Skeletal system biol 305

How can we classify bones based on their shape?

Long, short, flat, and irregular

How can we classify bones based on location?

Axial and Appendiular

What do axial bones form and whats some examples

Form the central axis of the body. Skull, sternum, ribs, vertebral column 

The main job of appendicular bones

Movement

Why are most appendicular bones long bones and what can we say about their function due to their shape

They are long bones, such as arm and leg bones, meaning they are responsible and assist with mobility, movement, and flexibility.

Cranial bones

Flat bones that enclose and protect the brain

Why are all skull bones flat bones?

Because their job is to protect the brain and support the structures. 

What are the connective tissues that make up the skeletal system? 

Bones, ligaments, and cartilage 

Bones

The hardest elements of the skeleton. Give the body shape and allow us to move, sit, and stand.

Ligaments

Dense fibrous connective tissues that attach bones to other bones.

Cartilage

Specialized connective tissue, fibers of collagen and elastic in a gel-like ground substance. Reduces friction in joints and are categorized into 3 parts

Why do bones have a hard, rigid appearance? 

Because of the nonliving extracellular crystals of calcium minerals. 

Are bones living or nonliving tissues? explain.

Bones are living tissue containing several types of cells involved in bone formation and remodeling. Despite their hard appearance from mineral crystals 

What are the 5 important functions of bones? 

Support, protection, movement, blood cell formation, and mineral storage 

How do bones contribute to movement? 

Bones serve as attachment points for muscles and provide rigid levers that enable movement when muscles contract. 

What is a compact bone and where is it located in long bones?

A compact bone forms the shaft (diaphysis) and ends (epiphyses) of long bones and contain marrow space

Diaphysis 

The shaft (long middle portion) of a long bone, formed by the compact bone. 

Epiphyses

The ends of long bones, formed by compact bones on the outside

What is yellow bone marrow, and where is it found?

Mostly fat and is found in the marrow space within compact bones.

What is spongy bone and where is it located?

Spongy bone consists of trabeculae that forms a lattice-like support in the ends (epiphyses) of long bones.

Trabecular

The lattice-like structures that make up spongy bone, proving support while keeping the bone lightweight.

What is red bone marrow and what does it produce? 

Found in the spaces of spongy bone and contains stem cells that product red blood cells, white blood cells, and platelets

The difference between red and yellow bone marrow

red bone marrow produces blood cells and platelets, while yellow bone marrow is mostly fat

periosteum

The connective tissue covering of bone

What are osteoblasts and what is their function? 

Osteoblasts are bone-forming cells that generate new bone during growth and repair 

Osteons (Harvesian systems)

The cellular arrangement found in compact bone, consisting of extracellular deposits of calcium phosphate enclosing living cells (osteocytes) arranged in rings.

Osetocytes

Living bone cells that are trapped in spaces called lacunae within the bone matrix. They are arranged in rings called osteons

What are lacunae

Small spaces in bone where osteocytes are trapped

Canaliculi

Thin canals that connect osteocytes to each other, allowing for communication and nutrient exchange,

What is found in the central canal of an osteon?

Blood vessels

What is the primary function of ligaments 

To attach bones to bones

What type of tissue are ligaments made of?

Dense fibrous connective tissue

How do ligaments contribute to joint function?

By providing strength in joins yet enable movement.

What is the general function of cartilage?

providing support under pressure

What is fibrocartilage and where is it found?

A type of cartilage found in intervertebral disks between vertabrae and in menisci in knee joints. It provides strong support under compression

What is hyaline cartilage and what is it’s main 2 functions?

It forms embryonic structure, which later forms bone and covers and protects ends of long bones in joints, providing protection and reducing friction

What is elastic cartilage and where is it found?

A flexible cartilage found in the outer ear, nose and epiglottis.

Where would you find hyaline cartilage in an adult?

In adults, hyaline cartilage covers and protects the ends of long bones in joints

What forms the initial bone models in early fetal development?

Cartilage models form the initial bone structre

Chondroblasts

A cartilage forming cell that creates the cartilage models during early fetal development 

What happens to cartilage during later fetal development?

During later fetal development, osteoblasts replace cartilage with bone

Osteoid

A mixture of proteins, including collagen, that is secreted by osteoblasts and forms the structural framework of bone

What 2 substances do osteoblasts secrete during bone formation?

Osteoid (protein mixture including collaged) and enzymes to crystallize calcium phosphate

What happens to osteoblasts as they mature?

They become osteocytes trapped in lacunae that maintain the bone matrix

Where does bone lengthening occur in long bones?

At the growth plate (epiphyseal plate)

Epiphyseal plate

The region where long bones continue to lengthen during childhood and adolescence

What do chondroblasts do at the growth plate?

Produce cartilage on the outer surface of the growth plate

How do long bones lengthen?

Chondroblasts produce cartilage on the outer surface of the growth plate. Osteoblasts replace this with bone on the inner surface, and the growth plate migrates further apart. 

How do bones grow in diameter?

As osteoblasts deposit bone beneath the periosteum

What hormone is associated with bone growth?

Growth hormone (GH)

Bone remodeling

A change in the bone’s size, shape, and strength

What factors influence bone remodeling?

Diet, age, exercise and hormone activity 

Weight-bearing exercise affect on bones

Increases overall bone mass and strength. The compression generates electrical currents that activate osteoblasts to form bones where stress is high, thus strengthening bones

Bone homeostasis

The balance of osteoblast and osteoclast activity

Osteoclasts

Cells that remove bone through a process called resorption

What is the relationship between osteoblasts and osteoclasts in healthy bone?

In healthy bone, there must be a balance between osteoblasts (which deposit new bone) and osteoclasts (which remove bone) to maintain bone homeostasis

What happens when a bone is compressed?

Compression generates electrical currents in bone

What do electrical currents in bone activate?

Activate osteoblasts

Where do bones form/remove in response to stress?

Bones form where stress is high and are removed where stress is low

Osteoporosis

Bone loss that results from a long-term cell imbalance between osteoblasts and osteoclasts. Bone removal exceeds bone formation

Parathyroid hormone 

• secreted from

• target tissue(s)

• function

• effect

Secreted from the parathyroid

Targets osteoclasts

Regulates bone cells and calcium levels in the blood

Stimulates osteoclasts to secrete more bone-dissolving enzymes, which break bone down and release calcium into the blood

Pneumonic: Parathyroid↝ parent↝parents RAISE their kids↝para RAISES calcium levels in the blood

Calcitonin

• Secreted from

• target tissue(s)

• function

• effect

Secreted from thyroid gland

Targets osteoblasts

Regulates bone cells and calcium levels in the blood

Stimulates osteoblasts to deposit calcium and phosphate in bone, removing calcium from the blood

Hematoma in bone repair

A clotted blood that forms at the site of a bone fracture

Initial signs of a bone fracture

Inflammation, swelling, and pain appear at the fracture site

What cells migrate to start bone repair?

Fibroblasts migrate to start bone repair. Some fibroblasts become chondroblasts during bone repair

Fibrocartilage callus

Temporary structure that forms at the fracture site during bone repair

Osteoclasts role in bone repair

Osteoclasts remove dead bone and hematoma remnants during bone repair

What is the sequence of bone repair?

1. Hematoma forms

2. inflammation occurs

3. Fibroblasts

4. Some become chondroblasts

5. Fibrocartilage callus forms

6. Osteoclasts remove dead tissue

7. osteoblasts deposit new bone

8. callus converts to hard bone