IMMS Flashcards
Water distribution: how much water is there in:a) the ECF?b) the ICF?
a) 14Lb) 28L
Water distribution: how much water is there in the (ECF): a) interstitial fluid b) plasma
a) interstitial - 11Lb) plasma - 3L
What is the predominant electrolyte(s) in the ICF?
K+
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?
Protein synthesis
What is the function of smooth ER?
Lipid synthesis
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. 2. Regulates the movement of substances.3. Has receptors for cell to cell signalling. 4. Attaches the cell to the external environment.
Name 4 molecules you’d find in a plasma membrane.
- Cholesterol 2. Glycoproteins 3. Glycolipids4. Integral proteins
Define genotype.
The genetic constitution of an individual.
Define phenotype.
The appearance of an individual due to the environment and genetics.
Water distribution: How much water is there in the ICF?
28L
What is an example of type 1 collagen?
Bone, skin and teeth.
What is an example of type 2 collagen?
Cartilage.
What is an example of type 3 collagen?
Arteries, liver, kidneys, spleen, uterus
What is an example of type 4 collagen?
Basement membranes
What is an example of type 5 collagen?
Placenta
Define allele.
An alternative form of a gene at a specific locus.
Give an example of an autosomal dominant condition.
Huntingtons disease.
Give an example of an autosomal recessive condition.
Cystic fibrosis.
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?
Phosphofructokinase-1
Where in a cell does glycolysis take place?
Cytoplasm
Where in a cell does the Krebs cycle take place?
The matrix of the mitochondria
Define metabolism.
Chemical reactions that occur in a living organism.
Define BMR.
The energy needed to stay at live rest. (24kcal/Kg/day)
How much energy do carbohydrates provide?
4kcal/g
How much energy do proteins provide?
4kcal/g
How much energy do lipids provide?
9kcal/g
How much energy does alcohol provide?
7kcal/g
How much energy is stored as triglycerides?
15kg
How much energy is stored as glycogen? And where is it stored?
350g- 200g in the liver - 150g in muscle
How much energy is stored as protein?
6kg
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
- acetoacetate
- acetone
- 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
Define buffer.
A solution that resists changes in pH when small amounts of acid/base are added.
Name 3 biological buffers.
- Protein2. Haemoglobin 3. Bicarbonate
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?
Acetyl CoAUsed in the Krebs cycle
Name 4 ways in which ATP can be produced?
Glycolysis
Krebs Cycle/TCA 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. 2. Phosphate. 3. Nitrogenous base.
What is splicing?
The removal of introns from pre-mRNA
List 3 features of the genetic code.
- Non-overlapping2. Universal 3. Degenerate
What condition is trisomy 21?
Down’s syndrome
Define lyonisation.
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.
- Fenton’s2. Haber-Weiss
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.
- Phagocytosis.2. Pinocytosis.3. Receptor mediated.
Name 3 mechanisms by which a molecule can move across a plasma membrane.
- Diffusion - movement down a concentration gradient. 2. Facilitated diffusion.3. Active transport - uses ATP, against concentration gradient.
Name 3 types of cell receptors.
- Ion channel receptors.2. G-protein coupled receptors.3. Enzyme linked receptors.
Name 3 ways in which we intake fluids.
- Drink.2. Food.3. 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.
- Aldosterone.2. ADH - antidiuretic hormone.3. ANP - atrial natriuretic peptide.
What is oedema?
Excess H2O in the interstitial fluid.
Name the 4 types of oedema.
- Lymphatic.2. Venous.3. Hypoalbuminaemic.4. Inflammatory.
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?
mRNA
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.
Anaphase.
What enzyme catalyses the formation of 3-phosphoglycerate from 1,3-bisphosphoglycerate?
Phosphoglyceratekinase.
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?
ATP synthase.
Is the mitochondrial membrane permeable or impermeable to ions?
Impermeable.
What are steroid hormones synthesised from?
Cholesterol.
What will epiblasts in a 3-week embryo become?
Ectoderm.
How many days after fertilisation does implantation occur?
7-8 days.
How long is pregnancy?
40 weeks.
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.
- NAD.2. FAD.
Approximately how many ATP molecules are produced from oxidation of NADH?
2.5.
Approximately how many ATP molecules are produced from oxidation of FADH2?
1.5.
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?
7.35-7.45
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?
Acetyl CoA.
Where does the acetyl CoA from beta oxidation go?
To the krebs cycle.
What are removed in splicing of pre-mRNA?
Introns.
What is gametogenesis?
Precursor cells undergo cell division and differentiation to form haploid gametes.
Gametogenesis: when do meiotic divisions occur in a male?
At puberty.
Gametogenesis: when is meiosis 1 complete in a female?
At ovulation.
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.
Define karyotype.
The number and appearance of chromosomes in the nucleus of a eukaryotic cell.
Define penetrance.
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.
- AMP. 2. Fructose-2,6-bisphosphate.
Name 3 allosteric inhibitors of PFK-1.
- Acidosis. 2. ATP.3. Citrate.
Lipids have hydrophobic and hydrophillic parts. What is this called?
Amphipathic.
What layer of the tri-laminar disc does the epiblast form?
Ectoderm.
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?
Autosomal recessive.
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?
HBB gene.
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. 2. Law of independent assortment.3. Law of segregation.
How many hydrogen bonds form between adenine and thymine?
2
How many hydrogen bonds form between cytosine and guanine?
