Water distribution: how much water is there in:
a) the ECF?
b) the ICF?
Water distribution: how much water is there in the (ECF):
a) interstitial fluid
a) interstitial - 11L
b) plasma - 3L
What is the predominant electrolyte(s) in the ICF?
What is the predominant electrolyte(s) in the ECF?
Na+, Cl-, HCO3-
What is the definition of osmosis?
Movement of H2O across a partially permeable membrane from an area of high water potential to an area of low water potential.
What is the definition of osmolarity?
The number of solute particles per L of fluid. (A high osmolarity has more solute particles per L).
What is the definition of oncotic pressure?
Oncotic pressure is a form of osmotic pressure exerted by proteins, notably albumin, that tends to pull fluid into its solution.
What is the definition of osmotic pressure?
The pressure that must be applied to a solution to prevent inward osmosis through a partially permeable membrane.
Electrolyte homeostasis: what is the cause(s) of hypernatremia? And what are the risks?
Cause - water deficit (poor intake, diabetes insipidus etc).
Risks - Dehydration.
(High sodium = low H2O which dehydrates the brain).
Electrolyte homeostasis: What is the cause(s) of hyponatremia and what are its risks?
Causes: Excess water due to IV fluids, diuretics.
Risks: Over hydration - headache, confusion.
Electrolyte homeostasis: What is the cause(s) of hyperkalemia and what are its risks?
Causes: renal failure, acidosis, diuretic inhibitors.
Risks: Cardiac arrest.
Electrolyte homeostasis: What is the cause(s) of hypokalemia and what are its risks?
Causes: D+V, alkalosis, diuretics.
Risks: weakness and dysrhythmia.
Electrolyte homeostasis: What is the cause(s) of hypercalcemia and what are its risks?
Causes: hyperparathyroidism, Vit D toxicity, malignancy.
Risks: renal stones and metastatic calcification.
Electrolyte homeostasis: What is the cause(s) of hypocalcemia and what are its risks?
Causes: renal disease, Vit D deficiency, intestinal malabsorption.
Risks: tetany (spasms).
What is the function of rough ER?
What is the function of smooth ER?
What is the function of the golgi apparatus?
Processes and modifies ER products.
What is the cis face of the golgi apparatus?
The cis face is nearest the nucleus and receives ER vesicles.
What does the medial Golgi do?
It modifies products by adding sugars forming oligosaccharides
What does the trans face of the golgi do?
It sorts molecules into vesicles.
What are the functions of vesicles?
Transports and stores materials. These are membrane bound organelles.
What are desmosomes?
Attach cells via the intermediate filaments.
What are tight junctions?
Binds cells together to prevent leakage of molecules in between them.
What is the function of gap junctions?
Conduct electrical signals.
List 4 functions of a plasma membrane.
- Physical boundary for the cell.
- Regulates the movement of substances.
- Has receptors for cell to cell signalling.
- Attaches the cell to the external environment.
Name 4 molecules you’d find in a plasma membrane.
- Integral proteins
The genetic constitution of an individual.
The appearance of an individual due to the environment and genetics.
Water distribution: How much water is there in the ICF?
What is an example of type 1 collagen?
Bone, skin and teeth.
What is an example of type 2 collagen?
What is an example of type 3 collagen?
Arteries, liver, kidneys, spleen, uterus
What is an example of type 4 collagen?
What is an example of type 5 collagen?
An alternative form of a gene at a specific locus.
Give an example of an autosomal dominant condition.
Give an example of an autosomal recessive condition.
Summarise autosomal dominant inheritance.
- Manifests in the heterozygous state.
- Male to Male transmission is seen.
- Both males and females are affected equally.
- The disease is present in several generations.
- There is a 50% chance of offspring having the disease.
Summarise autosomal recessive inheritance.
- Manifests in the homozygous state.
- The disease is often not seen in every generation.
- 25% chance of offspring having the disease.
- 50% chance of offspring being carriers.
- Healthy siblings have a 2/3 chance of being carriers.
Give an example of an X linked recessive condition.
Duchenne muscular dystrophy
What is a mis-sense mutation?
A single nucleotide change results in a codon coding for a different amino acid. This can result in a non functional protein or can have no effect (degenerative nature of the genetic code).
What is a non-sense mutation?
A single nucleotide change that produces a premature stop codon. This results in an incomplete/non-functional protein.
What are the products of glycolysis?
2 ATP, 2 NADH, 2 Pyruvate
What is the rate limiting enzyme in glycolysis?
Where in a cell does glycolysis take place?
Where in a cell does the Krebs cycle take place?
The matrix of the mitochondria
Chemical reactions that occur in a living organism.
The energy needed to stay at live rest. (24kcal/Kg/day)
How much energy do carbohydrates provide?
