Tissues

Question 1

describe the stages required for tissue preparation for histology

Answer 1

collecting - depends on where the tissue is, skin punch biopsy, organ needle biopsy
fixation - to preserve tissues as they are invivo, done using chemical formaldehyde stops processes
dehydration - must be put in wax which is incompatible with water - series of increasing alcohol conc. to remove
embedding - placed in a wax block of paraffin wax
sectioning - 7um thick sections cut using microtome, mounted on to glass slide
staining - to see certain structures of the cell

Question 2

what stains are used in histology

Answer 2

H&E - stains nuclei purple and cytoplasm pink
PAS - stains complex carbohydrates pink
Masson’s trichrome - nuclei blue, collagen green and muscle red

Question 3

what is immunohistochemistry

Answer 3

using antigen to antibody binding to see a specific protein, antigen bound to fluorescence

Question 4

what are the 2 main types of epithelium

Answer 4

glandular and surface

Question 5

name 4 roles of epithelium

Answer 5

protection - many layers protecting underlying tissue, secretion - secreting sweat when temperature too high, absorption - many creams or topical medication, diffusion - in lungs, diffusion of gases

Question 6

where can simple squamous epithelium be found

Answer 6

in the alveoli of the lungs, for diffusion

Question 7

where can simple cuboidal epithelium be found

Answer 7

in several glands, kidney or salivary, for secretion

Question 8

where can simple columnar epithelium be found

Answer 8

can either be ciliated or non-ciliated - nonciliated in gastrointestinal tract role in absorption, ciliated in female fallopian tubes, cilia waft egg along tube

Question 9

where can pseudostratified epithelium be found

Answer 9

most commonly, columnar found in respiratory tract with cilia

Question 10

where can stratified squamous epithelium be found

Answer 10

surface epithelium, keratinised in skin and masticatory mucosa of the mouth, non-keratinised in lining mucosa

Question 11

where can transitional epithelium be found

Answer 11

in bladder, transitional to accommodate the stretching of the bladder

Question 12

what components make up the connective tissue

Answer 12

ground substance, fibres and cells

Question 13

what is ground substance

Answer 13

gel-like, weak substance to allow transfer between cells made of glycoproteins or hyaluronic acid

Question 14

what fibres can be found in connective tissue

Answer 14

collagen - several different types found in different areas, provides mechanical strength, elastin - to provide elasticity in areas eg the lungs

Question 15

what different cell types can be found in CT

Answer 15

blasts - producing tissue, cytes - maintaining and clasts breaking it down. also several blood vessels as is highly vascularised and immune cells

Question 16

what are the main types of connective tissue

Answer 16

connective tissue proper - loose or dense, skeletal - bone or cartilage, fluid - blood or lymph

Question 17

what are the types of loose connective tissue

Answer 17

reticular, areolar and adipose

Question 18

how can reticular loose CT be classified and where can it be found

Answer 18

characterised by black reticular fibres - type 3 collagen, provides framework for highly cellular structures, found in liver, lymph nodes and spleen

Question 19

how can areolar loose CT be classified and where can it be found

Answer 19

high volume of ground substance, found in submucosa and under skin epithelium

Question 20

how can adipose loose CT be classified and where can it be found

Answer 20

adipocytes in the ground substance, either found within tissue - subcutaneous - or on its own mamillary tissue

Question 21

what are the types of dense connective tissue

Answer 21

regular, irregular and elastin

Question 22

how is regular dense CT characterised and where can it be found

Answer 22

characterised by collagen fibres in the one direction, providing tensile strength in the one direction, found in ligaments and tendons

Question 23

how is irregular dense CT characterised and where can it be found

Answer 23

characterised by collagen fibres in multiple directions, providing tensile strength in many ways, found in subcutaneous, connective tissue surrounding organs (e.g. pericardium)

Question 24

how is elastin CT characterised and where can it be found

Answer 24

characterised by elastin fibres, providing elasticity, around major blood vessels, lungs, bladder

Question 25

what is scurvy

Answer 25

deficient in vitamin C, unable to make collagen fibres effectively, results in connective tissue lacking strength, tooth loss

Question 26

in bone, how much percentage of the ECM becomes mineralised with hydroxyapatite

Answer 26

70%

Question 27

how is bone mineralised

Answer 27

osteoblasts deposit collagen fibres and vesicles - osteoid, over time these vesicles become mineralised to hydroxyapatite crystals

Question 28

what is the periosteum composed of

Answer 28

2 layers - fibrous layer of dense irregular CT, blood vessels and lymphatics, cellular layer of osteogenic cells and osteoblasts

Question 29

how is cortical bone arranged

Answer 29

in osteons, which contains bone in layers of lamellae with a central canal of blood vessels, lymphatics and nerves,

Question 30

how are osteons produced

Answer 30

osteoclasts break down bone in the centre to make a central canal, osteoblasts around the outside of each layer lay down new bone, when the osteoblasts become trap in the bone they are known as osteocytes

Question 31

where can traberculae bone be found

Answer 31

ends of long bones, in epiphysis

Question 32

how is traberculae bone arranged

Answer 32

arranged in lamellae in rods to form a lattice shape

Question 33

where can endosteum be found

Answer 33

surrounding the central canal, around the rods of the traberculae bone

Question 34

what is different about cartilage compared to other CT

Answer 34

it is avascular

Question 35

what are the cells of cartilage

Answer 35

chondroblasts laying down cartilage, chondrocytes - when blasts get trapped in lacunae

