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
Where do afferent (sensory) neurons have their cell body?
Part way along the axon rather than at the start
What does increasing the extracellular K+ concentration do?
Decrease K+ concentration gradient.
This will sustain a smaller electrical equilibrium and therefore depolarise the resting membrane potential
When does the equilibrium potential for an ion occur?
When the concentration gradient for the ion is matched by an equal and opposite electrical gradient
Does each neurotransmitter in the central nervous system have a unique function?
No
What does the blood brain barrier do?
Insulate the brain from changes in plasma ion concentrations
What does acetylcholine act on at the neuromuscular junction?
Nicotinic receptors on the postsynaptic membrane
Describe the compound action potential in a patient with MS
A smaller A alpha curve but a normal C wave
MS is a demeylinating disease. A alpha are the largest myelinating fibres and would therefore be affected. C fibres are unmyelinated and would not/
What is the principle excitatory transmitter in the central nervous system?
L - glutamate which acts on ionotropic and metabotropic receptors to generate fast and slow excitatory postsynaptic potentials throughout the central nervous system.
What is the function of graded potentials?
Determine when a cell will fire its action potential
Where do afferent and efferent fibres enter and leave the spinal cord?
Afferent: sensory fibres enter via dorsal root
Efferent: motor fibres leave via ventral root.
What is the most important factor in establishing a resting membrane potential?
K+ concentration gradient
Where are neurotransmitters packed and what are they released by?
Packed into vesicles and released by CA2+ dependent exocytosis.
What impact does a larger stimulus have on the action potential?
A larger stimulus produces a larger generator potential and a higher frequency of action potential firing.
This is called frequency coding of stimulus intensity.
What can an antagonist do to the effect of a endogenous signalling molecule?
An antagonist can be used to block the action of the endogenous signalling molecule.
What does activation of the sympathetic nervous system cause?
The features characteristic of the fight or flight reaction.
What are the features of the fight or flight response?
Dilation of the pupil
Focussing far away
Increased heart rate
Increased stroke volume
Dilation of the airways
Redirection of blood to the working muscle
Inhibition of Gut motility
Inhibition of enzyme secretion
Breakdown of energy stores
How many stages of change cycle are there and when can patients enter?
6
Any stage
What does the size of a a sensory receptive field indicate?
The relative sensitivity of an area.
A large number of small receptive fields are found in highly sensitive areas of skin.
What effect does a selective beta 1 receptor antagonist have?
A selective beta 1 receptor antagonist would block the effect of noradrenaline and adrenaline on the pacemaker cells which normally increases heart rate.
What do beta 2 receptors work on and what do they do?
The beta 2 receptors are the ones on smooth muscle that make it relax, eg in the airways of the lungs and in some blood vessels.
Where do parasympathetic ganglia lie and how does this effect the size of the preganglionic fibres?
The parasympathetic ganglia lie close to, or even within, the target. Therefore, the preganglionic fibres are longer than the postganglionic fibres.
What feature of skeletal muscle can explain rigor mortis?
t fails to relax if the [ATP] falls well below normal.
What causes withdrawal reflexes to arise?
Withdrawal reflexes arise from activation of nociceptors which sense pain
What are the features of the withdrawal reflex?
They are multisynaptic, operate ipsilaterally and contralaterally to create coordinated muscle movements that prevent you falling over and can radiate up and down the spinal cord by several segments to engage multiple muscle groups.
What division of the autonomic nervous system demonstrate mass activation?
Sympathetic division
What two things allow mass activation of the sympathetic nervous system?
Firstly, there is a lot of convergence and divergence in the paravertebral ganglia (aka the sympathetic trunk) and so it is impossible to activate just one postganglionic fibre.
Secondly, the hormonal component of the sympathetic system means that when adrenaline is released, it can act on all adrenoceptors through out the body.
What do selective antagonists and agonists have?
Selective agonists and antagonists often have structural similarities to the endogenous signalling molecule that they mimic or block.
What would A nicotinic cholinergic antagonist would be expected to block
in the autonomic ganglia?
A nicotinic cholinergic antagonist would be expected to block transmission at parasympathetic and sympathetic, autonomic ganglia.
What do muscle spindles register?
Both the rate of change of length and the difference in length between the start and end of a change in muscle length.
What is the tension of skeletal muscle developed according to?
The tension developed is related to the length of the muscle before it contracts.
What does the autonomic nervous system innervate?
Smooth muscle and cardiac muscle
What effect do anti-chlolinesterases have on ACh?
Anti-cholinesterases block the activity of the enzyme acetylcholinesterase, which breaks down ACh in the synaptic cleft.
Anti-cholinesterases therefore potentiate the activity of ACh.
What does the sensory reflex arch arise from?
The stretch reflex arises from a sharp tap to tendons which quickly changes the muscle length and so activates muscle spindles which drive a reflex contraction of the muscle that was stretched.
What do voltage gated Ca2+ blockers do?
Block Ca2+ dependent cytokines and therefore prevent the release of Ach
What DNA stand for?
Deoxyribose nucleic acid
What is DNA made up of?
Phosphate
Deoxyribose sugar
Nitrogenous base
What is a nitrogenous base also known as?
Nucleotide
What is DNA transcribed into?
mRNA aka Messenger RNA
What happens to mRNA?
Translated into protein
What are genes?
DNA that proteins are made from
What happens if there is an error in a gene that leads to proteins not working properly?
