Bone Tissue: Supportive Connective Tissue

What are 3 important cells of the bone tissue?

1. Osteoblast
2. Osteocyte
3. Osteoclast

What does an osteoblast do?

Builds bone tissue (immature cell)

What does an osteocyte do?

This is a **mature bone cell**; maintain bone tissue, matrix and mineral homeostasis

What does an osteoclast do?

Collapse/destroy bone matrix; macrophages

Proximal and Distal meanings?

* Proximal = close to middle
* Distal = away from middle (Ends of the bone)

What are PTH and calcitonin?

Antagonists

Know where these parts and structures are

What does Diaphysis mean?

Shaft of any bone

What does Epiphyseal line mean?

Growth Plate

What is the inner most layer of the bone?

Endosteum

What is the outermost layer of the bone?

Periosteum

What does epiphysis mean?

Ends of bones

What are the two kinds of bone?

1. Compact bone
2. Spongy bone

What are the units in which compact bone is arranged called?

Osteons or Haversian systems

What are Osteons?

White center parts in compact bones

What are osteocytes?

Black dots that communicate through **canaliculi** (lines) filled with fluid

**Patient Case:**

* around 5 years old
* Bone break from jumping on trampoline
* Arm was S - shape
* Doesn’t hurt
* Since the person is young, the bones will still have cartilage

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What happened?

Green-stick fracture

* kinda breaks but still attached (one side of shaft broke)
* bones are more flexible on younger people

Identify and remember **osteocyte, canliculi and most of the highlighted** items?

What are canaliculi?

The lines used for Osteocytes to communicate through; filled with fluid; connects cells

Identify and remember where Osteons and Osteocytes are located

Understand where the caniliculi are as well

Spongy bone

* No Osteons
* vascular

What is mesenchyme?

This is how all embryonic connective tissue begins as

What is bone formation termed as and what does it mean?

* Osteogenesis (creating bone)
* Ossification (cartilage becoming bone)

What are the two types of ossification?

* Intramembranous ossification
* Endochondrial ossification

What is Intramembranous ossification?

formation of bone **directly from or within fibrous connect tissue membranes**

What is Endochondrial ossification?\*

formation of bone from **hyaline cartilage models**

Where does intramembranous ossification occur?

* All roofing bones of the skull
* Frontal bone
* Parietal bones
* Occipital bone
* Temporal bones
* Mandible
* Clavicle

What are the soft spots between skull bones?

Fontanelles

Where is a good area to diagnose meningitis in infants?

Anterior Fontanelle

Why do we have the centers of ossification?

* Because the brain is growing faster than skull, and these allow the skull to stretch
* Shaping of skull going through birth canal for baby to come out

**Patient Case:**

* Know that the bones in xray are not broken, but are just developing
* They will eventually connect
* The two bumps circled are important

What are the Zones of epiphyseal plates?

* Zone of Resting Cartilage
* Zone of Proliferating Cartilage
* Zone of Hypertrophic Cartilage
* Zone of Calcified Cartilage

What is the function of the Zone of Resting Cartilage?

Anchors growth plate to bone

What is the function of the Zone of Proliferating Cartilage?

Rapid cell division **(stacked coins)**

What is the function of the Zone of Hypertrophic (enlargement) Cartilage?

Cells enlarged & remain in columns

What is the function of the Zone of Calcified Cartilage?

thin zone, cells mostly dead since matrix calcified

Which side of the body is the bone thicker on?

Dominant side/arm

How can bone grow in thickness or diameter?

Only by appositional growth

Steps of bone growth:

1. Periosteal cells differentiate into osteoblasts
2. Ridges fuse and the periosteum becomes the endosteum
3. New concentric lamellae are formed

What do periosteal cells differentiate into?

Osteoblasts

What do osteoblasts secrete?

Collagen fibers and organic molecules to form the matrix

What fuses and what becomes the endosteum during bone growth?

Ridges fuse and the periosteum becomes the endosteum

How does Calcium affect bone growth?

Makes bone matrix hard

What is hypocalcemia?

Low blood calcium levels

What are two ailments due to hypocalcemia?

Chvostek’s sign and Trousseau’s sign

What is hypercalcemia?

High blood calcium levels

How does Phosphorus affect bone growth?

Makes bone matrix hard

How does magnesium affect bone growth?

Deficiency in magnesium inhibits osteoblasts

How does Manganese affect bone growth?

Deficiency inhibits formation of new bone tissue

What does the lack of Vitamin C cause?

Scurvy Disorder

Why is Vitamin D important to Bone Growth?

Calcitriol helps build bone by increasing calcium absorption

What does Vitamin D deficiency result in?

