Anatomy Test Unit 2

What is a bone?

A rigid but living organ made of all four tissue types: connective, nervous, epithelial, and muscle tissue.

What is the main tissue in a bone?

Osseous, or bone, connective tissue.

What other connective tissues cover or support bone?

Cartilage and dense connective tissue.

What does nervous tissue do in a bone?

Forms the nerves found in the bone.

What role does epithelial tissue play in a bone?

It is associated with the blood vessels that nourish bone tissue.

What muscle tissue is associated with bones.

Skeletal muscle tissue.

How many bones are in the adult human skeleton?

206

Approximatley what fraction of a healthy person’s body weight does the skeleton make up.

Almost 1 fifth.

What does it mean that the skeleton is constantly rebuilding itself?

Bone is a living tissue that is continually remodeled and renewed. The skeleton is substantially renewed over Approximatley 7-10 years.

What are the fix major functions of the skeletal system?

Support, protection, movement, mineral and energy storage, blood cell formation, and hormone production.

How does the skeleton protect the body?

It shields vital organs. For example, the skull protects the brain, and the rib cage protects the heart.

How does the skeleton provide support?

It provides the framework that holds up the body.

How does the skeleton help produce movement?

Skeletal muscles attach to bones through tendons and use bones as levers at joints.

Which minerals are stored in bone?

Calcium and phosphate, which can be released into the blood when needed.

What is stored in yellow bone marrow?

Fat, which stores energy.

What is hematpoiesis?

Blood cell formation, which occurs in red bone marrow.

What is one hormone-related function of bone?

Bone produces osteocalcin, which helps regulate insulin secretion, glucose regulation, and energy use.

How does the skeletal system help maintain homeostasis?

It stores and releases minerals, produces hormones such as osteocalcin, support blood cell formation, and helps the body maintain table internal conditions.

How are bones classified?

By location in the axial or appendicular skeleton and by shape.

Why does bone shape matter?

A bones shape is related to its function.

What are the four main bone-shape categories?

Long, short, flat and irregular bones.

What is a long bone?

A bone that is longer than it is wide, generally with a long shaft and wider ends.

What is the main function of long bones?

They act as levers to help produce movement.

Give examples of long bones in the arm.

Humerus, radius, and ulna

Give examples of long bones in the leg

Femur, tibia, and fibula

Give examples of long bones in the foot.

Metatarsals and phalanges.

Give examples of long bones in the hand.

Metacarpals and phalanges.

What is a short bones?

A roughly cube shaped bone that is as wide as it is long.

What is the main function of short bones?

Providing support and stability while allowing relatively little movement.

What bones of the wrist are short bones.

Carpals/

Which bones of the ankle are short bones?

Tarsals.

What is a sesamoid bone?

A specialized short bone embedded within a tendon.

What is the classic example of a sesamoid bone?

The patella, or kneecap.

What is a flat bone?

A thin, often curved bone with a large surface area for muscle attachment and or protection.

Name four examples of flat bones or flat-bone groups

Sternum, scapulae, ribs, and most cranial bones.

What is an irregular bone?

A bone with a specialized shape that does not fit the long, short, or flat categories.

Give two examples of irregular bones.

Hip bones sand vertebrae.

A bone is cube shaped and provides stability with little movement. What type is it?

A short bone

A bone is thin, curved, and protects organs. What type is it?

A flat bone.

A bone has a long shaft, wider ends, and functions as a lever. What type is it?

A long bone.

A vertebrae has a complex shape and projections for attachment. What type is it?

An irregular bone.

What are the two major types of bone tissue?

Compact bone and Spongy Bone

Where is compact bone found?

As the dense, relatively smooth outer layer of bone.

Where is spongy bone found?

Toward the inside of the bone where it forms a more porous structure.

What is an osteon?

The basic structural unit of compact bone, shaped like a long cylinder that acts as a weight bearing pillar.

What are lamellae?

Layers arranged within an osteon, containing mineral salts and collagen fibers.

How do the mineral salts and collagen fibers help bone?

They help bone resist stress, including torsion or twisting stress.

What is the Haversian canal?

The central canal running through an osteon.

What does the Haversian canal contain?

Small blood vessels that nourish bone and nerve fibers involved in signaling.

Does spongy bone contain osteons?

No. It is les organized than compact bone and does not have osteons.

What are trabeculae?

Tiny struts of bone within spongy one that help it resist stress.

Where is bone marrow found?

Within the spaces of spongy bone among trabeculae.

