Facts Flashcards
What is NADPH required for?
Fatty acid biosynthesis
Steroid synthesis
GSH regeneration
Functions of the Pentose Phosphate Pathway
- Produce NADPH in cytoplasm
- Biosynthesis reducing power for lipid synthesis - high activity in liver and adipose tissue.
- Maintain free cysteine groups SH on certain proteins and prevent oxidation to -S-S- disulphides bonds
- Produce C5 sugar for nucleotides - high activity in dividing tissue for example bone marrow
A deficiency is G6PDH causes what is RBCs?
In RBCs the level of NADPH decreases which results in inappropriate disulphides bonds forming which forms aggregated proteins called Heinz bodies. This increases the cells likelihood of haemolysis.
Osteogenesis Imperfecta
brittle bone
• Mutation in the COL1A gene
• Incorrect production of collagen 1 fibres
• Weak bones and increased risk of fracture
• Shortened stature
• Blue sclera
• Hearing loss
Rickets
- Mainly affects children
- Vitamin D deficiency
- Poor calcium mobilisation
- Ineffective mineralisation
- Weakened bone development
- Soft bones
- Shortened height and stature
- Painful to walk
- Bowed legs
Osteomalacia
- Rickets in adults
- Vitamin D deficiency
- Lower mineralisation
- Increased osteiod
- Increased calcium resorption
Primary osteoporosis
- Type 1 occurs in post menopausal women due to an increase in osteoclast numbers due to a loss of oestrogen.
- Type 2 occurs in order men and women due to loss of osteoblast function due to loss of androgen and oestrogen.
Secondary Osteoporosis
- Results of drug therapy - corticosteroids
- Process affects bone remodelling
- Metabolic bone diseases
Risks factors for osteoporosis
- insufficient calcium intake
- Lack of exercise - immobilisation of bones lead to accelerated bone loss. Physical activity is needed to maintain bone mass.
- Cigarette smoking - in women linked to higher rates of osteoporosis.
Achondroplasia
- Inherited mutation in the FGF3 receptor gene
- FGF promotes collagen formation from cartilage - endochondral ossification affected
- Results in short stature but normal sized head and torso - long bones cant lengthen properly.
Osteoarthritis
- Mechanical failure of articular cartilage
- Narrowing of joint space
- Bones rub against one another
- Bone growths called osteophytes may occur
Rheumatiod arthritis
- Autoimmune disease
- inflammation of synovial membrane as it is attacked
- Thickening of joint capsule
- Subsequent damage to underlying bone and articular cartilage
- Both bone and cartilage disintegrate.
- Increase in number of macrophages, osteoclasts, fibroblasts, T cells, B cells, mast cells, dendritic cells and plasma cells.
Bone repair - haematoma
Blood vessels in bone and periosteum break
A mass of clotted blood forms
Bone cells at the edge of the fracture die.
Swelling and inflammation occur (granulocytes enter the cell)
Phagocytic cells and osteoclasts enter and begin to remove dead tissue
Macrophages will eventually remove the blood clot
Bone repair - fibrocartilaginous callus
New blood vessels infiltrate the fracture haematoma
A soft callus of granulation tissue develops
Fibroblasts produce collagen fibres. Others differentiate into chondroblasts that produce
hyaline cartilage
Osteoblasts from the periosteum and endosteum invade the fracture site and begin bone re
construction
Bone repair - bony callus
New trabeculae begin to form
The soft callus is converted to bony callus of cancellous bone
Endochondral ossification replaces the cartilage with cancellous bone and intramembranous
ossification replaces any spaces with bone
Bone repair - bone remodelling
Cancellous bone begins to be remodelled into compact bone in the cortical region
Material bulging from the outside and inwards is removed by osteoclasts
The final shape of the re-modelled area is the same as prior to the fracture.
Mast cells
inflammatory cells found in loose connective tissue near blood vessels. They release histamine - increases blood vessel wall permeability, heparin - anticoagulant and cytokines - attract immune cell.
Galactosaemia - enzymes
galactokinase,
UDP galactose 4 epimerase
galactose-1-P uridyl transferase.
Essential fructosuria
fructokinase missing causing fructose in urine with no clinical signals
Fructose intolerance
Aldolase B missing causing fructose 1 P to accumulate in the liver causing liver damage.
Hashimotos
Low T3 and T4 high TSH
Graves
Low TSH high T3 and T4
Haemoglobin structure
a quaternary structure with 4 subunits - 2 alpha 2 beta. Each subunit has a prosthetic haem group
Sickle cell anaemia structure
a mutation in the HBB gene which coverts the glutamate molecule to valine in the beta haemoglobin chain. Glutamate is hydrophilic and valine is hydrophobic. This mutation creates sticky pockets when Hb is in the T state. This causes polymerisation and sickling
Foetal Haemoglobin
remains high after birth until the baby is roughly 2-4 months old. This means sickle cell anaemia isn’t noticed til a few months after birth. This is due to the foetal haemoglobin having a higher affinity for oxygen than adult haemoglobin so the baby can still reach the same level of demand despite possibly having anaemia.
Deamination
the hydrolysis of cytosine into uracil.This is due to the removal of the amine group. 5-methylcytosine can undergo deamination to become thymine.
Transition and transversion
Transition is change to the same type of base purine to purine (A to G) and pyrimidine to pyrimidine (C to T).
Trans version is a change to an alternative base type. (A to T and G to C).
Missense / non-synonymous
• Gene product - (change in amino acid)
mutation affecting regulatory sequences
• Amount of gene product
silent or neutral / synonymous
No effect
frame shift / mutation in STOP codon
• Polypeptide length
Fork slippage
occurs in a repetitive area where are newly synthesised strand loops out. A nucleotide is added on the new strand. It can also occur on the template strand which results in one less nucleotide on the new strand as it isn’t read as it has bulged out. This can lead to a trinucleotide expansion causing diseases like Huntington’s.