Rickets in Children

**Patient Case:**

* dog tripped patient
* nothing is abnormal
* taking SSRIs -- anti depressants

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How can SSRIs impact fractures and bone density?

* SSRIs decrease bone density, especially in women
* Anti depressants can also lead to easier fractures

What is the function of Human growth hormone?

* Promotes general growth of all
* Body tissue and normal growth in children

Don’t need to know bone fractures, but this is the picture

What are the steps in fracture repair?

1. Formation of a fracture hematoma; some swelling
2. Fibrocartilaginous callus formation
3. Bony callus formation -- makes it thicker
4. Bone remodeling -- around 5-6 months

What is a fracture hematoma?

Collection of blood where the bone first breaks

Is it true that it is easier to break the bone after it has already broken once?

No, this is not true. Happens if not formed/repaired properly

**Patient Case:**

* mainly child or elder abuse cases
* spinning arm around during abuse

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What does this cause?

Spiral fracture

What is the problem if there is blue on the whites of eyes?

Membrane disorder; not bone problem

What is the function of Synovial joints?

Allow for more or less free movement

What does synovial fluid help with?

Helps lubricate and protect the bones

What sacks contain Synovial fluid?

Bursa sacks

What are the two classifications of Joints/Articulations?

1. Functional
2. Structural

What are the 3 functional classifications of joints?

* Synarthroses
* Amphiarthroses
* Diarthroses

What are Synarthroses?

immovable joints

What are Amphiarthroses?

slightly movable joints

What are Diarthroses?

freely movable joints

What are Fibrous Joints?

Bones joined by dense fibrous connective tissue

What are the 3 types of Fibrous Joints?

* Sutures
* Syndesmoses
* Gomphoses

Sutures and fontanelles have same functions

What are gomphoses?

Peg-in-socket joints of teeth

What is the fibrous connection of gomphoses?

Periodontal ligament

What are the two types of Cartilaginous Joints?

* Synchondroses
* Symphyses

What are synchondroses joints?

Bar/plate of hyaline cartilages unites bones

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\-- Hyaline are more structural/supportive

What are Symphyses Joints?

Fibrocartilage unites bone

What are the two layers of the articular joint capsule in synovial joints?

* External **fibrous layer**
* Inner **synovial membrane**

What is the external fibrous layer?

Dense irregular connective tissue

What is the inner synovial membrane?

Makes synovial fluid drawn from plasma; mostly sterile

**Patient Case:**

* round bumps on finger
* Synovial fluid leaks out

Osteoarthritis; pushes fluid out

**Patient Case:**

* Track athlete
* joint pains
* Can cause bull’s eye rash; though most patients with this disease do not have this

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What was the problem?

Lyme disease

**Patient Case:**

* girl running
* pain and fatigue
* there is a tick, but is rarely outdoors
* was in a field one time

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What is the problem?

Lyme disease

What can age do to synovial fluid? What does this do to bones?

Age can cause synovial fluid to calcify, and this pokes at bone like needles causing pain

What are hinge joints?

allows extension and retraction (Elbow & Knee)

What are ball and socket joints?

Radial movement in almost any direction (Hip & Shoulder)

What is bursitis?

* inflammation of bursa, usually cause by blow or friction
* Treated with rest and ice and, if severe, anti-inflammatory drugs

What is tendonitis?

* inflammation of tendon sheaths, typically caused by overuse
* symptoms and treatment similar to those of bursitis

What is Osteopenia?

Bone mineral density is lower than normal peak BMD but not low enough to be osteoporosis

What is osteoporosis?

* loss of both bone salts and collagen fibers
* increased osteoclast activity and decreased osteoblast activity

Is Osteoporosis more common in males or females? Why?

* common in females because calcitonin and BTH are needed and work better in sex hormones
* while testosterone is common, women have menopause which affects hormones

What is Osteomalacia?

loss of bone salts but NOT collagen

What is an example of a disorder due to osteomalacia?

Rickets in young children

What is Rickets?

* softening and weakening of bones in children
* usually due to extreme and prolonged vitamin-D deficiency

What is Paget’s disease?

* Abnormal bone remodeling
* Very high ratio of spongy to compact bone and reduced mineralization = bone made fast and poorly causing something called pagetic bone

What is Osteomyelitis?

Infection of bone most commonly due to Staphylococcus Aureus

Where can you find Staphylococcus Aureus and what does it commonly cause?

It is literally everywhere and lives off on us. It most commonly causes Osteomyelitis

What is Osteogenic Sarcoma?

Bone cancer that affect osteoblasts

What is Arthritis?

Inflammatory joint disease

How is Arthritis pain characterized?

* unilateral, one side
* pain 1st thing in morning
* less pain with movement