Lesson 12

Arthropods

________ such as insects and crustaceans have an exoskeleton made of the polysaccharide chitin.

Starburst

________ like extensions of the osteocytes can interact with neighboring cells through the colliculi, providing a means of intercellular communication.

hydrostatic skeleton

A(n) ________ incorporates a fluid- filled central cavity surrounded by muscles.

Chondroblasts

________ produced cartilage, and eventually become mature chondrocytes and osteoblasts, which form bone and become osteocytes.

rigid internal skeleton

The endoskeleton is a(n) ________ that forms the body's framework and offers a surface for muscle attachment.

frequency of stimulation

If the ________ is increased, there is no relaxation between twitches and the contraction is smooth and sustained.

Fibroblasts

________ are cells that produce collagen.

ATP

________ can bind to the myosin head, which weakens the link between myosin and actin.

motor neuron

When a(n) ________ releases a neurotransmitter into the synapse at the neuromuscular junction and the muscle cell is depolarized.

Cartilage

________ is designed to withstand compression and tension.

multiple stimuli

When ________ are applied to a muscle before it can relax, the subsequent twitches will be stronger than the first.

D.

The osteoblasts are signaled to produce more matrix and the newly thickened bone resists bending as shown in ________ Once the bone is thick enough to resist bending, bone deposit stops.

single action

The response of a motor unit to a(n) ________ potential is called a twitch.

Osteocytes

________ reside in lacunae which have little canals extending out called canaliculi.

Exoskeleton

________ is not as strong as a bony skeleton.

Rigor mortis

________ begins approximately 3 h after death and reaches peak rigidity around 12 hours.

disc of protein

Each I- band is divided in half by the Z- line, which is a(n) ________.

Oxygen

________ and nutrients reach the cells by diffusion from surrounding blood vessels.

blood vessels

The canals run parallel to the length of the bone and contain ________ and sometimes nerve fibers.

somatic motor neurons

The ________ that stimulate muscle cells have branched axons, which allow them to make synapses with a number of muscle fibers.

Transverse tubules

________ are invaginations of the cell membrane which carry the depolarization deep into the muscle cell, to the sarcoplasmic reticulum, which then releases calcium ions.

Halvorson lamella

________ are layers of bone laid down around narrow channels called and canals.

network of fibers

And the ________ are connected by intercalated discs, which allow the fibers to contract as a unit.

Smooth muscle

________ is normally found in the internal organs, is in voluntarily controlled and tends to contract and relax very slowly.

cardiac muscle cells

The ________ are found only in the walls of the heart, are involuntarily controlled.

Cartilage heals

________ slowly, as many people with sports injuries can attest to.

dark bands

The myofibrils have alternating light and ________.

internal organs

And exoskeleton consists of a rigid outer covering that protects ________ and provides an attachment site for muscles.

hydrostatic skeleton of earthworms

The ________ uses two sets of muscles working against the fluid- filled body cavity.

concentration of calcium ions

When a muscle is stimulated to contract, the ________ in the muscle fiber cytoplasm increases.

myosin

During contraction, the actin and ________ myofilaments interact.

Calcium ions

________ bind to troponin, which changes its shape and causes the attached tropomyosin filaments to move, thus revealing actin binding site.

greatest amount of movement

Ball and socket joints allow the ________ and are located in the hip and shoulder.

Vertebrate endoskeletons

________ are composed of bone and cartilage and dense fibrous connective tissue.

Myosin proteins

________ are motor proteins that are able to convert the chemical energy in ATP into mechanical energy.

Bone

________ is also a specialized connective tissue and is composed of both organic and inorganic components.

Muscles

________ need a steady supply of calcium for contraction and store it in a modified endoplasmic reticulum called the sarcoplasmic reticulum.

vascular bones

Most mammals have ________ with internal blood vessels.

Bone remodeling

________ is stimulated by mechanical stresses and regulatory hormones, which will be discussed in future lectures.

Halvorson system

The ________ is the internal organization of vascular bone.

depolarization

The ________ is conducted down the cell membrane and down the transverse tubules.

Hinge joints

________ allow only movement forward or backward and are found in the knee, elbow, and within the fingers.

smallest unit of muscle contraction

The sarcomere is the ________.

Cells

________ that make up bone and cartilage are derived from embryonic connective tissue called mesenchyme.

ATP

________ hydrolysis returns myosin to the energized conformation and the cycle can begin again.

Chondroblasts

________ secrete extracellular matrix and often becomes stuck inside cocoon like spaces called lacunae and are then called chondrocytes are cartilage cells.

exoskeleton

A(n) ________ completely encases the muscles and internal organs and therefore limits growth of the animal.

Cartilage

________ is a specialized connective tissue.

Bone

________ is stronger but less flexible than cartilage.

dark bands

The ________ are produced by stacked thick filaments.