Topic_3_Ch_36

To produce movement, _______ must generate _____ to pull against a resistance, typically the skeleton to move bones.

muscles; force

There are other 'movements' that only require __________, e.g., heart contraction, respiration.

muscle contractions

Muscles can contract very quickly, _______ times a second in vertebrates and even faster in insects.

30

Skeletal muscles connect bones _____________ and are __________.

stratified; voluntary

Cardiac muscles are __________, have __________ nuclei per cell, and contain intercalated discs.

stratified; 1-2

Smooth muscles are ________, have __________ nuclei per cell, and are found in blood vessels and organs.

unbranched; 1

Muscle fibers are composed of bundles of elongate cells called __________.

muscle bundles

Myofibrils are organized into sections called ______ __________ between Z discs.

sarcomeres

Shortens when muscle contracts and lengthens when muscle relaxes or is stretched = ________.

1 cell

A longitudinal section shows the organization of thick (________) and thin (actin) filaments.

myosin

In the Sliding Filament Model, muscles produce force by the sliding of _________ filaments relative to _________ filaments.

actin; myosin

Very important: _______ of the thick and thin filaments do not change during muscle contraction.

lengths

To generate force, myosin heads bind to actin and __________ must be present for myosin to release from actin.

ATP

When no ATP (death), myosin head cannot detach: ___________.

rigor mortis

In excitation-contraction coupling, an action potential leads to the release of ___________ (ACh).

acetylcholine

Striated muscles contract when troponin and __________ move in response to Ca2+.

tropomyosin

With activation, calcium binds to __________ which causes movement of tropomyosin.

calmodulin

Hydrostatic skeletons __________ in a body cavity surrounded by muscle.

exist

Animal skeletons provide attachment sites for muscles to transmit muscle forces for __________.

movement

Exoskeletons are _______ structures that envelop the body.

hard hollow

Vertebrate ____skeleton provides internal scaffolding to which muscles attach.

axial

Bone made by ___________, cells that secrete calcium phosphate and collagen fibers.

osteoblasts

___________ are made up of cells scattered in a gelatinous matrix.

Cartilage

Joints with a broader range of motion are less stable, subject to __________ and injury.

dislocation

Ball-and-socket joints allow motion along ____________ axes.

three