Polyploidy
the gain of a haploid set of chromosomes for instance triploidy - 69. Most common cause is polyspermy.
Aneuploidy
the loss or gain of whole chromosomes (trisomy or monosmy caused by meiotic non disjunction) For example Down syndrome - chromosome 21 trisomy or Turner syndrome - one of the sex chromosomes is missing 45 X
Mosaicism
presence of two or more cell lines in an individual caused by mitotic non-disjunction.
Non disjunction
occurs when the chromatids fail to separate from another leading to monosomy or trisomy
Reciprocal translocation
Balanced - when 2 chromosomes swap a piece of chromosomal material. No DNA has
been lost. This can occur between any 2 chromosomes. This person is still healthy.
Unbalanced - when 2 chromosomes swap information and the person receives an unequal amount of one chromosome. This means they have lost DNA. The larger the imbalance the more likely there will be a miscarriage. The baby if survives could be born with birth defects
Robertonsian translocation
Only occurs between the acrocentric chromosomes (13,14,15,21,22). 2 acrocentric
chromosomes get stuck together. This results in aneupoldy. Females have a higher
risk than males.
Base excision repair
corrects deamination. The uracil is detected and removed leading to a base-less nucleotide. The baseless nucleotide is removed leaving a hole in the DNA backbone. The hole is filled with the correct base by DNA polymerase and the gap is sealed by ligase.
Nucleotide excision repair
corrects thymine dimers created by UV radiation. Once it is detected the surrounding DNA is opened to form a bubble. Enzymes cut away the damaged region. A DNA polymerase replaced the removed DNA and ligase seals the backbone.
Mismatch repair
cuts the mismatch area including the mismatch neighbours and removes them by exonuclease. The missing areas is replaced by DNA polymerase and ligase seals the DNA backbone.
Single strand repair
not error-free but not error-prone. Relatively simple as the other strand is used to replicate the missing section.
Non homologous end joining
The broken ends are recognised by proteins and protected. A complex forms and damaged ends are removed. The broken ends are then ligated together. Thus is error prone.
Homologous directed repair
uses the other set of DNA in the chromosome to replicate the missing section
Compartment syndrome
caused by trauma to one compartment. This can lead to internal bleeding increasing the pressure in one compartment which exerts pressure on another compartment, skin and nerves. This is because muscles are found in compartments separated by fascia. This causes: • Deep constant pain • Paresthesia • Compartment feeling firm and tight • Swollen, red and shiny.
Skeletal muscle growth
shows hypertrophic growth. This means that the number of muscle cells stays the same but the size of the cells increases
Power stroke
ATP attaches to the myosin head which causes the cross bridge to detach.
ATP hydrolysed to ADP and Pi cocking the head.
Myosin cross bridge attaches to the actin filament.
Working stroke - the myosin head pivots and bends as it pulls on the actin filament sliding it towards the midline.
A new ATP binds repeating the cycle.
Lymph movement aided by:
- Adjacent arteries pulsing
- Skeletal muscle movement
- Pressure changes in the thorax during breathing
Lymph nodes
- Multiple afferent lymphatic vessels that enter via the convex surface.
- A single efferent lymphatic vessel leaves through the concave hilum.
- Each lymph node has a feeding artery and draining vein that also enter and leave via the hilum.
- Dendritic cells are located in germinal centres and when they detect an antigen causes proliferation of B cells. These can then activate T cells.
Enlarged lymph node causes
- As lymph nodes fight an infection the germinal centres fill with lymphocytes which causes swelling.
- Cancers can metastasise to lymph nodes causing swelling
- Lymphoma is a cancer originating in the lymph nodes.
Thymus
maturation of bone marrow derived stem cells into immunocompetent T cells
changes in Thymus associated with myasthenia gravis.
Spleen
Red pulp - filters blood, white pulp - immune systems
-Immune functions -
antigen presentation by APC
Activation of B and T cells
Removal of macro molecular antigens
-Haemopoietic functions -
Removal and destruction of old, damaged erythrocytes and platelets
Retrieval of iron from erythrocyte protein
Erythrocyte storage
Tonsils
Prevents pathogen ingress through nasal or oral routes
prevents ingress though aural routes
Crytps increase surface area.
Vermiform appendix
prevents ingress through GI route
prevents ingress arriving from the ileum
crypts increase surface area
Peyers patches
prevents pathogen ingress though digestion
Loose connective tissue
- Multiple cell types
- Contains 2 fibres - collagen and elastin
- Gel like ground substance
Functions • Hold vessels that supply fluids • Permit cell migration • Involved in inflammation • Packs organs • Hold things in place • Insulted and cushions organs
Located beneath epithelia
Dense irregular
• Fibroblasts
• Col 1 in all direction
• Resits stress in all directions
Deep layer of dermis
Dense regular
• Fibroblasts
• Col 1 parallel
• Resists stress in one direction
Tendons and Ligaments
Cholera - diarrhoea
causes diarrhoea by inhibiting the action of GTPase which breaks down the G alpha S complex. As there is more of type complex adenylyl cyclase is activated more and will convert ATP to cyclic AMP. This causes stimulation of the CFTR transporter in the small intestines which moves chloride ions into the lumen. This causes water to follow by osmosis into the lumen increasing the amount of water in your stool causing diarrhoea.
Malignant hyperthermia
Severe reaction to anaesthetics such as succinylcholine
Shows an autosomal dominant pattern
Massive contractile fasciculation
Muscle rigidity caused by excessive Calcium release
Outcome is excessive heat and metabolic acidosis
Muscle breakdown and hyperkalaemia
Types of dependence
Physical dependence relates to experiencing the associated side effects from withdrawal from the substance.
Psychological dependence involves feelings of satisfaction and desire to repeat the use of the drug in order to produce pleasure and avoid pain.
Uptake of screening
the proportion of those invited who take up the invitation to participate
Coverage of screening
the proportion of eligible population who have been screened within a given time.
