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

Week 1 - Cells and Tissue Flashcards

(107 cards)

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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
function of a desmosome in skin
provides integrity of epidermis - between keratinocytes
26
function of hemidesmosomes in skin
holds epidermis to dermis (at demo-epidermal junction)
27
function of focal adhesions
connects cells to the underlying extra cellular matrix
28
function of an adherens junction in skin
joins epithelial cells together
29
which cells do not have mitochondria
RBCs
30
how does the structure of a muscle cell allow it to have extensive calcium storage
they contain a specialised ER called a sarcoplasmic reticulum
31
how does a plasma cells structure relate to its function
function is to produce immunoglobulin and so they have an extensive rough ER
32
consequence of defective mitochondria
mitochondrial cytopathies - defects in oxidative phosphorylation
33
consequence of defective lysosomes
tay-sachs disease - lysosomal storage disorder - destroy neurons
34
consequence of defective microtubules
kartagener syndrome - mutation in dynein motor protein - immotile cilia
35
consequence of defective gap junctions
recessive mutation in Cx26 leads to sensorineural hearing loss
36
consequence of defective IFs/hemidesmosomes
lack of integrity at demo-epidermal junction - epidermolysis bullosa simplex
37
two strategies for segregating two separate intracellular processes
multicomponent complexes eg. ribosome or proteasome | compartmentalisation in membrane bound organelles separates reactions
38
how do hydrophilic proteins get across the hydrophobic membrane
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
39
how do proteins know where to go
through a signal sequence which is a short amino acid sequence attached at N terminal - usually removed once protein reaches its destination
40
protein sorting process
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
41
why are ribosomes the main antibiotic targets of a bacterial cell
bacteria have different sized ribosomes to humans
42
two pathways for the transport vesicles after they've budded from Golgi apparatus
protein will either end up in the plasma membrane or will be packaged into a lysosome
43
process of proteins going to lysosome
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
process of proteins going to plasma membrane
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
when do proteins stay in the cytosol
if there is no signal peptide it will stay in cytosol
46
process of proteins going to nucleus
nuclear localisation signal in their protein sequence | importin receptor and nuclear pore are the equivalent go SRP receptor and ER pore
47
enzyme that is responsible for protein degradation
proteases
48
how to proteases degrade proteins
they hydrolyse the peptide bonds between amino acids
49
two methods of protein degradation
lysosomal degradation and proteosomal
50
when is lysosomal degradation used
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
when is proteosomal degradation used
for proteins with a short half life and need to be removed quickly from the cytosol
52
process of proteosomal degradation
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
how do proteosomes know which protein to degrade
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
functions of skin
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
major layers of skin
epidermis, dermis and subcutis/hypodermis
56
layers of the epidermis
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
describe the stratum basale layer
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
structure of the stratum spinosum layer
made up of several layers of keratinocytes held together by desmosomes
59
describe the granulosum layer
cells contain keratohyalin granules which contain molecules that are important for aggregating keratin filaments
60
describe the stratum corneum
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
process of skin regeneration (not in wound healing)
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
components of the dermis
fibroblasts, collagen type one, elastin, ground substance, blood vessels, nerves
63
two layers of the dermis
papillary layer and lower reticular layer
64
difference between two dermis layers
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
what separates the dermis and epidermis
demo-epidermal junction
66
functions of demo-epidermal junction
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
what is the subcutis composed of
adipose tissue
68
functions of subcutis
provides an energy source insulation acts as a shock absorber
69
which skin layer(s) are nerves located in
most free nerve endings end in the dermis but others extend into epidermis where they attach with Merkel cells
70
the glands found in skin and their function
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
function of langerhans cells
antigen presenting - plays a role in immunosurveillance its cytoplasmic processes support its role to detect foreign antigens in epidermis type of dendritic cell
72
what are Merkel cells
found in basal layer | involved in sensation
73
function of a melanocyte
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
where does vitamin d synthesis take place
initiated in the plasma membrane of basal and suprabasal keratinocytes
75
function and location of profilaggrin
found in keratohyalin granules | converted to filaggrin which aggregates keratin filaments into tight bundles
76
function and location of involucrin
formation of a cell envelope around cells in the stratum corneum located in keratohyalin granules
77
function and location of loricrin
found in keratohyalin granules | cross links to involucrin
78
where are polysaccharides, glycoproteins and lipids found in the epidermis
lamellar granules
79
function of fibroblasts in the dermis
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
damage caused by abrasions, erosions or ulcerations of skin
only damage is to the epidermis
81
what does a partial thickness wound damage
structures in the epidermis and parts of the dermis
82
what does a full thickness wound damage
removes epidermis, dermis and deeper structures
83
3 phases of repairing damaged skin
inflammation proliferation remodelling
84
what happens in the inflammation phase of wound healing
partial or full thickness would will result in a blood clot | inflammatory cells recruited to the area
85
proliferation phase of would healing
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
remodelling phase of wound healing
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
function of epidermal growth factor (EGF)
signals to cells about re-epithelialisation
88
local factors affecting wound healing
infection, foreign body, oxygenation, vascular supply
89
systemic factors of wound healing
age, disease, alcohol, smoking, immunocompromised conditions, obesity, medications
90
tissue definition
groups of similar cells working together to carry out a common function
91
types of tissue and their functions
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
organ definition
made up of several tissue types compromised in a morphologically recognisable structure
93
metastasis
the spread of disease-producing agency (eg. Cancer cells) from the initial or primary site of disease to another part of the body
94
steps of tissue processing
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
what colour would a basic dye stain cells
purple/blue - stains acidic structures
96
what colour would a acidic dye stain cells
red/pink
97
two types of epithelia
covering epithelia which lines body surfaces | glandular epithelia which is secretory epithelium arranged into glands
98
simple epithelia
single layer, good for absorption/secretion
99
stratified epithelia
2 or more layers of cells, good for protection
100
pseudostratified epithelia
one layer with mixture of cell shapes
101
four shapes of epithelial cells
squamous - flat shaped cuboidal - cube shaped columnar - tall cylindrical shaped transitional - readily change shape, accommodates stretching
102
function and location of simple squamous epithelium
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
function and location of simple cuboidal epithelium
diffusion, secretion and absorption | found in kidney tubules, glands and their ducts, lining of terminal bronchioles of lungs, surfaces of ovaries
104
function and location of simple columnar epithelium
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
function and location of stratified squamous epithelium
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
describe pseudostratified epithelium
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
describe transitional epithelium
``` 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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