Compare red and yellow bone marrow.

Red bone marrow produces blood cells; yellow marrow stores energy as fat.

What are bone markings?

Distinct projections, surfaces, depressions, or openings on the external surface of bones that relate to attachment, joints, or the passage of vessels and nerves.

What are the three broad types of bone markings?

1; Projections where muscles and ligaments attach.

2; Surfaces that form joints.

3; Depressions and openings for blood vessels and nerves.

What is the difference between compact and spongy bone?

Compact bone is dense and organized into osteons. Spongy bone is porous, contains trabeculae, and does not contain osteons.

What are osteocytes?

Mature bone cells that maintain healthy bone structure and monitor conditions within bone.

Where are osteocytes housed?

In lacunae, the small spaces between lamellae.

What is the construction site foreman analogy for osteocytes?

Osteocytes monitor bone condition and signal the cells that build or break down bone in response to stress, strain, damage, or lack of loading.

What do osteoblast do?

Build bone by forming and calcifying bone matrix.

What do osteoclast do?

Breaks own or absorb bone tissue during bone remodeling.

Which cells build bones: osteoblasts or osteoclast?

Osteoblast.

Which cell reasons bone: osteoblasts or osteoclast?

Osteoclast.

Which bone cell helps monitor and coordinate remodeling?

Osteocytes.

What is bone reabsorption?

The breakdown of bone tissue, releasing stored minerals such as calcium and phosphate.

What is ossification, also called osteogenesis?

The process of forming bone tissue.

When does bone formation begin during development.

During the embryonic period, beginning around week 8.

During what stage of life is ossification important?

Embryonic skeletal development, growth from childhood through early adulthood and later-life bone remodeling and repair.

What is intramembranous ossification?

Bone formation from a fibrous membrane.

What are examples of bones formed through intramembranous ossification?

The clavicle and skull bones.

What is endochondral ossification?

Bone formation by replacing cartilage.

Which type of ossification forms most bones.

Endochondral ossification.

Where does cartilage remain after endochondral ossification?

At articular cartilage on the ends of bones and at epiphyseal plates involved in bone elongation.

What is articular cartilage?

Cartilage covering the ends of bones at joints.

What is the epiphyseal plates?

A growth region associated with bone elongation.

Why is continuous bone remodeling important?

It helps maintain healthy bone Without remodeling, calcium in bone could crystallize, making bones more brittle and more likely to fracture.

What is the sequence of bone remodeling described in notes?

Osteocytes signal in response to damage; osteoclasts break down bone and release calcium+phosphate; macrophages promote remodeling; osteoblasts build new bone and later undergo apoptosis.

What do osteoclasts release during the remodeling process?

Enzymes that digest the calcium-phosphate component of bone, allowing minerals to return to the blood.

What is apoptosis?

Programmed cell death. Example: Osteoblasts undergo apoptosis after their role in rebuilding bone.

What role do macrophages play in the remodeling sequence?

They promote bone tissue remodeling

What is a fracture.

A break in a bone.

What is reduction of a fracture?

Realigning the broken ends of a bone.

What is immobilization?

Keeping a fractured bone stable so it can heal.

What is the first repair stage.

A hematoma forms from blood that escapes damaged blood vessels at the fracture site.

What is a hematoma?

A collection or clot of blood at the injury site.

What is a fibrocarilaginous callus?

A repair strucutre that spans the fracture and connects the broken ends.

What happens after the fibrocartilaginous callus forms?

Osteoblast begin forming spongy bone and replacing the cartilaginous callus.

What is the final repair stage?

Bone remodeling.

Put the bone-repair sequence in order.

Hematoma forms> Fibrocartilaginous callus forms> osteoblasts form spongy bone and replace the callus> bone remodeling.

What is a joint, also called an articulation?

A meeting place between two or more bones.

What are two major functions of joints?

They hold the skeleton together and allow mobility

How does body movement happen at a joint?

Muscles contract across joints, moving one bone toward another.

What do ligaments connect?

Bone to bone

What do tendons connect?

Muscle to bone.

What are the two ways joints are classified?

Structurally and functionally.

What does functional joint classification describe?

How much movement a joint allows.

What is the relationship between mobility and stability?

In general, the less moveable a joint is, the more stable it is, and vice versa.

What is synarthosis.

A functionally classified joint that does not move.

Give the example of a synarthrosis.

The sutures between bones of the cranium.

What is an amphiarthrosis?

A functionally classified joint that moves slightly.