3
How many genes are there in the human genome?
20,000.00
What enzyme, expressed normally in embryonic cells and abnormally in neoplastic cells, lengthens telomeres?
Telomerase.
Give 2 reasons why cancers are more commonly in the elderly.
- The elderly are more likely to have accumulated mutations.2. 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.
Anticipation.
Give 4 functions of tight junctions.
- Holds cells together.2. Generates a concentration gradient across the epithelium. 3. Allows the passage of water and glucose.4. 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.
Name some supersecondary structures in proteins.
Helix-turn-helix, Beta alpha beta unit, leucine zipper, zinc finger.
What is a nucleotide?
A base joined to a sugar and any number of phosphates
What is a nucleoside?
A base with a sugar group
What are the base pairings (also RNA)?
A-T(U) G-C
What are the name of proteins that attach to DNA to make them coil?
Histones (bunch to make nucleosomes)
Which direction does DNA polymerase synthesise DNA
5’ to 3’
What is the function of Helicase
It unzips the DNA strands
What is the function of Topoisomerase?
It unwinds and relieves the supercoils of the DNA it is a Gyrase
What doe SSbs do?
They bind to the DNA to stop the strands annealing
Describe the process of transcription on the lagging strand
RNA primase lays primers for DNA polymerase in small sections cannot be done in one go like the leading. when the okazaki fragments are made DNA ligase joins the sections DNA polymerase replaces the RNA primers
What differentiates mature mRNA from full mRNA
the 5’ cap and the Poly A tail
What are the type of ribosomes in humans? and components
80S made from 60S and 40 S
what are the segments of tRNA?
Anticodon that binds to the strand. Amino acid binding site opposite side.D loop and T loop and a variable loop.
What are intorns and exons?
exons are exported to the final mRNA introns are discarded and broken down.
What are the characteristics of DNA?
Degenerate many AA are coded my more than one codon.Unambiguous as each codon specifies only one AAuniversal all organisms use the same.Non overlapping each nucleotide is only read once.
What is a chromosomal abnormality?
An abnormality where there is the wrong number of chromosomes from non-disjunction or where large parts of the chromosome has been deleted
Name for trisomy 21
Down Syndrome
Which mode of inheritance allows direct male to male transmission?
Autosomal dominant
Features of autosomal recessive pedigree
“skipped generation”males females affected equallyaffected individual only in a single generation
Name some AR conditions
Cystic fibrosis, Sickle cell anaemia, Haemochromotosis, Tay-Sachs Disease, Connexin-26
Autosome
Any chromosome, other than the sex chromosomes (X or Y), that occurs in pairs in diploid cells
Recessive
Manifest only in homozygotes
Allele
One or more alternative forms of a gene at a given location (locus)
Homozygous
Presence of identical alleles at a given locus
Heterozygous
Presence of two different alleles at a given locus
Allelic heterogeneity
The situation where different mutations within the same gene result in the same clinical condition e.g. cystic fibrosis. Thus an individual with an autosomal recessive condition may be a compound heterozygote for two different mutations
Consanguinity
Reproductive union between two relatives.
Autozygosity
Homozygosity by descent, i.e. inheritance of the same altered allele through two branches of the same family.
If affected sibling how likely to be carrier in AR
2/3 likely
Characteristics of AD pegigree
male to male transmission and female to femaleaffected individuals in multiple generationsmale females equally affected
Penetrance
The percentage of individuals with a specific genotype showing the expected phenotype
Expressivity
Refers to the range of phenotypes expressed by a specific genotype
Recurrence risk
50% for transmission of mutation
BUT will the person be affected?
Depends on penetrance and expression
Anticipation
Whereby genetic disorder affects successive generations earlier or more severely, usually due to expansion of unstable triplet repeat sequences
Somatic Mosaicism
Genetic fault present in only some tissues in body.
Gonadal (germline) Mosaicism
Genetic fault present in gonadal tissue.
Sex-limited
Condition inherited in AD pattern that seems to affect one sex more than another
Late-onset
Condition not manifest at birth (congenital), classically adult-onset
Predictive testing
Testing for a condition in a pre-symptomatic individual to predict their chance of developing condition
Characteristics of X-linked inheritance pedigree
Only usually males affected
transmitted through unaffected females
no male to male transmission why?
Lyonization (X inactivation)
Generally only one of two X chromosomes active in each female cell. Can be skewed
List mendelian inheritance types
Autosomal dominant/ recessiveSex linked
List non-mendelian inheritance types
Imprinting
Mitochondrial inheritance
Multifactorial
Genomic imprinting
to do with methylation of DNA etc
Homoplasmy
a eukaryotic cell whose copies of mitochondrial DNA are all identical (identically normal or have identical mutations)
Heteroplasmy and how can heteroplasmy vary?
there are multiple copies of mtDNA in each cell
heteroplasmy can vary between cells in the same tissue or organ, from organ to organ within the same person, and between individuals in the same family
types of prenatal screening
Non-Invasive Prenatal Testing (NIPT) of blood looking for foetal DNA, amniocentesis, ultrasound
What are the roles of genetic testing?
To confirm a clinical diagnosis
To give information about prognosis
To inform management
Allow pre-symptomatic/predictive testing in close relativesCarrier testing
To give accurate recurrence risks Prenatal diagnosis
What is tested for in newboon heel prick?
