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MCD > Tissues 1 > Flashcards

Tissues 1 Flashcards

1
Q

Describe a typical nucleus

A

Contains cell DNA
Double lipid membrane + pores
Nucleolus (sometimes more than 1) where large ribosome subunits are synthesised from rRNA

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2
Q

What is nuclear lamina

A

Specialised cytoskeleton on the internal surface which control (dis)assembly of the nuclear envelope during division

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3
Q

Describe a ribosome

A

2 subunits (rRNA and protein)

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4
Q

Describe the endoplasmic reticulum

A

Nuclear envelope continuous with the ER
Flattened sacs (cisternae)
RER = +ribosomes
SER = tubular (lipid synthesis + calcium storage)

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5
Q

Describe the golgi apparatus

A

Flattened membrane sacs
Vesicles bud off
Cis face (towards ER) and trans face (Towards membrane)

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6
Q

Describe the mitohondria

A

Site of ATP synthesis
Double membrane with folds into Cristae
High numbers = high metabolic activity

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7
Q

Describe peroxisomes

A

Important in oxidative pathways
Single membrane + contain enzymes involved in lipid metabolism
Eukaryotic cells
Enzymes = high conc. = crystallise into dorm cores
Peroxide produced as a by-product

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8
Q

What are the three main types of cytoskeleton

A

Microtubules, intermediate filaments and microfilaments

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9
Q

What is the size of microtubules

A

20nm

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10
Q

What is the size of intermediate filaments

A

10-15nm

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11
Q

What is the size of microfilaments

A

5-9nm

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12
Q

What are microtubules a polymer of

A

alpha and beta tubules heterodimers

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13
Q

What is the function of microtubules

A

cell shape and tracks for movement of organelles and cellular components

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14
Q

What are microtubules a major component of

A

cilia and flagellae
cilia = 9 MT doublets and 2 central MT
mitotic spindle

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15
Q

What type of intermediate filaments do the following cells have: epithelia, mesenchymal, neurones. muscle cells

A

Epithelia - cytokeratins
Mesenchymal - vimentin
Neurones - neurofilament protein
muscle cells - desmin

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16
Q

What is the function of intermediate filaments

A

Mechanical strength

Desmosome cell-cell adhesions are connected by IFs

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17
Q

What are microfilaments a polymer of

A

actin

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18
Q

What do microfilaments associate with

A

adhesion belts in epithelia

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19
Q

What is the functions of microfilaments

A

cell shape and movement

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20
Q

Give an example of an accessory protein to microfilaments

A

myosin

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21
Q

What are the 5 main cell groups

A 
Connective tissue cells
Contractive muscle
Haematopoietic cells
Neural cells
Epithelial cells
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22
Q

What are tissues made up of

A

Cells, extracellular matrix and fluid

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23
Q

What is the name of the cancers in the following tissues: epithelial, mesenchymal, haematopoietic, neural

A

Epithelial - carcinoma
Mesenchymal - Sarcomas
Haematopoietic - Leukaemias (marrow) or lymphomas (lymphocytes)
Neural - neurblastomas (neurones) or gliomas (glial)

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24
Q

What is the ECM

A

Material deposited by cells to form the insoluble part of the extracellular environment. Fibrillar proteins embedded in a hydrated gel

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25
Q

What is the function of cell-cell junctions

A

Formation and maintenance of epithelia

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26
Q

What are the 2 forms of cell-cell junctions

A

Zonula (belts) or maculae (spots)

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27
Q

Describe cell-cell junctions in epithelia

A

Arranged as an apical junction complex

Tight junctions, adhesion belts and desmosomes

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28
Q

Describe zonula occludens

A

Tight junction - points on adjacent membranes
more networks = more seals
Blocks paracellular pathways
Prevents ion diffusion (polarity)

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29
Q

Describe zonula adherens

A

forms before others
closely associated to actin cytoskeleton
cadherins bind to similar molecules on adjacent cells