Definition of adherence
The extent to which a persons behaviour - taking medication, following a diet and/or executing lifestyle changes - corresponds with agreed recommendations from the healthcare provider
Non-adherence might involve …
- Failing to pick up a prescription or repeat prescription
- Stopping medication before the course is complete
- Taking more or less of the medication than prescribed
- Taking medication at the wrong time, missing doses etc.
- Taking some but not all of the medication
- Patients may also fail to adhere to treatment recommendations other than medication e.g. lifestyle changes
Consequences of non-adherence
health benefits forgone (poor health-related quality
of life, increased hospitalisations and premature
mortality)
wider economic burden (personal, health and social
cost).
Unintentional non-adherence
Patients want to follow their treatment but are prevented
from doing so by barriers outside of their control
Intentional non-adherence
The person decides not to follow the treatment regime based on their beliefs, attitudes and expectations
Interventions to improve adherence
Educating patient on the medicine to
But these interventions don’t address intentional non-adherence increase their knowledge
Simplifying the regimen
Making it easier to remember to use the medicine (physical aids and reminders)
Explicit rationing
when care is limited. The decisions and basis of decisions are justified by defined rules of entitlement. Technical processes and political processes.
Implicit rationing
When care is limited. The allocation of resources are taken through individual clinical decisions without a set criteria. This can lead to inequalities as could be based on social deservingness.
Explicit rationing - advantages
Transparent, accountable
Opportunity for debate
More clearly evidence-based
More opportunities for equity in decision-making
Explicit rationing - disadvantages
Very complex Heterogeneity of patients and illnesses Patient and professional hostility Impact on clinical freedom Some evidence of patient distress
Purpose of screening
. To give a better outcome compared with finding
something in the usual way (having symptoms and self- reporting to health services)
• If treatment can wait until there are symptoms, there is no
point in screening • Finding something earlier is not the primary objective
Five areas of criteria for screening
- Condition
- Test
- Intervention
- Screening programme
- Implementation
Screening criteria - condition
It needs to be an important health problem with epidemiology, incidence, prevalence and natural history understood.
All cost effective primary preventions have been implemented
Criteria of screening - the test
Simple, safe, precise and validated
Agreed cut off level
Acceptable to public
Agreed policy for further diagnostic investigation
Criteria of screening - intervention
Evidence that intervention at pre-symptomatic phase leads to better outcomes.
Good evidence based policies covering which individuals should receive intervention
Criteria of screening - screening programme
Proved effectiveness in reducing mortality and morbidity
Clinically, socially and ethically acceptable
Benefits outweigh harms
Criteria of screening - implementation
All of other options for managing the condition have been considered
Management of monitoring programme
Adequate staffing and facilities
Evidence based information available for internet participants
Classical learning theories
Environmental cues have connection with behaviour.
Avoid cues and change association of cue with behaviour
Pair behaviour with unpleasant response
Operant conditioning
Act on environment and behaviour shaped by consequences
Behaviour is reinforced if rewarded or a punishment is removed
Limitations of conditioning theories
Classical and operant conditioning based on simple stimulus-response associations
No account of cognitive processes, knowledge, beliefs, memory, attitudes, expectations etc.
No account of social context
Social learning theory
Behaviour is goal related
People are motivated to perform behaviours if they are valued and believe they can do it
Modelling more effective if models are if high status or are like us
Influenced by peers, family and media figures
Cognitive dissonance
Discomfort when hold inconsistent beliefs or
actions/events don’t match beliefs
– Reduce discomfort by changing beliefs or behaviour
– Health promotion:
• providing health information (usually uncomfortable) creates
mental discomfort and can prompt change in behaviour
Health belief model
Beliefs about health treat
- perceived susceptibility
- perceived severity
Beliefs about health related behaviour
- perceived benefits Cues to Action
- perceived barriers
Theory of planned behaviour
. Attitude towards behaviour
. Subjective norm
. Perceived control
Leads to intention
Leads to action
COM-B model - capability
Physical and psychological capability
Knowledge, skill, strength, stamina
COM-B model - motivation
Reflective amp automatic
Plans, evaluations, desires, impulses
COM-B model - opportunity
Physical and social opportunity
Time, resources, cues and prompts
Cost minimisation analysis
• Outcomes assumed to be equivalent
• Focus is on costs (i.e. only the inputs)
• Not often relevant as outcomes rarely equivalent
• Possible example:
– Say all prostheses for hip replacement improve
mobility equally. Choose the cheapest one.
Cost effectiveness analysis
• Used to compare drugs or interventions which have a
common health outcome e.g. reduction in blood pressure • Compared in terms of cost per unit outcome e.g. cost per reduction of 5mm/Hg
• If costs are higher for one treatment, but benefits are too,
need to calculate how much extra benefit is obtained for the extra cost
• Key question: Is extra benefit worth extra cost?
Cost benefit analysis
- All inputs and outputs valued in monetary terms
- Can allow comparison with interventions outside healthcare
- Methodological difficulties e.g. putting monetary value on non-monetary benefits such as lives saved
- “Willingness to pay” often used, but this is also problematic
Cost utility analysis
- Particular type of cost effectiveness analysis
- Cost utility analysis focuses on quality of health outcomes produced or foregone
- Most frequently used measure is quality adjusted life year (QALY)
- Interventions can be compared in cost per QALY terms We are going to look more closely at QALYs…
Gaucher disease
The bulid up of certain fatty substances in organs particularly the spleen and liver. It causes them to enlarge and this affects their function. It can also occur in bone tissue causing them to become weaker and fracture easier.
