TEAS 1.12 Skeletal System

What are the three main functions of the skeletal system?

1. Movement - works with muscles to enable body motion

2. Protection - shields vital organs

3. Storage - holds minerals (calcium, phosphate) and fat

What additional functions does the skeletal system perform beyond the three main functions?

Provides support and shape to the body, synthesizes blood cells (RBCs, WBCs, platelets), produces immune cells, and acts as a dynamic tissue that constantly remodels based on body needs

What are the characteristics of long bones and provide examples?

Length exceeds width, found in arms and legs.

Examples: femur, humerus, ulna, radius, tibia, fibula.

Contain yellow marrow in the shaft and red bone marrow at the ends. Have growth plates where bone lengthens during development

What is yellow marrow and where is it located?

stores lipids (fat) and is found in the shaft of long bones

What is red bone marrow and where is it found?

produces blood cells (RBCs, WBCs, and platelets).

It is found at the ends of long bones and in flat bones

What are the characteristics of short bones and provide examples?

Similar length and width (cube-shaped). Examples: wrist and ankle bones. Function as gliding joints with limited movement

What are the characteristics of flat bones and provide examples?

Thin and plate-like, protect vital organs. Examples: ribs and cranial bones. Contain red bone marrow for blood cell production

What are irregular bones and provide examples?

Bones that don't fit other categories.

Examples: hip bones and vertebrae

What are the two main types of joints?

• Movable joints (allow motion, e.g., ball-and-socket in hips and shoulders, hinge joints in elbows)

• immovable joints (bones fused together, e.g., skull plates)

What are ligaments?

Tough connective tissue that attaches bone to bone

What is hyaline cartilage and what is its function?

Connective tissue that covers articulating surfaces of bones to prevent them from grinding against each other

What is synovial fluid and where is it found?

A lubricating fluid found in movable joints such as pivot, ball-and-socket, and hinge joints

What is unique about the hyoid bone?

it is the only bone not connected to other bones

it is held in place by muscles alone (suprahyoid and infrahyoid muscles)

What is a ball-and-socket joint and where is it found?

A point of articulation that allows for abduction, adduction, circumduction, and rotation. Examples: hip socket and shoulder

What is a hinge joint?

A joint that allows for flexion and extension of the more distal bone along only one plane. Example: elbow

What are osteons (Haversian systems)?

Tubular functional units of compact (dense) bone made of calcium and phosphate-rich hydroxyapatite embedded in a collagen matrix, organized in concentric rings around a central canal

What is found in the central canal of an osteon?

Blood vessels and nerves

What are lacunae?

Small cave-like spaces (microscopic pits) in the bone matrix that contain osteocytes and connect to each other within an osteon

What is the periosteum?

A fibrous outer sheath (thin layer) that surrounds bone and contains nerves and blood vessels. It serves as the surface for attachment of tendons and ligaments

What are osteoblasts and what do they do?

Mononucleate cells that build bone by replacing cartilage, secrete mineral deposits that form the bone matrix, and develop into osteocytes for bone maintenance

What are osteocytes and what do they do?

Star-shaped cells that maintain bone, sense physical stresses on bone, and carry out metabolic functions

What are osteoclasts and what do they do?

Multinucleate cells that break down bone minerals from the matrix, working in balance with osteoblasts for bone remodeling

What is the important balance needed for healthy bones?

Healthy bones require equilibrium between osteoblast (building) and osteoclast (breaking down) activity

What is osteoporosis and what causes it?

A disease where osteoclasts break down bone faster than osteoblasts build it, resulting in weak, brittle bones. Caused by excessive mineral withdrawal from bone, leading to loss of rigidity

What is osteoarthritis?

A degenerative joint disease that damages the cartilage between joints

What is brittle bone disease (osteogenesis imperfecta)?

A genetic defect affecting the collagen matrix. The gene that codes for collagen needed to form the bone matrix is missing, causing bones to break easily

How do skeletal muscles attach to bones?

Skeletal muscles attach to bones via tendons, which are made of connective tissue

How does muscle contraction create movement?

Muscles receive signals from the central nervous system to contract.

When the muscle contracts, it pulls on the bone to which it is connected, creating movement

What does it mean that muscles work in tandem (pairs)?

Muscles work in pairs where one muscle contracts while the other relaxes to create movement

What is a prime mover (agonist)?

The contracting muscle in a pair of muscles involved in a given movement

What is an antagonist muscle?

The relaxed muscle in a pair of muscles involved in a given movement

Explain how biceps and triceps work together to control elbow movement

When the biceps contracts (prime mover), the triceps relaxes (antagonist) to bend the arm.

When the triceps contracts, the biceps relaxes to straighten the arm

What are tendons?

Connective tissue structures that connect muscles to bones

What is the growth plate (epiphyseal plate)?

Hyaline cartilage in long bones where bone elongation happens during development