Week 6

Question 1

The ___ contains all thoracic structures except pleural cavities.

Answer 1

Mediastinum

Question 2

The central mediastinum is divided interior superior and inferior parts by a line from the ___ junction to the the T___/___ disc.

Answer 2

Line from manubriosternal junctional anteriorly to the T4/5 IVD

Question 3

The heart and roots of great vessels are in the middle of the ___ mediastinum.

Answer 3

Inferior

Question 4

Under the manubrium, from superficial to deep are the great ___ -> the aortic arch associated with the ___ and ___ nerves -> trachea, ___, thoracic duct and left ___ ___ nerve.

Answer 4

Great veins ->
Aortic arch associated with the vagus and phrenic nerves ->
Trachea, oesophagus, thoracic duct and left recurrent laryngeal nerve

Question 5

The ___ ___ vein drains the head and neck, and the ___ vein drains the upper limb. These arteries join behind the ___ joint to form ___ veins (1 for each side) that join to form the SVC behind the ___ ___ costal cartilage.

Answer 5

Internal jugular vein (1 for each side) 
Subclavian vein (1 for each side)
Sternoclavicular joint
Brachiocephalic veins
SVC behind the first right costal cartilage

Question 6

Why is the JVP ideally measured on the right side?

Answer 6

The right brachiocephalic vein has a shorter and more vertical course compared to left (longer and more horizontal course) - pressure column directly from RA

Question 7

The brachiocephalic veins join to form thje SVC behind the ___ ___ costal cartilage.
The azygous vein comes up the posterior thoracic wall and arches forwards over the lung roots into the back of the SVC behind the ___ ___ costal cartilage.
The SVC enters the right atrum behind the ___ ___ costal cartilage

Answer 7

First right
Second right
Third right

Question 8

The ascending aorta changes to the arch of the aorta at the ___ ___.

Answer 8

Manubriosternal junction

Question 9

___ ___ is a fibrous ligament between the bifurcation of the pulmonary trunk and the underside of the arch of the aorta. This was a duct in the embyological circulation to bypass pulmonary circulation if blood did not pass through ___ ___ in the septum. In the embryo, the duct is called ___ ___.

Answer 9

Ligamentum arteriosum
It is a backup if blood did not pass through foramen ovale in the septum
Ductus arteriosus

Question 10

What are the first 3 branches of the arch of the aorta?

Answer 10

1st - brachiocephalic trunk - divides right common carotid and right subclavian arteries behind the right sternoclavicular joint
2nd - left common carotid artery
3rd - left subclavian artery

Question 11

In a retroesophageal right subclavian vein variation, the order of branches of aortic arch is right common carotid, left common carotid, left subclavian and THEN right subclavian. To supply the right limb, the right subclavian must pass behind the ___ to get to the right upper limb.

Answer 11

Oesophagus

These patients may present with difficulty swallowing

Question 12

The ___ nerve is formed by the ___ rami of nerves C3/4/5.

Answer 12

Phrenic nerve

Ventral/anterior rami

Question 13

What is the course of the phrenic nerves?

Answer 13

Through neck, down on scalenus anterior and between subclavian vein and artery on each side into mediastinum
It is ALWAYS anterior to the lung root structures and ALWAYS the MOST lateral structure in the mediastinum
Right goes through caval orifice at T8
Left pierces diaphragm where apex of heart contacts left dome of diaphragm

Question 14

The phrenic nerve pierces the ___ and supplies it from its underside.

Answer 14

Diaphragm

Question 15

The ___ phrenic nerve is lateral to venous structures, and the ___ phrenic nerve is lateral to arterial structures.

Answer 15

Right - lateral to venous

Left - lateral to arterial

Question 16

The phrenic nerve is a ___ nerve. The phrenic nerve supplies ___ supply to the diaphragm. It supplies sensory supply to the mediastinal and diaphragmatic ___ and ___.

Answer 16

Mixed
Motor
Pleura and pericardium (i.e. all structures it passes)

Question 17

The ___ nerve is a cranial nerve that moves down the mediastinum - it tries to stay in the midline.

Answer 17

Vagus

Question 18

What is the course of the vagus nerves?

