Cells, Plasma, and Cell Death Flashcards
What is the cytoskeleton made of?
Microtubules
Microfilaments
Intermediate Filaments
What are microtubules made of and what is their specific function?
Hollow tubes of tubular dimers (alpha and beta) made by MTOCs (microtubule organising centres)
(Dimers usually dissolve in the cytoplasm)
Provide framework for the movement of Intracellular components and Extracellular cilia/flagella
What are centrioles made of and what are their specific function?
Contain 9 groups of microtubule triplets
Forms cilia and flagella
What are centrosomes made of and what are their specific function?
Contains two centrioles
Creates spindle fibres during cell division
How do cilia/flagella work?
Centrioles anchor to the cell membrane forming basal bodies (extracellularly)
Basal bodies have ten pairs of microtubules (9 surrounding a single pair in the centre) and motor proteins which move the cilia/flagella
How are vesicles moved within the cytoplasm?
Vesicles are moved via motor proteins along the cytoskeleton - requiring ATP hydrolysis
What are microfilaments made of and what is their specific function?
Linear polymer of globular actin (G-actin) that is helically shaped
Provides specific structure and strength to a cell (filaments have flexibility and strength)
What are intermediate filaments made of and what is their specific function?
Variety of proteins are grouped into dimers, tetramers, unit-length filaments (ULF), and rope-like Intermediate filaments
Provide the support for other filaments
What is apoptosis?
Highly regulated (caspase activated) process of programmed cell death
What are the steps in apoptosis?
1) Cell shrinks
2) Chromatin aggregates at the nuclear membrane
3) The cell membrane loses its integrity and forms apoptosis bundles
4) The DNA is fragmented among the bundles
5) No immune response (although phagocytes destroy vesicles formed) and ATP is used
What is necrosis?
Response to cell injury that leads to premature cell death
What are the steps in necrosis?
1) Na+ enters cell, causing swelling of the cytoplasm as water enters as well
2) Cell membrane loses its integrity and bursts (lyses)
3) Organelles and K+ are released into the Extracellular environment
4) DNA is fragmented randomly
5) Cytotoxic chemicals are also released leading to a immune response
6) No vesicles are formed, no ATP is used
Define osmolality
Define osmolarity
Concentration of solute / kilogram of solvent
Concentration of solute / litre of solution
Normal range of plasma osmolality
285-295 mmol/Kg
Define osmotic pressure
Define oncotic pressure
Pressure due to ions
Pressure due to colloids in the blood
Show the relationship between:
Tonicity
Osmolality
Osmotic pressure
Hypertonic - increased osmolality - increase in osmotic pressure
Isotonic - normal osmolality - normal osmotic pressure
Hypotonic - decreased osmolality - decrease in osmotic pressure
Normal plasma pH
7.36 - 7.44
Normal plasma lactate
0.5 - 1.6 mmol/L
What is the complement pathway?
Cascade of proteins which when activated cause inflammation, and opsonisation and phagocytosis of pathogens
What are the different pathways of the complement pathway?
Classical
Alternative
Mannose-binding Lectin
These 3 lead onto the lytic pathway
What are the steps in the classical pathway?
1) C1 forms a complex with the antigen-antibody complex
2) C3 convertase (C4b2a) is activated (from C2a and C4b fragments)
3) C3 convertase will now cleave C3 into C3a and C3b
What are the steps in the alternative pathway?
1) Factors B,D,H,I interact with C3b and the pathogen cell wall
2) Together they form the C3 convertase C3bBb
3) C3 convertase will now cleave C3 into C3a and C3b (amplification loop)
What are the steps in the Mannose-binding Lectin pathway?
1) MBL binds to mannose residues on the pathogen surface activating MBL-Activated Serine Proteases (MASP) 1 and 2
2) MASP-1 and MASP-2 activate C2 and C4 to form the C3 convertase C4b2a
3) C3 convertase will now cleave C3 into C3a and C3b
What are the roles of C3a and C3b proteins?
C3a (C4a, C5a): Anaphylatoxin - activate mast cells
C3b (C4b, C1q): Attache to pathogens covalently (opsonisation)
What are the steps in the lytic pathway?
1) C3b activates C5 convertase which cleaves C5 into C5a and C5b
2) C5a is an anaphylatoxin (activates mast cells) and a chemotactic (attracts nuetrophils and macrophages)
3) C5b forms the MAC (membrane attack complex) with C6, 7, 8, 9
4) The MAC inserts itself into the membrane (transmembrane complex) causing cell lysis
What is the specific function of the ER?
Post-translation modification of proteins (+ packages them into vesicles)
Converts fatty acids into Lipids