Question 36

what is the 3 types of cartilage

Answer 36

hyaline cartilage, fibrocartilage, elastic cartilage

Question 37

where is hyaline cartilage found

Answer 37

around the ends of bones, preventing friction at joints

Question 38

what is hyaline cartilage lacking

Answer 38

perichondrium, means it lacks the ability to repair, once lost it cannot be repaired

Question 39

where is fibrocartilage found

Answer 39

abundant cartilage fibres so more strength, surround joint capsule and vertebral disc

Question 40

where is elastic cartilage found

Answer 40

more elastin fibres, epiglottis, larynx and external ear

Question 41

what is osteomalacia and what is it commonly known as in children

Answer 41

lack of vitamin D, results in weaker bones due to lack of absorption of calcium, known as rickets in children as weight bearing bones more effected

Question 42

what are the different types of endocrine secretion and give an example of each

Answer 42

chronic - always secreted at same levels, no stimulus required, thyroid hormone
acute - released in response to stimulus, amount secreted dependant on level of stimulation, adrenaline
episodic - released in response to stimulus, same amount released regardless of activation, insulin

Question 43

what regulates endocrine secretions

Answer 43

other molecules - glucose levels - humoral
neurones - noradrenaline causes adrenaline release
other hormones - hypothalamus to pituitary

Question 44

what are the two structures an exocrine gland may have

Answer 44

tubule or acinus

Question 45

what is meant by a compound structure of an exocrine gland

Answer 45

when many branches of tubules or acinars come together to form a duct

Question 46

what are the different methods of secretion of exocrine glands

Answer 46

merocrine - packaged into vesicle, contents released

apocrine - packaged into vesicle, vesicle then pinched off holocrine - whole cell pinched away and released

Question 47

what types of secretions are released from exocrine glands

Answer 47

mucous, serous or mixed

Question 48

how do mucous secretions appear histologically

Answer 48

appear pale in colour with nuclei around periphery of cell

Question 49

how do serous secretion appear histologically

Answer 49

appear pink in colour with central nuclei

Question 50

why can cancer of the pancreas not be removed surgically

Answer 50

it releases enzymes in surgery to cause degradation of the pancreas structure resulting in death of the organ

Question 51

describe 4 functions of the skin

Answer 51

sensation, absorption, protection and thermoregulation

Question 52

what are the layers of epidermis of the skin

Answer 52

stratum basale, stratum spinosum, stratum granulosum, stratum corneum

Question 53

what is the difference between thick and thin skin

Answer 53

thick skin has an extra layer - stratum lucidum, can produce waxy oils, also has a thicker stratum corneum

Question 54

what cells can be found in skin, other than epithelial cells

Answer 54

merkel cells - nerve receptors, melanocytes for skin pigmentation, langerhans cells detecting infection

Question 55

what layers make up the dermis

Answer 55

papillary layer and reticular layer

Question 56

where is the papillary layer of the dermis found and what is it composed of

Answer 56

found in rete pegs, underlying rete ridges, composed of loose areolar connective tissue, blood vessels and nerves

Question 57

where is the reticular layer of the dermis and what is it composed of

Answer 57

found under the papillary layer, composed of dense irregular connective tissue with collagen and elastin fibres

Question 58

what is psoriasis

Answer 58

a skin condition in which the cells are dividing too quickly so the cycle is only 7 days, the cells at the top superficial layer are not dead and are pron to bleeding

Question 59

what is pemphigus

Answer 59

when the desmosomes attaching adjacent cells are attacked, the cells break away from one another allowing fluid between them, results in blisters, can occur in the oral cavity

Question 60

how is cystic fibrosis characterised

Answer 60

goblet cells over secreting mucous, blocks duct and airways

Question 61

describe the general structure of a skeletal muscle

Answer 61

one muscle fibre covered by endomyosium, a bundle of fibres held together in a fasicle by perimyosium, and then several fasicles form the muscle, covered in epimyosium

Question 62

what myofilaments make up the sacromere

Answer 62

actin and myosin

Question 63

how are the filaments arranged in the sacromere (in terms of bands)

Answer 63

Z line between each sacromere, M line in the centre of the sacromere, H band where myosin only filament, I band with actin only filaments and the A band where actin and myosin filaments overlap

Question 64

what is the sacrolemma

Answer 64

membrane of the sacromere, contains invaginations called T-tubules, containing receptors for acetylcholine

Question 65

what is the sacroplasmic reticulum

Answer 65

similar to endoplasmic reticulum but contains calcium ions

Question 66

what are the layers of the heart muscle

Answer 66

endocardium, myocardium, pericardium

Question 67

what are the similarities between cardiac and skeletal muscle

Answer 67

both have sacrolemma, sacroplasmic reticulum, sacromere, contract by sliding filaments

Question 68

how do skeletal and cardiac muscle differ

Answer 68

cardiac has intercalated discs - gap junctions to allow electrical transmission from one cell to another, cardiac has a constant leakage of calcium, cardiac can be altered by hormones or nerves, cardiac is involuntary

Question 69

what is the shape of the smooth muscle

Answer 69

spindle shaped when relaxed, globular when contracted. with one central nuclei

Question 70

how are myofilaments arranged in smooth muscle

Answer 70

in a criss-cross lattice shaped, attached on one end to the membrane by focal densities - contraction brings the membrane closer together