Mutation
What happens if there is an error in a gene that leads to no change in protein’s function?
Varient
How is DNA organised and stored?
- DNA wrapped around protein histone
- They wrap and coil to form fibre
- They then form a chromosome
- Chromosome stored in nucleus
What makes up a nucleotide?
Phosphate
Deoxyribose sugar
Nucleotide/nitrogenous base
In a double strand of DNA, two strands are joined together thorugh hydrogen bonds. What forms this bond?
Nitrogenous base/nucleotide
What is the end goal of DNA replication?
Two identical DNA helixes made up of a new and original DNA strand
What is trisomy 21 also known as?
Downs Syndrome
What happens in the central dogma?
Where DNA is transcribed inro RNA which is then translated into protein
What is the name of the bond that forms between two DNA strands?
Hydrogen bond
Steps of DNA replication
- Unzipping
- RNA strips bind
- New DNA is added
- Errors corrected
What does serious gram-negative infection such as E. coli need to be treated with?
Gentamicin
A teratoma is most commonly:
Benign in women
Malignant in men
Serious systemic fungal infection needs treatment with IV:
Amphotericin B
The pathogenesis of systemic Type III hypersensitivity requires:
Immune complex formation
What are neutrophil polymorphs a major component of?
The acute inflammatory response
What is the last step in the production of daughter cells?
Cytokinesis
What is a condition that does not occur due to the presence of an additional chromosome?
Turner’s Syndrome
What do fibroblasts produce?
Collagen
What does histamine do in acute inflammation?
Releases vascular smooth muscle
What does hypoxia impede?
Tissue healing
What phase of mitosis do chromosomes line up at the equator?
Metaphase
In what stage of mitosis do chromosomes become visible?
Prophase
Why is GTN administered by the sublingual route?
To avoid first pass metabolism
What is a double blind trial?
When both doctor and patient do not know what drug is being taken
What procedure does not require the use of an electric field to separate DNA fragments for analysis?
PCR
What does a nonsense mutation result in?
Protein being finished immaturely
What is a retrospective clinical trial?
Data collected from case records after treatment is given
What is a cross-over trial?
When patients take both treatments being tested one after the other
What is the adapter molecule in the process of transcription and translation that acts between a coded amino acid and mRNA?
tRNA
In DNA replication, the leading strand is…
Formed continuously
What is an example of an ADR?
Failure of treatment
What enzyme is involved in phase 1 drug metabolism?
CYP1A2
Only one side of DNA is replicated during:
Transcription
What is a process that requires cooperation and coordination between mRNA, rRNA, tRNA?
Protein Synthesis
mRNA forms an amino acid sequence for the process of?
Regeneration
Mitosis produces
Diploid cells from diploid cells
What mechanism is used for Type III sensitivity?
Immune complex
What causes rubor and calor in acute inflammation?
Increased local blood flow
Why are somme drugs administered via IV?
To avoid first pass metabolism
What should be given to treat an unknown gram -ve bacteria?
Gentamicin
What does meisosis produce?
Haploid cells from diploid cells
What does fertilisation result in?
Produced diploid cells from haploid cells
What is the primary site of protein synthesis?
The ribosome
Who is the X chromosome transmitted by?
By fathers to daughters but not to sons
Who is the Y chromosome transmitted by?
Only by fathers to sons
What is retinoblastoma caused by?
Loss of tumour suppressor gene
What is leukaemia?
Malignant tumour of white blood cells
What is a liposarcoma?
Malignant tumour of fatty tissue
What is an adenocarcinoma?
Malignant tumour of glandular epithelium
What is used for herpres and varicella zoster virus?
Aciclovir
What is used tropically or in suspension for serious fungal infection therapy?
Nystatin
What can treat B-lactamase producing Staph aureus?
Flucloxacillin
What is treatment via IV for serious pneomocaoocal, meningoccal, strep pyoges and other gram positive infection?
Benzylpenicillin
Pathogenesis of systemic Type I hypersensitivity requires?
Imunoglobulin E (IgEff) production
Pathogenesis of systemic Type IV hypersensitivity requires?
Gamma interferon production
Pathogenesis of systemic Type II hypersensitivity requires?
IgG and IgM production
Gian cells are:
A major component of the acute inflammatory response
What does serotonin produce?
Vasoconstriction in inflammation
How can amphotericin be administered?
Via IV
How can B-lactamase resistanece be combated?
With co-amoxicillin
What reaction involved hydrolysis, redox and cytochrome P-40?
Phase I metabolism
What involves conjugation to increease water solubility and enhance excretion of a metabolised compound?
Phase II metabolism
What binds to a protein to form a ribosome?
rRNA
What inhibits nucleic acid synthesis?
Ciprofloxacin which is a fluroquinolone
An osteosarcoma is a
Malignant bone tumour
A lipoma is a
Benign tumour of fatty tissue
An adenoma is
Benign tumour of glandular epithelium
A squamous papilloma is a
Benign tumour of squamous epithelium
What is used in HIV therapy?
Saquinavir
What is an effect of a benign tumour?
Pressure
What can treat UTIs?
Nitrofurantoin
What does serious staph aures (MRSA) need?
Vancomycin
What happens to body water content in obesity?
Decreases
Can plasma proteins move freely between plasma and interstitial fluid?
No - proteins are too large to cross the capillary wall and are contained within the plasma fluid compartment
What parts make up an amphipathic molecule?
Hydrophibic part, hydrophillic part
