Topic 2 - Cells and Tissues Flashcards
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1
Q
What is histology?
A
The study of cells & tissue by microscopy
2
Q
What are the ABCDE of looking at skin legions?
A
- Asymmetry (if asymmetrical may be melanoma)
- Border (Uneven? Crusty? Notched?)
- Colour (Healthy moles are uniform in colour)
- Diameter (Larger than a pencil eraser?)
- Evolving (Gotten bigger? Different colour? Bleeding/scabbing?)
3
Q
What is histopathology?
A
The study of diseased tissues by microscopy
4
Q
What are the clinical applications of histology?
A
- Making a diagnosis
- Determine a prognosis
- Plan/confirm treatment
- Predict/confirm response to some drugs
5
Q
How do we made a diagnosis on a skin legion?
A
- Examination
- Biopsy
6
Q
What is an adjuvant treatment?
A
Applied after initial treatment for cancer, especially to suppress secondary tumour formation - post operative
7
Q
What is a neoadjuvant treatment?
A
The administration of therapeutic agents before a main treatment - pre operative
8
Q
What are the steps of actually performing histology on a lesion?
A
- Fixation of tissue
- Cut up/block selection
- Tissue processing
- Section cutting and mounting
- Section staining
- Section scanning
- Microscopy
- Diagnosis and prognosis prediction
9
Q
How can we preserve tissues?
A
- Stop autolysis
- Prevent putrefaction
- Increase mechanical strength to preserve the structure and morphology
10
Q
What is putrefaction?
A
Bacterial contamination of tissue
11
Q
What is morphology?
A
A particular form, shape, or structure (of cells)
12
Q
What are the different types of fixatives used in histology?
A
- Aldehyde
- Alcohol
- Oxidizing
- Freezing (quick but poor morphology)
13
Q
What is formalin, it’s strengths and weaknesses?
A
- Formaldehyde solution
- Most common available
- Forms protein covalent cross-links
- Good penetration/mechanical strength
- Good tissue morphology preservation
- Poor nucleic acid preservation
14
Q
What is Glutaraldehyde?
A
- Similar to formalin but larger molecule
- Needs smaller tissue samples
- Works well at low temperature
- Used for electron microscopy
15
Q
What is ethanol?
A
- Fixes by precipitation
- Reduces protein solubility -> precipitate
- Used in cytology smears
- Nucleic acid research (doesn’t cross link)
16
Q
What is the aim of tissue processing?
A
A thin slice of tissue to examine under a microscope
17
Q
How do we prepare tissue to be placed in wax?
A
- Remove water from tissue with alcohol (dehydration)
- Replace alcohol with xylene (clearing)
- Replace xylene with paraffin wax (wax infiltration)
- Orientate tissue to form a paraffin block (embedding)
18
Q
What is the most common tissue dye stain?
A
Haematoxylin and eosin stain
19
Q
What does haematoxylin do?
A
- Basic dye
- Stains acidic structures purple
- Hence nuclei/DNA are purple
20
Q
What does eosin do?
A
- Acidic dye
- Stains basic structures pink
- Hence proteins in cytoplasm are pink
21
Q
What is Periodic Acid Schiff?
A
- Also a very useful tissue dye
- Detection of mucin/mucopolysaccharides
- Detection of fungal organisms
- Visualization of basement membranes
- Glycogen is PAS +ve
22
Q
What is PAS combines with diastase?
A
DPAS
- Enzyme diastase removes glycogen
- Δ of enzyme deficiencies in liver
- Exclude glycogen staining in other situations
23
Q
What is the gram stain for bacteria?
A
G +ve is blue
G -ve is red
24
Q
What is the Giemsa stain?
A
- For H.pylori
- Other uses eg. toxoplasm
- primarily designed for the demonstration of malarial parasites in blood smears, but it is also employed in histology for routine examination of blood smear
25
What is the Grocott's stain?
- For fungi
| - Highlights fungal walls black
26
What is the Oil Red O stain?
- For fat
| - Can only be used on frozen tissue not processed
27
What is the Orcein stain?
- For copper associated protein
| - Also for elastic fibres and Hep B sAg
28
What is Perl's stain?
- For iron (blue)
| - For ferruginous (asbestos) bodies
29
What is the Ziehl Neelsen stain?