Properties of peptide bonds
Planar
Stereoisomerism
Bonds either side are free to rotate
Rigid
Resting potential of cardiac myocytes
-80mV
Resting potential of neurones
-70mV
Resting potential of skeletal muscle myocytes
-90mV
Resting potential of smooth muscle myocytes
-50mV
Generation of glands - in utero development
Exocrine
Growth signal received - fibroblast growth factor
Proliferation of daughter cells occurs and extracellular protein degrades enzyme produced
Central cells die off through apoptosis to produce a duct
Generation of glands - in utero development
Endocrine glands
Growth signal received - fibroblast growth factor
Proliferation of daughter cells occurs and extracellular protein degrades enzyme produced
Production of angiogenic factors to stimulate blood vessel growth in and around the tissue
Link to mother cells broken through apoptosis
Difference between endocrine gland for normal and for thyroid follicles
In thyroid follicles, production of colloid between
epithelial cells causes expansion of follicle into a
sphere
When does gland generation occur
Weeks 5 and 6
Mucous membranes
Line certain internal tubes which open to the exterior
GI Tract, respirator tract and urinary tract
Bear mucus secretion cells - goblet
Carries blood and lymphatic vessels and nerves
Serous membrane
Thin, two part membrane which lines certain closed cavities and envelop the viscera.
The peritoneum
Pleural sacs
Pericardial sac
Secrete watery lubricating fluid
Simple squamous cells
Carries blood and lymphatic vessels and nerves
Types of hair
Vellus - short thin and covers most of your body
hair on arms
Terminal - thick long - vellus replaced by terminal in puberty
Hair on head, pubic hair
Lanugo - covers the developing foetus
Function of hair
Thermoregulation
Sexual attraction
Sensation
Protection
Blood clotting cascade
Intrinsic and extrinsic pathways cause the activation of factor X. This causes thrombin activation which causes the formation of a fibrin clot. This occurs by thrombin converted fibrinogen into fibrin
Stopping the clotting cascade
Localisation of prothrombin - dilution of clotting factors by blood flow and removal by liver
Digestion of factors by proteases
Factor Va and 8a degraded by protein C
Breaking the clot - fibrinolysis
Plasminogen - inactive precursors - are activated by streptokinase anf t-PA to produce plasmin. This converts fibrin into fibrin fragments.
Key components of diet and functions
Carbohydrates - source of monosaccharides
Protein - source of amino acids
Lipids - essential fatty acids, reduced bulk of diet
Water - replaces lost water
Fibre - essential for normal function of GI tract
Vitamins - prevents deficiencies
Essential amino acids
Isoleucine Lysine Threonine Valine Phenylalanine Tryptophan Leucine Histidine Methionine
Essential fatty acids
Linoleic acid and linolenic acid
Osteiod
Collagen
Calcium hydroxyapatite
Sodium hydroxyapatite
Lineweaver Burke plot y intercept
1/vmax
Lineweaver Burke plot x intercept
-1/km
Lineweaver Burke plot gradient
Km/ vmax
Where are ketone bodies synthesised
Liver mitochondria
Three different ketones
Acetoacetate
Acetone
Beta hydroxybutyrate
Normal plasma ketone concentration
Less than 1mM
Ketone production pathway
Acetylcholine Co-A is converted into HMG-CoA by synthase. That is then converted into acetoacetate by lyase. It then can become acetone or beta hydroxybutyrate.
Ketone body production in fed state
Insulin to glucagon ratio is high. Lyase is inhibited and reductase is activated so cholesterol is synthesised instead of ketone bodies.
Ketone body synthesis in starvation state
When insulin to glucagon ratio is low. Lyase is activated, reductase is inhibited. Ketone body synthesised.
Features of ketone bodies
Water soluble
Volatile acetone may be excreted via the lungs
Acetoacetate and beta hydroxybutyrate are relatively strong organic can lead to ketoacidosis.
Above renal threshold so excreted in the urine - ketonuria
What are some cancer repair defects
DDR defect
Mutated gene
Syndrome
Cancer predisposition
Cancer evolution - differential sensitivity
Chemotherapy is applied.
One clone may be susceptible to the chemotherapy. The other clone may not be. This means it can reproduce and grow as there is no competition with other clones.
Cancer evolution - chemotherapy induced mutagenesis
When chemotherapy is applied a mutation occurs creating a new clone. This develops and grows to form a tumour as it is resistant to chemotherapy.
Synthetic lethality strategies
Clever stratifies are put in place that if a cancer cell develops the healthy gene is knocked out so the cancer gene is the predominant gene. This causes cellular death.
Southern Blotting uses
To analyse clones
Investigate gene structure - large deletions
Investigate gene expansions, triplet repeats - Huntington’s
To investigate mutations in genetic tests
Investigate variation - DNA fingerprinting
Southern Blotting process
DNA fragments are added to an agarose gel for electrophoresis. Transfer to more solid support like a nitrocellulose sheet by blotting. Addition of a fluorescent DNA probe will bind to the complementary sequence. An image is then created using an auto radiogram.
Characteristics of probes in southern blotting
Probs dont align completely
Less than 80% similarity with the DNA
Don’t affect the position of the target sequence in the gel.
Microarrays
1000s of genes to be analysed simultaneously
Contain single stranded oligonucleotides with sequence corresponding to coding regions of the genome attached to a solid support
Changes in gene expression can be monitored.
FISH - fluorescent in situ hybridisation
Probes are made against particular DNA sequences and can be added to cells that have been isolated. It can light up chromosomes to show monosomy or trisomy.
Requirements for gel electrophoresis
Gel - a matrix that allows separation of the protein sample
Buffer - maintains charge on the protein samples
Power supply - generates charge difference across the gel
Stain / detection - identify the presence of the separated proteins
SDS-PAGE
Abolishes 2nd and 3rd structure Separates proteins based on size Ionic detergent breaks down non covalent interactions within proteins Slow - large Fast - small
Sanger DNA sequencing
Based on use of dideoxyneucleotides to terminate chain elongation
Recognised by DNA polymerase as it has a 2 prime H on the ribose sugar.
DNA molecules of increasing size are created with fluorescent molecule being the dideoxyneucleotides.
Separated out by capillary electrophoresis
Detect fluorescently labelled molecules.
