Formatives Flashcards
Define aetiology
The process in by which a disease developes
What is plasma pH proportional to?
Bicarbonate ion concentration/carbonic acid concentration
What is a condensation reaction?
Two smaller molecules join to make a bigger molecule and water is released
What does the rough endoplasmic reticulum do?
Modifies protein after it has been synthesised
What is used to measure extracellular fluid volume?
Sucrose or radio labelled Na+
How can ISF be measured?
ECF - plasma
% of body that is water?
60
What nucleic acid is only found in DNA?
Thymine (T)
What are membrane channels primarily composed of?
Protein encoded by the cells DNA
Can ions move freely between plasma and interstitial fluid?
Yes
Can plasma protein move freely between plasma and ISF?
No
How does the breakdown of a disaccharide to a monosaccharide occur?
Via a reaction that consumes water - hydrolysis
What is the primary site of cellular respiration?
Mitochondria
What does the amphipathic nature of proteins do?
Increases their water solubility
What type of feedback is having a drink of water when you are thirsty?
Negative
What synthesises new protein?
Ribosome
What does the Golgi apparatus do?
Packages protein in preparation for transport out of the cell
Are uncharged molecules generally water soluble?
No
They are generally hydrophobic and do not dissolve readily in water
What is the role of the capillary wall?
It separates plasma from the extracellular fluid and is freely permeable to all fluid constituents except protein and cells
How are phospholipids orientated in the cell membrane?
In a double layer with the hydrophobic tails pointing to the inside of the double layer and the hydrophilic heads pointing to the intra- and extra-cellular fluid.
Which of the following mechanisms of moving particles across a cell membrane is not influenced by concentration gradients?
Exocytosis
Exocytosis occurs where substances, often proteins synthesised by the RER and packaged into vesicles by the Golgi apparatus, move out of the cell when their vesicle membrane merges with the cell membrane and the contents of the vesicle get released into the extracellular space.
How would you describe a solution containing 100mM urea, 200mM NaCl in comparison to normal extracellular fluid?
Hypertonic
What will happen to cells placed in a solution containing 100mM urea and 200mM NaCl?
Shrink because the solution is hypertonic (400mosmol/L) the cells will lose water to the ECF and therefore shrink.
What will happen to cells placed in a solution containing 100mM urea and 150mM NaCl?
Not change volume - it is an isotonic solution
Why can there not be a difference between ICF and ECF osmolarity?
Because water will always move down any osmotic gradient.
It is always water that moves, not ions. Ions are non-penetrating particles and cannot cross membranes without some form of help – channel proteins, mediated carriers etc and only then move under specific conditions e.g. action potential of nerves.
If you drink 1L of water, where will the water go?
33% ECF
67% ICF
If you were to transfuse 1L of isotonic saline, where would it go?
All in the ECF
The saline solution will remain in the ECF as the ions cannot cross the cell membrane and therefore effectively “hold” the water in the ECF due to their osmotic effect. The Na+ and Cl- ions prevent the water moving into the cell. Most effective way to increase plasma volume quickly.
What is the average circulating blood volume in an adult male?
5L
What do viral infections give rise to?
Generally show a rise in lymphocytes
Is the cell freely permeable to gases?
Yes
How can water freely move between interstitial fluid and intracellular fluid?
Through the use of aquaporin channels that are studded through the membrane and are permanently open to allow water to move freely between interstitial fluid and intracellular fluid.
What are G proteins an example of?
Peripheral proteins that are involved in cell communication
What do anaemia, heart and lung disease stimulate?
Release of erythropoietin which stimulates the production of red blood cells
What is the osmolarity of 2mM urea?
2 millosmoles
What two diseases can cause hypoproteinaemia?
Liver disease
Kidney disease
Where is erythropoietin stimulated?
In the liver
Can a solution be both:
Iso-osmotic and hypotonic
Hyperosmotic and hypotonic
Yes to both
What are the different types of T cells?
Cytotoxic T cells
CD4
CD8 T
What are antibodies?
Proteins that are produced against antigens
Describe the structure of an antibody
Y shaped divided into two regions
Upper region - antigen binding region/fab - specific antigen that recognises and binds with the antigen
Lower region - Fc
What are some examples of myeloid cells?
Monocytes
Neutrophils
Plateletes
What are the steps in the adaptive immune response against a pathogen?