-For mycobacterium
30
How is immunohistochemistry different from tinctorial stains?
- Unlike stains which are not specific it uses antibodies against a specific protein target
- Can provide specific information on protein impression
- Used in diagnosis and prognosis
- Prediction of response to therapy
31
What drug does estrogen/progesterone receptor cancer respond to?
Tamoxifen
32
What drug does HER2 cancer respond to?
Herceptin
33
What is epithelium?
Layer or layers of cells that cover body surfaces or line body cavities
34
What are the features of epithelia?
- Derived from endoderm/mesoderm/ectoderm
- Line almost all body surfaces
- Cellular
- Sits on a tissue layer called the Basal Lamina
- Stuck together tightly
- Polar (apical/basal)
- Avascular (rely on diffusion)
- Regenerative
35
What will ectoderm form?
The epidermal layer of skin
36
What will neural ectoderm form?
The nervous system
37
What will endoderm form?
The lining of the gut, liver and lungs
38
What will mesoderm form?
Muscle, bone, kidneys, blood, gonads and connective tissues
39
Which body surfaces do epithelia NOT line?
- articular cartilage
- tooth enamel
- anterior iris
40
What are the main functions of epithelia?
- Absorption (nutrients)
- Surface movement (cilia in airways/fallopian tubes)
- Secretion (glands)
- Gas exchange (lungs)
- Surface lubrication (mesothelial linings)
- Sensation
- Protection
41
What is a tight junction?
Occuludin/claudin seals to protein movement/paracellular diffusion, apical
42
What is an adherens junction?
Transmembrane proteins connect
43
What is a gap junction?
Small channels (nm wide) allow intercellular ion/small molecule exchange
44
What are desmosomes?
Transmembrane proteins connect to others (linked to intermediate filaments) from adjacent cells
45
What are Hemi-desmosomes/focal adhesion?
Provide attachment to underlying basal lamina
46
What do we use to classify epithelia?
1st - number of layers
2nd - shape of cells at the surface
3d - specialisation/adaptions
47
What are 1 layered epithelia called?
simple
48
What are the shapes cells in simple epithelia can be?
- Squamous (flat)
- Cuboidal
- Columnar
- Pseudo-stratified
49
What do we call multilayered epithelia?
Stratified
50
What are the shapes cells in stratified epithelia can be?
- Squamous (flat)
- Cuboidal
- Columnar
- Transitional
51
What ate the features of pseudo-stratified epithelium and where is it found?
- Single layer of columnar
- Different heights
- Looks like multiple layers
- Found in upper airways - cilia/goblet cells
52
What are the features of transitional epithelia and where are they found?
- Multiple layers
- Changes shape (columnar AND flat)
- Distention
- Found in bladder/urinary tract
53
What are the adaptations epithelia might have?
- Cilia
- Secretory
- Microvilli
- Keratinisation
54
How does epithelium work for protection?
- Prevents dehydration, chemical and mechanical damage
- Covers inter/outer surfaces
- Multi-layered for strength
- Replicative to replace sloughed/damaged cells
- Tight seals between cells
- Specialisations such as keratinisation
55
Where can squamous epithelium be found?
- Oesophagus
- Skin
- Vagina
56
Where can transitional epithelium be found?
- Bladder
| - Urinary tract
57
How is the epithelial lining of the gut adapted to absorption?
- Glucose, ions, water absorbed
- Relies on cell polarity
- Brush border (to increase surface area, hence more absorption)
58
What is the purpose of cilia?
To move in co-ordination to provide unidirectional movement to move mucus/sperm/ova towards their destination
59
Where can cilia be found?
- Airways
- Testis
- Fallopian tubes
60
How is epithelium at sites of gas exchange adapted?
- Single layer of squamous cells
- Line blood vessels
- Minimal distance for gas diffusion
61
What are some possible adaptations of endothelial cells?
- Production of prostacyclin
- Control of vascular cell growth
- Modulate smooth muscle activity
- Trigger blood coagulation
- Regulate traffic of inflammatory cells
62
What is prostacyclin?
- Formed by endothelial cells
- From arachidonic acid catalysed by prostacyclin synthase
- Prevents adhesion of platelets to endothelium and avoids blood clot formation
- Vasodilator
63
How do endothelial cells modulate smooth muscle activity?
