PCS 2 Flashcards
What is the most common white blood cell?
Neutrophil. (40-60% prevalence)
It’s multinucleated.
What is the function of the initiation factor eIF-4?
It binds to the methylated cap of mRNA so that 40S ribosomal subunit can start scanning mRNA in 5’ – 3’ direction.
Name the components and function of the conducting zone.
Trachea –> Main Bronchus –> Lobar bronchi –> Segmental Bronchi –> Terminal Bronchioles.
1-16.
NO gas exchange occurs - only ‘bulk flow’ in one direction.
Name the components and function of the respiratory zone.
Respiratory Bronchioles –> Alveolar Ducts –> Alveoli. 17-23.
Gas exchange DOES take place.
What is the equation for Boyle’s law of pressure?
Pressure is inversely proportional to 1/Volume.
Name the myofilaments in a muscle cell.
ACTIN (thin - represents the I band)
MYOSIN (thick - represents the A band)
Where are chief cells found? What do they secrete?
Body of the stomach.
Secrete pepsinogen (zymogen) which is converted into its active form pepsin.
What is the function of transporter GLUT2?
Present on the basolateral membrane only when glucose levels are low.
When glucose levels are high, it appears on the apical membrane aswell.
Name the three sites on a ribosome.
What site does the first and second tRNA bind to?
Exit -> Peptidyl -> Aminoacyl
1st tRNA binds to P site, 2nd tRNA to A site, then they move to the E site.
What is the size of the small subunit? How many rRNAs and proteins?
40S. 1 rRNA and 33 proteins.
What is the size of the large subunit? How many rRNAs and proteins?
60S. 3rRNAs and 49 proteins.
What is Oxytocin responsible for?
Milk ejection
Stimulates uterine contractions
What is the action of the hormone Relaxin?
Relaxes: pelvic ligaments, joints and cervix.
What is the term given to the volume of air that cannot be expelled after vital capacity?
Residual Volume.
How many phases does the SA node have in an action potential? What goes on at each stage?
Phase 4 - pre potential activated upon hyperpolarisation. Sodium ions leak out of the cell via funny/pacemaker channels
Phase 0 - depolarisation (influx of calcium ions via voltage gated calcium channels. T-type first followed by L-typ
e) Phase 3 - repolarisation (potassium ions leave the cell)
What is Haemochromatosis? How can it be dangerous?
Excess of iron in the blood which can be genetic or diet related.
It causes increased deposition in tissues due to free radical reactions (oxidative damage to proteins, lipids and nucleic acids).
It can cause skin pigmentation, diabetes and liver/heart failure.
What are the two Anaphylatoxic properties?
Bronchoconstriction
Vasodilation
What is a Pleural Effusion? How would it look on an X ray?
A build-up of fluid between the lung and the chest wall in the pleural cavity.
X-ray indications: blunting of costophrenic angles
What can be the result of a vitamin D deficiency?
Rickets.
Vitamin D is necessary for calcium absorption therefore lack of it will lead to soft bones and stunted growth.
How does thrombin stimulate a positive feedback system?
Thrombin catalyses the activation of factor 11, 8 and 5 further accelerating the intrinsic pathway.
How many tanner stages are there?
5 for both males and females
1 being the earliest stage of puberty 5 being the latest stage of puberty.
What is primary haemostasis? 6 steps involved?
Formation of a platelet plug.
- vascular contraction
- exposure of collagen
- adherence of platelets to vessel
- release of activating factors from platelets.
- aggregation of platelets to form a platelet plug.
- repair of vessel wall.
Glycoprotein receptors. What is linked to Ia, Ib, IIa?
Ia = collagen. Ib = thrombin. IIa = fibrinogen
What is secondary haemostasis?
Formation of a fibrin clot.
What is the order of coagulation factors from the start of the intrinsic pathway?
12
11
9&8
10&5
What is a nucleoside?
Base and a sugar but NO phosphate group.
E.g. guanosine, adenosine.
Go through the steps involved in fibrinogen to fibrin formation.
- Thrombin cleaves 4 fibrinopeptide A peptides from each molecule of fibrinogen to yield fibrin monomers.
- Fibrin monmers polymerize into long fibrin theads.
- Held togehter by weak non-convalent hydrogen bonding. Not cross linked so it’s a weak clot.
- Thrombin cleaves the fibrinopeptide B peptides.
- This creates side to side aggregation. Strengthens the clot.
What bond does thrombin cleave from fibrinogen?
Arg-Gly
What feature of fibrinogen keeps them apart? What happens after their release?
Fibrinogen has a large negative charge due to aspartate and glutamine residues.
Fibrin moonmers have a different surface charge pattern leading to their specific aggregation.
What type of fatty acid is arachidonic acid? Notation?
Omega 6 fatty acid. 20:4 (n-6)
What type of fatty acid is linoleic acid? Notation?
Omega 6 fatty acid. 18:2 (n-6)
What type of fatty acid is alpha linolenic acid? Notation?
Omega 3 fatty acid. 18:3 (n-3)
Name some examples of the products of housekeeping genes.
Ribosomal proteins, metabolic enzymes, RNA polymerase
What factors does Vitamin K activate?
II, VII, IX, and X
These are factors that also require Ca2+
(& prothrombin)
Example of a Mineralocorticoid?
Example of a Glucocorticoid?
Mineralocorticoid - aldosterone
Glucocorticoid - cortisol
What is only water soluble vitamin that can be stored in the body?
Vitamin B12
Where can vitamin D2 and D3 be found?
D2 in plants
D3 in milk and fish
If you were looking at a white blood cell count, what would be the order of white cells for % present?
