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year 1 flash cards > TOPIC 2 - cells and tissues > Flashcards

TOPIC 2 - cells and tissues Flashcards

1
Q

what is histology?

A

the study of cells and tissue by microscopy

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2
Q

what is histopathology?

A

the study of diseased tissues by microscopy

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3
Q

give 4 clinical applications of histology

A
  • make a diagnosis
  • determine prognosis (ie is it malignant or agressive)
  • plan or confirm treatment
  • predict or confirm response to some drugs
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4
Q

give additional benefits to histology

A
  • audit of pathology services
  • see how succesful a surgery was
  • collect epidemiological data
  • pathogenesis
  • education
  • can recognise normal tissue
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5
Q

give the 10 steps for histological preparation and examination

A
  1. tissue
  2. fixation
  3. cut up/ block section
  4. tissue processing
  5. section cutting and mounting
  6. section staining
  7. section scanning
  8. microscopy
  9. diagnosis
  10. prognosis prediction
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6
Q

what is step 1 of histology?

A

tissue - could be a surgical excision, biopsy etc

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7
Q

how do we stop the tissue degrading?

A

fixation (step 2)

  • stop intrinsic autolytic enzyme action (autolysis)
  • prevent bacterial contamination (putrefaction)
  • increase mechanical strength to preserve structure/ morphology
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8
Q

give the general types of fixatives and their mode of action (4)

A

aldehyde - form protein covalent cross links
alcohol - denature proteins causing aggregation
oxidising - form protein cross links via oxidation
freezing - v quick but poor morphology

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9
Q

what is the most common fixative?

A

formalin (a formaldehyde solution)

  • forms protein covalent cross links
  • good penetration/ mechanical strength
  • good tissue morphology preservation
  • poor nucleic acid preservation
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10
Q

what fixative is used for electron microscopy?

A

glutaraldehyde

  • larger molecule than formalin
  • needs smaller tissue samples
  • works well at low temperatures
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11
Q

what fixative is used for nucleic acid research?

A

ethanol

  • fixes by precipitation
  • reduces protein solubility –> precipitate
  • used in cytology smears
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12
Q

what is step 3 of histology prep and examination

A

block section

  • choosing what we want to see histologically
  • cut up a larger section into smaller pieces
  • can select area of interest
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13
Q

where do you place tissue slices (name of plastic box)

A

a cassette

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14
Q

what is step 4 of histology prep and examination

A

tissue processing

- aim - thin slice of tissue to examine under a microscope

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15
Q

what are the 4 steps of processing?

A
  • dehydration (remove water with alcohol)
  • clearing (replace acohol with xylene)
  • wax infiltration (replace xylene with parrafin wax)
  • embedding (orientate tissue to form a block)
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16
Q

what is the end product of tissue processing?

A

a parafin block

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17
Q

what does FFPE stand for

A

formalin fixed parafin embedded tissue

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18
Q

what is step 5 of histology prep and examination?

A

section cutting and mounting

- cut thin sections to be viewed under a microscope

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19
Q

what machine is used to cut the thin sections?

A

a microtome

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20
Q

what is step 6 of histology prep and examination?

A

section staining

  • unstained tissue section is translucent
  • make visible using dyes
  • dyes can be specific
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21
Q

what is the H&E stain?

A

haematoxylin and eosin stain

- most common (95%)

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22
Q

what does haematoxylin stain?

A

PURPLE
basic dye = stains acidic structures
DNA - NUCLEI

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23
Q

what does eosin stain?

A

PINK
acidic dye = stains basic structures
PROTEINS - CYTOPLASM

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24
Q

what is PAS stain?

A

periodic acid schiff

  • detection of mucin/ mucopolysaccarides
  • detection of fungal organisms
  • visualisation of basement membranes
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25
Q

what is DPAS?

A

PAS combined with diastase

- diastase removes glycogen

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26
Q

what stain is used on bacteria to see if gram + or-?

A

crystal violet and safranin counter stain
gram postive = purple
gram negative = pink (with counter stain)

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27
Q

what is the giesma stain?

A

H.Pylori bacteria and toxoplasma (and others)

- attaches itself to phosphate group of DNA

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28
Q

what is grocott’s stain?

A

fungi

- fungal walls go black

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29
Q

what is oil red O stain?

A

fat

- can only be used on frozen tissue not processed as alcohol fixation removes most lipids

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30
Q

what is orcein stain?

A

copper associated protein
elastin fibres
HEP B sAg

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31
Q

what is perl’s stain?