Sickle cell disease, CF, congenital hypothyroidism, phenylketonuria (PKU)medium-chain acyl-CoA dehydrogenase deficiency (MCADD)maple syrup urine disease (MSUD) isovaleric acidaemia (IVA) glutaric aciduria type 1 (GA1) homocystinuria (pyridoxine unresponsive) (HCU)
What is analysis of chromosomes good for detecting
Chromosome number abnormalities, abnormalities in chromosome structure
what are FISH used for
Detection of abnormalites in number of chromosomes and microdeletions or duplications, can bee good for gene deletions.
What is a multi gene panel used to detect
single nucleotide changes
List benefits of Sanger sequencing/ disadvantages
Very accurate simple to read gold standard. but time consuming high cost per gene
What are the types of mutation
Deletion,inesertion, frame shift, splice site, missence, nonsence
What are incidental/secndary findings in a genetic test?
Additional findings concerning a patient or research participant that may, or may not, have potential health implications and clinical significance, that are discovered during the course of a clinical or research investigation, but are beyond the aims of the original test or investigation
What are targeted panels used for in genetic testing?
sequence a specific genes to look for specific mutations from a panel
what cell types can be genetically tested?
Blood (t lymphocytes) skin, umbilical cord, bone marrow, solid tumour, amniotic fluid,
how are chromosome abnormalities detected?
karyotype, comparing to ideograms, FISH, Microarrays
Describe what non-disjunction and how it can arrise in two forms
when there is an diffenet number of chromosomes in a cell. from meiosis one or two. in first anaphase or anaphase two both chromosomes/tids move to the same cell.
Trisomy 18
Edward’s syndrome
Trisomy 13
Patau syndrome
missing x/y
Tuners syndrome
what is triploidy
all chromosomes have three copies. results in miscarrage
What is Robertsonian translocation
when one of the chromosomes is added to another
what is Cri Du chat
5p deletion
Deletion 15q results in what condition?
Prada Willi/ Angleman syndrome
what is the resolution of microarys
5-10Mb mega bases
What is a constitutional genetic change?
Occurs at gametogenesis affects all of the body cells and is heritable
What is an aquired genetic change?
Occurs during lifetime, usually only affects some tissue and is non- heritable
what is a fusion/hybrid gene and how can it cause disease?
break points occur in the genes that creates a protein that behaves differently
what is a deregulation mutation?
Where a regulator gene is affected by a mutation and causes uncontrolled activity in the cell
What is an unbalanced genetic change?
One which changed the quantitiy of genetic material
What is a polymorphism?
A benign variant of a gene
What is splicing?
When exons are joined together
What is alternative splicing and where is it useful in the body?
Alternative slicing is the splicing of exons in a different order it can be useful in the prodction of antibodies
List many types of variant
Duplications of genes or part of geneDeletions (whole gene or some exons)Variants within the regulatory sequenceSplice site variantsIntroduce premature stop codon-nonsense variantReplace one amino acid in protein with another – mis-sense variantExpansion of trinucleotide repeats
What is an out of frame deletion?
Out of frame deletion clearly disrupts the protein removes just one base and affects codons
What is an in frame deletion?
Where 3 bases or a multiple of 3 are deleted simply removing one codon.
Splice site variant
Affects the accurate removal of an intron
Non-sense variant
changes a codon to a stop one. this could be from out of fram deletion or single base change.
What is non-sense mediated decay?
when mRNA doesn’t have the correct ending which can be detected and this mRNA can be destroyed before it is translated
Mis-sence variants
single base substitution that changes the amino acid can be pathogenic of benign.
Name 3 diseases with expansion of tri-nucleotide repeat
Huntington’s disease CAG
Myotonic dystrophy CTG
Fragile X CGG
Anticipation
when a disease is onset earlier and more severely over time. Repeat gets bigger when transmitted to the next generationand so symptoms develop earlier and are more severe
ALLELIC HETEROGENEITY
Lots of different variants in one gene e.g. cystic fibrosis
LOCUS HETEROGENEITY
Variants in different genes give the same clinical condition e.g. hypertrophic cardiomyopathy
Name the mechanisms of dominance
Loss-of-function variants Only one allele functioning recessive.
If a pathway is very sensitive to the amount of gene product– Haplo-insufficiency
Gain of Function variants Increased gene dosage a variant may occur at the recognition site for protein degradation leading to an accumulation of undegraded protein within the cell
Dominant-negative variants Where the protein from the variant allele interferes with the protein from the normal allele.
What is a diagnostic test?
Patient has signs and symptoms suggesting a particular diagnosisA molecular genetic test will confirm a diagnosisIn this context a genetic test is being used to confirm a clinical diagnosis.
What is a predictive test?
Testing health at-risk family members for a previously identified familial variant – often dominantHD No interventionBRCA1/2 some intervention
What is carrier testing?
Autosomal recessive and X-linked disorderTesting an individual in isolation not particularly helpful – couple testingReproductive decision making
What is Pre-natal testing
Genetic test performed in pregnancy where there is a increased risk of a specific condition affecting the fetusChorionic villous sample or amniocentesisOften chromosomal or DNA if specific variant in the family has been identified
What is a multifatorial disease?
A disease whose severity is affected by genetic and envoronmental factors
How can genetic effect of a disease be studied?
twin studies
what are the characteristics of a multifactorial inheritance?