Neurophils (40-60%)
Lymphocytes (20-40%)
Monocytes (2-8%)
Eosonophils (1-4%)
Basophils (0.5-1%)
What molecule causes leukocytes to stick to the endothelial cells in the vessel walls?
Selectins.
L selectin is presented on leukocytes.
E selectin is presented on endothelial cells
What molecule aids transmigration of leukocytes through the endothelial cells?
CD31
What does a degenerative code mean?
Many codons can code for a single amino acid.
A maximum of 64 codons & 20 amino acids is possible.
Give examples of minerals that compete in the body.
Zinc and Copper / Calcium and Phosphate
e.g. zinc in excess reduces the amount of copper the body can absorb. This can lead to anaemia and weakening of bones.
What is a conditionally essential amino acid?
An amino acid that you can normally produce yourself but in certain conditions e.g. being a premature infant, you are unable to produce the amino acid required. eg. arginine.
What are cyclin dependant kinases?
Activated by cyclin.
Together, the complex initiates entry into phases.
e.g. G1 –> s or G2 –> M
What molecule is activated upon DNA damage?
What does this do to cyclin-CDKs?
DNA damage triggers activation of P53*** that increases the amount of proteins that ***inhibit G1/S cyclin-CDK.
Therefore, no cell division starts.
What happens if there is a mutation in p53?
The cell doesn’t arrest.
Damaged DNA is allowed to divide.
What is Go phase?
What is a post mitotic cell?
Go - resting state. The environment is not favourable for replication.
Post mitotic cell is terminally differentiated e.g. muscles or neurons - they can lomger lomger undergo mitosis and are inhibited from entering the cell cycle.
Go through the stages of the cell cycle.
In what form is iron stored and transported?
Stored as Ferrous: Fe2+
Transported as Ferric: Fe3+
How does DNA damage arrest the cell cycle in G1?
The p53 protein is activated and stimulates transcription of the p21 gene.
p21 is a protein which inhibits Cdk, so the cell cycle arrests.
p21 binds to S-Cdk and G1/Cdk and inactivates them, so stops the cell moving from G1 phase to S-phase.
How does the SGLT1 transporter work for glucose transport?
Secondary active transport with Na+ (symporter)
Na+K+ATPase on basolateral surface.
Talk through this diagram.
- IgE antibodies are made from interaction between T helper cell and a B cell.
- Mast cells reside in tissues in the body and basophils are in the blood stream. Both have receptors that are specific for the IgE antibody.
- IgE binding causes mast cell degranulation.
- Degranulation of mast cells usually releases histamine - more cells are recuited e.g. eosinophils etc.
Humans cannot insert a double bond in a fatty acid beyond ….?
n-9
The reason why the body can’t make an n-3 or n-6 fatty acid is that human metabolism can’t add a double bond to a fatty acid that is more than 9 carbons away from the delta end (water soluble end).
Name the purines and pyrimidines. How do they differ in structure?
Base pairs?
How does the ribose and deoxyribose sugar differ in structure?
Purines = A and G (two rings)
Pyrimidines = C, T and U (one ring)
A+T(or U) / C+G
Ribose has an OH group on the second carbon. Deoxyribose does not.
Calculation for mean arterial blood pressure?
Total peripheral resistance x Cardiac Output
Cardiac cyle timings
atrial systole?
ventricular systole?
diastole?
atrial systole = 0.1s
ventricular systole = 0.3s
diastole = 0.4s
Go through voltage changes for
a) pacemaker cells
b) ventricular cells
a) NO resting potential. Unstable pacemaker potential = -70mv –> -50mv. Peak at 10mv.
b) resting potential -90mv. Peak at 20mv.
What is Poiseuille’s Law?
What is the equation linking resistance and radius?
What is the equation linking flow, pressure and resistance?
Label
I —- 0
II —- +120
III —- +60
What is measured in a CT scan? Equation?
White - more dense
Black - less dense
Name 4 contraindications for MRI.
- heart pacemaker
- heart valve replacement
- cochlear / metallic implants
- first trimester pregnancy
Briefly go through the gram staining process.
What is the main difference in structure between gram -ve and +ve bacteria?
During translocation, what three events requires
GTP –> GDP?
- 2nd tRNA at A site (EF-1a)
- Translocation (EF-2)
- 3rd tRNA to A site, release of 1st from E site
Proteins can be taken up
a) enterocytes
b) M cells.
Where are they located? What do they do with the proteins?
a) Small intestine. Degrade the proteins in lysosomes.
b) line the Peyer’s patches in terminal ileum. Package proteins into vesicles.
What molecule do fatty acids travel bound to in the plasma?
What parts of the body can’t use fatty acids as a source of energy?
Albumin
RBC and the brain - can’t use fatty acids as a source of energy
Beta oxidation is a cycle of … ?
Oxidation, hydration, oxidation, thiolysis
Fatty acid synthesis is a cycle of … ?
Condensation, Reduction, Dehydration, Reduction
Describe the four stages of apoptosis.
PROGRAMMED cell death
- Decreased membrane permeability to prevent water entering the cell; therefore the cell shrinks
- Chromatin condenses to make it easier to digest
- Nuclear fragmentation
- Cell ‘blebs’* into small fragments or vesicles, ready for *phagocytosis
Describe the three stages of necrosis.
TRAUMA / INJURY
- Increased membrane permeability allowing water inflow to the high osmolarity cytoplasm
- cell swells and eventually bursts (lysis)
- Intracellular contents including ROS released to extracellular environment - may damage other cells
At which point in the menstrual cycle is a women most fertile?
Days 1-5
Days 9-16
Days 17-21
Days 22-28
The most fertile period of the menstrual cycle is from 5 days before ovulation to 1-2 days after. Couples often use this knowledge to increase there chances of conception.
