Histology

Question 1

what three key words describe skeletal muscle cells

Answer 1

striated, unbranched, multinucleated

Question 2

where are the nuclei in muscle cells found

Answer 2

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

Question 3

how long are muscle cells

Answer 3

as long as the muscle

Question 4

what are muscle cells grouped into

Answer 4

fascicles

Question 5

what is the epimysium

Answer 5

the connective tissue that surrounds the whole muscle

Question 6

what is the perimysium

Answer 6

the connective tissue around a single fascicle

Question 7

what is the endomysium

Answer 7

the connective tissue around a single muscle fibre

Question 8

what are sarcomeres

Answer 8

the functional unit- unit of contraction of the muscle cell (smallest contractile element)

Question 9

list what makes up a muscle cell

Answer 9

muscle fibre= lots of myofibrils= lots of sacromeres

Question 10

what makes up band A

Answer 10

myosin (dark, thick)

Question 11

what makes up the I band

Answer 11

actin (light)

Question 12

what creates the striations in muscle cells

Answer 12

regular patterns of alternating dark and light bands (z discs aligned)

Question 13

what is the motor unit

Answer 13

one motor neurone and all of the muscle fibres that it innervates

Question 14

what happens to the axon of the muscle fibre as it nears its termination

Answer 14

branches to synapse with more neuromuscular junctions

Question 15

describe type I muscle fibres

Answer 15

relatively slow contracting, depend on oxidatitive metabolism, have abundant metabolism and are resistant to fatigue. produce relatively less force- red fibres

Question 16

describe type IIa muscle fibres

Answer 16

relatively fast contracting, reasonably resistant to fatigue, relatively uncommon

Question 17

describe type IIB fibres

Answer 17

fast contracting, depend on anaerobic metabolism, few mitochondrian, less myoglobin, fatigue easily, produce greater force- white fibres

Question 18

does cartilage have a blood supply

Answer 18

no is avascular- blood diffuses into it through matrix

Question 19

is bone permeable

Answer 19

no

Question 20

what are chondrocytes

Answer 20

the cell found in cartilage

Question 21

what are chondroblasts

Answer 21

immature cartilage cells

Question 22

what is a lacuna

Answer 22

space in the extracellular matrix in which chondrocytes live

Question 23

what do chondrocytes do

Answer 23

seceret and maintain the extracellular matrix around them

Question 24

what organic material makes up hyaline (extra cellular matrix) cartilage

Answer 24

type II collagen and proteoglycan aggregates

Question 25

what is the most common type of cartilage

Answer 25

hyaline

Question 26

describe hyaline cartilage

Answer 26

blue/white in colour and translucent

Question 27

describe elastic cartilage

Answer 27

light yellow, elastic fibres make it quite flexible

Question 28

describe fibrocartilage

Answer 28

hybrid between tendon and hyaline cartilage

has bands of densely packed type one collagen interleaved with rows of chondrocytes surrounded by small amounts of cartilagenous ECM

appears white

Question 29

where is hyaline cartilage found

Answer 29

articular surfaces

tracheal rings

costal cartilage

epiphyseal growth plates

precursor in fetus to many bones

Question 30

what are the functions of bone (5)

Answer 30

support
levels 
protection of internal organs 
calcium store 
haemopoiesis (blood cell production)

Question 31

what makes up bone

Answer 31

23% collagen
65% bioapatitie (form of calcium phosphate, mostly hydroxyaptite)
10% water
2% non collagen proteins

Question 32

what type of bone makes up the diaphysis (shaft)

Answer 32

cortical bone

Question 33

what type of bone makes up the epiphyses (ends of the bone)

Answer 33

cancellous or trabecular bone

Question 34

does bone remodel

Answer 34

yes constantly throughout life

Question 35

what is a haversian canal

Answer 35

blood vessel inside each lamellae circle (osteon)

Question 36

what is the main different between compact and trabecular bone

Answer 36

presence of spaces (marrow cavities) adjacent to trabecular bone

Question 37

what are osteocytes

Answer 37

bone forming cells found on the surface of developing bone

Question 38

what are cement lines

Answer 38

line visible around osteons, formed during remodelling

Question 39

describe the morphology of trabecular bone

Answer 39

has osteocytes and is lamellar in nature but generally lacks haversian canals

Question 40

what are osteoprogenitor cells

Answer 40

cells located on bone surfaces (e.g. under periosteum) that serve as pool of reserve osteoblasts

Question 41

what is an osteocyte

Answer 41

a bone cell trapped within the bone matrix

Question 42

what is an osteoclast

Answer 42

large multinucleated cells found on the surface of bone and are responsible for bone resorption

Question 43

describe the ‘cutting cone’ of bone remodelling

Answer 43

when a number of osteoclasts congregate and ‘drill’ into bone forming a tunnel. a blood vessel will grow into the tunnel bringing with it osteoblasts which line the tunnel and begin laying down new lamellar bone. this continues until only space of a haversian canal remains

Question 44

what us a basic multicellular unit

Answer 44

collection of osteoclast and osteoblasts involved in bone remodelling

Question 45

what do osteoblasts do

Answer 45

secret collagen, glycosaminoglycans (GAGs), proteoglycans and other organic components of matrix= osteoid which becomes mineralised over time

Question 46

what are osteoclasts derived from

Answer 46

macrophage lineage

Question 47

what do osteoclasts form if they fuse

Answer 47

giant cells

Question 48

where matrix secrete that will become be added on to

Answer 48

only to surface of existing bone

Question 49

what is woven bone

Answer 49

disorganised bone that is layed down in response to a fracture