Agarose gel electrophoresis process
Samples placed in wells at the negative electrode
DNA moved towards the positive electrode
Smallest samples move furthest
DNA is visualised by staining with ethidium bromide
Oxidative Phosphorylation
Electron transport coupled to ATP synthesis
Electrons are transferred from NADH to FAD2H to molecular oxygen
Energy is released to generate a proton gradient, Proton motive force.
Energy from the dissipation of the proton motive force is coupled to the synthesis of ATP from ADP.
Regulation of oxidative phosphorylation
When [ATP] is high and [ADP] is low there is less substrate for ATP synthase.
Concentration of H+ increases in the inter mitochondrial space.
Prevents further H+ pumping - stops electron transport
Inhibition of Oxidative phosphorylation
Inhibitors like cyanide block electron transport as it prevents the acceptance of electrons by 02.
Uncoupling of oxidative phosphorylation
Uncouplers increase the permeability of the mitochondrial inner membrane to protons which dissipates the proton gradient reducing the proton motive force
No drive for ATP synthesis
Substrate level phosphorylation
Requires soluble enzymes
Energy coupling occurs directly through the formation of high energy bonds.
Can occur in limited extent in absence of O2.
Myelination in the PNS
Schwann cells surround the axon
Mesaxon membrane begins to wrap around the axon
This squeezes the cytoplasm towards the outer surface
Plasma membrane is consequently compacted to form myelin sheath.
Vasculogenesis
Formation of new blood vessels
Angioblast precursors in the bone marrow
During embryonic development
Angiogenesis
Formation of new blood vessels from existing ones
Collateral arteries
Sprouting angiogenesis
FGF produced by mesenchymal cells causes pericytes to convert into smooth muscle cells.
This process is slow and takes hours to days to form blood vessels
Division of primary vessel - intussusception
Twinned vessels from primary vessel
Needs multiple growth factors
Process is quick and takes minutes to hours to form.
Types of drug administration
Subcutaneous Intravenous Oral Intramuscular Rectal Sublingual
Factors affecting drug absorption
Physiological factors - GI length, drug lipophilicity,
GI Physiology - blood flow, GI mobility, food/pH
First Pass Metabolism - gut lumen may denature drugs, gut/liver have 2 main enzymes Phase 1 and 2 enzymes
Effect on first pass metabolism
Reduces availability of drug reaching the systemic circulation therefore affects therapeutic potential
Bioavailability
Fraction of a defined dose which reaches the systemic circulation.
Factors affecting drug distribution
Drug molecule lipophilicity or hydrophilicity
Degree of drug binding to plasma or other tissues and proteins - albumin
Vd on penetration
Smaller Vd means less penetration
Larger Vd means more penetration
Phase 1
Cytochrome P450 enzymes
These are versatile generalists which metabolise a large range of molecules.
Phase 2
Carried out by hepatic enzymes
Mainly cytosolic
Generalists but are more rapid
Main factors of direct clinical relevance are …
Age
Sex
General health
CYP450 Inhibition
Concurrent administration of certain drugs can inhibit specific CYP450 isozymes
Inhibition can be competitive and non competitive
Plasma levels increase
Examples are grapefruit juice inhibits CYP 3A4
Main route of exit of a drug
Through the kidneys
Renal excretion of drugs - process
. Free drug enters the glomerular filtrate through the bowmans capsule
. Active secretion of drugs through the proximal tubule.
. Passive reabsorption of lipid soluble drug which has been concentrated so drug is higher in lumen so enters the perivascular space.
. Lipid Insoluble drug into urine.
Clearance of drug
The volume of plasma that is completely cleared of the drug per unit of time
Total body clearance =
Hepatic clearance + renal clearance
Drug half life
The amount of time over which the concentration of a drug in plasma decreases to half of that of the original concentration.
Multi pass membrane protein
Consists of one polypeptide chain that penetrates the membrane at least twice
Multi subunit membrane protein
Consists of more than one polypeptide chain - where one is anchored to the membrane
Which way to sodium ions move?
Into the cell from the extracellular space
Which way does potassium move?
Out of the cell
Which way does chloride ions move?
Into the cell
Which way do anions other than chloride move
Phosphate, amino acids and bicarbonate
Out of the cell
Hypodermis - location, function and structure
Location - lowest layer of skin - subcutaneous layer
Structure is mainly adipose tissue and loose connective
Functions - provides energy store, shock absorber and acts as an insulator
Dermis location, structure and function
Location - between epidermis and hypodermis
Structure - 2 layers upper and lower
Functions - contains hairs and sweat glands, contains sensory structures
Epidermis
Location - outermost layer of epithelial cells
Structure - 4 or 5 layers, Held together by focal adhesions and desmosomes
Functions - prevents water loss, prevents pathogen entry, synthesis of keratin
Layer of epidermis
Stratum corneum
Stratum lucidum - only soles of feet and palms of hands
Stratum granulosum
Stratum spinosum
Stratum basale
Stratum corneum
- Outermost layer made of squames (dead keratinocytes) • Thick on palms and soles of feet – prone to injury
- Continuously shed
Stratum Granulosum
• Stratified squamous epithelium
• Lamellar granules (filament-associated proteins that assemble keratin fibrils and secrete it)
• Tonofibrils (bundles of keratin filaments and keratohyalin granules)
made by lamellar bodies
Stratum Spinosum
- Cuboidal epithelium arranged in 3 layers (held together by desmosomes)
- Producers of lamellar bodies (keratohyalin factories)
Stratum basale
• Tall columnar epithelial cells
• Constantly renew keratinocytes by cell division
• As daughter cells differentiate they move away from the epidermis-dermis junction
• These make keratin filaments (tonofilaments)
- They lose their ability to divide
• Also home to the melanocytes – produce melanin
Melanocytes
Occurs at intervals
Produces melanin the main pigment of the skin
Langerhans cells
Highly specialised capacity to present antigens to T lymphocytes and mediate a response.
