Lesson 6

Front 1

Function of bones

Back 1

Support-structural framework.Protection-skull, vertebrae, rib-cage.Movement-attachment for muscles.Mineral homeostasis-calcium balance.Blood cell production-RBC & WBC red bone marrow.Fat storage-yellow bone marrow

Front 2

Types of bones

Back 2

Long bone (humerous), Flat bone (sternum, skull), irregular bone (vertebrae), sesamoid bone (patella, forms in a tendone when there is a lot of stress), short bone (carpal)

Front 3

Diaphysis

Back 3

the bone's shaft or body-the long, cylindrical main portion of the bone. Consists of compact bone, makes up most of the bones length.

Front 4

Epiphysis

Back 4

are the distal and proximal ends of the bone. They are made of spongy bone(containing red marrow) and is covered by a layer of compact bone

Front 5

metaphyses

Back 5

are the regions in a mature bone where the diaphysis joins the epiphyses, located between the epiphysis and diaphysis. In a growing bone each metaphysis includes a epiphyseal plate, which is a layer of hyaline cartilage that lets the bone grow in length but not width.

Front 6

Epiphyseal plate

Back 6

a layer of hyaline cartilage that allows the diaphysis of the bone to grow in length, but not in width.

Front 7

Epiphyseal line

Back 7

the boney structure that results when a bone stops growing in length and the cartilage in the epiphyseal plate is replaced by bone

Front 8

articular cartilage

Back 8

a thin layer of hyaline cartilage covering the part of the epiphysis where the bone forms an articulation (joint) with another bone. reduces friction and absorbs shock

Front 9

periosteum

Back 9

a round tough sheath of dense irregular connective tissue that surounds the bone surface wherever it is not covered by articular cartilage. allows growth in width, protects bone, assists fracture repair, nourish bone tissue, an attachment point for ligaments and tendons. outer layer-connective tissue, inner layer-osteogenic cells and osteoblasts(allow the bone to grow in thickness)

Front 10

perforating fibers

Back 10

thick bundles of collagen fibers that extend from the periosteum into the extracellular bone matrix

Front 11

Medullary cavity

Back 11

the space within the diaphysis that contains fatty yellow bone marrow in adults

Front 12

endosteum

Back 12

a thin membrane that lines the medullary cavity. has single layer of bone-forming cells and a bit of connective tissue

Front 13

bone matrix

Back 13

25%water, 25%collagen, 50% salts. Collagen contributes to flexibility. Salts-calcium phosphate & calcium hydroxide combine to form crystals of hydroxyaphite. calcium carbonate, magnesium, flouride, potassium, sulfate.

Front 14

calcification

Back 14

the process where mineral salts are deposited on the framework of fibers making bones hard...initiated by osteoblasts

Front 15

Osteogenic cells

Back 15

stem cells drived from mesenchyme...only bone cells undergoing mitosis, resulting cells develop into osteoblasts. found inner portion of periosteum, in the endosteum and the canals w/in bone that contain vessels

Front 16

osteoblasts

Back 16

bone building cells. no cell division, synthesize and secrete collagen fibers and other organic components necessary for extracellular matrix of bone tissue, initiate calcification. they get trapped in own secretions and become osteocytes.

Front 17

Osteocytes

Back 17

Maintain bone tissue...no cell division.

Front 18

Osteoclasts

Back 18

huge cells derived from many monocytes (type of WBC) and are concentrated in endosteum. brake down bone either to remodel or free up calcium

Front 19

Compact bone tissue

Back 19

contains few spaces, strongest form of bone tissue, beneath the periosteum of all bones, makes up the bul of the diaphyses of long bones. support and protection

Front 20

perforating canals

Back 20

blood vessels, lymphatic vessels, and nerves from the periosteum penetrate compact bone through these transverse canals

Front 21

central (haversian) canals

Back 21

run longitudinally through the bone, connect with the vessels and nerves of the perforating canals

Front 22

concentric lamellae

Back 22

rings of calcified extracellular matrix surrounding the central canals.

Front 23

lacunae

Back 23

small spaces between the lamellae which contain osteocytes.

Front 24

canaliculi

Back 24

tiny channels filled w/extracellular fluid that radiate in all directions from the lacunae. system of canaliculi provides many routes for nutrients and oxygen to reach osteocytes and for waste removal

Front 25

osteon

Back 25

or haversian systems, components of compact bone tissue are arranged into these repeating units. each osteon has a central canal with its rings of lamellae, lacunae, osteocytes and canaliculi. aligned in the same direction along lines of stress

Front 26

intersticial lamellae

Back 26

fragments of older osteons that have been partially destroyed during bone rebuilding or growth, between osteons look like triangles

Front 27

circumferential lamellae

Back 27

lamellae that encircle the bone just beneath the periosteum or encircle the medullary cavity. the outside circle

Front 28

spongy bone

Back 28

consists of lamellae arranged in an irregular lattice of thin columns called trabeculae; spaces between trabeculae of some bones are filled w/red bone marrow;found inside short, flat and irregular bones and in the epiphyses of long bones.

Front 29

Trabeculae

Back 29

with in each are lacunae that contain osteocytes and canaliculi radiate outward from the lacunae. osteocytes of spongy bone are located on the superficial surfaces of trabeculae they get nourishment directly from the blood circulating through the medullary cavities.

Front 30

Periosteal arteries

Back 30

along with nerves they enter the diaphysis through many perforating canalsand supply the periosteum and outer part of the compact bone

Front 31

nutrient artery

Back 31

passes through a hole in compact bone called the nutrient foramen.

