Other

Question 1

Most common medical imaging file format

Answer 1

DICOM

Question 2

Imaging resolution

Answer 2

Number of pixels across each axix

Question 3

intensity/ grey scale

Answer 3

Number for a pixel (identity)

Question 4

Intensity/ grey scale resolution

Answer 4

range of possible intensity values

Question 5

Spacial resolution

Answer 5

measure of smallest discernable detail in an image

Question 6

Aspect ratio

Answer 6

ration of its width to its height

Question 7

Dynamic range

Answer 7

range of intensity values to display the image

Question 8

Difference between low intensity and low spatial resolution

Answer 8

Low intensity: not able to discen objects that look similar Spatial resolution: not able to see small object/ structures

Question 9

Visualisation in slice vs volume mode

Answer 9

slice: slices of a 3d image Volume: 3D visualisation progamme.

Question 10

How x ray works

Answer 10

electrons fired at a target, x rays are reflected back and they have different penetrances in the body.

Question 11

From black to white state order of following tissues water, fat, air, bone, metal, soft tissue

Answer 11

air, fat, soft tissue, water, bone, metal

Question 12

What is a CT scan

Answer 12

x rays at many different angles, giving depth to the image

Question 13

Difference between alpha and beta decay

Answer 13

Alpha decay: alpha particle (H2+) ejected Beta decay: positron (beta plus) or electron (beta minus) is released

Question 14

Gamma emission

Answer 14

particles decay and give off gamma rays

Question 15

Most penetrating ionising radiation: beta, gamma or alpha

Answer 15

Gamma, then beta then alpha

Question 16

PET scans

Answer 16

Emits gamma rays, creating 3D image

Question 17

MRIs

Answer 17

Emits magnetic waves which detect hydrogen concentration. Very good for soft tissue differentiation

Question 18

US (ultrasound imaging)

Answer 18

emits ultrasound pulse and see what is reflected

Question 19

Match body compartment with amount of fluid in l it has Interstitial space, plasma space, Intra cellular space 3.5, 28, 10.5

Answer 19

Intracellular : 28 Interstitial : 10.5 Plasma: 3.5

Question 20

Plasma and intracellular concentrations of: NA, K, Ca

Answer 20

Question 21

Crystalloid vs oncotic pressure

Answer 21

Crystalloid: pressure excerted by small diffusible particles (usually equal on both sides of membrane)

Oncotic: pressure created by non diffusible larger particles like proteins (usually slightly higher on one side of membrane)

Question 22

Normal RBC and WBC Count

Answer 22

Red blood cell: 5*10ˆ12

White blood cells: 4-11 *10ˆ9

Question 23

Series vs parallel

Answer 23

check

Question 24

Darcy’s law

Answer 24

Flow proportional to pressure difference (P1 -P2 ) and inversely proportional to the resistance to flow

Question 25

Poisseuille's law

Answer 25

resistance to flow is 4 times to the power of the radius of the tube

Question 26

Axial streaming in blood vessels

Answer 26

Particles in blood tend to move to area with fastest moving fluid - the center. Reduces viscocity

Question 27

Normal blood pH and living range pH

Answer 27

Normal blood: 7.35-7.45 Living range: 7.0 - 7.8

Question 28

What is pH, and what is the equation of pH

Answer 28

pH: concentration of **free** hydrogen ions pH = -log [H+]

Question 29

What is pKa, what a high or low pKa means

Answer 29

pKa: the log of the pH at which an acid is half dissociated. The lower the pKa, the stronger the acid is.

Question 30

The pH at which a certain buffer will work best is...

Answer 30

at the pKa of the acid in the buffer

Question 31

Which amino acid is a buffer in the body? Why?

Answer 31

Histidine: it's pKa is around physiological pH It is part of haemoglobin and it's pKa changes depending on oxygenation: Oxyhaemoglobin: pKa of 6.8 Deoxyhaemoglobin: pKa of 7.8

Question 32

What is the concept of cooperativity thinking about haemoglobin

Answer 32

Haemoglobin displays cooperativity because it's affinity for it's ligand changes with the amount of ligand already bound (oxygen) Will bind oxygen better if it already has oxygen bound to it

Question 33

What action does BPG have on O2 binding? What is the difference in it's effect in fetal and adult haemoglobin?

Answer 33

BPG lowers Hb's affinity for oxygen by binding to the center of the tetramere in it's t-state and stabilising the structure. It is produced by all metabolic tissues. BPG is less effective in fetal haemoglobin, which means that fetal haemoglobin will have a higher affinity for O2 compared to HbA.

Question 34

Location of the heme group within the globin molecule (and the letter name of alpha helices it is bound to). Role of E7 his residue

Answer 34

Bound between E and F helices. E7 histidine group stabalizes the bond of O2 with Fe and destabilizes the bond of CO2 with Fe.

Question 35

Difference between tense and relaxed conformations of haemoglobin

Answer 35

Tense occurs at tissues in presence of low pH and other, causes low affinity for oxygen Relaxed occurs at lungs where higher pH, low BPG, causes higher affinity for oxygen.

Question 36

Classify the following types of protein as being targeted by a) signal peptide or b) other peptide signal Secretes protein Membrane Protein Mitochondrial proteins Lysosomal proteins Perixosomal Proteins Nuclear Proteins

Answer 36

Question 37

Describe the pathway of protein synthesis and its binding to the membrane using Signal Recognition Particle

Answer 37

Translation begins, and signal sequence is the first to be synthesised. It binds to a SRP, which itself binds to a **SRP receptor** on the ER. This binds the ribosome to the ER, and the rest of the protein synthesised gets guided through a **translocon** into the ER membrane. **Signal Peptidase** cleaves this signal sequence, and SRP is recycles

Question 38

Fate of membrane proteins

Answer 38

Membrane proteins remain in the ER membrane. The **translocon** goes away when stop sequence is reached , leaving the matured protein.

Question 39

Protein processing in the golgi and 4 different pathways they follow after that

Answer 39

Proteins enter **cis-golgi** where they more through its **cisterna** via vescicles and get packaged and sorted. They become: Membrane proteins Stimulated secretory pathway (insulin) Continuous secretory pathwy (matrix proteins) Lysosomes

Question 40

Pathway for mitochondrial proteins

Answer 40

Get translated and released in an **unfolded** form into the cytoplasm (still has signal sequence). They bind to **chaperones** which brings them to specific receptors on the mitochondria. They translocate through the membranes and are cleaved of their signal sequence and fold once iside.

Question 41

Pathway for nuclear proteins

Answer 41

Nuclear proteins have a specific signal called a **nuclear localisation signal** (PKKKRKV). They are not folded either before entering nucleus. The **NLS** binds to an **importin** protein which transports it through nuclear pores. The complex then dissociates and protein folds.

Question 42

Pathway of lysosomal proteins

Answer 42

Lysosomal proteins are tagged with **mannose-6-phosphate** in the **golgi.** This directs the protein within the golgi to transport vescicles. In inclusion-cell disease, the proteins are not tagged and get secreted instead.