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30
Q

Describe desmosomes

A 
Macula Adherens
Cluster of pores formed my membrane protein
Allows passage of ions/small molecules
Cadherin-like
Associated with intermediate filaments
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31
Q

What are the epithelial classifications

A

Shape and layering

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32
Q

Describe simple squamous epithelia

A

Single layer of cells with a flattened plate shape
Exchange
Alveoli, mesothelium, vessel endothelium

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33
Q

Describe simple cuboidal epithelia

A

Single layer of cells with a cube shape (irregular)

Lining of the kidney collecting duct and other ducts

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34
Q

Describe simple columnar epithelia

A

Single layer of cells that are pillar-shaped.

Enterocytes (absorptive intestinal) and absorptive and secretory epithelia

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35
Q

Describe stratified squamous epithelia

A

Multiple layers of cells with a flattened plate shape

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36
Q

Describe the two types of squamous epithelia

A

Keratinising - upper layer is dry due to hardening and death (epidermis)
Non-keratnising - upper surface is wet, cells are alive (mouth, oesophagus, anus, cervix, vagina)

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37
Q

Describe pseudo stratified epithelia

A

“Falsely stratified”
Multiple layers of nuclei and surface cells have contact with the basal membrane
Airway epithelium, ducts, urinary and reproductive tracts

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38
Q

Why is polarity of cells important

A

Produces directionality so that functions are unidirectional e.g. secretion, transport, absorption

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39
Q

How is activity restricted to only some parts in transporting epithelia

A

ion pumps and channels are distributed unevenly

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40
Q

What is the difference between paracellular and transcellular

A 
para = between
trans = through
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41
Q

What are kiss points

A

Focal connections

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42
Q

Give an example of transporting epithelia

A

Mitochondrial membrane

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43
Q

Give an example of absorptive epithelia

A

Intestinal epithelium (enterocytes)

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44
Q

What are the two types of secretory epithelia and give examples

A

Exocrine (apical surface to duct or lumen) - goblet cells, acinar cells
Endocrine (apical surface to bloodstream) - islets of langerhans

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45
Q

What can secretion be classified into

A

Constitutive - secretory vesicles move directly to the plasma membrane
Stimulated - secretory vesicles are stored in the cytoplasm and fuse on stimulation

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46
Q

Give examples of the constitutive and stimulated secretory pathways

A

Constitutive - plasma protein production in hepatocytes

Stimulated - release of adrenaline from the adrenal medulla

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47
Q

Why do protective epithelia usually form thick layers

A

Protect underlying tissue from physical and chemical insults (heat, cold solvents, abrasion etc.)

48
Q

Which cells are replaced every 3-10 days

A

Gut lining

49
Q

Which cells are replaced every 8-10 days

A

Heart muscle, fat tissue, bone

50
Q

What is the turnover rate of the epidermis

A

48 days

51
Q

Give an example of changes in steady turnover rate

A

cyclic production and loss of the endometrial epithelial lining of the uterus in the menstrual cycle
Increase in no. and size of epithelial glands in the breast

52
Q

Describe the turnover in intestinal villi

A

Cells migrate up the villus as cells are constantly lost from the tip. New cells are constantly produced by the crypt stem cells

53
Q

Describe turnover in the epidermis

A

Surface cells are constantly lost, but constantly replaced by new cells formed at the basal layer
As cells migrate up they flatten and keratinise

54
Q

How does pressure affect turnover in the epidermis

A

Increases the rate of proliferation of stem cells and the loss of cells decreases

55
Q

What does the ECM comprise of

A

Proteins and carbohydrates

56
Q

What are the functions of ECM

A

Physical support
Mechanical and physiochemical properties of the tissue
Influence growth, adhesion and differentiation status
Development, tissue function and organogenesis

