chapter 12

Question 1

function of skeletal system x5

Answer 1

1. provides a firm framework that gives shape to the body and supports the internal organs.
2. Articulation (movement) anchor points for muscle. skeleton determines extent of movement of body parts
3. protection of vital organs
4. bones act as storage organs for mineral salts and fats (Ca, P, Na, K). distributed via circulatory system when required
5. blood cell production. red bone marrow has stem cells that can differentiate into blood cells. which cell is produced depends on the bodily factors

Question 2

structure of bone x3

Answer 2

1. diaphysis: shaft makes up main part of bone. hollow cylinder of compact bone surrounding a cavity. cavity filled with yellow bone marrow which is a fat storage site.
2. epiphysis: enlarged ends of bone, covered by articular cartilage. have compact bone on the outside but their central regions contain spongy or cancellous bone (more porous with large spaces filled with marrow-may contain red bone marrow)
3. periosteum: dense, white, fibrous cartilage covering on the outside surface of the bone. no periosteum on joints where bone is covered with articular cartilage

Question 3

microscopic bone structure

Answer 3

bone is classified as connective tissue (cells w matrix)
l-> inorganic salts in matrix increase rigidity, strength and hardness)
single units called osteons/Haversian canals

Question 4

osteon

Answer 4

centre of each osteon is a central canal around which are lamellae (concentric layers of bony matrix)
between lamellae are small spaces in matrix called lacunae (bone cell occupies each lacunae)
projectuions from each bone cell enter canacliculi (tiny canals)and make contact with adjacent bone cell (materials passed)

central canal contains at least one blood vessel, (or lymph vessel and nerves)

Question 5

osteon of compact bone

compact bone structure

Answer 5

run parallel to the long axis of the bone giving it maximum strength
lamellae surround Haversian canal

Question 6

cancellous bone structure

Answer 6

not organised into osteons.
consist of an irregular arrangement of tiny bony plates called trabeculae.
bone cells occupy spaces in trabeculae, but lamellae are not organised in concentric layers and nerves and blood vessels pass through irregular spaces in the matrix

found only in epiphysis region.red bone marrow confined to these cavities
epiphyseal lines of cartilage are remnants of plate seen in young growing bones

Question 7

bone classification

Answer 7

1. shape
   - long: femur
   - short: carpals/tarsals
   - flat: scapula, sternum
   - irregular: pelvis
   - sesamoid: develop in tendons, patella
2. structure:
   - compact bone: dense, thicker, harder
   - spongy/cancellous bone: porous, many large spaces, filled with yellow or red marrow and has network of bony plates (trabeculae)

Question 8

long bone structure

femur

Answer 8

shaft called diaphysis
medullary cavity filled with yellow bone marrow that stores energy as fat
ends called epiphysis
thin layer of cartilage (articular hyaline cartilage) covers each epiphysis to reduce friction at the joint

Question 9

hardness of bone

Answer 9

brittle calcified matrix (calcium phospate) increase hardness
while collagen fibres give bone a degree of pliability

Question 10

osteoblast

Answer 10

young cells that produce bone

forms bone matrix (calcium phosphate and collagen fibres)

Question 11

osteocyte

Answer 11

formed from osteoblast
mature bone trapped in matrix
maintains bone tissue

Question 12

osteoclast

Answer 12

reabsorbs/destroys bone tissue
releases acidic enzymes to dissolve bone and make cavities
during growth and healing
active during ageing

Question 13

Ossification

Answer 13

bone formation and remodelling

bones of skeleton are formed from hyaline cartilage oin embryo by ossification

Question 14

cartilage x3

Answer 14

1. hyaline: closlely packed fine fibres (collagenous) in matrix. chrondocytes seen in lacunae
   - strength and flexibility
   - rings of trachea and bronchi, end of bones
2. elastic: elastic and collagen fibres
   not so closely packed, flexible/elastic support
   - ear cartilage
3. fibrocartilage: thick collagenous fibres
   allows for compression
   supports body weight and endures heavy compression
   -intercollated discs between vertebrae
   - knee joint
   - connecting pubic bones

no blood vessels in cartilage
*nutrition and waste removal for cells is through diffusion through matrix-> slow process
chrondocytes have slow metabolism (slow cell division)-> slow healing process

Question 15

joint

Answer 15

site where two or more bones come together
some are rigid (tightly fit)
some allow bones to move in relation to each other (loosely fit)

Question 16

types of joints x3

Answer 16

1. fibrous:
   no movement between bones (fit tightly together)
   held in place by fibrous connective tissue
   -sutures of skull
   hard to break, bone fracture before the joint

2. cartilaginous
held in place by cartilage, slight movement 
-between vertebrae
-pubic symphysis
- between ribs and sternum

3. synovial:
   freely movable, movemnt limited by ligaments, tendons muscles and adjoining bones
   has s cavity between articular cartilage surfaces of bone, covered with s membrane

Question 17

types of synovial joints x6

Answer 17

1. ball and socket joint
   can move in 360º plane (back to forth, side to side, rotation)
   - hip, shoulder
2. hinge joint:
   back and forward
   -knee, interphalangal, elbow
3. pivot (trochoid/rotary)
   rotation
   -vertebrae
   -radioulnar in wrists and elbow
4. gliding
   side to side, back to front
   -between ribs and vertebrae
   -base of thumb
5. condyloid:
   back and forward, lateral (similar to hinge)
   -wrist joint
   -between phalanges and metacarpals/metatarsals
6. saddle joint:
   back and forward, side to side, some rotation
   -thumb

Question 18

knee joint

Answer 18

articular capsule surrounds and encloses the bone

1. the fibrous outer layer capsule (made of dense fibrous connective tissue) attached to the periosteum. Flexibility permits motions and strength avoids dislocatio. hold bones together.
2. synovial membrane: makes up inner layer of capsule. loose CT and lots of blood capillaries. lines entire joint except articular cartilage and articular disc

Question 19

types of movement at joint

Answer 19

flexion (decrease angle between bone)
extension (increase angle between bone)
abduction (movement away from midline)
adduction (movement towards midline)
rotation (movement around long axis)

Question 20

cartilage

Answer 20

within matrix are spaces that contain cartilage cells (chrondoblasts), the produce matrix and gradually become surrounded by it until they are trapped in small spaces called lacunae (chrondocytes)

variation of fibrous structure of cartilage classifies it into three types

Question 21

synovial fluid

Answer 21

secreted by synovial membrane and fills synovial cavity
lubricates joint and provides nourishment
contains phagocytic cells that remove pathogens
keep surface of bone from touching, small amount that coats
increase fluid means swelling

Question 22

articular cartilage

Answer 22

covers articulating surfaces of bone forming the joint

smooth surface for movement

Question 23

articular disc

Answer 23

in knee (meniscus)
split cavity in two to direct fluid into areas of greater friction

Question 24

bursae

Answer 24

little sacs of synovial fluid

prevent friction between bone and ligament/tendon or bone and skin

Question 25

accessory ligaments

Answer 25

holds the bones together in many joints

Question 26

osteoporosis

Answer 26

when loss of bone mass with ageing becomes sufficient to impair normal functioning l-> minor injuries could lead to serious fractures need to increase calcium intake, vitamin D, exercise and quitting smoking

Question 27

Osteoarthritis

Answer 27

joint cartilage deteriorates and bone surface is no longer protected exposed bone begins to wear way and bony spurs/growths may develop from exposed end of bone that forms the joint, the spurs decrease space in joint cavity which restricts the movement symptoms: pain and stiffness in joints (more severe after pressure applied or exercise), crackling sound when they move no cure joint replacement surgery