Cell Basics Flashcards
How heavy is the average human?
70Kg
How much of us is water?
60%
How much of the water in our body is extracellular?
1/3
How many litres of interstitial water are there in an average human?
11l
How many litres of blood does the average human have?
3l plasma +2 l blood cells=5l
What is the resting heart rate?
70bpm
What is the cardiac output at rest?
70ml
How much blood passes through the heart in 1 min?
70ml/beat * 70 bpm = 4900ml/min = 5l
Therefore the total blood volume circulates once per minute
What does haematoxylin do?
Stains nuclei
What does eosin do?
Stains cytoplasm and extracellular matrix
How does autoradiography work?
Molecules are labelled with a radioactive marker eg.monoclonal antibodies. These are then injected into the patient and wherever the molecules bind onto cells or are taken up will be shown on x-ray.
What is the relationship between wavelength, frequency, energy and penetration and hence resolution in ultrasound?
Shorter wavelength means higher frequency so more energy and good resolution .
How does transmission electron microscopy work?
Uses an electron beam generated in a vacuum
Shorter wavelength than light so higher resolution
Electron beam passes through the tissue - the portions which the beam have passed through appear bright, those which the tissue has absorbed or scattered appear dark.
How are samples prepared for TEM?
Fix with glutaraldehyde
Embed in epoxy resin
Stain (osmium tetroxide)
Use microtome with diamond knives
What needs to stay constant in the internal environment?
O2, CO2, Na+, K+, Cl-, Ca2+ Glucose, urea PH Temp Volume and pressure
What is the difference between necrosis and apoptosis?
Necrosis- death of cells due to trauma- cell membrane ruptures and cell bursts as water rushes in
Apoptosis- programmed cell death due to DNA damage or other- initiated by kinases
What is osmolality?
Moles/l-
Write as Osm/L
If sodium chloride - two ions present so double final answer
What is normal plasma osmolality?
290mOsmol/Kg
What is the most common protein found in the blood ?
Albumin
Why don’t cells burst due to their intracellular proteins?
Sodium/potassium ATPase pumps 3 sodium out and 2 potassium in leading to a net loss of osmotically active ions so balances out effect of proteins.
This causes cells to have a membrane potential of -70mV
When can intracellular potassium become life threatening?
More potassium present in ECF
Therefore lesser diffusion gradient for potassium out of cell so more remains inside cell making it more positive
This raises the membrane potential- voltage gated sodium channels activate and cannot reprime as not negative enough- this causes reduced opening of channels during action potential so membrane potential rises less- may not reach threshold
=no action potential- in heart this causes MI
What is physiological pH?
7.4
How are cells attached to each other?
Desmosomes, adherens junctions, occluding junctions
How are cells attached to the basement membrane?
Focal adhesions, hemidesmosomes
What makes up a hemidesmosome?
Integrins attach to basement membrane
What are focal adhesions?
They have actin filaments and integrins which anchor the cell to the extracellular matrix and allow cell migration
What is the function of integrins?
Attachment of cell to ECM
Signal transduction from ECM to the cell
What chemical is used to separate cells?
Collagenase
How do cultured cells behave differently to those in the body?
Stop growing, senescence
What are the different ways cells can communicate with one another?
Autocrine-to self Paracrine- to others Endocrine-secrete into blood Neurocrine-synapse secretes into blood Synaptic transmission
How are prokaryotic cells different?
Pili Plasmids No membrane bound organelles Capsule Nuceloid circular DNA