The incidence of the condition is greatest amongst relatives of the most severely affected patients
The risk is greatest for the first degree relatives and decreases rapidly in more distant relatives
If there is more than one affected close relative then the risks for other relatives are increased
What is a metabolic process?
In biochemistry metabolism is a sequence of chemical reactions: a particular molecule is converted into some other molecule or molecules in a defined fashion.
What are the 4 dietary metabolic pathways?
Biosynthetic Fuel storageWaste disposal Oxidative processes
What is the cori cycle?
When 2 lactate is converted to 2 pyruvate then into 1 glucose by 6ATP where muscles are doing anaerobic respiration
Which of the following is a catabolic or anabolic process Storage ,Biosynthetic, Oxidative, Waste disposal?
Storage - anabolic Biosynthetic - anabolic Oxidative - catabolic Waste disposal - (either)
Name 4 diatary fuels
CarbohydratesLipidsProteinsalcohol
What is the energy per gram of Carbohydrate?
4kcal/g
What is the energy per gram of protein?
4kcal/g
What is the energy per gram of alcohol?
7kcal/g
What is the energy per gram of lipid?
9kcal/g
What is Basal metabolic rate?
A measure of the energy required to maintain non-exercise bodily functions such as; respiration, contraction of the heart muscle, biosynthetic processes, repairing & regenerating tissues,ion gradients across cell membranes.
What is the Average Basal metabolic rate with units?
1kcal/kg/hour
What condtions are needed for measuring BMR?
• Post-absorptive (12 hour fast) • Lying still at physical and mental rest • Thermo-neutral environment (27 – 29oC) • No tea/coffee/nicotine/alcohol in previous 12 hours • No heavy physical activity previous day • Establish steady-state (~ 30 minutes) * If any of the above conditions are not met, then = Resting Energy Expenditure (REE)
What factors affect BMR and how do they do this?
Increased age decreases BMRGender Male is higher than femaleDieting/ starvation decreases BMRHypothyroidism lowers itLower muscle mass causes lower BMRIncreased BMI increases BRMHyperthyroidism increases BMRFever/ infection and disease increases BMRCaffeine/ stimulants and exercise also raise BMR
What happens to excess enerygy intake?
Store as triglycerides in adipose (approx 15kg),Store as glycogen (up to 200g in liver & 150g in muscle), 80g in the liver after overnight fast,Store as protein in muscle (approx 6kg).
Explain what happens during starvation in terms of hormones and energy sources.
lowered insulin increased cortisol. lipolysis and proteolysis consequently increase. Gluconeogenesis happensafter 4 days the liver produces ketones from fatty acids and brain starts to use ketones
Malnutrition
A state of nutrition with a deficiency, excess or imbalance of energy, protein or other nutrients, causing measurable adverse effects
What are the dangers of re-feeding too quickly?
Re-feeding syndrome: Re-distribution of phosphate and magnesium due to insulin switch back to carbohydrates as the main fuel with requires more phosphate and thiamine.
What are essential fatty acids?
Ones that the body cannot synthesise itself. The main ones are polyunsaturated ones such as omega-3 and omega-6
What are some uses of trace elements and vitamins
Co-factors for metabolism (iron) gene espression, structural components, Antioxidants
What are the uses of Vitamin C (ascorbic acid)?
Heat labileCollagen synthesisImprove iron absorptionAntioxidant
What are the uses of Vitamin B12 cobalamin?
Protein synthesis, DNA synthesis, regenerate folate, nerve cells, fatty acid synthesis, energy production
What are the uses of Vitamin B1 thiamine?
helps with energy production
What are the uses of Vitamin D?
increases Ca absorption and helps deposit Ca and phosphate to teeth and bones.
how much protein should you take in?
0.8g/kg/day
What is the substrate of glycolysis?
Glucose
What mechanism is used in respiration for the “creation” of energy?
Substrate level phosphorylation
Describe the preparative step in glycolysis
Glucose is phosphorylated twice using ATP, by hexose kinase and phosphofructokinase-1
What is the ATP generating phase in glycolysis?
When Phosphoglycerate Kinase converts 1,3-bisphosphoglycerate to 3-phosphoglycerate yielding 2 ATP.
And when Pyruvate Kinase converts Phosphoenolpyruvate to Pyruvate yielding 2 pyruvate molecules and 2 ATP molecules.
What is the name of the enzyme that converts glucose into glucose 6-phosphate?
hexokinase
What is glucokinase?
An enzyme in the liver that does same job as Hexokinase but has a much higher km
At what stage in glycolysis is the fate is the substrate committed to glycolysis?
When PFK-1 converts fructose 6-phosphate to fructose 1,6bisphosphate this process is irriversible and requries ATP
What happens once glucose is phosphorylated to glucose 6 phosphate?
Phosphoglucose isomerase converts it to fructose 6-phosphate.
How many molecules and at what stages are ATP required in glycolysis?
Hexokinase turning glucose into G6P. when PFK-1 converts fructose 6-phosphate into fructose 1,6-phosphate. these are the investment steps
What regulates PFK-1?
AMP increases its effects so does F1,6bisphosphate. ATP inhibits it as does citrate.
What is the rate limiting step of glycolysis?
PFK-1 converting fructose 6 -phosphate into fructose 1,6- phosphate.
what regulates hexokinase?
its product G6P
What is the name of the enzyme that converts fructose 1,6-phosphate into two triose phosphates?
Aldolase it is a reversible reaction.
