Histology

Question 1

how far along muscle do muscle fibres run

Answer 1

origin to insertion

Question 2

desribe the nuclei of skeletal muscle fibres

Answer 2

multinucleated

nuclei at periphery of fibre, just under cell membrane (sacrolemma)

at periphery as they have been pushed there by all the actin and myosin

Question 3

what are the bundles that muscle fibres are grouped into called

Answer 3

fascicles

Question 4

define epimysium, perimysium and endomysium

Answer 4

epimysium - connective tissue that surrounds the muscle as a whole

perimysium - surrounds single fascicle

endomysium - surrounds single muscle fibre

Question 5

what are the units of contraction

Answer 5

sarcomeres

Question 6

how are cartilage cells nourished

Answer 6

avacular but permeable - diffusion through the Extracellular matrix

Question 7

how are bone cells nourished

Answer 7

by blood vessels that pervade the tissue

Question 8

what are the resident cells in cartilage

and what were they called when they were immature

Answer 8

chondrocytes

chondroblasts

Question 9

where do chondrocytes live

Answer 9

in a space in the extracellualr matrix called a lacuna

Question 10

what do chondrocytes do

Answer 10

produce and maintain ECM

Question 11

what is the most common form of cartilage

Answer 11

ECM (hyaline)

Question 12

what is ECM formed from

Answer 12

75% water

25% type II collagen and proteoglycan aggregates made up of GAGs

Question 13

how does type II collagen differ from type I

Answer 13

type II is finer and forms a mesh instead of linear bundles

Question 14

what is the most common form of cartilage in connective tissue

Answer 14

type I

Question 15

hyaline cartilage example

Answer 15

tracheal ring

Question 16

elastic cartilage and example

Answer 16

elastic fibres make it flexible

eg penna of ear

Question 17

fibrocartilage and example

Answer 17

eg minisci of knee

hybrid between tendon and hyaline cartilage

bands of densely packed type I collagen interleaved with rows of chondrocytes surrouned by small amounts of cartilagenous ECM

Question 18

functions of the bone

Answer 18

support, lever, protection

calcium store

haemopoiesis

Question 19

haemopoiesis in the bone

Answer 19

production of RBC and platelets in bone marrow

by early 20s only the axial and limb girdle skeleton is involved in blood production

Question 20

where is blood produced in utero

Answer 20

liver and spleen

Question 21

composition of bone

Answer 21

Question 22

what are the 2 types of bone

Answer 22

outer shell of dense hard cortical bone that makes up shaft (diaphysis)

cancellous/trabecular/spongy bone occupies the ends of the bone (epiphyses)

Question 23

where are the marrow cavities found

Answer 23

• adipose tissue is found in the medullary cavity of the diaphysis
• red marrow is found in the proximal cancellous material of bones and the flat bones

Question 24

compare the bone cells and matrix of compact and trabecular bone

Answer 24

• similar, but the trabecular bone has marrow cavities in it
• both types are lamellar - made up of layers

Question 25

cortical bone

Answer 25

Question 26

what are the haversion canals in cortical bone surrounded by and what do they contain

Answer 26

layers of lamellar bone contain blood vessels

Question 27

what are canaliculi

Answer 27

Bone canaliculi are microscopic canals between the lacunae of ossified bone. The radiating processes of the osteocytes project into these canals

Question 28

what are cement lines in cortical bone

Answer 28

lines that are visible surrounding the osteon are only found in osteons that have formed during remodelling (not original development)

Question 29

describe osteocytes and haversion canals in trabecular bone

Answer 29

has osteocytes and is lamellar in nature lacks Haversian canals

Question 30

osteoprogenitor cells

Answer 30

located on bone surfaces, pool of reserve osteoblasts

Question 31

osteoblasts

Answer 31

bone forming cells on surface of developing bone plentiful RER and prominent mitochondria

Question 32

osteocytes

Answer 32

bone cell trapped within bone matrix

Question 33

osteoclast

Answer 33

large multinucleated cells responsible for bone resorption (destroyer)

Question 34

describe bone remodelling

Answer 34

osteocalsts congregate and drill into bone forming a tunnel blood vessel grows in the tunnel and brings with it osteoblasts which line the tunnel and begin laying down new lamellar bone process continues until only space of Haversian canal remains

Question 35

what is the collection of osteoblasts and osteoclasts that participate in bone remodelling called

Answer 35

basic multicellular unit

Question 36

what do osteoblasts secrete

Answer 36

components of the matrix (collagen, GAGs, proteoglycans etc) that is collectively called an **osteoid**

Question 37

what is the mineral of bone made up of

Answer 37

principally Ca phosphate

Question 38

what lineage of cells are osteoclasts believed to be from

Answer 38

macrophage they fuse and form a single giant cell

Question 39

what do young remodelling osteons often do to older osteons

Answer 39

obliterate them

Question 40

howis bone laid down during development/following break

Answer 40

differently from normal lamellar bone angle of deposition changes - **woven** bone not as strong so subsequently remodelled to lamellar bone