Movement (Test Two) Flashcards
What does animal movement rely on?
The fundamental mechanism called contractile proteins.
What is the most important protein contractile system composed of?
Actin and Myosin
Briefly explain what actin is.
Spherical protein that forms filaments (strands) that are involved in the cytoskeleton and muscle contraction.
Briefly explain what myosin is.
A motor protein that is involved in muscle contraction by converting ATP into mechanical energy
In what organisms does ameboid movement occur?
- Macrophages
- ameboid/unicellular
- WBC
- some embryonic cells
- some cancer cells
How do ameboid cells change shape?
By extending and withdrawing pseudopodia (false feet)
How do ameboid cells move?
By assembling and disassembling actin and myosin filaments, the cell membrane is pushed forward, and the cytoplasm follows.
What are cilia and what are their functions?
They are tiny, hairlike processes that extend from surfaces of many animal cells, that do not use actin or myosin
Functions:
- To move whole unicellular organisms and some cnidarians in water
- Also used to propel fluids and materials across epithelial surfaces in larger animals.
What are flagella?
Flagellum are whip-like structures (longer than cilia) that are usually used for locomotion or movement of things
They also do not use actin or myosin
What is the difference between Ciliary and Flagellar movement?
- Flagella beat symmetrically, and water is propelled parallel to its length like a propeller (sideways movement)
- Cilia have a fast power stroke down and slow recovery, like oars (upward movement)
Nearly all movement in animal bodies is the result of what?
Muscle cell (fibers) contractions
Describe skeletal muscle.
Striated muscles that are transversely striped with alternating dark and light bands (striations) and are multi nucleated.
They are long cylindrical cells that are packed together in bundles called fascicles and enclosed by tough connective tissue.
What is the purpose of skeletal muscle?
They are attached to skeletal elements that move the trunk, appendages, eyes, respiratory organs and mouthparts.
What does skeletal muscle do at the ends when it connects to bones via tendons?
It reduces thickness (tapers)
What does skeletal muscle look like in abdominal muscles?
They look like flattened sheets.
How are skeletal muscles stimulated? Are they voluntary?
They are stimulated by motor fibers under conscious control.
Describe Cardiac Muscle.
- Fast acting, with similar contraction mechanism to skeletal muscle, but has involuntary control.
Where does the heat beat originate?
Within a specialized cardiac muscle, and can continue to beat outside the body
Describe Smooth Muscle.
Smooth (visceral) muscle lacks striations and the cells are much smaller, tapering at both ends, with a single central nucleus.
Where is smooth muscle located?
Smooth muscle forms sheets of muscle to circle the walls of tubes, ducts and passages.
Is smooth muscle slow acting or fast acting?
Is it under voluntary control?
- Smooth muscle is slow acting and uses little energy.
- Smooth muscle is under involuntary control
What is the functional unit of skeletal muscle?
Sarcomere
Describe sarcomeres in more detail.
Sarcomeres span protein complexes called z-lines and are primarily.
Explain the structure of myosin.
- Myosin Filament is composed of myosin molecules packed in a bundle
- Each myosin molecule consists of two polypeptide chains, each with a club shaped region
- The double heads face outward from the center of the filament, and point towards the z-line
- The heads act as binding sites for ATP and interact with the myosin filaments during muscle contraction