What are the products of the aldolase enzyme?
glyceraldyhyde 3-phosphate and dihydroxyacetone phosphate
Which enzyme converts dihydroxyacetone phosphate to glyceraldehyde 3-phosphate
triose phosphate isomerase
Describe how Glyceraldehyde 3-phosphate is converted to 1,3-bisphosphoglycerate
inorganic phosphate and NAD+ are used with a glyeraldehyde 3- phosphate dehydrogenase to produce an NADH molecule and 1,3-bisphosphoglycerate
At which stages are high energy phosphate molecules made in Glycolysis?
in 1,3-bisohosohoglycerate as an acyl-phosphate and in phosphoenol-pyruvate as an enolic phosphate.
which stages in glycolysis produce ATP?
1,3-bisphosphoglycerate turning to 3-phosphoglycerate by phosphoglycerate kinase and phosphoenol-pyruvate turning into pyruvate by pyruvate kinase
what enzyme converts 3-phosphoglycerate to 2-phosphoglycerate?
phosphoglycerate mutase
what is the action of enolase?
It converts 2-phosphoglycerate into phosphoenol-pyruvate it produces water
What acts to regulate the action of pyruvate kinase?
ATP decreases its activity, fructose 1,6-bisphosphate increases its activity
What are the net products of glycolysis?
2ATP and 2NADH per molecule of glucose 2 pyruvate
What happens to NADH when aerobic respiration cannot take place?
It is used to reduce pyruvate to lactate which oxidises the NADH to NAD+ which can be used in glycolysis again.
Which tissues rely on anaerobic glycolysis and why?
Red and white blood cells, kidney medulla and sometimes muscles. in RBC there is no mitochondria so this is only source of ATP
Where in the cell does glycolysis take place?
In the cytosol/cytoplasm.
What is the action of Adenylate kinase?
2 ADP AMP+ATP to keep balance
Where does the citric acid cycle take place?
In the cytosol of the mitochondria aka the matrix
How does pyruvate enter the TCA cycle?
It is transported across the mitochondrial membranes inside it is converted to acetyl co-A a CO2 molecule is lost and a reduced NAD is formed. pyruvate dehydrogenase inhibited by products
What are the products of one turn of the TCA cycle?
2x CO2 3x NADH 1x FADH 1x GTP
Name the chemical intermediates in Krebs’ cycle in order
Oxaloacetate, Citrate, Isocitrate, Alpha-ketoglutarate, Succinyl-CoA, Succinate, Furmate, Malate
Which enzyme joins oxaloacetate with acetyl-CoA?
Citrate synthase
What does aconitase do?
Converts citrate into isocitrate.
What converts isocitrate into alpha-ketoglutarate and what are the products?
isocitrate dehydrogenase which produces CO2 and NADH
What converts alpha-ketoglutarate into succinyl-CoA?
alpha-ketoglutarate dehydrogenase and it produces CO2 and NADH
What does Succinyl CoA thiokinase do?
converts succinyl-CoA into succinate producing a GTP
What happens to Succinate in the TCA cycle?
it is dehydrogenated to furmate by succinate dehydrogenase producing an FADH2
What converts furmate to Malate?
furmase and water is added to it
How is oxaloacetate regenerated in the last step?
malate dehydrogenase converts malate to oxaloacetate while producing NADH
What inhibits citrate sythase?
high citrate concentration, NADH which also affects the amount of malate and oxaloacetate.
What are the rate limiting steps of the citric acid cycle?
Citrate synthase converting oxaloacetate to citrate
isocitrate deh2ase converting isocitrate to alpha-ketoglutarate
a-KG deH2ase converting a-KG to succinyl CoA
Which enzyme is activated by Ca2+?
alpha-ketoglutarate dehydrogenase
What are the sources of fatty acids?
from triglycerides and phospholipid.
What is a carnitine shuttle?
It moves fatty acids that are more than 14 carbons long across the mitochondrial membrane.
Describe the structure and function of a chylomicron
It is made of fatty acids and cholesterol and apoproteins which carry lipids in the lymphatic system and the bloodstream.
Describe fatty activation
ATP is added to a fatty acid to turn it into acyl adenylate and an inorganic phosphate is released. then Coenzyme A is added to produce acyl-CoA
What is the purpose of fatty acid beta-oxidation?
To produce acetyl CoA that can be used in the krebs cycle
Outline the process of beta-oxidation
A long acyl-CoA is split into many smaller acetyl-CoA molecules
What are the stages of fatty acid oxidation?
First one of the carbons 2nd to the Co-A is dehydrogenated to make a double bond.
Then water is added to make an alcohol group.
Then that is oxidised to a double bond O.
Then the acetyl-CoA is released and an acyl-CoA
Which enzyme creats the double bond on the beta carbon in fatty acid oxidation?
Acyl-CoA dehydrogenase it produces an FADH2
What is the function of Enol-CoA hydrate?
it adds a water to the double bond to produce an alcohol.
What is the function of Hydroxyacyl CoA-deydrogenase?
It oxidises the OH to a O= and produces an NADH
what is the action of Thiolase?
It separates the Acetyl-CoA from the acyl and adds a CoA to the remaining acyl
Where does beta oxidation of fatty acids take place?
In the matrix of the mitochondria
What happens if there is an excess of acetyl CoA?
it can be converted into ketones
Name the three ketones we can synthesise
Acetone, acetoacetate and betahydroxybutyrate
What regulates ketogenesis?