Answer 18

Down neck with common carotid and IJV -> right tucks against trachea, but aortic arch is in way of left, so left passes lateral to aortic arch, BEHIND the lung roots -> left and right ramify on oesophagus to form oesophageal plexus -> through muscular diaphragm with oesophagus at T10 (left of midline)

Question 19

The trachea bifurcates at a plane between the ___ junction and T___/___ (i.e. same as division of superior and inferior mediastinum).

Answer 19

Manubriosternal junction

T4/5

Question 20

Where are the 4 NORMAL sites of narrowing of the oesophagus?

Answer 20

1 at the start of the tube where oesophagus starts as continuation of pharynx (superior narrowing)
1 where it passes through the diaphragm (inferior narrowing)
1 where the aorta arches up/back/left (aortic narrowing of oesophagus)
1 where left main bronchus crosses to LHS from bifurcation of trachea

Question 21

A lymphatic collection sac called ___ ___ collects ALL lymph from below the ___ (lower limbs, pelvis and abdomen). From here, the thoracic duct starts (at the level of T___, between the crura), at the back of the oesophagus and ascends. After it ascends, it descends and collects lymph from the LHS of the head/neck thorax and the left ___ limb. It then drains into the junction of the left ___ ___ vein and left ___ vein.

Answer 21

Cisterna chyli
All lymph from below the diaphragm
Thoracic duct starts at T12
LHS of head/neck/thorax and left upper limb
Drains into junction of left internal jugular vein and left subclavian vein

Question 22

What are the 5 structures in the posterior mediastinum (space behind heart and under the plane b/w manubriosternal junction and T4/5 IVD)?

Answer 22

Descending thoracic aorta and its branches - intercostal (posterior), bronchial, pericardial, oesophageal arteries
Oesophagus and oesophageal plexus (from vagus)
Azygous system
Thoracic duct
Sympathetic trunks
Note - trachea is NOT in the posterior mediastinum as it bifurcates AT the plane, does not extend below the plane

Question 23

___ antimicrobials are used mostly in immunocompromised patients, but in patients with functioning immune system, ___ antimicrobials are often used.

Answer 23

Bactericidal - if immunocompromised

Bacteriostatic - if functioning immune system

Question 24

Penicillin G is non-___ (except if a patient is allergic). But it is acid ___ so most is destroyed in the stomach. Therefore it is injected.

Answer 24

Non-toxic

Acid labile

Question 25

Penicillin V is a modified version of penicillin G by the addition of a ___ group. Penicillin V is acid ___ so can be administered orally.

Answer 25

Benzyl | Stable

Question 26

Glycopeptide drugs like vancomycin are used to treat ___ (abbrev., basically resistant to all beta lactams). They bind to terminal D-Ala-___-___ residues directly. Why does vancomycin not act on G-ve bacteria?

Answer 26

MRSA D-Ala-D-Ala directly G-ve bacteria have outer membranes that are impermeable to large macromolecules and highly charged molecules - vancomycin is large and highly charged

Question 27

Enterococci are Gram ___ cocci. They increasingly show resistance to vancomycin - this is achieved by replacing the D-Ala-D-Ala with D-Ala-D-___.

Answer 27

Positive | Lac

Question 28

VRSA (S. aureus) are rare because the mechanism for resistance appears to cause increased cell stress so the bacteria die out. But vancomycin intermediate SA (VISA) are more common - what is their mechanism of resistance?

Answer 28

They produce extra cell wall material (i.e. peptidoglycan) to mop up vancomycin You can't just increase the dose because vancomycin is assoc. with toxicity

Question 29

Transpeptidases or ___-binding proteins are the enzymes involved in cross-linking of building blocks of peptidoglycan.

Answer 29

Penicillin-binding proteins

Question 30

Penicillin is a suicide inhibitor - it mimics D-Ala-D-Ala bond and binds to transpeptidases or ___-binding proteins. It cannot be hydrolysed so the enzyme is inactivated and synthesis of PTG stops. When PTG synthesis stops, bacteria activate cell wall destroying enzymes that break down their own cell walls resulting in cell death. Therefore, penicillin is a ___ antimicrobial.

