IMMS editing Flashcards
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.
- Protein
- Haemoglobin
- 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 CoA
Used in the Krebs cycle
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’s
- Haber weiss
2. Haber-Weiss
What is Fenton’s equation?
Fe2+ + H2O2 -> Fe3+ + OH• + OH-
What is the Haber Weiss equation?
O2- + H2O2 -> O2 + OH• + OH-
Define insensible losses.
Water loss that we are unaware of. It is comprised only of solvent and can not be measured.
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 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.
Name 2 allosteric activators of PFK-1.
- AMP.
2. Fructose-2,6-bisphosphate.
Name 3 allosteric inhibitors of PFK-1.
- Acidosis.
- ATP.
- 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.
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 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%.
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.
- 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.
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.