Overloading of TCA Cycle (when there is too much acetyl CoA from increased FFA oxidation)
High G3P In liver increases triglyceride production and low level increases ketone production
ATP demand being high will result in more acetyl CoA in TCA cycle
Fat oxidation is dependent on glucagon (activation) or Insulin (inhibition)
What is the clinical significance of Ketogenesis?
normally ketones are produced in low levels. if there is a shortage of carbohydrates then fatty acids are released. excess ketogenesis can cause ketoacidosis.
What are the conditions can lead to ketoacidosis?
Chronic alcohol abuse, insulin dependant diabetics when not enough insulin given and newly diagnosed type 1 diabetics
Why does low levels of insulin cause production of ketone bodies?
insulin usually inhibits lipolysis enzymes so with lower levels lots of lipid is released causing high levels of fatty acids and acetyl CoA so TCA overload and increased ketone bodies
How does high blood ethanol concentration lead to ketogenesis?
high alcohol levels cause impared gluconeogenesis so low glucose and decrease insulin secretion which increases lipolysis and then too many fatty acids overload the TCA cycle.
What are the blood stats for ketoacidosis.
Low blood pH, high pO2 low pCO2 and low HCO3.
Membrane permeability is regulated by what?
transport proteins and the size of molecules.
What can membrane channels select for?
Size of molecule, the charge the voltage over the membrane
What type of transport do membrane channels allow?
passive diffusion
List the types of carriers across membranes and their functions?
Uniport- single substancesymport- two substances in the same directionAntiport- two substances in the opposite direction
are carriers active or passive??
the can be either
Name the types of forces that drive movement across membranes.
Electrical gradients, electrochemical gradients chemical and electrical combined,
What are the types of passive and active transport across a membrane.
Passive: simple diffusion, facilitated diffusion.Active: Primary, Secondary
What is simple diffusion?
When small/lipid soluble molecules pass through the membrane by diffusion down a concentration gradient alone. eg gases
What is facilitated diffusions?
this is when diffusion down a gradient is assisted by a protein carrier but no energy is expended
What is an example of facilitated diffusion?
Glucose transport into the cells though GLUT2/4
What is primary active transport?
Directly uses a source of ATP eg sodium potassium pump
What is secondary active transport?
It is when a substance is transported against its concentration gradient while another ion or product moves with its concentration gradient. eg sodium glucose co transporter in the renal tubules.
Describe some mechanisms of cellular signalling
intracellular peptide or steroid hormones. peptides happen on the surface. they can change genes
What is endocytosis?
transport into a cell through invaginations of the cell membrane.
What is the action of proton pump inhibitors?
Act on H+/K+ ATPase in gastric parietal cells to reduce acid production
What is the role of cholesterol in the phospholipid bilayer?
it regulates fluidity of the membrane
What is the general structure of a phospholipid?
fatty acid chain tail that is non polar and hydrophobic and a head which is a phosphate group which has a charge and is hydrophillic
What substances can pass freely though a phospholibid bilayer?
Water (aquaporins), CO2, N2 O2 small uncharged molecules like urea and ethanol.
Which types of substances cannot pass through a membrane?
Ions charged polar molecules or large molecules
What types of proteins can be present in a membrane?
Receptors, ATP driven transporters, Transporters, Ion channels, Self:non self proteins
why are membrane proteins needed?
cell polarisation and compartmentalisation.
What is the total water in a 70kg male?
42L
Which has the most water and what quantity intra or extracellular fluid?
Intracellular what is inside the cells at 28L
What is the volume of water in the extracellular fluid and what proportion of the total fluid is that?
14L 1/3 of the total water
What is intravasuclar fluid?
Fluid that is in the blood 3L
What is intersititial fluid and how much of it is there?
11L it is the fluid that is in tissues between the cells
What determines the movement of water between compartments?
the osmotic gradients
What are the main ions in the ECF?
Sodium, chloride and bicarbonate
What is the predominant ion in the intracellular fluid?
potassium
Which molecules contribute to the osmolarity of the ECF?
sodium ions glucose urea chloride and bicarbonate
What is the equation for plasma osmolarity?
2[Na]+2[K]+urea+glucose
what are some of the ways we can lose water?
Sweat, water vapour in breath, urine, faeces
why is water not given intravenously?
it is hypo-osmolar/ hypotonic meaning cells would burst near to it in the blood
What is the normal osmolarity of plasma
275- 295 mmol/kg
What is extracellular fluid?
plasma and intersitital fluid
How does the body react to dehydration?
It senses increased osmolarity in the ECF.Anti-diuretic hormone(vasopressin) is released from the posterior pituitary.This increases renal water retention by increasing reabsorption of water.also stimulates thirst centre in the hypothalamus.
What is the action of ADH/ vasopressin?
It increases the permeability of the collecting ducts of the kidneys buy causing aquaporins to be added meaning more water is reabsorbed.
What does ACE do?
converts angiotensin 1 to angiotensin 2
Which organ produces angiotensinogen?
The liver
Which organ produces ACE?
The surface cells of pulmonary and renal endothelium.
what is the function of renin?
To cleave angiotensinogen into angiotensin 1
Name some of the effects of angiotensin 2
increase sympathetic activity
increase tubular sodium and chloride re absorption
Potassium excretion and water retention
adrenal gland cortex produces aldosterone to increase water retention
arterioles constrict to increase blood pressure
In sever cases ADH is secreted
What is the different between ADH and aldosterone’s action?