Recognition of a pathogen
Production of specific weapons against this pathogen
Transport of these weapons
What is critical for blood clot formation?
Platelets
What are the subsections of the T helper cells?
Th1
Th2
Th17
What can cause a decrease in intracellular fluid volume?
If body sodium intake exceeds sodium output
Do R groups of aliphatic amino-acid contain a hydrocarbon ring?
No - The R-group of an aliphatic amino-acid consists of a hydrocarbon chain, eg alanine or leucine.
What R groups contain a hydrocarbon ring?
The R-group of an aromatic amino-acid contains a hydrocarbon ring, eg phenylalanine or tyrosine.
What are lipids broken down into and what is it used for?
Lipids are broken down to acetyl coA and this is used as fuel
Define Km
At ½ Vmax, the substrate concentration is equal to Km.
What does a low Km indicate?
A low Km indicates a good fit between the enzyme and its substrate.
What has a high and low Km for glucose?
Glucokinase has a high Km for glucose, and hexokinase a low Km for glucose
How can glucokinase collect large amounts of glucose after a meal?
Glucokinase, which is present in the liver, has a high Km and therefore low affinity for glucose but has a high Vmax and can therefore “grab” large amounts of glucose after a meal.
What type of protein are most enzymes?
Globular
What do substrates do at Vmax?
At Vmax, substrate occupies all available active sites of the enzyme.
Hence the rate (velocity) of the reaction as at its maximum.
Where do electrons pass along and what is their energy used for?
Electrons pass along the inner membrane of the mitochondria and their energy is used to pump protons across the membrane.
What is the primary structure of a protein?
The primary structure refers to the sequence of amino acids in a protein.
What does the 3D structure of a protein refer to?
The 3-dimensional structure is referred to as the tertiary structure
Do all lipids increase the risk of cardiovascular disease?
No
VLDL and LDL if in high concentrations in the blood or trans fatty acids can accelerate cardiovascular disease.
However, omega 3 fatty acids can lower cholesterol levels and help prevent the severity of cardiovascular disease.
What does the citrate shuttle do?
Moves acetyl CoA from the mitochondria to the cytosol to make fatty acids.
On what conditions does the citrate shuttle work?
When citrate levels in the mitochondria are high and fatty acyl molecules are low in concentration.
What characterises phenylketonuria?
Classical phenylketonuria results from the lack of the enzyme phenylalanine hydroxylase which converts phenylalanine to tyrosine.
There is therefore a high concentration of phenylalanine and a low concentration of tyrosine in the blood.
Is glycogen in a cell osmotically inactive?
Yes
This is an important benefit of storing glucose molecules as glycogen rather than as free glucose.
What are the three structural categories of proteins?
Globular, fibrous and membranous.
What does the catabolism of glucose to CO2 generate per mol of glucose?
2 mol ATP, 2 mol GTP, 10 mol NADH and 2 mol FADH2.
How do enzymes increase the rate of a reaction?
Enzymes increase the rate of a reaction by lowering the activation energy.
What can cause hyperammonaemia?
Kidney failure can cause hyperammonaemia.
What does a competitive inhibitor structurally resemble?
A competitive inhibitor structurally resembles the normal substrate.
What do G protein coupled receptors linked to adenylyl cyclase produce?
cAMP as a 2nd messenger which regulates the activity of protein kinase A.
What do G protein coupled receptors linked to phospholipase C (PLC) produce?
Inositol triphosphate (IP3(=) and diacylglycerol (DAG) and 2nd messengers.
What synapses have less influence on the firing activity of a cell and why?
Synapses that are distant from the initial segment (Axon hillock) as it gets smaller as it passes along the membrane.
One that is evoked further will have further to travel before it can evoke an action potential and will then have a smaller effect.
What does the refractory period ensure?
That action potentials can only travel forwards down the axon
In skeletal muscle, what does one motor neuron innervate?
Several muscle fibres and forms the motor unit.
What is each muscle fibre innervated by?
One motor neurone
What is the function of the astrocytes?
Generate cerebrospinal fluid that supports and protects the brain
Describe the endplate potential in a healthy neuromuscular junciton
Always sufficient to reach threshold as the endplate is a very large EPSP.
Discuss EPSPs in the central nervous system
Usually small and need cells to integrate the depolarisation from many synapses to reach potential whereas the NMJ has no truck with synaptic integration and does everything to ensure that every time the motor neuron fires, the motor unit reaches threshold and contracts