L13- Bone introduction

Question 1

bone is a type of

Answer 1

connective tissue

Question 2

how many types of bone in the body

Answer 2

5

Question 3

name the 5 types of bone in the body

Answer 3

1) long bones 2) short bones 3) flat bones 4) irregular bones 5) sesamoid

Question 4

long bones

Answer 4

• Longer than wide • Function: support weight of the body and allow movement • e.g. Humerus, small bones in fingers

Question 5

short bones

Answer 5

• As long as they are wide • Function: short bones provide stability and some movement • e.g. Trapezoid, wrist (carpals) bone, ankle (tarsals)

Question 6

flat bones

Answer 6

• Flattened, with parallel edges • Function: protects internal organ- large area of attachment for muscle • e.g. Sternum and ribs , cranial bones, pelvis

Question 7

irregular bones

Answer 7

• Vary in shape and structure (complex shape) • Function: protect internal organs • e.g. Vertebra protect spinal cord • e.g. Pelvis (sacrum) protects organs in the pelvic cavity

Question 8

sesamoid (sesame like)

Answer 8

• Embedded in tendons • Function: protect tendons from stress and damage from repeated wear and tear • e.g. small round bones found in the tendons of the hands, knees and feet - Patella is a good example- forms postnatally

Question 9

outer most layer of bone is called the

Answer 9

periosteum

Question 10

inner portion of the bone called

Answer 10

cancellous or spongy bone

Question 11

features of cancellous/ spongy bone

Answer 11

• Strong - Light - Filled with bone marrow (trabeculae)

Question 12

outer portion (external surface) of bone

Answer 12

compact bone

Question 13

features of compact bone

Answer 13

80% of bone mass - Much more dense than cancellous bone o Fewer spaces

Question 14

organisation of compact

Answer 14

Compact bone is tightly organised into osteons

Question 15

osteons

Answer 15

Osteons are formed by layers of lamellae that wrap around each other.

Question 16

in the centre of the osteon what is found

Answer 16

haversion canal

Question 17

what is found within haversion canal

Answer 17

blood vessels and lymphatics and nerves

Question 18

within sheets of lamella (in compact) are tiny channels called

Answer 18

Canaliculi

Question 19

Canaliculi branch

Answer 19

out from the central/ haversian canal to empty spaces called lacunae.

Question 20

Lacunae are empty spaces for

Answer 20

Osteocytes- branch through canaliculi to contract other osteocytes via gap junctions.

Question 21

volkmanns canal

Answer 21

branch horizontally (unlike aversion which branch verticallY)

Question 22

osteoblasts

Answer 22

make bone

Question 23

osteoclasts

Answer 23

break down bone and reabsorbed

Question 24

spaces between trabecular in cancellous bone

Answer 24

contain bone marrow and blood vessels

Question 25

blood cells and platelets leave the bone via

Answer 25

different routes

Question 26

how do blood cells leave the bone

Answer 26

• Nutrient artery comes into the bone at one point • This artery takes blood all the way through the bone till the end supplying capillaries • Here the RBC go through the sinusoids into the central marrow vein to leave the bone • Some capillaries go through the sinusoids and into the bone marrow which pick up cells • Cells flow back through the capillaries into the central marrow vein and out back into the blood via the vena commitans

Question 27

how do platelets leave the bone

Answer 27

not through sinusoids

• Start off as a hamopoteic stem cell
• Fuse together and take nuclei from a number of cells to form a megakaryocytes
• Megakaryoctes have long processes which release platelets into the blood vessels (Apocrine)

Question 28

why do blood cells and platelets have to leave the bone

Answer 28

because they are produced in the bone marrow