Chapter 45: Animal Movement

calcium ions

When ________ bind to troponin，the troponin- tropomyosin complex moves in a way that exposes the myosin binding sites on actin.

Cartilage

________ is made up of cells scattered in a gelatinous matrix of polysaccharides and protein fibers.

Osteoblasts

________ are bone- building cells一they secrete the protein- and calcium- rich extracellular matrix at hardens to form bone.

Hugh Huxley

In 1952, biologist ________ examined cross sections of sarcomeres using electron microscopy.

exoskeleton

A(n) ________ " (outside skeleton) "is an exterior skeleton that encloses and protects an animals body.

Chitinous ingrowths

________ of the skeleton form apodemes, where muscles attach.

rigid structures

Endoskeletons " (inside skeletons) "are ________ that occur within the body.

Ligaments

________ are bands of fibrous connective tissue, primarily collagen, that bind bones to other bones.

Smooth muscle

________ is autorhythmic, meaning that it can spontaneously contract, with no stimulation by the nervous system.

Bones

________ attach to skeletal muscle via bands of fibrous connective tissue called tendons.

muscle fibers

The myofibrils inside ________ often look striped, or striated, due to the alternating light- dark units called sarcomeres, which repeat along the length of a myofibril.

tropomyosin

Besides actin, thin filaments contain two key proteins called ________ and troponin, which work together to block the myosin binding sites on actin.

Vertebrate skeletons

________ are composed of three main elements:

Hydrostatic skeletons

________ " (still- water skeletons), "or hydrostats, are constructed of an extensible body wall in tension surrounding a fluid or deformable tissue under compression.

circumferential muscles

Longitudinal and ________ in earthworms make up an antagonistic muscle group, a group of two or more muscles that reextend one another via the skeleton.

Bones

________ are made up of cells in a hard extracellular matrix of calcium phosphate with small amounts of calcium carbonate and protein fibers.

smooth muscle

Because ________ is innervated only by autonomic neurons, it is involuntary.

Osteoblasts are bone-building cells一they secrete the protein

and calcium-rich extracellular matrix at hardens to form bone

Myofibrils

Within each muscle cell are many threadlike, contractile structures

sarcomeres

The myofibrils inside muscle fibers often look striped, or striated, due to the alternating light-dark units

thin filament

composed of two coiled chains of actin, a common component of the cytoskeleton of eukarγotic cells