Aldosterone increases the volume whilst maintaining osmolarity by reabsorbing ions. Whereas ADH increases the volume and decreases osmolarity since it doesn’t reabsorb minerals as well.
What are some common causes of dehydration?
reduced water intake, vomiting diarrhoea, sweating
What are the signs of dehydration?
Thirst, dry mouth, inelastic skin, sunken eyes, raised haemocrit, weight loss, confusion, hypotension
What is the body’s response to water excess?
ECF osmolarity decreases, there are no thirst hormones released, there is inhibition of ADH production so the amount of urine passed is increased.
what are the consequences of excessive water intake?
Hyponatremia and cerebral overhydration which can cause headache confusion and convulsions.
What is volume overload and some common causes?
when there is too much fluid in the interstitial space. this can be caused by heart failure, kidney failure or cirrhosis
What happens during volume overload?
The interstitial volume is increased while the intravascular volume is decreased which causes increased ADH and aldosterone prodction which can worsen the symptoms leading to oedema
What is oedema?
excess accumulation of fluid in interstitial space
What are some general causes of oedema?
Loss of plasma protein, Inflamation: increased capillary permeability or obstruction of venous blood or lymphatic return.
What is serious effusion?
excess water in a body cavity
What is the mechanism for inflammatory oedema?
the vessels become inflamed and the spacese between cells increase which causes albumin to be released into the interstitial fluid.
what is venous oedema?
blood pools in the calves and causes higher pressure and the hydrostatic pressure is increased.
What is lymphatic oedema?
where the water is not as readily absorbed into the lymphatics system leading to oedema.
What is hypoalbuminaemic oedema?
When there are lower levels of albumin in the blood so the oncotic pressure is reduced.
What is a pleural effusion?
fluid outside the lungs.
Describe what transudate is?
fluid that is pushed through the capillary die to high pressure in the capillary and has a low protein content.
Describe exudate
it is fluid that has leaked around the cells due to inflamation and has a high protein content.
What is the relevance of sodium concentration levels?
It tells you the concentration but not the total body content as this is affected by the water quantities.
what are some causes of hypernatraemia?
Water deficit: poor intake osmotic diuresis, diabeties insipidusSodium excess: mineralocorticoid(aldosterone)salt poisoning
What are some causes of hyponatraemia?
Artefactual from excess water.sodium loss: diuretics, Addison’s diseaseExcess water: IV fluids(iatrogenic) SIADH
what is a severe effect of hypernatraemia and hyponatraemia?
cerebral intracelllular dehydration (tremors, irritability, confusion) and for hypo cerebral intracellular overydration (headache, confusion, convulsions)
after fertilisation but before implantation describe the structure of the embryo
there is a group of amniotic cells forming a cavity, one outside this lining the trophoblast called the yolk sac and then the outer layer of trophoblast cells.
What is the name for the type of structure of the embryo before implantation?
Blastocyst where the ICM has differentiated into the bilaminar disk
what are the three layers of the trilaminar disk?
the ectoderm in blue, the mesoderm in red, and the endoderm in yellow
Describe the formation of mesoderm
cells from the base of the primitive streak break of and migrate to between the two layers of the bilaminar disk. this is by day 17.
List some of the tissues the Ectoderm develops into.
Epidermis of skin, hair, nailsMammary, sweat and sebaceous glandsCentral nervous systemPeripheral nervous systemPituitary glandEnamel of the teethLens of the eye and parts of the inner earSensory epithelium of nose, ear and eye
List some of the tissues the mesoderm develops into.
All of the musculoskeletal systemDeep layers of the skinAbdominal and chest walls and liningThe walls of the bowel (but not the lining of the bowel)The urogenital system
List some of the tissues the Endoderm develops into.
Epithelial lining of the gastrointestinal tract, respiratory tract and urinary bladder.Parenchyma of the thyroid gland, parathyroid gland, liver and pancreas.Epithelial lining of the tympanic cavity and auditory tube.Plays a part in the development of the notochord.
Describe the formation of the notocord.
Mesoderm develops a tube from the end of the primitive streak extending towards the cranial end.
The tube fuses with the endoderm to become a groove
the plate fold and become a full tube which is the notochord
How is the neurual tube formed?
the layer of cells above the notocord in the ectoderm converge to form the neurual fold and crests. one part forms a tube the other the neural crest the forms components of the PNS
where are somites derived from?
the paraxial mesoderm after the nevelopment of the neural tube.
What do somites become?
the myotomes
what produces dermotomes?
the ectoderm overlying the somites.
what is unique about each somite?
it is supplied by a single spinal nerve
What does the intermediate mesoderm give rise to?
urogenital system—the kidneys, the gonads, and their respective duct systems.
what does the lateral mesoderm give rise to?
Lateral mesoderm – splits into two layers; The outer layer covers the inside of the chest and abdominal walls; the somatic (parietal) layer mesoderm.The other layer covers the organs in the thorax and abdomen; the splanchnic (visceral) layer mesoderm.
How is the embryo folded?
In lateral folding the outer layers of amneaon fold to bring in part of the yolk sac to form the primitive gut made of endoderm.
Caudal folding: cranial area contains the mouth which needs moving to the front. heart needs moving down and brain up the tail end rolls up.
What has happened after a week in the embryonic development?