57
Q

What are the components of ECM

A

Collagens - I, II, III, IV
Multi-adhesive glycoproteins - fibronectin, fibrinogen, laminins
Proteoglycans - aggrecan, version, decor, perlecan

58
Q

What proportion of protein mass does collagen make up

A

25%

59
Q

Give an example of how alignment of collagen relate to function

A

in skin, successive layers arrange at right angles to allow resistance to tensile force in all directions

60
Q

How many types of collagen are there in humans

A

28 types with 42 genes

61
Q

Describe the structure of collagen

A

3 𝛼 chains in a triple helix

Every 3rd amino acid is a glycine that occupies the interior as it is the only AA small enough

62
Q

Describe the biosynthesis of collagen

A
  1. Synthesis on the RER
  2. Ribosomes synthesise collagen polypeptides
  3. Hydroxylation with lysine and proline
  4. Glycosilation
  5. 3 chains form the helix
  6. Release from the cell via a vesicle
63
Q

What is the purpose of lysine and proline hydroxylation

A

interchain H-bond formation

64
Q

When is lysine and proline modified

A

Synthesis of collagen and in formation of cross-linkages after secretion

65
Q

What is the function of cross-linkages

A

Tensile strength and stability

66
Q

Describe type IV collagen

A

network-forming collagen
Present in all basement membranes
assembles into a sheet-like network

67
Q

Describe elastin

A

Important for elasticity e.g. skin, blood vessels, lungs

Core of elastin and surface microfibrils rich in fibrillin

68
Q

Why are collagen and elastic fibres interwoven

A

Limit the extent of stretching

69
Q

Give an example of a disorder relating to elastin

A

Marfan’s

Elastic fibres cannot function due to mutations in fibrillar 1

70
Q

What is a basement membrane

A

Flexible, thin mat of ECM underlying epithelial sheets and tubes.
Muscle, nerve, fat/

71
Q

Give an example of a disorder relating to the basement membrane

A

Alport syndrome
Mutations n gene for type IV collagen
Basal membrane is split and laminated - filtration issues and loss of kidney function

72
Q

Describe the structure of the basement membrane

A

Glycoprotein network associated with cells

Constituents - collagen IV and laminins

73
Q

Describe the structure of multi-adhesive glycoproteins

A

Large and modular

Multifunctionality due to multiple binding sites for matrix components and receptors

74
Q

Describe the structure of laminins

A 
𝛼 chain, β chain, 𝛾 chain
Very large (160-400 AA) and multi-adhesive
75
Q

What is the function of laminins

A

Interacts with receptors such as integrins and dystroglycan

Self-associate with the basement membrane and other components (type IV collagen, proteoglycans)

76
Q

Give an example of a condition associated with laminins

A

Congenital muscular dystrophy
or
Epidermolysis bullose

77
Q

What occurs in congenital muscular dystrophy

A 
Absence of 𝛼2 in laminin 2
Symptoms evident from birth
Hypotonia 
Weakness
Deformities of joints
78
Q

Describe fibronectin

A

A family of major connective tissue glycoproteins
Insoluble fibrillar matrices or soluble plasma protein
Derived from one gene where different forms arise from splicing or mRNA

79
Q

Describe the structure of fibronectin

A 
Multi-adhesive
Large multi domain molecule
open hairpin shape/horeshoe 
Collagen, integrin and heparin binding sites 
50nm
80
Q

What is the function of fibronectin

A

Regulating cell adhesion and migration in embryogenesis and tissue repair
wound healing
continuum with actin

81
Q

What is a proteoglycan

A

Core protein with one or more glycosaminoglycan chains covalently attached

82
Q

What is a glycosaminoglycan chain

A

GAGs are long, unbranched sugars of repeating disaccharides

83
Q

Which property of GAGs contribute to function

A

Large volume to mass ratio and the hydrated gel can be very resistant to compression

