Bone Basics and Skeletal System Study Guide

Comprehensive practice flashcards covering bone histology, macroscopic long bone anatomy, cell functions, axial versus appendicular classifications, and the step-by-step process of endochondral ossification.

What two types of tissue make up the human skeleton?

Bone and cartilage

What type of tissue is the skeleton composed of before it becomes bone?

Cartilage

Are bones living organs made of cells?

True; bones are living and are made of cells.

How many bones are in the adult human skeleton?

206

Which of the four major tissue types includes bone?

Connective tissue

Does bone possess an extracellular matrix, and what is it called?

Yes, bone has a matrix called osteoid.

Which of the lettered micrographs (A, B, C, or D) represents bone tissue under a microscope?

Picture D

What are the 7 primary functions of bone tissue?

1. Support, 2. Protection, 3. Anchorage, 4. Mineral Storage, 5. Blood cell Formation, 6. Fat storage, 7. Hormone Production

How does bone tissue perform its anchorage function?

Skeletal muscles attach to bones by tendons, using bones as levers to move the body.

Which minerals are stored within bones and released into the bloodstream as needed?

Calcium and phosphate

What is hematopoiesis, and where in the bone does it occur?

Hematopoiesis is blood cell production, and it occurs in red bone marrow.

Where is fat stored inside long bones?

Fat is stored in the yellow marrow inside long bones.

What hormone is produced by bone tissue to assist with multiple body processes?

Osteocalcin

Which specific bones protect the brain, heart, lungs, and spinal cord?

The brain is protected by the cranium (skull); the heart is protected by the rib cage (ribs and sternum); the lungs are protected by the rib cage (ribs); and the spinal cord is protected by the vertebrae (spinal column).

Which tissue type interacts directly with bones to produce body movements?

Muscle tissue

What is the distinction between the axial skeleton and the appendicular skeleton?

The axial skeleton consists of bones that fall along the midline (sagittal plane), while the appendicular skeleton consists of bones that are not on the midline (the limbs and bones attaching limbs to the trunk).

Which bones belong to the axial skeleton according to the classification guide?

Skull, mandible (lower jawbone), ribs, and vertebral column (backbone)

Which bones belong to the appendicular skeleton according to the classification guide?

Limbs, humerus (upper arm bone), bones that attach limbs to the trunk, scapula (shoulder blade), pelvis (hip bones), phalanges (fingers or toes), tibia (shin bone), and clavicle (collar bone)

What type of bones are carpals and tarsals?

Short bones

What type of bone is the femur?

Long bone

What type of bones are vertebrae?

Irregular bones

What type of bone is the patella, and how is this class of bone defined?

The patella is a sesamoid bone; sesamoid bones are defined as bones that form within a tendon.

What type of bones are the sternum and ribs?

Flat bones

What type of bones are phalanges (finger bones)?

Long bones

What are 10 examples of long bones in the human body?

Clavicle, ulna, tibia, femur, humerus, fibula, radius, phalanges, metacarpals, and metatarsals

What is the periosteum, and what does its name literally mean?

A connective tissue membrane covering the outside of the bones; it is full of osteoblasts that allow bones to grow in width. Its name literally means 'outside-bone.'

What is the endosteum, and what does its name literally mean?

A connective tissue membrane that lines the medullary cavity. Its name literally means 'inside-bone.'

What is the nutrient foramen of a long bone?

A tiny hole through which blood vessels thread into the bone.

What is yellow bone marrow and where is it found?

Adipose tissue found within the medullary cavity of long bones.

What are the roles of blood vessels within bone tissue?

They allow newly formed blood to exit the bone and enter the bloodstream, and allow bone tissue to receive nutrients, oxygen, and hormones.

What is the medullary cavity?

The hollow space inside the diaphysis that is filled with yellow marrow.

Where is red bone marrow found and what cells does it contain?

Found inside spongy bone tissue at the ends of bones; it is full of stem cells that produce red blood cells, most white blood cells, and platelets.

What are epiphyseal plates, and between what ages do they permanently ossify?

Growth plates made of hyaline cartilage that repeatedly ossify and regrow as a person grows in height; they ossify permanently between ages 18 and 25.