Fertilization, formation of the morula and blastocyst
What has happened after 2 weeks in the embryonic development?
Implantation of the blastocyst and formation of bilaminar embryonic disc and early placenta
What has happened after 3 week in the embryonic development?
Differentiation of cell layers to form the tri-laminar embryonic disc
What has happened after 4 weeks in the embryonic development?
Folding of the embryo and continuing developmentOf the three germ layers
What has happened after 5-8 weeks in the embryonic development?
Development of all organs
Which diseases are caused by endocrine failure?
Diabetes, thyroid disorders, acromegaly.
What is homeostasis?
Maintenance of a constant internal environment
What kind of things does your body control?
Temperature, pH, Blood pressure, Oxygen concentration, glucose and energy production or demans
How do cells communicate with each other to allow homeostasis to happen?
Endocrine, nerves and immune system.
What are the three types of signals in the body?
Electrical, Ions and Hormones
What are the three mechanisms of hormone communication?
Autocrine, paracrine, endocrine
What is autocrine communication?
A cell produces a signal and the signal stimulates a receptor on the surface of the same cell
What is paracrine communication?
Cells talking to neighbouring cells that are close to them. produces a signal that acts on a receptor that is close by
What is an example of paracrine hormones?
Acetylcholine in nerve cells and muscles
What is endocrine communication?
When a cell releases a hormone into the blood and then goes to a distant site to reach a target cell
Name some key endocrine organs
Hypothalamus, pituitary, thyroid, parathyroid, thymus, adrenal, pacreas, ovaries, testes
Explain the link between hypothalams and an endocrine gland?
Hypothalamus produces 6 main hormones, to the anterior pituitary it releases 6 main hormones and these can stimulate endocrine glands or affect target tissue directly
What are the hormones that the hypothalamus releases?
gonadotrophin-releasing hormone,
Growth hormone-releasing hormone,
Somatostatin,
Thyrotropin-releasing hormone,
Corticotropin-releasing hormone
dopamine
What are the chemicals that the anterior pituitary releases?
FSH
LH
GH
TSH
Prolactin
ACTH
What does the posterior pituitary do?
The hypothalamus uses special nerve cells to transmit the transmitter to send signals to the posterior pituitary to release oxytocin and anti-diuretic hormone which it has stored
What is a positive feedback loop?
a cell stimulates a cell and that cell does an action that stimulates the first cell.
What is a negative feedback loop?
A cell produces a hormone to stimulate a cell then this effect inhibits te orignal signal
What is the pituitary-thyroid axis?
Anterior pituitary reases thryoid stimulating hormone, then the thyroid produces thyroxine that affects cells, this thyroxin inhibits release of TSH it also inhibits the hypothalamus which stimulates anterior pituitary with thoxine releasing hormone. TSH can also inhibit the hypothalamus
What is the definition of a homone?
A molecule that acts as a chemical messenger
What are the three types of hormone?
Amino- acid derivative, peptide and steroid
How do peptide hormones work?
They produce a quick response like adrenaline, thyroid stimulating hormone is as well. they are hydrophilic and can be glycoproteins. they are synthesised from tyrosine. they bind to external receptors on cells
How do steroid hormones work?
Eg testosterone. It is produced in the testes and diffuses into the blood bound to transport proteins. it can pass though cell membranes into cells and the receptors are in the cell and it affects the DNA expression
What is a primary hormone problem?
Problem with the endocrine gland itself
What is a secondary hopothyroidism?
The initial problem is wih the pituitary or hypothalamus
What is simple diffusion?
High concentration to low concentration travell across the membrane, urea free fatty acids blood gasses water and ketone bodies
Give an example of facilitated diffusion?
Glucose is transported down concentration by GLUT4 enzyme from the enterocyte into the blood
What is primary active transport?
Where ATP is used to pump something against its gradient
Secondary active transport?
It is where the gradient from one molecule is exploited to transport another in the opposite direction.
What molecules might be present on the membrane surface?
Ion exchange proteins, nutrient transport, self noself molecules ion channels g protein coupled receptors
What is para-cellular absorption?
When molecules are absorbed alongside the cells not from the apical surface
What are gap junctions?
allow flow of ions or molecules between the cytoplasm of two cells
What are some different types of receptors
steroid receptors in the nucleus, receptor linked ion channels in the membrane, G protein coupled receptors, some steroids can bind to receptors on the membreane, neurotransmitter receptors, growth factor receptors.
What is a G protein couples receptor?
The receptor is on the outside to recieve the signal, then there are three g protiens alpha beta gamma, alpha gives the specificity there is an enzyme that makes a second messenger often anenylyl cyclase that produces cAMP. can be inhibitory or exitatory
What regulates Citrate Synthase?
ATP and NADH and Citrate inhibit it
Succinyl CoA inhibits it
ADP activates it
What regulates Isocitrate dehydrogenase?
ATP, NADF inhibit it
ADP activates it
Isocitrate deH2ase increased then this leads to a decrease in citrate level which subsequently increases citrate synthase rate
What regulates alpha-ketoglutarate dehydrogenase?
Inhibited by its products, NADH and succinyl-CoA
Also inhibited by GTP, ATP and ROS.
Activated by Ca2+ which means it can generate ATP during intense muscle exercise
What do all the symbols mean on a hereditary genetic tree diagram?
What type of protein structure would zinc fingers, helix-turn-helix and beta-alpha-beta be classed as?
Super Secondary protein Structure