How much energy do proteins provide?
How much energy do lipids provide?
How much energy does alcohol provide?
How much energy is stored as triglycerides?
How much energy is stored as glycogen? And where is it stored?
- 200g in the liver
- 150g in muscle
How much energy is stored as protein?
What factors increase BMR?
Being overweight, pregnancy, low temperature, exercise, hyperthyroidism
What factors decrease BMR?
Increasing age, being female, starvation, hypothyroidism
What are reactive oxygen species?
Reactive molecules and free radicals derived from O2
Name 3 exogenous sources of ROS?
Smoking, UV radiation, drugs
Name an endogenous source of ROS?
Produced as a by product of O2 metabolism
Name 3 ketone bodies
- beta hydroxybutyrate
Where does ketogenesis usually occur?
In the liver
When would ketogenesis occur?
During high rates of fatty acid oxidation too much acetyl CoA is produced; this overwhelms the Krebs cycle and so you get ketone body formation
What molecules make up ATP?
1 adenine, 1 ribose, 3 phosphate
A solution that resists changes in pH when small amounts of acid/base are added.
Name 3 biological buffers.
What is the equation to demonstrate the mechanism of a bicarbonate buffer?
H2O + CO2 -> H2CO3 -> HCO3- + H+
Arrows are reversible
How do protein buffers work?
If the pH falls H+ binds to the amino group of the protein.
If the pH rises H+ can be released from the carboxyl group of the protein.
What can cause respiratory acidosis?
Inadequate ventilation due to airway obstruction (COPD, asthma).
What happens to the PaCO2 levels in respiratory acidosis?
PaCO2 increases leading to an increase in H+ ions and so pH decreases.
CO2 production is greater than CO2 elimination
What can cause respiratory alkalosis?
Hyperventilation in response to hypoxia.
CO2 elimination exceeds O2 reabsorption.
List 3 causes of metabolic acidosis?
Renal failure, loss of HCO3-, excess H+ production.
List 2 causes of metabolic alkalosis.
Vomiting (loss of H+), increased reabsorption of HCO3-.
What do fatty acids produce.
Where is this product used?
Used in the Krebs cycle
Name 4 ways in which ATP can be produced?
- Krebs cycle.
- Oxidative phosphorylation.
- Substrate level phosphorylation.
What is gonadal mosaicism?
When there are 2 different populations of cells in the gonads. One population is normal and the other is mutated. All gametes from the mutated line are effected.
What type of cells are produced in mitosis?
2 diploid daughter cells which are genetically identical to the parent cells.
What is mitosis used for?
Growth and repair.
What are the 4 phases of the cell cycle?
G1, S, G2 and M
What phases of the cell cycle make up interphase?
G1, S and G2
What happens in prophase?
Chromatin condenses into chromosomes. Nuclear membrane begins to break down.
What happens in prometaphase?
Spindles form. Nuclear membrane completely breaks down.
What happens in metaphase?
The chromosomes line up along the midline of the cell. The spindles attach to the centromeres.
What happens in anaphase?
The chromosomes are pulled apart and the sister chromatids are pulled towards the nuclear poles.
What happens in telophase?
The nuclear membrane reforms and the chromosomes unravel to form chromatin. The spindle fibres disappear.
What happens in cytokinesis?
The cytoplasm divides producing 2 genetically identical daughter cells.
What type of cells are produced in meiosis?
4 haploid daughter cells that are genetically different to the parent cell.
What is meiosis used for?
The production of gametes.
How is genetic diversity introduced in meiosis?
- Metaphase 1 = random assortment.
- Prophase 1 = crossover.
Name 3 molecules that make a nucleotide.
- Pentose sugar.
- Nitrogenous base.
What is splicing?
The removal of introns from pre-mRNA
List 3 features of the genetic code.
What condition is trisomy 21?
One of the female X chromosomes becomes inactivated early in embryogenesis.
What is a triglyceride?
A glycerol backbone with 3 fatty acids.
What 2 carbohydrates form sucrose?
Glucose and fructose
What 2 carbohydrates form maltose?
Glucose and Glucose
What 2 carbohydrates form lactose?
Glucose and galactose
What is the respiratory burst?
WBC’s using ROS in phagocytosis to damage the membrane of invading cells.
Name 2 equations that form hydroxyl radicals.
What is Fenton’s equation?
Fe2+ + H2O2 -> Fe3+ + OH• + OH-
What is the Haber Weiss equation?
O2- + H2O2 -> O2 + OH• + OH-
Give 3 examples of endocytosis.
- Receptor mediated.
Name 3 mechanisms by which a molecule can move across a plasma membrane.
- Diffusion - movement down a concentration gradient.
- Facilitated diffusion.
