BIO 360 - Exam 3 - Chapter 12 Summary Questions

Question 1

______ generate motion, force, and heat.

Answer 1

Muscles

Question 2

The three types of muscle are:

Answer 2

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

Question 3

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.

Answer 3

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

Question 4

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.

Answer 4

origin / insertion

Question 5

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.

Answer 5

Flexors / extensors / antagonistic

Question 6

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

Answer 6

muscle fibers

Question 7

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

Answer 7

T-tubules / sarcoplasmic reticulum

Question 8

______ 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.

Answer 8

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

Question 9

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

Answer 9

crossbridges

Question 10

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.

Answer 10

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

Question 11

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

Answer 11

muscle tension / load

Question 12

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.

Answer 12

sliding filament theory of contraction

Question 13

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.

Answer 13

tropomyosin / Ca2+ / troponin

Question 14

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

Answer 14

Ca2+ - ATPase / Ca2+

Question 15

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

Answer 15

Myosin ATPase / Pi

Question 16

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.

Answer 16

Pi / power stroke / rigor state

Question 17

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

Answer 17

excitation-contraction coupling

Question 18

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

Answer 18

Ca2+ / Ca2+-ATPase

Question 19

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.

Answer 19

twitch / latent period

Question 20

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.

Answer 20

phosphocreatine

Question 21

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

Answer 21

Muscle fatigue

Question 22

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.

Answer 22

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

Question 23

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

Answer 23

Myoglobin

Question 24

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

Answer 24

length / sarcomeres

Question 25

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

Answer 25

tetanus

Question 26

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.

Answer 26

motor unit

Question 27

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

Answer 27

recruitment

Question 28

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.

Answer 28

isotonic / isometric

Question 29

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

Answer 29

series elastic elements

Question 30

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.

Answer 30

levers and fulcrums

Question 31

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

Answer 31

zero

Question 32

XXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Answer 32

XXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Question 33

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

Answer 33

Smooth / skeletal

Question 34

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

Answer 34

Phasic / Tonic smooth

Question 35

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

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

Answer 35

Single-unit smooth / multiunit smooth

Question 36

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

Answer 36

myosin / troponin

Question 37

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

Answer 37

Ca2+ / calmodulin

Question 38

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

Answer 38

myosin light chains

Question 39

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

Answer 39

myosin phosphatase

Question 40

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

Answer 40

calcium sensitivity

Question 41

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

Answer 41

myogenic

Question 42

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

Answer 42

slow wave / pacemaker

Question 43

Cardiac muscle fibers are what three things?

Cardiac muscle shares features with both ______ and ______ muscle.

Answer 43

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

skeletal and smooth muscle