Skeletal System: Bone Structure

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Questions and Answers

What is the primary composition of bone?

Bone cells embedded in a matrix of protein and sugar

Active cells within a liquid medium

Fatty cells within a rigid protein framework

Bone cells embedded in a matrix of collagen and calcium salts (correct)

Why is spongy bone lighter than compact bone?

It has a more open structure (correct)

It contains air pockets

It is composed of fewer minerals

It has a hollow interior structure

Which type of cartilage is found at the ends of bones and in the respiratory system?

Fibrocartilage

Hyaline cartilage (correct)

White fibrous cartilage

Elastic cartilage

What is the primary function of tendons?

To connect muscles to bones Signup and view all the answers

What characteristic allows ligaments to hold bones together while also permitting movement?

Elastic tissue composition Signup and view all the answers

What would happen if tendons were to stretch excessively?

They would allow bone movement potentially leading to injury Signup and view all the answers

Which of the following describes white fibrous cartilage?

Densely packed collagen with low flexibility Signup and view all the answers

What role do ligaments play in joint stability?

They provide secure attachment for bones and allow limited joint movement Signup and view all the answers

What is the primary purpose of synovial fluid in certain joints?

To lubricate and facilitate smooth movement between bones Signup and view all the answers

Which pair of joints provides the most freedom of movement?

Ball and socket joints Signup and view all the answers

What is the role of antagonistic pairs of muscles?

To create movement by contracting and relaxing in opposition Signup and view all the answers

How do the thick and thin myofilaments contribute to muscle contraction?

They slide past each other, allowing the muscle to contract. Signup and view all the answers

What is the function of the sarcoplasmic reticulum in muscle fibers?

To store and release calcium ions for contraction Signup and view all the answers

What differentiates a ball and socket joint from a hinge joint?

Shape and range of motion Signup and view all the answers

In terms of muscle fiber structure, what do the Z-lines demarcate?

The ends of each sarcomere Signup and view all the answers

Study Notes

Bone Tissue

Main tissue of the skeleton, composed of bone cells within a collagen and calcium salt matrix.
Extremely strong under compression forces; designed to be both strong and lightweight.
Compact bone is dense, found in long bones; spongy bone is lighter, located in areas like the pelvis and femur head.

Cartilage

Hard yet flexible tissue made up of chondrocytes in an organic matrix of collagen fibrils.
Can stretch elastically and withstands compressive forces, serving as an effective shock absorber.
Types of cartilage:
- Hyaline cartilage: Located at bone ends, found in the nose, airways, and parts of the ear.
- White fibrous cartilage: Contains densely packed collagen, providing high tensile strength, situated in joints and between vertebrae.

Tendons and Ligaments

Tendons: Composed mainly of white fibrous tissue, ideal for connecting muscles to bones; relatively inelastic.
Ligaments: Hold bones together, composed of yellow elastic tissue, allowing for elastic movement around joints while maintaining alignment.

Joint Structure and Function

Joints are lined with rubbery cartilage to prevent bone wear from friction and facilitate smooth movement.
Synovial fluid acts as a lubricant in mobile joints, ensuring easy movement by filling the joint cavity.
Joint types vary in structure:
- Ball and socket joints (e.g., hip, shoulder) allow for extensive movement.
- Hinge joints (e.g., knee) restrict movement.

Muscle Movement Mechanics

Movement occurs through muscle contractions on bones; each skeletal muscle connects two bones via tendons.
Muscles operate in antagonistic pairs: one muscle extends a joint (extensors), while the other flexes it (flexors).
Muscles relax without applying force, returning to their original shape.

Muscle Cell Structure

Skeletal muscle fibers: Long, multinucleate bundles, with membranes called sarcolemma.
Transverse (T) tubules spread electrical impulses within muscle fibers.
Sarcoplasmic reticulum stores and releases calcium ions necessary for muscle contractions.
Muscle fibers contain many mitochondria for ATP production and specialized organelles called myofibrils for contraction.

Myofibril Structure

Comprised of thick (myosin) and thin (actin) myofilaments, which slide past each other during contraction.
Visible alternating dark (A-bands with myosin and actin) and light (I-bands with actin) bands under an electron microscope.
Made of repeating units known as sarcomeres, characterized by Z-lines marking the ends and M-lines indicating the middle of myosin filaments.
H-zone present within sarcomeres contains only myosin filaments.

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Description

This quiz explores the structure and function of bone within the skeletal system. You will learn about the types of bone, their properties, and how they support the body. Delve into the differences between compact and spongy bone and discover the role of collagen and calcium in bone composition.