- Active transport - uses ATP, against concentration gradient.
Name 3 types of cell receptors.
- Ion channel receptors.
- G-protein coupled receptors.
- Enzyme linked receptors.
Name 3 ways in which we intake fluids.
- IV Fluids.
Define insensible losses.
Water loss that we are unaware of. It is comprised only of solvent and can not be measured.
Name 3 hormones involved in water homeostasis.
- ADH - antidiuretic hormone.
- ANP - atrial natriuretic peptide.
What is oedema?
Excess H2O in the interstitial fluid.
Name the 4 types of oedema.
What is serous effusion?
Excess H2O in a body cavity.
Name 2 places DNA can be found.
- Nucleus of a cell.
2. Mitochondria (purely maternal DNA).
What is the function of topoisomerase?
It unwinds the DNA double helix by relieving the supercoils.
In what direction does DNA polymerase read?
3’ to 5’ (but replication occurs in the 5’ to 3’ direction).
What is the product of transcription?
Where does translation occur?
At a ribosome.
Briefly describe translation.
A tRNA with a complementary anticodon to the codon on mRNA binds. Peptide bonds from between amino acids = polypeptide chain.
What are the 4 bases in RNA?
Adenine, Cytosine, Guanine, Uracil.
What is non-disjunction?
The failure of chromatids to separate.
For example; Down’s syndrome - trisomy 21. Turner’s syndrome - Monosomy of X chromosome.
What enzyme of glycolysis is inhibited in acidosis?
Phosphofructosekinase-1 (PFK-1 is pH dependent).
Which phase of mitosis is this: The chromosomes are moving towards opposite poles of the cell and there are no nuclear membranes.
What enzyme catalyses the formation of 3-phosphoglycerate from 1,3-bisphosphoglycerate?
What enzyme catalyses the formation of glyceraldehyde-3-phosphate from dihydroxyacetone phosphate?
Triose phosphate isomerase.
Oxidative phosphorylation: What enzyme transports protons into the mitochondrial matrix?
Is the mitochondrial membrane permeable or impermeable to ions?
What are steroid hormones synthesised from?
What will epiblasts in a 3-week embryo become?
How many days after fertilisation does implantation occur?
How long is pregnancy?
What does the blastocyst divide into?
Embryoblast (inner cell mass) and Trophoblast (outer cell mass).
What does the embryoblast divide into?
Epiblast and Hypoblast = bi-laminar disc.
What does the trophoblast divide into?
Cytotrophoblast (inner) and Syncytiotrophoblast (outer).
How is the primary utero-placental circulation established?
Lacunae form in the syncytiotropohoblast and maternal blood enters.
What happens in the third week of embryonic life?
Gastrulation - formation of a tri-laminar embryonic disc.
What is the function of chorionic villi?
Allows the transfer of nutrients from maternal blood to foetal blood.
What part of the tri-laminar disc are somites formed from?
Paraxial plate mesoderm.
What part of the tri-laminar disc is the circulatory system formed from?
Lateral plate mesoderm.
What does the ectoderm form?
CNS, PNS, skin, posterior pituitary and sweat glands.
What does the endoderm form?
Respiratory tract, GI tract, urinary tract, auditory tube, liver, pancreas, thyroid and parathyroid glands.
What happens in the 4th week of embryonic life?
The flat tri-laminar disc folds into a cylindrical embryo.
What are the 3 layers of the walls of arteries and veins called?
Intima, Media, Adventitia
What causes trisomy 21?
Failure of the chromatids to separate; non-dysjunction.
Name 2 electron accepting coenzymes.
Approximately how many ATP molecules are produced from oxidation of NADH?
Approximately how many ATP molecules are produced from oxidation of FADH2?
Briefly describe what happens in anaerobic respiration.
NAD is regenerated from NADH. Pyruvate, from glycolysis, forms lactate. Lactate dehydrogenase catalyses this reaction. NAD goes back to glycolysis so ATP can be produced.
What is the normal pH range of the human body?
What is the importance of acylcarnitine?
It is required to transport fatty acids into the mitochondria for beta oxidation.
What is the product of fatty acid beta oxidation?
Where does the acetyl CoA from beta oxidation go?
To the krebs cycle.
What are removed in splicing of pre-mRNA?
What is gametogenesis?
Precursor cells undergo cell division and differentiation to form haploid gametes.
Gametogenesis: when do meiotic divisions occur in a male?
Gametogenesis: when is meiosis 1 complete in a female?
Gametogenesis: when is meiosis 2 complete in a female?
If fertilisation occurs.
What is Mendel’s second law?
The law of independent assortment. The alleles of one gene sort into gametes independently of the alleles of another gene.
Why can X linked genes not be passed from father to son?