Merkel cells
Mechanoreceptor cells associated with sensory nerve endings
Polygenic Inheritance
occurs when one characteristic is controlled by two or more genes
Anaphase lag
a consequence of an event during cell division where sister chromatids do not properly separate from each other because of improper spindle formation.
Main types of RNA.
Ribosomal RNA
Messenger RNA
Transfer RNA
Transcription initiation
Transcription factor binds promoter. Binding is directional on the TATA box RNA polymerase is recruited Unwinding of DNA helix Formation of a transcription bubble Transcription initiates directionally 5’ to 3’
Transcription Elongation
RNA synthesis from 5’ to 3’
Template reads 3’ to 5’
Single stranded RNA molecule is made
Transcription termination
Sequence dependent, other factors involved
Results in a primary RNA molecule
RNA processing
Post transcriptional modifications
rRNA and tRNA have chemical modifications and cleaveage
mRNA is capped, slipiced and tailed.
Initiation code for translation
AUG
Termination
UAA, UAG, UGA
Translation - initiation
Recognition of cap by tRNA-Met
Recognition of the AUG anticodon
Translation - elongation
Another tRNA molecule moves to its complementary codon. A peptide bond forms and the first tRNA molecule leaves and another one comes ….
Growing polypeptide pushed into exit tunnel
Translation - termination
Release factor recognises the STOP codon
Hydrolysis resulting in a free peptide and uncharted tRNA
Dissociation of ribosome into subunits
Cells with an absolute requirement for energy
RBCs
Neutrophils
Cells in the lens of the eye
Cells in the kidney medulla
Effect of lactate dehydrogenase
Lactate to pyruvate
Where does lactate form?
Skeletal muscle and RBCs
Organs which metabolise lactate into pyruvate
Liver
Kidneys
Heart
What is glycerol phosphate formed from
DHAP
Enzyme that produces glycerol phosphate
Glycerol 3 phosphate dehydrogenase
Where is glycerol phosphate made in the body
Adipose tissue and liver
Function of glycerol phosphate
Used in triglycerides
Phospholipid biosynthesis
What is 2,3 bisphosphoglycerate formed form
1,3 bisphosphoglycerate
What enzyme produces 2,3 bisphosphoglycerate
Bisphosphoglycerate mutase
Where in the body is 2,3 bisphosphoglycerate formed in the body
RBC
Function of 2,3 bisphosphoglycerate
Regulator of Hb O2 affinity, promotes release of O2 from Hb
Re-feeding syndrome
Kwashiorkor - unable to deal with protein rich food in large amounts due to down regulation of enzymes in urea cycle. This can lead to a build up of ammonia causing toxicity.
This is why small amount of proteins need to be increased at regular intervals.
How does re-feeding syndrome increase the risk of cardiac arrhythmias.
When a starving individual consumes large amounts of glucose there is a risk of increased insulin levels. Insulin causes potassium into the cell which causes hyperkalaemia which can cause arrhythmias.
Transposable elements
Sections of DNA that move around the genome. If they insert themselves into a functional gene it could cause damage.
Process that occurs when noradrenaline binds at the beta 1 adrenoceptors which increase blood pressure?
Binding of noradrenaline causes a conformational change to the GPCR.
GPCR interacts with the G protein which causes GTP to displace GDP on the alpha G subunit
Th complex separates and the alpha-GTP interacts with adenylyl cyclase to convert ATP into cAMP. cAMP binds to PKA. This increases Calcium concentration of cardiac muscles.
Mindfulness
Mindfulness means paying attention on purpose, in the present moment, and in a non-judgemental way
What is hereditary spherocytosis ?
Decreased levels of spectrin in the cytoskeleton of RBCs which then become round in shape.
What is hereditary elliptocytosis?
Defective spectrin causes RBCs to become rugby ball shaped and become more prone lyse.
What does ESSENCE stand for?
Education Spirituality Stress management Environment Nutrition Connectedness Exercise
What does SMART stand for?
Specific Measurable Attractive Realistic Timely
Types of collagen
1 - found in fibrocartilage, bone, connective tissue
2 - found in cartilage
3 - found in lymph vessels, tissues
4 - found in basement membrane
What causes the shocking absorbing property of articular cartilage?
Hydration of glycosaminoglycans
Why is cartilage different to other connective tissue?
It is an a vascular tissue - no blood supply
What does the endosteum do?
Lines the medulla cavity
Where do you find sensory neurone cell bodies
The dorsal root ganglia
What is a synonym for anterior
Ventral
What is a synonym for posterior
Dorsal
What is ipsilateral?
Structures are on the same side
What is contra lateral?
Structures are on opposite sides
Flexion does what to the angle
Decreases angle between the moving part and the stationary part
Extension
Increases the angle with the moving part and stationary part
Abduction
Takes structures away from the midline
Addiction
Brings structures back towards the body
Supine
Facing upwards on your back
Prone
On your front back upwards
Inversion - feet
Foot points inwards
Eversion - feet
Foot points outwards
Dorsiflexion
Foot points upwards
Plantarflexion
Foot points downwards
Importance of glycosylation for proteins and lipids
Prevent digestion by proteases and lipases
Where are protein hormones synthesised
Ribosomes and RER
Where are steroid hormones synthesised?
Precursors are made in the mitochondria and created in the SER.
Which hormones are packaged into vesicles?
Protein
Is vitamin C stored in the body?
No
Growth factor of RBC
Erythropoietin
Growth factor of WBC
G-CSF
Growth factors for lymphocytes
Interleukins
Growth factors for platelets
Thrombopoietin
Stein berg sign
Thumb test
Walker murdoch sign
Wrist test
What is a lacuna in relation to cartilage
Depression that a chrondrocytes sits in
Slipped epiphyses what is it and what causes it
Epiphyses of femur slips downwards down the bone
Obesity, trauma, inflammation
Perthes disease
Poor blood supply to the femur so the femur head cells die.
