Glossary of Biology - CH 10 - Muscles and Locomotion

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How do protozoans and primitive algae move?
By beating cilia or flagella
How do cilia and flagella work?
Cylindrical stalk of eleven microtubules-nine paired microtubules arranged in a circle with two single microtubules in the center

Move using power stroke using sliding action of microtubules

Recovery stroke is return of cilia or flagella to original position
How do amoeba move?
Extend pseudopodia

Advancing cell membrane extends forward, allowing cell to move
How do longworms move?
Muscles are arranged in two antagonistic layers: longitudinal and circular

Muscles contract against incompressible fluid within animal's tissue (termed hydrostatic skeleton)

Contraction of circular muscles causes elongation of worm

Contraction of longitudinal muslces causes shortening of worm
How do annelids move?
Segmented worms

Advance primarily by action of muscles on a hydrostatic skeleton

Bristles in the lower part of each segment, called setae, anchor the earthworm temporarily in the earth while muscles push it ahead
What is an exoskeleton?
Hard skeleton that covers all muscles and organs and some invertebrates
Where are exoskeletons mostly found?
Principally in arthropods (insects)
What are insect skeletons composed of?
What are exoskeletons composed of?
Noncellular material secreted by epidermis
What is a limitation of an exoskeleton?
Growth is limited and periodic molting and deposition of a new skeleton is necessary to permit body growth
What is cartilage?
Connective tissue that is softer and more flexible than bone

Retained in places where firmness and flexibility is needed
What are the two types of bone?
Spongy Bone
Compact Bone
What type of tissue is bone?
Mineralized connective tissue
Describe compact bone
Dense bone that does not appear to have cavaties when observed with naked eye

Bony matrix is deposited in structural units called osteons (haversian systems)
What is an osteon?
Bony matrix is deposited in structural units called osteons (haversian systems)

Each osteon consists of a central microscopic channel called a haversian canal, surrounded by number of concentric circles of bony matrix called lamellae
What is lamellae?
Concentric circles of bony matrix surrounding the haversian canal
Describe spongy bone:
Less dense and consists of interconnecting lattice of bony spicules (trabeculae)

Cavities filled with yellow and/or red marrow
What are spicules (trabeculae)?
Innterconecting lattice of bony material in spongy bone
What does yellow marrow do?
Yellow marrow is inactive and infiltrated by adipose tissue
What does red marrow do?
Active production of red blood cells
What do osteoblasts do?
Synthesize and secrete the organic consituents of bone matrix

Once they are surrounded by their matrix, they mature in osteocytes
What are osteoclasts?
Large multinucleated cells involved in bone resorption
What is part of the axial skeleton?
Skull, vertebral column, rib cage
What is part of the appendicular skeleton?
Appendages, pectoral and pelvic girdles
What are ligaments?
Support bone joints
What are tendons?
Muslcle to bone attachment
What is the origin and insertion of a muscle?
Origin - Attachment of muscle to stationary bone

Insertion - Attachment of muscle to moving bone
What is extension and flexion?
Extension - Straightening of a joint

Flexion - Bending of a joint
What is skeletal muscle?


Multinucleated fiber cells

Within each fiber are filaments called myofibrils, further divided into contractile units called sarcomeres
What is the sarcoplasmic reticulum?
Modified endoplasmic reticulum that stores calcium ions
What is the cytoplasm of a muscle cell called?
What is the cell membrance called in a muscle cell?
What is capable of propagating a signal in a muscle cell?
sarcolemma, connected to system of transverse tubules (T system) oriented perpendicular to myofibrils
What is the T system?
Transverse tubules

Provides channels for ion flow throughout the muscle fibers, and can also propagate an action potential
Why are mitochondria very abundant in muscle cells?
Muscle cells require substantial amounts of energy to perform well
What type of filaments are sarcomeres composed of?
Thick and Thin filaments
What type of molecules are thin and thick filaments?
Thin - actin molecules
Thick - myosin
What are Z-lines?
Define boundaries of a single sarcomere and anchor thin filaments
What is the M line?
Runs down center of sarcomere?
What is the I Band?
Region containing thin filaments only
What is the H zone?
Region containing thick filaments only
What is the A band?
Spans the entire length of the thick filaments and any overlapping portions of the thin filaments
During contraction, which segments are reduced in size?
H zone and I band are reduced
A band is not reduced in size
What is the link between the nerve terminal and sarcolemma called?
Neuromuscular Junction
Once an action potential reaches the muscle fiber, how is it propagated within the fiber?
Along sarcolemma and the T system, and into interior of the muscle system

Causes sarcoplasmic reticulum to release calcium ions into the sarcoplasm

Calcium ions initiate the contraction of the sarcomere

Actin and myosin slide past each other and the sarcomere contracts
How is the strength of the entire muscle contraction increased?
By recruiting more muscle fibers
What is a simple twitch?
Response of a single muscle fiber to a brief stimulus at above threshold stimulus

Consists of latent period, contraction period, relaxation period
What is the latent period?
Time between stimulation and onset of contraction

Action potential is spread throughout sarcolemma and Ca2+ ions are released
What is the contraction period?
Period in which fibers contract
What is relaxation period?
Muscle is unresponsive to stimulus

AKA absolute refractory period
What is summation?
When fibers are exposed to very frequent stimuli, muscle can not fully relax

Contraction begin to combine, become stronger and more prolonged
What is tetanus?
Contractions become so frequent muscle can not relax

If tetanus is maintained, muscle will fatigue and contraction will weaken
What is tonus?
State of partial contraction

Muscles are never completely relaxed and maintain a partially contracted state at all times
What are the basics of smooth muscle?
Involuntary actions and innervated by autonomic nervous system

One centrally located nucleus

Lack striations
What are the basics of cardiac muscle?
Striated appearance

Only one or two centrally located nuclei
What are two energy reserves when ATP is depleted?
Creatine Phosphate (vertebrates) and Arginine Phosphate (invertebrates)

Temporary storage of high energy compound
What is myoglobin?
Hemoglobin like protein found in muscle tissue

Very high affinity for oxygen
What is myogenic?
Not sure

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