- Secrete smooth muscle cell relaxing factors (eg. Nitric Oxide)
- Secrete smooth muscle cell contraction factors (eg. Endothelin 1)
64
How so endothelial cells trigger blood coagulation?
- Release tissue factor that binds factor VIIa to convert factor X into factor Xa and initiate common pathway of blood clotting
- Thrombin acts on fibrinogen to form fibrin monomers
- Fibrin monomers self-aggregate to form a soft fibrin clot cross linked by factor XIII
- Both platelets and fibrin form a hemostatic plug when there is an injury to the wall of a blood vessel
65
How do endothelial cells regulate the traffic of inflammatory cells?
- Facilitate transendothelial migration of cells involved in an inflammatory reaction in the surrounding extravascular tissue.
- Activated macrophages secrete tumor necrosis factor alpha and interleukin-1, which induce the expression of E-selectin by endothelial cells.
66
What is the mesothelium?
- The epithelium that lines the pleurae, peritoneum, and pericardium
- Simple (unilayer) and lines all body cavities
67
How is mesothelium adapted for surface replication?
- Potential spaces contain protein rich fluid
| - Lubrication of surfaces that move against each other specifically
68
What is the ectoderm?
One of the three primary germ layers in the very early embryo. It forms the nervous system and the epithelia of sensory organs
69
What are exocrine glands?
Ducts open onto epithelial surfaces
70
What are endocrine glands?
Glands without ducts secreting into blood stream
71
How are exocrine glands formed?
- Localised proliferation and beginning of the epithelial cell downgrowth into the underlying tissue
- Epithelial downgrowth
- Secretory portion with an excretory duct
72
How is an endocrine gland formed?
- The stalk degenerates
- The secretory portion is surrounded by capillaries
- An endocrine gland develops
73
How so we classify glands?
1st - Look at the DUCT of the gland
| 2nd - Describe the gland
74
What is a gland called if the excretory duct is unbranched?
'simple' gland
75
What is a gland called if the excretory duct sub-divides?
'compound' gland
76
What can the shapes of glands be described as?
- Tubular with coils
- Tubular with branches
- Alveolar/acinar
77
What classification are Intestinal glands of Lieberkuhn?
- Have no excretory duct or with a very short excretory duct
- Gland opens directly onto epithelial surface
- SIMPLE TUBULAR
78
What classification are sweat glands?
- Long excretory duct
- Coiled secretory portion
- SIMPLE TUBULAR COILED
79
What classification are glands of the stomach and uterus?
- Gland is split into two or more branches
- A short excretory duct is present in glands of tongue ad esophagus
- SIMPLE TUBULAR BRANCHED
80
What classification are sebaceous glands of the skin?
- Has an excretory duct
- The terminal secretory portion is divided by partitions into sacs called acini or alveoli
- SIMPLE ALVEOLAR/ACINAR
81
What are the mechanisms of exocrine secretion?
- Merocrine
- Apocrine
- Holocrine
82
What is the mechanism of merocrine secretion?
- 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
83
What is the mechanism of apocrine secretion?
- Protein product in vesicle
- Approaches apical membrane
- Apical membrane pinches off with loss of some apical membrane
84
What is the mechanism of holocrine secretion?
- Secretory product accumulates in cytoplasm
- Cell disintegrates to release product
- Sebum in sebaceous glands
85
Which type of exocrine secretion releases breast milk casein?
Merocrine
86
Which type of exocrine secretion releases breast milk lipids?
Apocrine
87
What is epidermolysis bullosa?
- Blistering skin disorder
- Inherited
- Gene mutation of adhesion molecules that stick the epithelium to the basement membrane
- Abnormal anchoring of epidermis to dermis
- Blisters
88
What is cystic fibrosis?
- Mutations in CFTR gene
- Defective chloride channel on apical surface of epithelial cells
- Lungs but also exocrine glands e.g. pancreas
- Less water in mucous > thickened
- Builds up > cannot expel
- Infection
89
What is congenital ciliary dyskinesia?
-Autosomal recessive
-Abnormal cilia function > secretion accumulation
-“Kartageners syndrome”
(Bronchiectasis, Sinusitis, Situs inversus)
90
What are mesenchymal tissues?
Connective tissues
91
What are the types of mesenchymal tissues?
- General connective tissues
- Blood, blood vessels and lymph
- Bone
- Cartilage and joints
- Fat
- NB muscle
92
Where do mesenchymal tissues originate?
