muscle actin lacks ______.

A

myosin / troponin

37
Q

In smooth muscle contraction, ______ binds to ______ and activates myosin light chain kinase (MLCK).

A

Ca2+ / calmodulin

38
Q

MLCK phosphorylates ______ ______ ______, which activates myosin ATPase. This allows crossbridge power strokes.

A

myosin light chains

39
Q

During relaxation, Ca2+ is pumped out of the cytosol, and myosin light chains are dephosphorylated by ______ ______ .

A

myosin phosphatase

40
Q

Smooth muscle ______ ______ can be altered by changing myosin phosphatase activity.

A

calcium sensitivity

41
Q

In ______ contraction, stretch on the cell depolarizes it and Ca2+ opens membrane channels.

A

myogenic

42
Q

Unstable membrane potentials in smooth muscle take the form of either ______ ______ potentials or ______ potentials.

A

slow wave / pacemaker

43
Q

Cardiac muscle fibers are what three things?

Cardiac muscle shares features with both ______ and ______ muscle.

A

(1) striated
(2) have a single nucleus
(3) electrically linked through gap junctions.

skeletal and smooth muscle