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Medicine phase 1 > Week 1 - Cells and Tissue > Flashcards

Week 1 - Cells and Tissue Flashcards

1
Q

3 types of integral plasma membrane proteins

A

pumps, carriers and channels

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2
Q

site of protein synthesis

A

rough ER

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3
Q

smooth ER function

A

lipid synthesis and calcium storage

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4
Q

function of Golgi apparatus

A

where proteins are sent for further modifications after coming from ER

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5
Q

post translational modification process

A

proteins are carried in vesicles which fuse to become the cis cisterns and then move though the stacks - as they do they undergo enzymatic modification which labels them for specific cell destination

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6
Q

endosome function

A

vesicles from plasma membrane which fuse with lysosomes to deliver their contents

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7
Q

describe peroxisomes

A

small vesicle containing oxidases and catalase
is involved in a number of oxidative reactions such as biosynthesis of bile acids, fatty acid metabolism and detoxification

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8
Q

describe a lysosome

A

a vesicle with an impermeable membrane that contains hydrolytic enzymes - used to degrade unwanted molecules

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9
Q

cause of tay-sachs disease

A

build up of lipid storage and neuronal bodies resulting in neurological regression, seizures and blindness

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10
Q

functions of the cytoskeleton

A

organise cell structure and maintain shape of cell
helps cells resist mechanical stress by providing mechanical linkages that let the cell/tissue bear stress
transports intracellular cargo
facilitates movement of organelles and other procedures such as cell division, growth, motility

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11
Q

three types of cytoskeleton filaments and their components

A

microtubules - tubular (dynein, kinesin)
intermediate filaments - keratin, lamina, vimentin, desmin
microfilaments - actin (myosin)
microbes and microfilaments have molecular motor proteins

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12
Q

uses of microfilaments (Actin)

A

cell projections - microvilli stereocilia
cytoplasm - cell contraction, shape change
membrane extensions - cell motility
contractile ring - cytokinesis

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13
Q

describe how an intermediate filaments structure relates to its function

A

filaments are composed of smaller subunits that are twisted into strong, rope-like structures - have high tensile strength
found in cells that require a lot of strength such as epithelial cells

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14
Q

what are keratins

A

a family of intermediate filaments that are present in keratinocytes of the epidermis

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15
Q

what are lamins

A

intermediate filaments that regulate chromatin organisation and other processes
nuclear lamins support nuclear shape and stability

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16
Q

what are microtubules

A

highly dynamic cylindrical tubes that continuously grow and shrink, pushing and pulling associated structures
responsible for movement of vesicles and organelles around the cell
important role in cell division (as a component of the mitotic spindle that attaches to chromosomes and segregates chromosome pairs into daughter cells)

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17
Q

what is the centrosome

A

a major microtubule organising centre located near nucleus and it imitates microtubule growth towards the periphery

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18
Q

what is an axoneme

A

axonemes are types of microtubules

a component of the cilia and flagella - helps to bend the structure

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19
Q

cause of kartagener’s syndrome

A

defects in the cilia and flagella are associated with this disease as a result of mutations in the dynein motor protein
patients will suffer from recurrent respiratory infections and males suffer from infertility

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20
Q

what are cell junctions

A

transmembrane protein complexes that interact with similar proteins on adjacent cells
links the cells and their cytoskeletons

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21
Q

functions of tight junctions

A

junction creates a seal preventing diffusion of molecules between adjacent cells - creating a barrier for epithelial cells
also creates a barrier within epithelial cell membranes which prevents mixing of membrane proteins - creates two distinct membranes: apical and basolateral membranes

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22
Q

function of gap junctions

A

provide a route for intercellular movement of small molecules

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23
Q

describe gap junctions

A

intracellular channels that connect the cytoplasm of adjacent cells
made up for connexions which are a large family of proteins

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24
Q

function of an adherens junction

A

joins cells together

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25
Q

function of a desmosome in skin

A

provides integrity of epidermis - between keratinocytes

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26
Q

function of hemidesmosomes in skin

A

holds epidermis to dermis (at demo-epidermal junction)

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27
Q

function of focal adhesions

A

connects cells to the underlying extra cellular matrix

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28
Q

function of an adherens junction in skin

A

joins epithelial cells together

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29
Q

which cells do not have mitochondria

A

RBCs

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30
Q

how does the structure of a muscle cell allow it to have extensive calcium storage