Because the dad is XY and gives only the Y chromosome to his son and the X to his daughter.
Can males ever be carriers of X linked conditions?
No. They are either affected or they do not carry the gene.
Would an X linked dominant condition be more common in males or females?
X linked dominant conditions occur twice as frequently in females as they do in males.
Would an X linked recessive condition be more common in males or females?
More common in males.
Would an affected male of an x-linked recessive condition and an unaffected female have any affected children?
No affected children but all the daughters would be carriers.
What is multifactorial disease?
A disease due to genetic and environmental factors e.g. diabetes or schizophrenia.
The number and appearance of chromosomes in the nucleus of a eukaryotic cell.
The proportion of people with a gene who show the expected phenotype.
Define sex limitation.
Both sexes have a gene but its expression is limited to only one of the sexes and it is turned off in the other.
Define variable expression.
Variation in clinical features of a genetic disorder between individuals with the same gene alteration.
Name 2 allosteric activators of PFK-1.
Name 3 allosteric inhibitors of PFK-1.
Lipids have hydrophobic and hydrophillic parts. What is this called?
What layer of the tri-laminar disc does the epiblast form?
What cells does the epiblast give rise to?
Amnioblasts that line the amniotic cavity.
What cells does the hypoblast give rise to?
Cells that line the blastocyst cavity.
What is the chorion composed of?
The extra-embryonic mesoderm and the 2 layers of trophoblast.
What is the role of ATP synthase in oxidative phosphorylation?
It transports H+ into the mitochondrial matrix.
What is the role of cytochrome-C oxidase complex in oxidative phosphorylation?
It transports H+ out of the mitochondrial matrix.
What generates the energy needed to phosphorylate ADP -> ATP?
The movement of H+ in and out of the mitochondrial matrix.
Where does oxidative phosphorylation occur?
In the mitochondrial matrix.
What transports H+ out of the mitochondrial matrix?
Cytochrome-C oxidase complex.
A gene sequence is coded in …
Single strand DNA.
A promoter sequence is coded in …
Single strand DNA.
What is a promoter sequence?
The promoter region controls when and where the RNA polymerase will attach to DNA so transcription can commence.
What is a transcriptome?
All the messenger RNA molecules in a cell.
Which protein structure is created by covalent bonds?
Primary structure (peptide bonds between amino acids are covalent).
What type of bond is a peptide bond?
A covalent bond.
What is a single nucleotide polymorphism?
A single nucleotide substitution in DNA resulting in variation amongst a population.
What type of inheritance pattern is seen with sickle cell disease?
What is the mechanism by which sickle cell RBC’s block capillaries?
They activate endothelial cells and cause inflammation, this results in blockage of the capillaries.
What are the sub-units of haemoglobin?
2 alpha and 2 beta subunits.
A mutation in what gene results in HbS production?
How do HbS sub-units cause sickling?
They bind to the cytoskeleton which causes sickling.
What is the affect on HbS in hypoxia?
The HbS sub-units polymerise.
What is the affect on insensible losses if temperature increases by 1 degree?
Insensible losses will increase by 10%.
Why is sodium doubled in the plasma osmolality equation?
To account for negatively charged ions.
If a patient has diabetes insipidus and is not producing any ADH what is her blood and urine osmolality after 3 hours of water deprivation going to look like?
Blood osmolality would be high.
Urine osmolality would be low - very dilute urine.
What are Mendel’s 3 laws?
- Law of dominance.
- Law of independent assortment.
- Law of segregation.
How many hydrogen bonds form between adenine and thymine?
How many hydrogen bonds form between cytosine and guanine?
How many genes are there in the human genome?
What enzyme, expressed normally in embryonic cells and abnormally in neoplastic cells, lengthens telomeres?
Give 2 reasons why cancers are more commonly in the elderly.
- The elderly are more likely to have accumulated mutations.
- Their immune system is weaker and so they’re more vulnerable.
What is Knudson’s two hit hypothesis?
The idea that a sporadic cancer requires 2 acquired mutations whereas an inherited cancer requires only 1 acquired mutation and 1 inherited. Therefore you are more likely to develop an inherited cancer as the chance of one mutation is greater than the chance of 2.
What is it called when a child shows a phenotype for a disease younger than their father/mother does? e.g. in huntington’s disease.
Give 4 functions of tight junctions.
- Holds cells together.
- Generates a concentration gradient across the epithelium.
- Allows the passage of water and glucose.
- Prevents the passage of large molecules.
What enzyme does high insulin levels stimulate?
PFK-1 due to increasing fructose-2,6-bisphosphate levels.
How does insulin increase the breakdown of glucose to pyruvate?
It stimulates PFK-1 indirectly through increasing fructose-2,6-bisphosphate levels and so increases the rate of glycolysis.