The mesoderm (middle germ layer of the embryo)
93
What is the purpose of connective tissues?
Hold together the human body and support the epithelial structures.
94
What are the purposes of connective tissues?
- Structure
- Metabolic (blood vessels)
- Defense (immune cells)
- Storage (fat)
- Repair (scarring)
95
What are the components of connective tissues?
- Extra-cellular matrix
| - Cells
96
What is the extra-cellular matrix?
- A gel called ground substance
- Through which run fibres
- And percolating tissue fluid
97
What does ground substance contain?
- glycosaminoglycans
- proteins
- glycoproteins
98
What are the types of fibre on connective tissues?
Elastin (stretch)
| Collagen (Structure/strength)
99
What are fibroblasts?
cells which make collagen, elastin, glycosaminoglycans
100
What are adipocytes?
cells which store fat
101
What kind of cells are found in connective tissue?
- fibroblasts
- adipocytes
- immune cells
102
What are the features of Marfan syndrome?
- It is a defect in Fibrillin
- Join flexibility
- Cataracts
- Valvular heart disease
- Aortic dissection
103
What are tissue macrophages/histiocytes?
- Cells which live IN connective tissues
| - Phagocyte debris/pathogens and can form multinucleate giant cells
104
What are mast cells?
- Live in connective tissues
| - Produce vasoactive substances such as histamine in allergy
105
What are leukocytes?
A colourless cell which circulates in the blood and body fluids and is involved in counteracting foreign substances and disease; a white (blood) cell.
106
What are the types of leukocyte?
- Mononuclear leukocytes (do not have lobed nuclei)
| - Granulocytes (Make granules and have lobed nuclei)
107
What is the difference between mononuclear leukocytes and granulocytes?
Mononuclear have a single non-lobed nuclei while granulocytes have a loved nuclei and produce granules
108
What are lymphocytes?
- Dense nuclei, poorly stained cytoplasm
| - Tcells and B cells
109
What are plasma cells?
- Granular nuclei and basophilic cytoplasm
- ‘Clock-faced nuclei'
- Type of B cell
- Antibody production
110
What are granulocytes?
- cytoplasmic granules
| - multilobed nucleus
111
What are the 3 types of granulocyte?
- Basophil
- Neutrophil
- Eosinophil
112
What do neutrophils work against?
Bacteria
113
What do basophils work against?
They act like mast cells!!!
114
What do eosinophils work against?
Parasites/allergens
115
What are the notable features of neutrophils?
Multilobed nucleus
116
What are the features of eosinophils?
- Bilobed nuclei
- Eosinophilic (pink) cytoplasmic granules
- ‘Tomato wearing sunglasses
117
What are the components in blood?
- RBC
- Immune cells (WBC, granulocytes)
- Platelets
- Proteins
- Hormones
- Metabolic waste
- Nutrients
- Gases
- Plasma
118
What are platelets?
Non-nucleated cells arising from megakaryocytes
119
What are the features of a eurythrocyte?
- No nucleus
| - Biconcave shape
120
What are the types of blood vessels?
```
Arteries
Arterioles
Capillaries
Venules
Veins
```
121
What are the layers of a typical blood cell?
Tunica intima - inner lining/endothelium
Tunica media-muscle layer
Tunica adventitia- outer CT network
122
What is the lymph?
lymph nodes filter lymph which returns to the blood at the thoracic duct and right lymphatic duct
123
What are the functions of human bones?
* Movement
* Protection
* Haematopoieis
* Structure
* Calcium homeostasis
124
How is bone made?
•Osteoblasts make osteoid (extracellular matrix)
•This is mineralised (calcium) to make bone
-Woven or lamellar
-Osteoblasts become trapped as osteocytes which maintain the bone
-Osteoclasts resorb bone in response to stress/growth/calcium status
125
What are the two types of bone?
Woven (immature)
| Lamellar (mature - compact or cancellous)
126
What are chondroblasts?
- Chondroblasts make ground substance and collagen fibres (extracellular matrix)
- Chondroblasts become trapped as chondrocytes
127
What are the 3 types of cartilage?
- Hyaline cartilage
- Elastic cartilage
- Fibrocartilage
128
Where is hyaline cartilage found?
