Histology

Question 1

describe skeletal muscle fibres

Answer 1

striated, unbranched and multinucleated (syncytium)

Question 2

where is the nuclei in skeletal muscle fibres?

Answer 2

periphery of the fibre, just under the cell membrane (sarcolemma)

Question 3

what are muscle fibres grouped into?

Answer 3

fascicles

a muscle contains several fascicles

Question 4

three layers of connective tissue around the skeletal muscle

Answer 4

• epimysium= surrounds the muscle as a whole
• perimysium= around a single fascicle
• endomysium= around a single muscle fibre

Question 5

describe the structure of cartilage

Answer 5

made up of chondrocytes (chondroblasts when immature)

Question 6

where are chondrocytes situated?

Answer 6

live in a space in the ECM called the lacuna

Question 7

three types of cartilage

Answer 7

• hyaline e.g. articular surfaces, tracheal rings, costal cartilage and epiphyseal growth plates
• elastic= addition of elastic fibres
• fibrocartilage- type I collagen with rows of chondrocytes surrounded by small amounts of cartilaginous ECM

Question 8

functions of bone

Answer 8

support
levers for movement
protection
calcium store
hemopoiesis (begins in bone marrow)

Question 9

what does bone consist of?

Answer 9

65% bioapatite (calcium phosphate, hydroxyapatite)
23% collagen
10% water
2% non-collagen proteins

Question 10

two types of bone

Answer 10

1. cortical= outer shell which makes up shaft (diaphysis)

2. cancellous/trabecular= occupies ends of bone (epiphyses), fine meshwork

Question 11

what is the main different between the types of bone?

Answer 11

presence of spaces (marrow cavities) adjacent to trabecular bone

Question 12

what is bone penetrated by?

Answer 12

small canals for blood vessels and nerves called Haversian canals (lacked in trabecular bone as it is thin enough that osteocytes survive from contact with marrow spaces)

Question 13

what living cells are found in bone?

Answer 13

osteocytes

Question 14

what are the lines surrounding osteons called?

Answer 14

cement lines (only found in osteons that have formed during remodelling not in original development)

Question 15

four types of bone cells

Answer 15

osteoprogenitors
osteoblasts
osteocytes
osteoclasts

Question 16

osteoprogenitors

Answer 16

bone surface

serve as pool of reserve osteoblasts

Question 17

osteoblasts

Answer 17

bone forming cells on surface with plentiful RER and mitochondria

Question 18

osteocytes

Answer 18

cells trapped within bone matrix

Question 19

osteoclasts

Answer 19

bone surface responsible for bone resorption

Question 20

describe process of bone remodelling (this is constantly happening)

Answer 20

osteoclasts congregate and drill a hole where a blood vessel grows
osteoblasts lay down new lamellar bone until only the Haversian canal remains

Question 21

what is the site where osteoclasts and osteoblasts form new bone called?

Answer 21

basic multicellular unit or BMU

Question 22

what do osteoblasts secrete?

Answer 22

the osteoid which becomes mineralised. it consists of:

collagen, GAGs, proteoglycans and other organic components

Question 23

what is the mineral of bone?

Answer 23

calcium phosphate crystals

Question 24

what do osteocblasts secrete

Answer 24

matrix that becomes solid and forms bone

Question 25

what happens in bone remodelling after a break?

Answer 25

collagen fibres are lay down in a haphazard fashion rather than one direction (woven bone)
it is not as strong