Dolor
Pain
Rubor
Redness
Calor
Hotness
Tumor
Swelling
Functio laesa
Loss of function
T1 what colour is water
Black
T2 what colour is water
White
Functions of the skin
Protection and repair Vitamin D synthesis Sensation Absorption Temperature regulation
Factors that affect the normal range of values for homeostasis
Age Sex Diet Smoking Ethnicity Exercise
What does serum bone alkaline phosphatase do?
Enzyme decreases over time.
Regulates bone mineralisation so bone density decreases.
What causes an increase in potassium entering the cell
Insulin level increase
Name a local anaesthetic
Lidocaine
What does atropine do?
Treats nerve gases and pesticide poisoning by blocking the mACh receptor which prevents excess ACh production.
Clinical signs of thyrotoxicosis
Weight loss Heart palpitations Anxiety Muscle weakness Fatigue Hair loss
What drugs can treat thyrotoxicosis?
Propranolol binds to beta adrenoceptors and reduce heart rate and anxiety
Thianomides which stop thyroid from producing excess hormones.
What effect does 0% first pass metabolism have?
Higher drug absorption so more reaches the hepatic blood supply
What effect does a higher gut wall metabolism do?
Lower passage into the hepatic blood supply.
Increasing the volume of distribution of the drug does what?
There is a decrease in concentration of the drug.
What does omeprazole do?
Treatment of GI reflux disease
Reduces stomach acid and treats heart burn and indigestion
What does warfarin do?
Blood thinner
Anti coagulant
What does verapamil do?
Treats high blood pressure
Angina and tachycardia
What does an increase in vd do to half life
Increases it
What does a low clearance level do to the half life
Longer half life
Define limit of resolution
The smallest distance at which 2 objects can be separated and still be distinguishable as 2 separate objects.
What is a curettage?
Surgical scraping done under local anaesthetics to remove a sample of cells - endometrial sample
What is a pipelle?
Plastic tube with a sharp hollow needle which is inserted inside, twisted to get a sample - endometrial, kidney
Trans vascular
Passing a small needle into a blood vessel.
Frozen section
Surgical specimen frozen to -20 to -30 degrees.
This is then cut using a cryostat.
Stained with h and e
Sample is faster than if fixed
Indirect immunohistochemistry
Antibody complementary to the protein is added. Then another antibody is added that is complementary to the previous antibody. This has an enzyme attached with converts a clear substance into a colourful product. The presence of the colour shows the protein is present. The sample must be washed each time to remove unattached antibodies.
What is immunofluorescence
An antibody complementary to the protein is added with a fluorescent tag. When light shines onto it it produces a signal.
What is a confocal microscope?
Laser excites a fluorescent dye and electrons are raised to a higher level. As the electrons decrease back to their original level a light wave is emitted through mirrors and a pinhole which causes a sharp image when it reaches the detector.
Cell culture
Allows manipulation of the cells and experiments to determine the tissue function
Advantages of cell culture
Absolute control over the physical environment
Homogeneity of sample
Reduced need for animals
Disadvantages of cell culture
Hard to maintain
Small amount grow at high cost
Dedifferentiation can occur
Haematoxylin and eosin
Identifies most things
Massons trichome
Red = keratin and muscle
Blue or green = collagen or bone
Brown or black = nucleus
Periodic acid-Schiff stain
Identifies anything with a glycocalyx
How does an x ray give an image?
Focused beam of high energy electrons
These can pass through the body onto a receiver but some are absorbed or reflected
Advantage of x ray
Quick
Portable
Cheap
Simple
Disadvantages of x rays
Radiation
One plane - 2D
Wont see all pathology
Fluoroscopy
Constant stream of x rays to examine anatomy and motion
Contrast - barium sulphide , iodine
Advantages of fluoroscopy
Dynamic studies
Cheap
Interventional procedure
Disadvantages of fluoroscopy
Radiation
Clinical exposure must be minimised
Uses of fluoroscopy
Angiography
Arthrograms
Screening in theatres
CT scans
Rotating gantry
X ray tube on one side and the detector on the other
Images put together by a computer
Advantages of CT scans
Quick
Good spatial resolution
Can scan most areas
Disadvantages of CT scans
Radiation
Lower contrast resolution
Affected by artefacts
Overuse
Requires breath to be held.
PET scans
Radionuclides that decay by positron emission bind to glucose. PET camera detects where decay occurs.
Larger signal more decay.
Advantages of PET
Performed instead of biopsy
Low radiation dosage
Disadvantages of PET
Radiation exposure
Expensive
MRI
Strong magnetic field aligns hydrogen atoms
Some point upwards and som downwards
Radio frequency pulse applied
Unmatched ions absorb energy and rotate to the opposite direction
Pulse is turned off so untaxed ions rotate back to their original position and release energy.
Computer creates an image.
MRI advantages
No radiation
Good contrast resolution
Disadvantages of MRI
Expensive
Time consuming
Loud
Claustrophobic
Need to lie still
No metal
Ultrasound
High frequency waves from transducer probe
The sound wave is reflected back by tissue where density differs
Probe detects reflected sound waves and a signal is created
Can determine distance and density
Advantages of ultrasound
Lack of ionising radiation
Low cost
Portable
Disadvantages of ultrasound
Operator dependant
No bone or gas penetration
Why use contrast?
It helps better differentiate tissues
Can allow motion to be detected
Common contrasts used
Barium sulphate
Iodine
When and where do somites first appear?
Day 20 in the occipital region
Definition of a gland
An epithelial cell or aggregate of epithelial cells that are specialised for the secretion of a substance
Simple tubular example
Intestinal
Simple branched tubular
Stomach
Simple alveolar
Urethra - male
Simple branches alveolar
Sebaceous
Compound tubular
Duodenal
Compound alveolar
Mammary
Compound tubuloalveolar
Salivary
Extracellular matrix
Fibres and ground substance
Ground substance
Viscous clear substance - high water content
Composed of proteoglycans - large central protein with GAGs bound
Parotid gland
Dark purple in h and e
Striated
Bilateral salivary gland
Cells replaced by adipocytes
Submandibular gland
Mixed serous and mucous
Striated
Functions of the liver
Storage of vitamins
Anabolism
Catabolism
Bile production
Innervation of smooth muscle
Varicosities release neurotransmitters which open gated calcium channels causing an influx. These bind to calmodulin to form calcium calmodulin complexes. This binds to MLCK where it allows phosphorylation of myosin so it can contract.