A

iron = blue

asbestos

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32
Q

what is ziehl neelsen stain?

A

mycobacterium

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33
Q

what does tinctorial mean?

A

relating to dying, staining or colouring

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34
Q

what is immunohistochemistry?

A

uses antibodies against a specific protein target (unlike tinctorial stains are not specific)

  • can provide specific information on protein expression
  • diagnosis - can tell you the origin of the cancer
  • prognosis
  • prediction of response to therapy
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35
Q

what are steps 7 and 8 in histology prep and examination?

A

section scanning and microscopy

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36
Q

what two drugs are used to treat breast cancer and the use of immunohistochemistry can predict reponse?

A

tamoxifen and herceptin

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37
Q

what is epithelilium?

A

layer or layers of cells that cover body surfaces (external and internal) or line body cavities

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38
Q

what are the 8 main features of epithelium?

A
  1. derived from endoderm/ mesoderm/ ectoderm
  2. line basically all body surfaces
  3. cellular
  4. sit on layer of connective tissue called basal lamina
  5. stuck tightly together (intracellular junctions/ complexes)
  6. polarity (composition of bottom and top different)
  7. avascular
  8. rapid turn-over
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39
Q

what are the 7 main functions of epithelium?

A
  1. absorption
  2. surface movement
  3. secretion
  4. gas exchange
  5. surface lubrication
  6. sensation
  7. protection of underlying tissue
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40
Q

what is a tight junction?

A

‘seal the cell’

  • occludin/claudin seals to protein movement/ paracellular diffusion
  • apical (at the top)
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41
Q

what is a adherens junction?

A
  • transmembrane proteins connect across cell cytoskeletons

- below TJs

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42
Q

what is a gap junction?

A
  • small channels that allow intercellular ion/ small molecule exchange
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43
Q

what is a desmosome?

A
  • transmembrane proteins connect to others (linked to intermediate filaments) from adjacent cells
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44
Q

what is a hemi-desmosome?

A
  • provide attachment to underlying basal lamina
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45
Q

what is the role of cell adhesion molecules?

A

critical for epithelium integrity, adherance to the underlying basal lamina and intrinsic function

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46
Q

what is the general approach for naming epithelia?

A
  1. number of layers of cells - single or more?
  2. shape of cells - flat, cuboidal or columnar?
  3. do the cells have any specialisation/ adaptations
47
Q

what do you call a singular layer of epithelium?

A

simple

48
Q

what do you call flat cells?

A

squamous

49
Q

what do you called multi-layered epithelium?

A

stratified

50
Q

how do you judge of the shape of stratified epithelial cells?

A

look at the top layer

51
Q

what is the most common epithelium?

A

stratified squamous epithelium - skin, oesophagus, oral cavity etc

52
Q

what is psuedo-stratified?

A
  • single layer of columnar
  • different heights
  • but look like multiple layers
  • upper airways - cilia/ goblet cells
53
Q

what is transitional?

A
  • multiple layers
  • but changes shape (columnar and flat)
  • distention (expands)
  • only found in bladder/ urinary tract (uroethelial)
54
Q

what 4 specialisations epithelial cells could have?

A
  • cilia
  • secretory
  • microvilli
  • keratinisation (ie when you scratch you skin and flakes come off)
55
Q

how are epithelial cells adapted to protect?

A 
prevent dehydration, chemical, mechanical damage
covering of inter/outer surfaces
multi-layered for strength (stratified)
replicative to replace damaged cells
tight seals between cells
keritinisation
56
Q

how are epithelial cells adapted for absorption?

A

lining of gut specialised for absorption (glucose, ions, water)
relies of cell polarity
brush border - increases surface area for absorption

57
Q

how are epithelial cells adapted for surface movement?

A

cillia move in co-ordination to provide unidirectional movement

  • airways (mucus)
  • testes (sperm)
  • fallopian tubes (ova)
58
Q

how are epithelial cells adapted for gas exchange?

A

single layer of squamous cells that line blood vessles (endothelium) - minimal distance for gaseous diffusion

59
Q

how are epithelial cells adapted for surface lubrication?

A

mesothelium is simple epithelium
lines all body cavities
potential spaces contain protein rich fluid (serous)
lubrication of surfaces that move against each other

60
Q

how are epithelial cells adapted for sensation?

A

sensory organs are highly specialised epithelia

ectoderm - nervous system - all senses

61
Q

how are epithelial cells adapted for secretion?

