ch. 6 - bones and skeletal tissue

what cartilage types are found in the skeletal system

hyaline, elastic, fibrocartilage cartilage

articular cartilage

covers the ends of most bones at movable joints. “Connecting things”. is hyaline cartilage

coastal cartilage

connects the tibs to the sternum

endochondral ossification

“within cartilage” or “bone formation”. Initially most of the embryonic skeleton is formed by fast growing hyaline cartilage, which is then gradually replaced by bone tissue in the fetal and childhood periods.

perichondrium

a layer of dense irregular connective tissue that surrounds the cartilage. acts like a saddle on a horse and resists outward expansion when subject to pressure. Fuctions in growth and repair of the cartilage

perichondrial hematoma

damage to the ear that leads to the separation of the cartilage and the perichondrium

how much water does cartilage contain

60-80%

what types of tissues do bones contain?

• bone connective tissue

• nervous tissue

• blood connective tissue

• cartilage connective tissue

• cartilage connective tissue (articular an costal)

• epithelial tissue lining of blood vessels

functions of bones

1. support

2. movement

3. protection

4. mineral storage

5. blood cell formation and energy storage

6. energy metabolism

what minerals are stored in bones that are released into the bloodstream for distribution to all parts of the body as needed?

calcium and phosphorus

what term is used to describe blood cell formation ?

hematopoiesis

what are bone producing cells called?

osteoblasts

osteocalcin

secreted by osteoblasts, a hormone (protein) that influences blood sugar regulation and energy metabolism. Stimulates insulin secretion in pancreas that reduce blood sugar levels

organic components of bones consists of

35% cells, fibers, ground substance.

what role does collagen play in bones ?

collagen contributes to the flexibility and tensile strength that allows it to resist stretching and twisting

inorganic components of bones

65%. mineral salts that invade bony matrix making bone tissues hard

what mineral is found in bones ?

primarily calcium phosphate mineral in the form of hydroxyapatite

osteoprogenitor cells

stem cells that differentiate into bone forming osteoblasts

osteoblasts

actively produce and secrete bone matrix (osteoid). once the osteoblasts are surrounded by bone matrix and no longer producing new osteoid, they become osteocytes

osteocytes

keep bone matrix healthy

osteoclasts

responsible for resorption of bone, meaning the remodeling. they are derived from a line of white blood cells. secrete hydrochloric acid and lysosomal enzymes

three types of cells in bone tissue that produce or maintain the tissue

• osteoprogenitor cells

• osteoblasts

• osteocytes

the cell in bone tissue responsible for resorption of bone tissue

osteoclasts

long bones

longer than wide and are weight bearing

short bones

roughly cube shaped found in the wrist and the ankle.

sesamoid bones

are short bones that form within tendons (kneecap)

flat bones

thin and flattened, usually curved. Most cranial bones of the skull are flat, ribs, sternum, scapula

irregular bones

have various shapes that do not fit into other categories. Vertebrae and hip bones

cortical bones

compact bone that is the dense outer layer of the bone

trabecular bone

spongy bone with needle like pieces called trabeculae

open spaced between trabeculae are filled with?

red or yellow marrow

around how much blood is found in the skeleton ?

3-11%

periosteum

a connective tissue membrane that covers the entire external surface of each bone.

endosteum

a thin connective tissue membrane that covers the internal bone surfaces

osteons

long cylindrical structures that function in support

lamella

a layer of bone matrix in which the collagen fibers and mineral crystals align and run in a single direction. fibers and crystals of adjacent lamellae run roughly the opposite direction. endosteum lies within each lamella layer

Haversian canal

runs through the center of each osteon containing its own blood vessels and nerve fibers.

volkmann’s canals / perforating canals

lie at the right angles to the central canals and connect the blood and nerve supply to the central canals and the marrow cavity. share resources between haversion canals

canaliculi

connect neighboring lacunae to one another

spongy bone trabecula contains …

several layers of lamellae and osteocytes

During endochondral ossification, bone tissue replaces what type of cartilage?

hyaline cartilage

Which bone cell is responsible for breaking down bone matrix during remodeling?

osteoclast

The diaphysis of a long bone refers to:

the shaft of the bone

Which hormone is released in response to low blood calcium and stimulates osteoclast activity?

Parathyroid hormone (PTH)

In bone repair, what forms immediately after a fracture and consists of a blood clot?

Fracture hematoma