What are the epiphyses of a long bone?

The knobby ends of the bone, composed of spongy bone.

How do the proximal epiphysis and distal epiphysis differ by definition?

The proximal epiphysis is the end closer to the trunk; the distal epiphysis is the end further from the trunk.

What is the function of articular cartilage, and what condition occurs if it is lost?

It protects the ends of bones from friction and shock as joints move and bear weight; when lost, arthritis develops.

What is the diaphysis of a long bone composed of?

It is the shaft of the bone, made up of compact bone.

How does bone marrow respond if a person suffers significant blood loss?

Red bone marrow may increase blood cell production to help replace the lost blood.

Is bone vascular or avascular, and why?

Bone is vascular; it requires blood vessels to deliver oxygen and nutrients to bone cells and to remove metabolic waste products.

What is an osteocyte, and what does its name translate to?

A mature bone cell located inside spongy and compact bone that allows bones to perform their daily functions; its name translates into 'bone cell.'

What is an osteoblast, and what does it produce?

A bone cell that creates the matrix of bones (osteoid) and builds new bone; it eventually becomes trapped and differentiates into an osteocyte.

What are osteogenic cells, and where are they located?

Bone stem cells capable of mitosis that divide to create osteoblasts; they are located in the epiphyseal plates and on the periosteum.

What is an osteoclast, and what does its name translate to?

A cell that shaves away old bone during widening and removes dead bone after a fracture; its name translates into 'bone break.'

Why are osteoblasts located on the periosteum?

They build new bone on the outside, helping bones grow wider and repair damage.

Why are osteoblasts located within epiphyseal plates?

They help form new bone as bones grow longer.

Why are osteoclasts located on the periosteum?

They break down old bone on the outside during bone remodeling.

Why are osteoclasts located within the endosteum?

They break down and remove old bone from the inner surfaces and help reshape the bone.

How are osteogenic cells, osteoblasts, and osteocytes related developmentally?

Osteogenic cells divide and create osteoblasts; osteoblasts build new bone; and when osteoblasts become trapped in the bone matrix, they turn into osteocytes.

What is bone remodeling, and why is it necessary?

The continuous process of breaking down old bone and replacing it with new bone. It repairs damaged bone, replaces old bone tissue, maintains bone strength, and regulates blood calcium levels.

What is endochondral ossification, and when does it begin?

The process of forming bone by replacing a hyaline cartilage model with bone tissue (osseous tissue); it begins before birth during embryonic development at 6 to 8 weeks.

What are the six sequential steps of endochondral ossification?

1. Cartilage model forms; 2. Bone collar forms; 3. Cartilage calcifies; 4. Primary ossification center forms; 5. Medullary cavity forms; 6. Secondary ossification centers form.

Which cell type initiates endochondral ossification, and what is its role?

Chondrocytes; they form and maintain the hyaline cartilage model that is subsequently replaced by bone.

What is the perichondrium, and what does it become during endochondral ossification?

A connective tissue membrane lining the outside of the cartilage model; it becomes the periosteum when bone begins to form.

How does the formation of the bone collar affect the cartilage inside the developing shaft?

The bone collar limits nutrients from reaching the cartilage inside, causing chondrocytes to die and cavities to form.

Why must blood vessels invade the developing diaphysis and epiphyses during ossification?

They grow into the developing bone to deliver oxygen, nutrients, and bone-forming cells required for ossification.

Where is the primary ossification center located, and when does it ossify relative to the epiphyses?

It is located in the diaphysis (shaft) and ossifies before the epiphyses.

Where are secondary ossification centers located, and when do they form?

They are located in the epiphyses (knobby ends) and form around the time of birth or shortly afterward.

What are the respective roles of osteoblasts and osteoclasts in endochondral ossification?

Osteoblasts produce new bone matrix to replace the cartilage model with osseous tissue; osteoclasts break down calcified cartilage and bone to hollow out the medullary cavity and reshape the bone.

Which cartilaginous structures remain after endochondral ossification is finished?

Articular cartilage at the ends of the bones (joint surfaces) and epiphyseal plates where bones continue to lengthen.