A

isolated epithelial cells (eg goblet cells)
organised multicellular glandular structures
- ducts open onto epithelial surfaces = exocrine
- ductless, straight into blood stream = endocrine

62
Q

how do you classify exocrine glands?

A
  1. look at the duct
    - unbranched = simple
    - branched = compound
  2. describe the gland
    - tubular with coils
    - tubular with branches
    - alveolar (hollow)/ acinar (like a berry)
63
Q

what are the 3 mechanisms of exocrine secretion?

A

merocrine
apocrine
holocrine

64
Q

what is merocrine?

A
  • protein product in intra-cellular vesicle
  • vesicle membrane fuses with cell membrane
  • protein product released by exocytosis
  • fused plasma membrane recycled by endocytosis
  • pancreatic enzymes in exocrine pancreas
65
Q

what is apocrine?

A
  • protein product in vesicle
  • approaches apical membrane
  • apical membrane pinches off with loss of some membrane
66
Q

what is holocrine?

A
  • secretory product accumulates in cytoplasm
  • cell disintergrates to release product
  • sebum in sebaceous glands
67
Q

what is epidermolysis bullosa?

A

blistering skin disorder

  • inherited gene mutation of adhesion molecules that stick epithelium to basement membrane
  • abnormal anchoring of epidermis to dermis
  • blisters
68
Q

what is cystic fibrosis?

A
  • mutations in CTFR gene
  • defective chloride channel on apical surface of epithelial cells
  • lungs but also exocrine glands eg pancreas
  • less water in mucus –> thickened –> builds up –> infection
69
Q

what is congenital ciliary dyskinesia?

A
  • autosomal recessive
  • abnormal cilia function –> secretion accumulation
  • kartageners syndrome - bronchiectasis, sinusitis, situs inversus
70
Q

what are mesenchymal tissues?

A

connective/supporting tissues

  • blood, blood vessels, lymph system
  • bone
  • cartridge and joints
  • muscle and fat
71
Q

what are mesenchymal tissues derived from?

A

mesoderm (middle layer of embryo)

72
Q

why do we need mesenchymal tissues?

A
  • act as supporting structure to hold the body together
  • give organs shape
  • key metabolic function
  • immune system
  • tissue repair
  • storage of fat (adipose tissue)
73
Q

what makes up supporting tissue?

A

extracellular matrix and cells

74
Q

what is the extracellular matrix?

A
  • a gel like amorphous substance called ground substance (composed of glycosaminoglycans - hyaluronic acid and proteoglycans)
  • percolating tissue fluid
  • fibres of collagen (strength) and elastin (stretch and elastic recoil)
75
Q

what composes the cell part of supporting tissue?

A

support cells
- fibroblast
- adipocytes
immune cells

76
Q

what is the function of fibroblasts?

A

secretion of extracellular matrix

77
Q

what is the function of adipocytes?

A

storage and metabolism of fat

78
Q

what is ehlers-danlos syndrome?

A

rare inherited condition caused by defect in structure or processing of collagen

  • joint hypermobility
  • predisposition to joint dislocations
  • skin laxity
  • can cause life threatening heart complications
79
Q

what is marfan syndrome?

A

rare inherited disorder with defect in gene that makes fibrillin
- marfanoid appearance (tall, thin

80
Q

what are basophils?

A
  • least common leucocyte
  • have large blue (basophilic) granules
  • similar to tissue mast cells
81
Q

what is fibrilin essential for?

A

proper formation of the extracellular matrix (maintenance of the elastic fibres)

82
Q

what defence cells are present in supporting tissues?

A
  1. tissue macrophages
    - phagocytosis
    - can join together to form multinucleate cells
  2. mast cells
    - produce histamine in allergy and anaphylaxis
  3. wandering cells - all remaining leucocytes from the blood
83
Q

how are leucocytes classified?

A

granulocytes (secretory granules in cytoplasm and multilobed nucleus)
- neutrophils, eosinophils, basophils
mononuclear (non-lobulated nuclei and can’t see granules)
- lymphocytes, monocytes

84
Q

how much of plasma is water?

A

90%

85
Q

what are neutrophils?

A
  • multilobed (up to 5) single nucleus
  • circulate in blood but enter tissues in response to disease/injury
  • key in acute inflammation (phagocytosis)
86
Q

what is pus?

A

defunct neutrophils

87
Q

what is a myocardial infarction?

A

heart attack

  • blood clot in one of the coronary vessels supplying the heart
  • stops O2 supply to heart muscle - damage
  • atherosclerosis (narrowing of coronary vessels)
88
Q

what are lymphocytes?