84
Q

Give an example of a glycosaminoglycan chain

A

Perlecan
Aggrecan
Decorin
Syndecans

85
Q

Describe the structure of a GAG

A

1 of the 2 sugars is always amino sugar

sulphated or carboxylate -> highly -ve

86
Q

Describe hyaluronan

A

Long repeated disaccharide with NO core protein
Unsulphated
Synthesised at the cell surface

87
Q

Describe decorin

A

Small proteoglycan

Binds to collagen, essential for fibre formation

88
Q

What is the cartilage matrix composed of

A

Type II collagen fibrils embedded in a network of proteoglycans

89
Q

Describe hyaline cartilage

A

Abundant type of cartilage found in many places

Cushions ends of long bones

90
Q

What is hyaline cartilage rich in

A

Aggrecan

91
Q

Describe the structure of aggrecan

A 
GAGs are highly sulphated and present in a no. of carboxyl groups
-ve charge (sodium attracted)
Feather like structure 
Chondroitin sulfate attachment largest
Keratan sulfate attachment
Hyaluronan binding region
92
Q

What is the function of aggrecan and how is structure related

A

Resistance of compressive forces

-ve charge helps retain water which is lost when compressed but then regained

93
Q

Give an example of a disease related to proteoglycans

A

osteoarthritis (aggrecan)

94
Q

Describe osteoarthritis

A

excessive loss of ECM so cushioning properties are lost

Cleavage of aggrecan by aggrecanase and metalloproteinase - loss to the synovial fluid

95
Q

Give an example of a fibrotic disorder

A

Liver cirrhosis

Excessive production of fibrous connective tissue

96
Q

What is the proportion of water in human adults

A 
female = 55%
male = 60%
97
Q

What are the proportions of extracellular and intracellular fluids

A 
intra = 55%
extra = 45%
98
Q

How much of fluids does blood plasma make up

A

7%

99
Q

How much of fluids does interstitial fluid make up

A

36%

100
Q

What are the main cation and anions extracellularly

A

sodium and chloride (+calcium)

101
Q

What are the main cation and anions intracellularly

A

Potassium and phosphate

102
Q

Is there more protein extracellularly or intracellularly

A

intracellularly

103
Q

Define diffusion

A

Spontaneous movement of solute down its concentration gradients until equilibrium is reached

104
Q

Define osmosis

A

Movement of water down its own concentration gradient toward the area of higher osmolarity

105
Q

Define osmolarity

A

Osmolarity is a measure of the concentration of all solute particles in a solution

106
Q

What is the osmolarity of CaCl2

A

3

107
Q

Define tonicity

A

The strength of a solution that takes into account cell permeability

108
Q

What makes up the university of Wisconsin solution

A

No sodium or chloride to prevent influx and swelling

extracellular impermeant solutes e.g. raffinose

109
Q

How do the following pass through the capillary wall: plasma proteins, lipid-soluble substances, small water-soluble substances, exchangeable proteins

A

plasma proteins = cannot cross
lipid-soluble substances = through the endothelium
small water-soluble substances = pores
Exchangeable proteins = vesicular transport

110
Q

What is solute and fluid movement across a vessel wall determined by

A

balance between osmotic pressure (plasma proteins) and hydrostatic pressure (blood)

111
Q

What is the name given to osmotic pressure due to plasma membranes

A

colloid osmotic pressure

112
Q

When does oedema occur

A

Leakage of plasma into the interstitial exceeds the capacity of the lympahtcis to collect and return it to the circulation so fluid accumulates

113
Q

Give an example of inflammatory oedema

A

insect bite causes vessels to become leaky

114
Q

How does hydrostatic oedema occur

A

high blood pressure

115
Q

How may breast cancer treatment cause oedema

A

Survivors are likely to have the axillary lymph nodes removed which removes the pathway of drainage

116
Q

Give an example of a disease that associated with oedema

A

Elephantiasis as parasitic worms block the lymph vessels to prevent lymphatic drainage

MCD (13 decks)

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