The skeletal system provides a strong framework for the body, protects vital organs, stores important materials, and works with muscles to enable movement. This lesson introduces the human skeleton and explains how its major divisions and bones support the body.
The adult human skeleton is an endoskeleton: a framework that develops inside the body. Unlike the external skeleton, or exoskeleton, of insects, an endoskeleton grows with the body. An adult skeleton contains 206 bones.
All flashcards
What are the five major functions of the skeleton?
It supports the body, stores minerals and lipids, produces blood cells, protects organs, and works with muscles to enable movement.
How do the axial and appendicular skeletons differ?
The axial skeleton forms the body's central axis; the appendicular skeleton consists of the limbs and the girdles that attach them.
How does skeletal muscle move bones?
When it contracts, skeletal muscle pulls on its attachment points; muscles pull rather than push, so groups often coordinate movement around joints.
What distinguishes skeletal, smooth, and cardiac muscle tissue?
Skeletal muscle is striated and usually voluntary; smooth muscle is nonstriated and involuntary; cardiac muscle is striated, involuntary, and found in the heart.
What happens to actin and myosin during skeletal-muscle contraction?
Myosin heads bind to and pull actin, causing the filaments to slide past one another; the filaments do not themselves shorten.
Quiz questions
How are bones connected in a fibrous joint?Answer: By fibrous connective tissue, without a joint cavity.
What is the primary role of synovial fluid in a synovial joint?Answer: It lubricates the joint and reduces friction.
What kind of disorder is rheumatoid arthritis?Answer: An autoimmune inflammatory disorder that commonly affects synovial joints.
Which feature helps coordinate contractions between cardiac muscle cells?Answer: Specialized junctions called intercalated disks.
What does ATP provide during skeletal-muscle contraction?Answer: Energy for myosin heads to bind, pull, and reset.
Based on Concepts of Biology by Samantha Fowler, Rebecca Roush, James Wise (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.