It is then dephosphorylated by phosphatase and myosin becomes inactive again.
Purkinje fibres
Specialised conducting fibres composed os electrically excitable cells.
Lots of mitochondria
Sliding filament model
Tropomyosin coils around the actin filament reinforcing it
Troponin complex attached to each tropomyosin
Myosin heads extend towards filaments in regions of potential overlap
When calcium binds to TnC of troponin a conformational change occurs
This moves tropomyosin away from actin binding site.
This allows the power stroke to occur.
Red bone marrow
Full of developing blood cells
Rich blood supply
Only found in spongy tissue
Function of red bone marrow
To replenish cells in the blood
Yellow bone marrow
Full of adipocytes
Poor blood supply
Function of yellow Bon marrow
Shock absorber
Energy source
Can convert to red marrow
Where do red blood cells degrades?
Liver or spleen
What happens to the spleen if someone has sickle cell anaemia?
Enlarged as it needs to take up more cells as more are defective.
Red blood cell structure
Biconcave
No nucleus
No mitochondria
Anaerobic respiration
Erythropoiesis
Erythroblasts start of with large nucleus
Gradually shrinks and is removed with the RNA present
Reticulocytes
Before the erythrocytes mature a small amount of RNA remains for the production of haemoglobin
High number of these cells are present after blood loss.
Erythropoietin
Glycoprotein produced by the kidneys to increase levels of red blood cells.
Produced in response tissue hypoxia.
Granulocytes
Granules present in their cytoplasm
Acts to mediate inflammatory reactions
Release cytokines, interleukins which recruit other immune cells.
Neutrophils
Multilobed nucleus
Most abundant granulocyte
Phagocytosis
Basophils
Release histamine to trigger inflammation
Purple granules
Granules contain histamine and heparin
Eosinophils
Fight parasitic worms
Red granules
Monocytes
Macrophage
Phagocytosis
Horse shoe shaped nuclei
Platelets
Biconvex shape
No nucleus
Contains vast amount of proteins and clotting factors
Thrombopoiesis
Unregulated by liver
Formed form megakaryocytes
B cells
Revolves around production of antibodies
Can activate T cells
Mature in bone marrow and then move to intestine - peyers patches - spleen, lymph nodes.
T cells
Kills virus infected cells, cancerous cells and transplanted cells.
Activate b cells to create antibodies
Start in bone marrow but mature in the thymus
What is a membrane potential?
The difference in electric potential between the interior and exterior of the cell that is separated by the membrane.
Ligand
Something that binds to a receptor
Affinity
The degree to which a substance binds to another
Lower Kd = high affinity
Efficacy
The ability of a drug to have a desired effect
Potency
The concentration of a drug to give a desired effect
EC50 lower = higher potency
Intrinsic efficacy
the drug’s ability to activate a receptor
Carnitine shuttle
Transports fatty acts-CoA
Acetyl-CoA binds with carnitine to form acyl-carnitine which moves into the matrix of the mitochondria by the carnitine shuttle transporter where it combines with CoA to reproduce acetyl-CoA.
What inhibits carnitine shuttle?
Malonyl CoA
What is CoA derived form?
Vitamin B5
Protein kinase
Transfer the terminal phosphate from ATP to -OH group of some amino acids
Protein phosphatase
Reverse effects of kinases by catalysing the hydrolytic removal of phosphoryl group form proteins
Proteolytic activation
Inactive precursor molecules - zymogens
Involves breakage of peptide bond - irreversible
For examples - blood clotting
Zymogens
Inactive precursor molecules - enzymes
Trypsinogen
Role of creatine phosphate
In muscle cells creatine + ATP is produced form creatine phosphate and ADP. When the concentration of ATP is high the drive for the synthesis of creatine phosphate increases. ATP can then be regenerated later.
Small store of energy
Lipid classes
- Fatty acid derivatives
- Hydroxy-methyl-glutaric derivatives
- Vitamins
What is metaphase spread?
View chromosomes
Stained metaphase chromosomes
Actively dividing cells are needed.
What is the relationship of the pK values and the pH?
pH is lower than pK value then the R group is protonated
pH is higher than pK value then the R group is deprotonated
What is the isoelectric point?
The pH at which there is no overall net charge
What is the pI value across the basic and acidic proteins?
Basic proteins have a pI value higher than 7
Acidic proteins have a pI value lower than 7
What is the relationship between the pI value and the pH value?
If the pH is lower than the pI it is protonated
If the pH is higher than the pI it is deprotonated
What are conjugated proteins?
where other components are covalently linked to amino acids.
Physical features of amino acids that may impact folding
Aromatic
Aliphatic
Chemical features that may impact folding
Polarity
Hydrophilic or phobic
Acidic or basic
How to disulphides bonds form?
the sulphydryl groups on the cysteine amino acid are oxidised to form a sulfur to sulfur bond or a disulphides bond
Why are disulphides bonds significant
they are important in the active site of many enzymes and are present and stabilise extracellular proteins such as albumin
What is an amyloid fibre?
the misfolded insoluble form of a normally soluble protein
Why use PCR?
To amplify a specific DNA fragment
To investigate single base mutations
To investigate small deletions or insertions
To investigate variation
What is PCR?
Amplification of a target DNA
Temperature cycles of denature, anneal, polymerase.
Pair of primers (forward and reverse) which define the region that is copied.
What is RT-PCR?
To determine if a gene is expressed - diet ti on of mRNA.
mRNA is converted back to cDNA by reverse transcriptase.
