Chapter 6: bone tissue

List all functions of bones /skeletal system.

Protection, support, mineral storage, blood cell production and assist movement

Name 5 types of bones and give an example for each.

Long- humerus

Short- carpals

Sesamoid- patella

Flat- sternum

Irregular- Vertebra

Describe the structure of a long bone and name its components. How is it different from a flat bone?

Long bone- long shaft with medullary cavity. 2 round ends with spongy bone middles. Covered with a layer of compact bone and periosteum.

Flat- Thin with compact bone covering and thing spongy bone middle

Name two types of bone marrow. What are the functions of bone marrow and where is it located?

Red bone marrow- Makes red blood cells

Yellow bone marrow- stores lipids

Name two types of bone tissue and describe where each one can be found.

Compact bone- outer layer of bone

Spongy bone- In the middle of flat bones and epiphysis of long bones

What is the chemical composition of bone extracellular matrix?

calcium phosphate + calcium Hydroxide = Hydroxyapatite

Which mineral is the most abundant in bone?

Calcium

Describe the structure of an osteon

the central canal is the middle of the osteon with rings of lamellae surrounding it with osteocytes embedded in those rings. The small lines going toward the middle are canaliculi

Name the types of cells associated with bone tissue. What is the function and origin of each cell type?

Osteoprogenitor- bone stem cells

Osteoblasts- immature bone cells that secrete extracellular matrix

Osteocytes- mature bone cells

Osteoclasts- remodels bones to release calcium (made from leukocytes)

How do osteocytes in an osteon get their nutrients, if they are surrounded by bone matrix?

Holes in the bones and the periosteum layer allow blood vessels to enter and provide nutrients to the bone tissue. The central canal gets the blood and it diffuses through the canaliculi to the osteocytes.

What is the structure and functions of periosteum?

The outer covering to compact bone (made of dense regular tissue) and plays a role in bone repair and growth.

Describe the differences between endochondral and intramembranous ossification. Give examples of a bone formed by each process.

Epichondral- Cartilage forms and the bone replaces that cartilage once it dies

Intramembranous- bone forms from membranes (mesenchyme)

What is the relationship between an epiphyseal plate and an epiphyseal line?

Once the epiphyseal plate closes, it forms the epiphyseal line

What is "closure of epiphyseal plate" and when does it happen?

The cartilage in the epiphyseal plate becomes all bone and seals off that area. The bone no longer grows in length. Happens in early adulthood or late teens

What are fontanels? Where and when would a person have them?

Soft plates in a baby's heads that allows cranial bones to move when being birthed. they harden up fully after a year.

Describe how bones grow after birth. What is the difference between interstitial and appositional growth?

The cartilage in the epiphyseal plate multiplies and is replaced by bone to grow in length. (interstitial) Osteoblast deposit bone on the surface of the while osteoclasts break down the middle for width. (Appositional)

Why do long bones in adult stop becoming longer but can continue to grow thicker?

The epiphyseal plate is closed so you no longer get taller, but the bones grow in width to support body weight and life stresses in the bones

Explain how epiphyseal plates work (what type of tissue are they?) and why it is dangerous to injure one.

The epiphyseal plate has hyaline cartilage that multiplies and becomes bone as you get closer to the head of the bone. Injury to a epiphyseal plate will cause the bone to not grow as much and be uneven with the other limbs.

Explain how bone remodeling works and list factors that may affect it.

Osteoclasts break down bone inside to secrete calcium. Osteoblasts deposit bone one the outside.

Calcium levels, Vitamine C and D, and Physical activity can effect this.

Name the hormones that affect bone metabolism and indicate how each one affects bone formation and resorption. For each hormone you listed indicate which cells in the bone it affects and if it has a positive or a negative effect on bone density.

Parathyroid hormone (PTH) stimulates calcium increase (negative)

Calcitonin stimulates decrease in calcium (negative)

Growth Hormone stimulates cartilage and bone growth

Sex hormones (Testosterone and Estradiol) inhibit osteoclasts to increase bone density. Cause sex related changes.

Cortisol stimulate osteoclasts

What is the effect of sex hormones testosterone and estradiol on bone growth?

Speed up growth.

causes sex related changes in males and females

As adults, sex hormones remodel old bone

Which vitamin is required for normal bone mineralization?

Vitamine D

Why is vitamin C important in bone metabolism?

Synthesises collagen needed for bone protein and growth

Explain the effects of PTH and calcitonin on bone tissue and calcium metabolism. Which cells in bone does each hormone stimulate?

PTH causes osteoclasts to break down bone to release calcium.

Calcitonin stops PTH

Describe the process of osteoporosis and name factors that can cause this disease.

Loss of bone tissue caused by hormonal imbalance.

deficiency in estradiol or testosterone, estrogen replacement therapy, and excess of PTH or glucocorticoids cause this

List common types of bone fractures.

Greenstick, open compound, impacted, comminuted, Pott's and Colle's, transverse, linear, spital, oblique

Why would someone have a "greenstick fracture"?

a kid may land on their arm causing the bone to bend and break on one side

Describe 4 steps of bone fracture repair.

Inflammation, Fibrocartilage makes fibrocartilage callus, bony callus forms, the bone remodels and heals with a small bump