Answer 30

Penicillin-binding proteins | Bactericidal

Question 31

Some bacteria produce beta-___ that ___ beta lactam drugs. P. aeruginosa has an ___ encoded class I beta lactamase. These are unaffected by older beta lactamase inhibitors (e.g. clavulanic acid which only acts on ___ encoded beta lactamases).

Answer 31

Beta-lactamases Hydrolyse Chromosomally Plasmid

Question 32

Aminoglycosides like gentamicin target ___. They bind to the site where the aminoacyl ___ recognises the codon. Growth continues initially but structural protein synthesis is affected and the cell cannot grow properly.

Answer 32

Ribosomes | Site where aminoacyl tRNA recognises the codon

Question 33

Resistance to aminoglycosides is by ___ entry into the cell by covalent modifications e.g. acetylation, adenylation, phosphorylation. What are some other mechanisms to ___ entry?

Answer 33

``` Reducing Reduce entry by: Modifications of outer membrane - low level resistance but affects all aminoglycosides Pump out of cell Ribosomal mutation - potent resistance ```

Question 34

Metronidazole is a ___ that is reduced to its active form by a ___ (an enzyme not in humans). This enzyme is esp. found in ___ organisms. Why? How can an organism develop resistance to metronidazole/prodrugs?

Answer 34

Prodrug Nitroreductase Anaerobic organisms - the nitroreductase keeps an environment anaerobic (removal of oxygen atoms) because O2 is damaging to anaerobic organisms Metronidazole is esp. used for anaerobic bacteria and protozoa (e.g. amoebae, Giardia) Resistance by failing to active prodrug e.g. altering nitroreductase enzyme

Question 35

Multidrug-resistant M. tuberculosis (MDR-TB) is resistant to ___ or ___ first line drugs. Extensively drug-resistant M. tuberculosis (XDR-TB) is resistant to all ___ first line drugs, so you can only use second line drugs.

Answer 35

MDR-TB - resistant to 2/3 first line drugs | XDR-TB - resistant to all 4 first line drugs

Question 36

ALL Gram negative bacteria are intrinsically resistant to ___.

Answer 36

Vancomycin - G-ve bacteria have outer membranes that are impermeable to large macromolecules and highly charged molecules - vancomycin is large and highly charged

Question 37

Lines of ___ occur in thrombi in vivo/flowing blood due to layers of red (red cells) and white (platelets and fibrin).

Answer 37

Zahn

Question 38

In arterial thrombi, there is a higher proportion of ___ and fibrin so the thrombus is called "___". Arterial thrombi are associated with ___ dysfunction/damage. ___ (drug) is useful to prevent arterial thrombosis.

Answer 38

Platelets and fibrin White thrombus Endothelial dysfunction Aspirin

Question 39

In venous thrombi, there is a higher proportion of ___ cells and fibrin so the thrombus is called "___". Venous thrombi is associated with blood ___ and hyper___. ___ (drug) is useful to prevent venous thrombosis.

Answer 39

Blood cells Red thrombus Blood stasis and hypercoagulation Warfarin

Question 40

What are the 3 components of Virchow's triad?

Answer 40

Abnormal endothelium - endothelial dysfunction/damage Abnormal blood flow - stasis or turbulent flow Abnormal coagulability - hypercoagulability

Question 41

What is a genetic cause of abnormal coagulability? What are some non-genetic causes of abnormal coagulability?

Answer 41

Genetic e.g. factor V Leiden | Non-genetic e.g. estrogen (OCP, pregnancy), cancer, smoking, obesity, ageing

Question 42

What are the 4 outcomes of thrombus?

Answer 42

1 Dissolution by fibrinolysis 2 Organisation and recanalisation (organisation = granulation tissue with capillaries) 3 Propagation - increase in size of thrombus 4 Embolisation

Question 43

Venous thrombosis usually results in blockage of ___ arteries. Arterial thrombosis can cause occlusion in situ, or in downstream organs. But they are unlikely to affect the ___ because valves cover the ___ ___ during systole.

Answer 43

Venous - pulmonary arteries (e.g. DVT) | Arterial are unlikely to affect heart because valves cover the coronary sinuses during systole

Question 44

___ refers to insufficient blood supply to organ/tissue, and ___ refers to tissue death due to insufficient blood supply.

Answer 44

Ischaemia | Infarction

Question 45

___ ischaemia may be due to coronary thrombosis, thromboembolus, exercise and atherosclerosis, torsion or shock. ___ ischaemia may be due to atherosclerosis, renal artery stenosis or hyaline arteriolosclerosis.

Answer 45

Acute | Chronic

Question 46

Red infarctions can occur at sites with ___ blood supply e.g. lungs, liver; in areas with ___ blood supply e.g. intestine; in venous infarction e.g. testicular torsion; or in reperfusion (common with emboli to the ___).

Answer 46

Dual blood supply Collateral blood supply Venous infarction Reperfusion - common with emboli to the brain

Question 47

Pale infarctions (i.e. no haemorrhage) can occur in ___ arteries in most organs e.g. heart, kidney, spleen.

Answer 47

End arteries

Question 48

Process of infarction: infarction -> ___ necrosis (ghost outlines) -> DAMPs -> inflammation -> ___ tissue -> scar.

Answer 48