Nose
Trachea
Joints
End of nose
129
Where is elastic cartilage found?
Ears
130
Where is fibrocartilage found?
- intervertebral discs
| - pubic symphysis
131
Where are joints found in the body?
* Bone
* Cartilage
* Synovium (synovial joints)
* Ligaments
* Tendons
* Muscles
132
How is a blood film taken?
* A drop of blood is placed on one end of a microscope slide
* Using a cover slip, the blood drop is spread out over the slide in a thin layer (producing effectively a single layer or monolayer of cells)
* Slide is air dried, fixed and stained
* Staining helps to identify the different blood cells (next slides)
133
What are blood films used for?
Diagnosis of haemotological diseases and parasites
134
What colours do cells come out with Romanowsky dyes?
Red blood cells/eosinophil granules stain pink/red
DNA/RNA stain blue/purple
Platelets/other cytoplasmic granules stain blue/purple
135
What is a normal WBC count range?
4.0 – 11.0 x 109/L
136
What is the differential count of neutrophils?
50-70%
137
What is the differential count of lymphocytes?
25-35%
138
What is the differential count of monocytes?
4-6%
139
What is the differential count of eosinophils?
1-3%
140
What is the differential count of basophils?
0-1%
141
What is the function of neutrophils?
- Defence against bacteria and fungi
| - chemotactic and phagocytic/destruction
142
What are the features of neutrophils?
- 12-14mm
- granular cytoplasm
- contain microbicidal agents
- nucleus has 2-5 lobes
- 2.0 to 7.5 x 109/L
- Lifespan 8-10 hours in circulation
- 50-70% of total WBC
143
What is the function of lymphocytes?
- in adaptive immune responses
| - antigen detecting, antibody producing
144
What are the types of lymphocytes?
- T lymphocytes
- B lymphocytes
- NK cells
145
What do T lymphocytes do?
cell mediated immunity
146
What do B lymphocytes do?
humoral immunity
147
What do Natural Killer cells do?
Target virus infected cells and tumour cells
148
What are the features of lymphocytes?
- 6-15 micrometers
- Large round nucleus, very little cytoplasm
- 1.3 to 3.5 x 10^9 per litre
- Long lifespan (years)
- 25-35% of total WBC
149
What is the function of monocytes/macrophages?
- Important in defense against bacteria and fungi
| - Chemotactic, phagocytic/destruction, antigen presenting
150
What are the features of monocytes/macrophages?
- 16-20 micrometers
- Granular cytoplasm contains vacuoles
- Nucleus has characteristic kidney shape
- 0.2 to 0.8 x 10^9 per litre
- Circulate for 1/3 days
- Tissue macrophage long lifespan
- Monocytes 4-6% of total WBC
151
What is the function of basophils?
- Defend against parasitic infection
| - Contribute to hypersensitivity reactions – bind IgE
152
What are the features of basophils?
- 14-16 mm
- Highly granular, dark staining cytoplasm, obscures nucleus, -Contain histamine, serotonin, prostaglandins
- Bi-or tri-lobed nucleus
- 0.02 to 0.1 x 109/L
- Lifespan ~1-5 days
- 0-1% of WBC
153
What is the function of eosinophils?
- Defend against parasitic (helminth/worm) infestations
| - Counteract hypersensitivity reactions - histaminase
154
What are the features of eosinophils?
- 12-17 mm
- Granular cytoplasm takes up eosin (characteristic pink/red colour)
- Usually bi-lobed nucleus
- 0.02 to 0.44 x 109/L
- Circulate for 4-5 hours
- Migrate into tissues
- Lifespan 8-12 days
- 1-3% of WBCs
155
What is the function of platelets?
Prevention of blood loss - primary haemostasis
156
What are the features of blood platelets?
- 1.5-3.5 mm
- No nucleus
- Cell fragments derived from megakaryocytes
- Contain secretory granules
- 150 to 400 x 109/L
- Lifespan 5-20 days
157
What is the function of RBCs?
Main function to transport O2 and CO2 - haemoglobin
158
What are the features of RBCs?
- 6.7-7.7 mm
- Flexible, biconcave disc shaped cells
- Maximum surface area for gas exchange
- No nucleus or other internal organelles
- 3.9 to 6.5 x 1012 cells/L
- Lifespan ~120 days
- ~45% of blood volume (haematocrit)