A

they contain a specialised ER called a sarcoplasmic reticulum

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31
Q

how does a plasma cells structure relate to its function

A

function is to produce immunoglobulin and so they have an extensive rough ER

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32
Q

consequence of defective mitochondria

A

mitochondrial cytopathies - defects in oxidative phosphorylation

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33
Q

consequence of defective lysosomes

A

tay-sachs disease - lysosomal storage disorder - destroy neurons

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34
Q

consequence of defective microtubules

A

kartagener syndrome - mutation in dynein motor protein - immotile cilia

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35
Q

consequence of defective gap junctions

A

recessive mutation in Cx26 leads to sensorineural hearing loss

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36
Q

consequence of defective IFs/hemidesmosomes

A

lack of integrity at demo-epidermal junction - epidermolysis bullosa simplex

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37
Q

two strategies for segregating two separate intracellular processes

A

multicomponent complexes eg. ribosome or proteasome

compartmentalisation in membrane bound organelles separates reactions

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38
Q

how do hydrophilic proteins get across the hydrophobic membrane

A

nuclear pores - for going to nucleus
via membrane translocator - for proteins living form cytosol; to ER, mitochondria or peroxisomes
transport vesicles - gone to ER then going somewhere else

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39
Q

how do proteins know where to go

A

through a signal sequence which is a short amino acid sequence attached at N terminal - usually removed once protein reaches its destination

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40
Q

protein sorting process

A

signal recognition particle attaches to the translated ribosomes and guides it towards a SRP receptor in ER membrane - once attached, protein can enter through transcolon - signal peptidase cleaves off the signal sequence - transport vesicles bud from ER and take protein to Golgi where they undergo enzymatic modification which labels them for a specific location

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41
Q

why are ribosomes the main antibiotic targets of a bacterial cell

A

bacteria have different sized ribosomes to humans

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42
Q

two pathways for the transport vesicles after they’ve budded from Golgi apparatus

A

protein will either end up in the plasma membrane or will be packaged into a lysosome

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43
Q

process of proteins going to lysosome

A

address label for lysosomal is mannose-6- phospate (M6P). Proteins labelled with M6P bind to a specific receptor in the golgi membrane before budding off as an endosome. The endosome matures to become a lysosome. An example of a protein targeted in this way is the enzyme hrydolase

44
Q

process of proteins going to plasma membrane

A

the C terminus of the protein has a ‘stop translocation’ code which tells it to remain anchored to the ER membrane. Vesicles from the ER then fuse with the plasma membrane

45
Q

when do proteins stay in the cytosol

A

if there is no signal peptide it will stay in cytosol

46
Q

process of proteins going to nucleus

A

nuclear localisation signal in their protein sequence

importin receptor and nuclear pore are the equivalent go SRP receptor and ER pore

47
Q

enzyme that is responsible for protein degradation

A

proteases

48
Q

how to proteases degrade proteins

A

they hydrolyse the peptide bonds between amino acids

49
Q

two methods of protein degradation

A

lysosomal degradation and proteosomal

50
Q

when is lysosomal degradation used

A

to degrade proteins with a long half life (autophagy)
can be extracellular proteins brought in via receptor-mediated endocytosis or membrane proteins brought in by endocytosis
also for pathogenic proteins brought into cell via phagocytosis

51
Q

when is proteosomal degradation used

A

for proteins with a short half life and need to be removed quickly from the cytosol

52
Q

process of proteosomal degradation

A

Each end of the protein contains a protein stopper which bind to proteins destined for degradation and then, using ATP hydrolysis, they feed the proteins into the inner chamber of the cylinder

53
Q

how do proteosomes know which protein to degrade

A

due to the covalent attachment of a protein called ubiquitin
ubiquitylated proteins are recognised and sucked into the proteasome by the protein stopper where they are unfolded and translocated

54
Q

functions of skin

A

protection from mechanical impacts, internal or external pressure, stretching in response to movement, variations in temp, microorganisms, radiation
physiological function - regulates body temp, fluid balance, synthesis of vitamin D
sensation - network of nerve cells that detect and relay changes in environment