``` Coagulative necrosis DAMPs Inflammation Granulation tissue Scar ```

Question 49

Digoxin is a cardiac ___. It has a ___ therapeutic index. It acts by increasing ___ influx to increase contractility. Digoxin binds to the ___ binding site of the Na+/K+ ATPase. This molecule is ubiquitous! Glycosides can cause ___ dysrhythmias, but they increase PNS activity (unknown mechanism) so they are used for ___ dysrhythmias. They are usually only used in ___-term.

Answer 49

``` Glycoside Low therapeutic index Calcium K+ Can cause ventricular dysrhythmias But they are used for atrial dysrhythmias because they increase PNS activity Short ```

Question 50

Amrinone is a ___ inhibitor - it slows down cAMP degradation so there is increased PKA activation and increased calcium influx -> increased contractility.

Answer 50

Phosphodiesterase

Question 51

In chronic heart failure, there is a ___ of beta1-adrenoceptor sensitivity. This occurs due to chronic overactivation with sympathetic compensation for reduced CO. Therefore, beta1-adrenoceptor ___ like dobutamine cannot be used for long-term.

Answer 51

Loss/reduction (due to reduced expression and impaired coupling of beta1-adrenoceptors) Agonists

Question 52

Reflex ___ is a side effect of arterial vasodilators used to reduce ___ in heart failure.

Answer 52

Reflex tachycardia Reduce afterload in HF Therefore, not used as much as other drugs e.g. ACEIs, AT1 antagonists, beta blockers

Question 53

___ ___ ___ inhibitors or ARBs are first line treatment for HF.

Answer 53

Angiotensin converting enzyme

Question 54

What are the side effects of ACE inhibitors?

Answer 54

``` First dose hypotension (titrate dose!) Dry cough Loss of taste Hyperkalaemia (+ thiazide diuretic) Acute renal failure Itching, rash, angioedema Foetal malformations ```

Question 55

ACE inhibitors are contraindicated in ___ ___ stenosis, ___ oedema and pregnancy.

Answer 55

Bilateral renal stenosis Angioneurotic oedema Pregnancy

Question 56

What are the side effects of beta adrenoceptor antagonists?

Answer 56

Hypotension, fatigue (cardiac and B2-mediated (vasodilatory) - interfere with redistribution of blood flow) Bronchoconstriction (due to B2 block) - therefore, contraindicated in asthma Cold extremities - A1-mediated reflex - therefore, contraindicated in peripheral vascular disease May cause/mask signs of hypoglycaemia - contraindicated in diabetes

Question 57

Beta adrenoceptors antagonists are contraindicated in ___ (due to potential bronchoconstriction), ___ ___ disease (due to A1 mediated reflexes), and ___ (may mask signs of hypoglycaemia).

Answer 57

Asthma Peripheral vascular disease Diabetes

Question 58

___ III is a natural inhibitor of Xa and thrombin.

Answer 58

Antithrombin III

Question 59

Heparin increases the activity of ___ ___ to exert its anticoagulant effects. It is mainly used ___ (time course).

