skeletal system

Question 1

functions of bone/skeletal system

Answer 1

support, protect, assist in movement, mineral homeostasis, blood cell production, triglyceride storage

Question 2

which minerals are bones a reservoir of?

Answer 2

calcium and phosphate

Question 3

where specifically does blood cell production take place?

Answer 3

red bone marrow –> hemapoiesis

Question 4

describe the medullary cavity in children vs adults

Answer 4

in kids, it has red bone marrow; in adults it has yellow bone marrow

Question 5

Describe metaphysis

Answer 5

it is where the diaphysis meets the epiphysis

It contains the epiphyseal line/plate

Question 6

Periosteum

Answer 6

• membrane that covers the outside of the bone
• outer layer = fibrous layer = dense irregular ct
• inner layer = osteogenic layer = osteoprogenitor cells (also osteoblasts + clasts)
• has perforating fibers
• super well supplied with nerves and blood vessels

Question 7

endosteum

Answer 7

areolar connective tissue that covers the trabeculae

Question 8

recipe for bone cell matrix

Answer 8

25% water
25% collagen fibers
50% crystalized mineral salts (mostly CaPO3)

Question 9

describe the extracellular matrix of bones

Answer 9

1. osteoid = organic part = collagen, proteoglycans (trap water), and glycoproteins
2. mineral salts = inorganic = calcium phosphate and calcium carbonate

Question 10

describe the calcification process

Answer 10

• initiated by osteoblasts

- mineral salts are layed down and crystalize on framework formed by collagen fibers

Question 11

4 types of bone cells

Answer 11

1. osteogenic = stem cells which undergo cell division to make cells that become osteoblasts
2. osteoblasts = bone building cells that lay down collagen
3. osteocytes = mature bone cells –> maintain bone tissue and exchange nutrients/waste with blood –> boxed in osteoblasts
4. osteoclasts = release enzymes that digest the mineral component of bone matrix –> regulate blood calcium levels

Question 12

what is the structural unit for compact bone? for spongy bone?

Answer 12

osteon and trabeculae

Question 13

canaliculi

Answer 13

tiny canals that connect lacunae –> provide routes for nutrient and oxygen to reach osteocytes

Question 14

what connects the central canals in osteons?

what are the layers of osteons called?

Answer 14

• perforating canals

- lamellae

Question 15

3 types of lamellae

Answer 15

1. concentric
2. interstitial
3. circumferential

Question 16

where are trabeclui lined?

Answer 16

they orient themselves along stress lines

Question 17

where is red bone marrow in kids? in adults?

Answer 17

kids: medullary cavity and all spongy bone areas
adults: spongy bone marrow of hip, ribs, sternum, skull, vertebrae, proximal epiphyses of humerus and femur

Question 18

names of the 2 major blood vessels associated with bones

Answer 18

1. periosteal arteries = supply blood to periosteum and compact bone
2. epiphyseal veins = carry blood away from long bones

Question 19

4 scenarios where ossification happens

Answer 19

1. formation of bone in embryo
2. growth of bones until adulthood
3. remodeling of bone
4. repair of fractures

Question 20

2 types of bone formation during embryo development

Answer 20

1 intramembranous ossification

• flat bones of skull and mandible
• soft spots allow head to fit thru birth canal

2. endochondral ossification
   - replacement of hyaline cartilage with bone
   - most bones are formed this way

Question 21

Steps of intramembranous ossification

Answer 21

1. development of ossification center
2. calcification
3. formation of tribeculae
4. development of compact bone and periosteum

Question 22

steps of endochondral ossification

Answer 22

1. formation of bone collar around hyaline cartilage
2. cavitation of hyaline within cartilage model
3. invasion of internal cavities by periosteal bud and spongy bone formation
4. formation of medullary cavity as ossification continues –> appearance of secondary ossification centers
5. ossification of epiphysis from the secondary ossification centers

Question 23

how do bones grow in length during childhood?