A
  • non-lobulated nuclei
  • dense nuclei and minimal cytoplasm
  • smallest leucocyte
  • key role in all immune responses
  • T and B cells
89
Q

what are monocytes?

A
  • largest leucocyte
  • large nucleus at edge of cell
  • circulate for 3-4 days then move into tissues as macrophages
  • no role in blood
90
Q

what are red blood cells?

A
  • no nucleus
  • biconcave
  • haemoglobin
  • highly adapted for oxygen and carbon dioxide transport
91
Q

what is anaemia?

A

failure to maintain an adequate haemoglobin concentration

  • shortness of breath
  • pale
  • lethargy
92
Q

what makes up blood vessels?

A

arteries - eleastic and thick muscular walls
arterioles - terminal branches that supply capillaries
capillaries - v thin walled vessels to enable exchange of fluids, gases, nutrients and waste products
venules - capillaries to veins
veins - contain valves to stop backflow of blood, thin muscular walls with few elastic fibres

93
Q

what are the three layers of blood vessels?

A
  1. tunica intima (inner lining)
  2. tunica media (muscular layer)
  3. tunica adventitia (outer connective tissue network)
94
Q

what is deep vein thrombosis?

A

formation of blood clot in a deep vein (most common in leg)
- unilateral swelling
- redness
- pain
risk factors = cancer, recent surgery, obesity, pregnancy
- can cause PULMONARY EMBOLISM
- treat with anticoagulants

95
Q

what are varicose veins?

A

weak or damaged valves in the superficial veins
risk factors = obesity, family history, pregnancy, leg trauma
- treat to reduce symptoms (mild pain) and appearance

96
Q

what is the lymph vascular system?

A

drains excess fluid (lymph) from extracellular spaces and returns it to blood vascular system

  • lymph passes through lymph nodes as it returns to blood
  • lymphatic spread is important route of metastasis in cancer
97
Q

what is lymphoedema?

A

localised swelling due to compromised lymphatics

  • most common in upper limbs
  • complication of surgery where sections of lymphatic system removed (eg breast cancer) = less drainage of lymph = swelling
98
Q

why is bone important?

A
  • structure
  • protection
  • movement
  • haematopoiesis (maturation of leucocytes)
  • maintaining calcium levels
99
Q

what is bone made of?

A

collagenous extracellular matrix called osteoid
osteoblasts
osteocytes
osteoclasts

100
Q

how does the bone have strength and rigidity?

A

osteoid is mineralised by deposition of calcium

101
Q

what are osteoblasts?

A

synthesise osteoid and mediate the mineralisation with calcium

102
Q

what are osteocytes?

A

inactive osteoblasts that get trapped within the formed bone

103
Q

what are osteoclasts?

A

cells capable of eroding and resorbing bone - important in refashioning and turnover of bone

104
Q

what are the two main forms of bone

A

woven (immature) - produced very rapidly in feotal development and fractures
lamellar (mature) - stronger and more resilient (all adult healthy bone)

105
Q

what is paget’s disease?

A

haphazard and excessive osteoclast erosion of bone

  • cause not known
  • osteoblasts increase activity to attempt to replace bone
  • new bone is weaker
  • common in elderly
  • pelvis, spine and skull
106
Q

what is osteogenesis imperfecta?

A

brittle bone disease

  • rare genetic disorder
  • lack of type 1 collagen
  • frequent fractures
  • blue sclera
107
Q

what is cartilage?

A

provides smooth articular surface at bone ends and structural support in pinna, trachea

108
Q

what is cartilage made up of?

A

chondroblasts, chondrocytes and fibrous extraceullar material

109
Q

what are chondroblasts?

A

synthesise and deposit ground substance and fibrous extracellular material

110
Q

what are chondrocytes?

A

chondroblasts trapped in ground substance

111
Q

what are the different types of cartilage and where are they found?

A

hyaline - nose, trachea, joints, end of ribs
elastic - ears
fibrocartilage - intervertebral discs, pubic symphisis

112
Q

what are joints made up of?

A 
bone
cartilage
synovium
ligaments
tendons
muscles
113
Q

what is rheumatoid arthritis?

A

autoimmune disease attacking synovium of joints

  • common in hands, knees and ankles
  • more common in women
  • pain, swelling, stiffness
114
Q

what is osteoarthritis?

A

wear and tear of cartilage in joints

  • knees, hips, spine and hands
  • joint pain, stiffness, swelling
  • risk factors = age, obesity, family history

year 1 flash cards (23 decks)

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