Answer 59

Antithrombin III | Acutely

Question 60

Vitamin K is essential for the formation of clotting factors ___, ___, ___ and ___. (All require gamma carboxylation after synthesis, and reduced vitamin K is the cofactor in carboxylation of glutamate.)

Answer 60

2, 7, 9, 10 (TV channels)

Question 61

Activated partial thromboplastin time (APTT) is used to monitor the anti-coagulant effect of ___. Prothrombin time and INR are used to monitor the anti-coagulant effect of ___.

Answer 61

APTT - heparin (intrinsic) | PT and INR - warfarin (extrinsic)

Question 62

Aspirin is an ___ inhibitor of ___/

Answer 62

Irreversible inhibitor of COX | Reduces thromboxane synthesis - decreases platelet aggregation and vasoconstriction

Question 63

Describe how the benefits of endothelial vasodilator function are maintained but platelet aggregation is reduced by low dose aspirin therapy.

Answer 63

COX allows thromboxane synthesis in platelets AND vasodilator synthesis in endothelium Aspirin is susceptible to first pass metabolism (90% eliminated by liver before it enters circulation) At low dose - most is inactivated in the liver Platelets in the portal vein are exposed to the highest dose where COX is inhibited, and thromboxane synthesis is reduced -> decreases platelet aggregation and vasoconstriction But endothelial cells are exposed to very low doses so that COX is not inhibited significantly - maintained PGI2 from endothelium to inhibit platelet aggregation and promote vasodilation

Question 64

Valve ___ refers to narrowing of the valves resulting in ___ overload. Valve ___ refers to regurgitation resulting in ___ overload.

Answer 64

Valve stenosis - pressure overload | Valve incompetence - volume overload (to maintain CO, the heart needs to pump a higher stroke volume)

Question 65

High flow may cause innocent flow ___. ___ are due to turbulence around stenotic or incompetent valves.

Answer 65

Innocent flow murmurs e.g. in children, fever, anaemia, pregnancy (high cardiac output) Murmurs are due to turbulent flow (e,g. due to valve defects or high cardiac output)

Question 66

Normal thickness of the LV is

Answer 66

LV

Question 67

Normal heart weight in women is

Answer 67

Women

Question 68

What are 3 histological features of myocardial hypertrophy?

Answer 68

Enlarged, rectangular (box-shaped) nuclei Bi-nucleated myocytes Increased collagen/connective tissue

Question 69

In left heart failure, there is often ___ congestion and oedema. In right heart failure, blood pressure in ___ veins increases resulting in haemorrhage and necrosis in middle of ___ (i.e. ___ ___).

Answer 69

L - pulmonary congestion and oedema | R - hepatic veins -> haemorrhage and necrosis in middle of lobules (nutmeg liver)

Question 70

___ is used to deal with confounding. ___ is used to deal with information bias. ___-___-___ ___ is used to deal with selection bias. This always ___estimates treatment effects.

Answer 70

Randomisation Blinding Intention-to-treat analysis (assume that subjects stay in randomised group, regardless of cross-over) Always underestimates

Question 71

NNT is ___ ___ to ___ and refers to the number of people needed to undergo intervention in order to prevent an outcome in ONE. It is equal to 1/(absolute ___ or ___ reduction).

Answer 71

Number needed to treat | NNT = 1/(absolute risk or rate reduction)

Question 72

What are some of the social determinants of health (there are 10)?

Answer 72

``` Social gradient (i.e. position on social ladder) Stress Early start (e.g. development and education) Social exclusion (e.g. poverty) Work (control) Unmployment Social support Addiction Food Transport ```

Question 73

There is a positive relationship between income and life ___.

Answer 73

Expectancy

Question 74

Describe the 4 stages of epidemiological transition.

Answer 74

1 - high birth rates, high death rates and small population (most of population 65) 4 - low birth rates, low death rates and high population (more > 65 and less

Question 75

What diseases predominate in stage 1 of the epidemiological transition? In stage 4?

Answer 75

Stage 1 - pestilence, famine, infectious disease | Stage 4 - delayed/chronic degenerative disease due to longer life expectancy