Answer 23

1. growth of cartilage at epiphyseal plate

2. replacement of cartilage by bone tissue in epiphyseal plate

Question 24

zones of cartilage in epiphyseal plate

Answer 24

Resting: attaches cartilage to bony epiphysis
Proliferating: chondrocytes divide and lay down more cartilage
Hypertrophic: chondrocytes swell and die (osteoblasts enter)
Calcified : transformation into bone

Question 25

how do bones grow in thickness?

Answer 25

It happens on the outer surface "appositional growth" osteoblasts and osteocytes

Question 26

Remodeling of bone | - what causes some issues with remodeling?

Answer 26

- ongoing --> constant replacement of old bone with new - need balance bt osteoblasts and osteocytes - too much osteoblast activity caused by growth hormone - too much osteoclast activity leads to osteoporosis or rickets/osteomalasia (vit D deficiency)

Question 27

3 factors affecting bone growth and remodeling

Answer 27

1. Minerals 2. Vitamins 3. hormones

Question 28

Minerals that affect bone growth

Answer 28

Lots of calcium and phosphorus | small amounts of magnesium, fluoride, and manganese

Question 29

vitamins that affect bone growth

Answer 29

- vit A stimulates osteoblasts - vit C is needed for collagen synthesis - vit D increases Ca absorption from food - vit K and B12 are needed for sythesis of bone proteins

Question 30

Hormones that affect bone growth pre puberty

Answer 30

Kids: Human Growth Hormone stimulates liver to produce growth factors (IGFs) for bone growth --> IGFs stimulate osteoblasts, promote cell division at epiphyseal plate, and enhance protein synthesis Thyroid hormones stimulate osteoblasts Insulin increases synthesis of bone proteins

Question 31

Hormones that affect bone growth post puberty

Answer 31

Estrogen and Testosterone - cause growth spurt at puberty - cause changes in females (widening of pelvis) - shuts down growth at epiphyseal plate Parathyroid hormone, calcitriol, and calcitonin can affect bone modeling/ mineral control

Question 32

``` Fracture types: 1. open 2. closed 3. comminuted 4. greenstick 5. impacted 6. Pott's 7 Colles' 8. Stress ```

Answer 32

1. (compound) = broken ends of bone stick through skin 2. (simple) = doesn't break skin 3. bone is splintered/crushed 4. one side is broken and other one is bent 5. one end of fractured bone is forcefully driven into other 6. fracture of fibula with injury of tibial articulation 7. fracture of radius where distal fragment is displaced 8. series of microscopic fissures --> need bone scan

Question 33

Steps of fracture repair

Answer 33

1. Formation of fracture hematona - blood leaks from torn ends of blood vessels and a clotted mass of blood forms around fracture 2. Fibrocartilage callus formation - fibroblasts invade fracture site and make collagen fibers, bridging broken ends of bone 3. bony callus forms - osteoblasts befin to produce spongy bone trabeculae joining portions of original bone fragments 4. bone remodeling - compact bone replaces spongy bone

Question 34

what is calcium used for in the body?

Answer 34

- nerve and muscle cells - blood clotting - enzymes need it as a cofactor

Question 35

How to elevate blood calcium levels?

Answer 35

Parathyroid hormone (PTH) from parathyroid gland! - PTH increases the number and activity of osteoclasts - PTH makes kidneys decrease the loss of calcium in urine - PTH increases the formation of calcitrol (a hormone that increases calcium absorption from food)

Question 36

How to decrease blood calcium?

Answer 36

Calcitonin (CT) from the thyroid! - CT decreases osteoclast activity - not significant in humans, but effective against osteoporosis

Question 37

Exercise effect on bones

Answer 37

- bones deposit more mineral salts and increase production of collagen fibers in response to stress - unstressed bones lose minerals and collagen fibers - weight training builds strong bones

Question 38

2 major effects of aging on bones

Answer 38

1. loss of bone mass - loss of Ca in bone matrix (can lead to osteoporosis) 2. brittleness - from decreased protein synthesis

Question 39

bones after menopause

Answer 39

- sex hormones decrease which causes bone mass to decrease - osteoclasts outdo osteoblasts - female bones are smaller with less mass, so they're more affected

Question 40

kyphosis

Answer 40

curved spine from vertebrae collapsing on themselves