Front 32

metaphyseal arteries

Back 32

enter the metaphyses of a long bone and together with the nutrient artery supply the red bone marrow and bone tissue of the metaphyses

Front 33

epiphyseal arteries

Back 33

enter the epiphyses of a long bone and supply the red bone marrow and bone tissue of the epiphyses

Front 34

nutrient veins

Back 34

carry away blood and accompany the nutrient artery in the diaphysis

Front 35

epiphyseal veins and metaphyseal veins

Back 35

exit their respective arteries in the epiphyses

Front 36

periosteal veins

Back 36

exit with their respective arteries in the periosteum

Front 37

ossification or osteogenesis

Back 37

process by which bone forms...happens in 2 ways

Front 38

intramembranous ossification

Back 38

flat bones form between 2 membranes...skull and lower jawbone formed this way

Front 39

endochondral ossification

Back 39

a cartilage model of the bone forms and bone tissue replaces the cartilage

Front 40

4 Zones of Epiphyseal plate

Back 40

Zone of resting cartilage-normal cartilage,Zone of proliferating cartilage-mitosis,Zone of hypertrophic cartilage-mature chondrocytes,Zone of calcified cartilage-bone formation. Because of the cell division in the epiphyseal plate, the diaphysis of a bone increases in length.

Front 41

Calcium homeostasis

Back 41

Parathyroid hormone (pth) secreted by the parathyroid gland increases blood calcium level, whereas calcitonin (CT) from the thyroid gland has the potential to decrease blood calcium level. EX. if blood calcium level is too low Parathyroid gland secretes PTH causing kidneys to retain calcium and stimulates osteoclasts which pull calcium from the bones and makes it available to blood.

Front 42

Osteoporosis

Back 42

condition of porous bones. Estrogen and testosterone stimulate osteoblasts

Front 43

Cartilage

Back 43

Like all other types of connective tissue, cartilage consists of cells suspended in a matrix that contains protein fibres embedded in a ground substance. It is avascular.

Front 44

Cartilage cells

Back 44

The cells of mature cartilage are called CHONDROCYTES, & these are located within spaces in the matrix known as LACUNAE.

Front 45

Cartilage-protein fibres

Back 45

The protein fibres of a matrix are a network of COLLAGEN and ELASTIN, which provide strength and flexibility

Front 46

Cartilage-ground substance

Back 46

This is gel like and largely made up of CHONDROITIN SULPHATE that gives cartilage it’s resilience

Front 47

Catilage membrane

Back 47

Most cartilage is covered with a membrane of dense connective tissue known as the PERICHONDRIUM that contains many blood vessels. This enables the transport of wastes, nutrients and water in and out of the cartilage, because the cartilage itself is avascular.

Front 48

Types of cartilage (3)

Back 48

Hyaline, fibrocartilage, elastic cartilage

Front 49

Hyaline cartilage

Back 49

The most abundant, and weakest type of cartilage.Forms articular cartilage in joints, major airways in lungs, parts of the nose and ribs. In embryonic development bones consists of hyaline cartilage before changing into bone tissue. This type of cartilage is usually covered in perichondrium except for articular cartilage.

Front 50

Fibrocartilage

Back 50

Strongest, most rigid form of cartilage, and doesn’t have a perichondrial covering. Found in the spine(annulus fibrosus), the pelvis(pubic symphysis) and forming major joints like the knee.

Front 51

Elastic cartilage

Back 51

Has many elastic fibres making up ot’s matrix. This gives it a large degree of flexibility, whilst still maintaining some strength. It has a perichondrial covering and found in locations like the ear

Front 52

Bone Tissue

Back 52

Is connective tissue, therefore consists of matrix (composed of collagen fibres is a solid, calcified ground substance) and cells (osteocytes). It is 35% organic material(eg proteins), 65% inorganic mineral salts(mainly calcium and phosphate). Calcium salts gives it hardness whilst organic parts provide flexibility and great tensile strength (resistance to breaking with some flexibility)

Front 53

Long Bones

Back 53

have greater length than width and consist of a shaft and a variable number of extremities (ends). They are slightly curved for strength. Long bones consist mostly of compact bone tissue, which is dense and has smaller spaces but they also contain considerable amounts of spongy bone tissue, which has larger spaces in the epiphysis. Long bones include the humerus (arm bone), ulna and radius (forearm bones), femur (thigh bone), tibia and fibular (leg bones), phalanges (finger and toe bones).

Front 54

Short Bones

Back 54

are somewhat cube-shaped and nearly equal in length and width. They consist of spongy bone except at the surface, where there is a thin layer of compact bone. Examples of short bones are the carpal (wrist) bones and tarsal (ankle) bones

Front 55

Flat bones

Back 55

generally thin, usually curved and composed of two nearly parallel plates of compact bone enclosing a layer of spongy bone. Flat bones afford considerable protection and provide extensive areas for muscle attachment. Flat bones include cranial (skull) bones, which protect the brain; the sternum (breastbone) and ribs which protect organs in the thorax; and the scapulae (shoulder blades).

Front 56

Irregular Bones

Back 56

have complex shapes and cannot be grouped into any of the three categories just described. They also vary in amount of spongy and compact bone present. Such bones include the vertebrae (backbones), certain facial bones,hip bones and aforementioned calcaneus (heel bone)

Front 57

Sesamoid Bones

Back 57

develop in certain tendons where there’s considerable friction, compression, and physical stress, like in the palms and soles of the feet. They protect the tendons from wear and tear and help to improve function of a joint. They are a few millimeters in diameter except for the two patellae (kneecaps). Sesamoid bones vary in number from person to person

Front 58

Sutural (Wormian) Bones

Back 58

are small bones located within the sutures (joints) of certain cranial bones. They are small found in immovable joints.