55
Q

major layers of skin

A

epidermis, dermis and subcutis/hypodermis

56
Q

layers of the epidermis

A

outer layer is stratum corneum, then stratum granulosum, stratum spinosum, stratum basale and basement membrane
extra layer called stratum lucidum found only in thick skin

57
Q

describe the stratum basale layer

A

mitotically active and contains stem cells that are responsible for populating all layers of epidermis
attached to the basement membrane by hemidesmosomes
lies adjacent to the dermoepidermal junction which separates the dermis and epidermis
merkel cells found in this layer which are involved in sensation

58
Q

structure of the stratum spinosum layer

A

made up of several layers of keratinocytes held together by desmosomes

59
Q

describe the granulosum layer

A

cells contain keratohyalin granules which contain molecules that are important for aggregating keratin filaments

60
Q

describe the stratum corneum

A

outer layer
varies in thickness
flattened dead cells have lost their nuclei here and are filled with bundled keratin
lipids between cells provide a water barrier

61
Q

process of skin regeneration (not in wound healing)

A

as keratinocytes in the stratum basale divide and mature, they progress towards the skin surface – in the next layer where they form the stratum spinosum, desmosomes begin to appear on the cells – these cells begin to flatten and they lose their nuclei and cytoplasm acquires a granular appearance – when the cells reach the outermost layer they are no longer viable

62
Q

components of the dermis

A

fibroblasts, collagen type one, elastin, ground substance, blood vessels, nerves

63
Q

two layers of the dermis

A

papillary layer and lower reticular layer

64
Q

difference between two dermis layers

A

superficial papillary layer of the dermis is loose and contains very fine interlacing collagen fibres - this is where most blood vessels are found
In the lower reticular layer, the collagen bundles are much stronger, and elastin fibres are much larger
blood vessels more concentrated in papillary layer

65
Q

what separates the dermis and epidermis

A

demo-epidermal junction

66
Q

functions of demo-epidermal junction

A

provides a regulated barrier both for movement of molecules from the epidermis to the dermis and in the opposite direction
provides a site of attachment for the epidermis through hemidesmosomes
it aligns cells of the epidermis
serves a base for re-epithelialisation in wound healing

67
Q

what is the subcutis composed of

A

adipose tissue

68
Q

functions of subcutis

A

provides an energy source
insulation
acts as a shock absorber

69
Q

which skin layer(s) are nerves located in

A

most free nerve endings end in the dermis but others extend into epidermis where they attach with Merkel cells

70
Q

the glands found in skin and their function

A

eccrine glands - excrete sweat
apocrine glands - restricted to the axillae and genital area - produce a scent
sebaceous glands - produce sebum which lubricates skin and hair shaft to protect against friction and make it more impervious to moisture

71
Q

function of langerhans cells

A

antigen presenting - plays a role in immunosurveillance
its cytoplasmic processes support its role to detect foreign antigens in epidermis
type of dendritic cell

72
Q

what are Merkel cells

A

found in basal layer

involved in sensation

73
Q

function of a melanocyte

A

synthesises melanin in melanosomes which are then transferred into neighbouring keratinocytes - melanosomes within a keratinocyte then form cap over the nucleus – protecting DNA from UV

74
Q

where does vitamin d synthesis take place

A

initiated in the plasma membrane of basal and suprabasal keratinocytes

75
Q

function and location of profilaggrin

A

found in keratohyalin granules

converted to filaggrin which aggregates keratin filaments into tight bundles

76
Q

function and location of involucrin

A

formation of a cell envelope around cells in the stratum corneum
located in keratohyalin granules

77
Q

function and location of loricrin

A

found in keratohyalin granules

cross links to involucrin

78
Q

where are polysaccharides, glycoproteins and lipids found in the epidermis

A

lamellar granules

79
Q

function of fibroblasts in the dermis

A

principle cell of connective tissue and are responsible for producing collagen, elastin and most components on connective tissue
important role in sending and receiving signals from other molecules
also have a role in wound healing

80
Q

damage caused by abrasions, erosions or ulcerations of skin

A

only damage is to the epidermis

81
Q

what does a partial thickness wound damage

A

structures in the epidermis and parts of the dermis

82
Q

what does a full thickness wound damage

A

removes epidermis, dermis and deeper structures

83
Q

3 phases of repairing damaged skin

A

inflammation
proliferation
remodelling

84
Q

what happens in the inflammation phase of wound healing

A

partial or full thickness would will result in a blood clot

inflammatory cells recruited to the area

85
Q

proliferation phase of would healing

A

re-epithelialisation occurs
In deeper wounds, epithelium covers the clot, fibroblasts are recruited to replace lost molecules - they produce collagen type 3 to form granulation tissue and endothelial cells proliferate to repair and form new blood vessels

86
Q

remodelling phase of wound healing

A

granulation tissue gets replaced by collagen type one (its stronger and organised into big bundles)
some fibroblasts differentiate into myo-fibroblasts which generate contractile force to close the wound
remaining granulation tissue matures into connective scar tissue with very few cells present

87
Q

function of epidermal growth factor (EGF)

A

signals to cells about re-epithelialisation

88
Q

local factors affecting wound healing

A

infection, foreign body, oxygenation, vascular supply

89
Q

systemic factors of wound healing

A

age, disease, alcohol, smoking, immunocompromised conditions, obesity, medications

90
Q

tissue definition

A

groups of similar cells working together to carry out a common function

91
Q

types of tissue and their functions

A

Connective tissue – protects and supports eg. Fat
Epithelial tissue – covers body surfaces eg. Skin
Muscle tissue – cells contract to generate force
Nervous tissue – generate electrical signals in response to environment

92
Q

organ definition

A

made up of several tissue types compromised in a morphologically recognisable structure

93
Q

metastasis

A

the spread of disease-producing agency (eg. Cancer cells) from the initial or primary site of disease to another part of the body

94
Q

steps of tissue processing

A

fixation - freezing or chemical fixation using aldehyde based chemical - preserves the tissue
embedding - provides support for the tissue when sectioning, can use paraffin wax or a water based alternative
sectioning - cutting into very thin slices using a microtome
staining - to colour cells and ECM so they’re visible with microscope

95
Q

what colour would a basic dye stain cells

A

purple/blue - stains acidic structures

96
Q

what colour would a acidic dye stain cells

A

red/pink

97
Q

two types of epithelia

A

covering epithelia which lines body surfaces

glandular epithelia which is secretory epithelium arranged into glands

98
Q

simple epithelia

A

single layer, good for absorption/secretion

99
Q

stratified epithelia

A

2 or more layers of cells, good for protection

100
Q

pseudostratified epithelia

A

one layer with mixture of cell shapes

101
Q

four shapes of epithelial cells

A

squamous - flat shaped
cuboidal - cube shaped
columnar - tall cylindrical shaped
transitional - readily change shape, accommodates stretching

102
Q

function and location of simple squamous epithelium

A

mainly diffusion, filtration, some secretion, absorption
little barrier/protection against friction
found in the lining of blood vessels, the heart, alveoli, lining of serous membranes of the body cavities, lining of some kidney tubules

103
Q

function and location of simple cuboidal epithelium

A

diffusion, secretion and absorption

found in kidney tubules, glands and their ducts, lining of terminal bronchioles of lungs, surfaces of ovaries

104
Q

function and location of simple columnar epithelium

A

movement of substances, absorption and secretion, offers more protection than flatter cells
found in glands and some ducts, bronchioles of lungs, auditory tubes, uterus, uterine tubes, stomach, intestines, gallbladder, bile ducts, ventricles of brain

105
Q

function and location of stratified squamous epithelium

A

protection against abrasion, barrier against infection, reduction of water loss from body
when keratinised its found in skin
nonkeratinised is found in mouth, throat, anus, vagina, larynx, inferior urethra, cornea , esophagus

106
Q

describe pseudostratified epithelium

A

structure - technically single layer, some cells reach the free surface others dont
nuclei at different levels so appears stratified
function - synthesise and secrete mucus and moves mucus that contains foreign particles over the surface
location - lining of nasal cavity, nasal sinuses, auditory tubes, pharynx, trachea, bronchi of lungs

107
Q

describe transitional epithelium

A 
structure - cuboidal/columnar when not stretched and squamous/flattened when stretched - number of layers from 5/6 to 2/3 when stretched
function - accommodate fluctuations in the volume of fluid in organs or tubes and protects against caustic effects of urine
location - lining of urinary bladder, ureters,superior urethra, pelvis of kidney

Medicine phase 1 (14 decks)

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