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54 Cards in this Set

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Blood composition




+serum vs. plasma

55% plasma (mostly water, with soluble proteins)


45% formed elements




Serum is plasma which has lost its fibrinogen due to in vitro clotting

Major diagnosis with FBC:


neutrophilia, monocytosis, eosinophilia, lymphocytosis, mature cell granulocytosis, leukoblast cytosis, general, marked leukocytosis

Neutrophilia: bacterial infection.


Monocytosis: chronic infection/inflammation


Eosinophilia: asthma. May be parasitic infection if also anaemic.


Lymphocytosis: viral infection. May be lymphocytic leukaemia if very raised (confirm by demonstrating clonality in flow cytology)


Mature cell granulocytosis: chronic myeloid leukaemia


Leukoblast cytosis: acute leukaemia. (B/T: immunophenotyping)


General, marked leukocytosis: Consider leukaemia.

Proteins involved in platelet aggregation at site of endothelial injury

Exposed collagen -> VWF -> GpIb on platelet




GpIIb/IIIa on bound platelet -> VWF -> Gpiib/IIIa on free platelet

Plasmin metabolism and action

Hepatic plasminogen


Converted to plasmin at site by t-PA


Catalyses fibrin degradation

Repair protein in erythrocytes

Methaemoglobin reductase - converts methaemoglobin (with iron atom oxidised such that oxygen can't be carried) present.

Carbon dioxide metabolism from tissue to alveolus

In erythrocyte:

CO2+H2O ---carbonic anhydrase---> H2CO3




Travels as HCO3- in plasma





In erythrocyte, reverse reaction (again using carbonic anhydrase), producing CO2 which diffuses into alveolus.


Function of oxygen dissociation curve modifiers

Heat and high CO2 indicate high metabolic need. They decrease oxygen affinity, promoting full release of Hb-bound oxygen




2-3 DPG also reduces oxygen affinity, and preferentially binds to partially deoxygenated Hb, again leading to full release.

Contents of superior mediastinum, anterior to posterior


x7

Thymus


Internal jugular and subclavian veins


Phrenic, vagus, and recurrent laryngeal nerves


Aortic arch, CCA and subclavian arteries


Trachea


Oesophagus


Sympathetic trunk

Contents of posterior inferior mediastinum


x7

Primary bronchi


Pulmonary trunk


Descending aorta, posterior intercostal branches


Oesophagus


Thoracic duct


Azygous venous system


Sympathetic trunk and splanchnic nerves

Features of right atrium


x5

Pectinate muscle: comb-like anterior muscle


Cristae terminalis: ridge between pectinate and smooth wall


SA node: at superior extent of CT


AV node: medial to opening of coronary sinus


Fossa ovalis: vestige of foramen ovale on medial wall

Structured supplied by standard coronary artery branches


x7 branches

RCA: SA nodal - SA node


Right marginal - right ventricle


Posterior IV - RV, IV septum, LV


AV nodal - AV node


LCA: LAD: RV, LV, IV septum


Left marginal - LV

ECG signs


x5

Absent P wave - AF


Multiple P waves - atrial flutter


Prolonged PR interval - heart block


Lack of QRS complex - VF


Non-isoelectric ST - ventricular ischemia



Permanent pacemaker lead sites


3 arrangements

1 chamber: RV apex


2 chambers: RV apex, RV appendage


Biventricular: dual chamber + external LV vein via coronary sinus

Skeletal, cardiac, smooth muscle




nuclei, striation, synchronicity, activation

Skeletal: Multinuclear, striated, no cell junctions, NMJ activation


Cardiac: uninuclear, striated, gap junctions, intrinsic activation


Smooth: uninuclear, non-striated, gap junctions in visceral smooth muscle, intrinsic/neural/hormonal activation (no NMJs)

Smooth myocyte filament structure


+molecule to which calcium binds


+neural activation

Oblique lattice of thick and thin filaments joined at dense bodies - so that contraction shrinks the cell as a whole




Calcium binds to calmodulin rather than trop.




ANS secretes NT around smooth muscle cells at varicosities

Vascular wall layers


+vessels supplying vessels

Tunica intima - endothelium


Tunica media - concentric smooth muscle, bounded by internal and external elastic laminae


Tunica adventitia - loose connective tissue, containing vasa vasorum in larger vessels

Elastic vs. muscular arteries

Elastic: just downstream of heart. High pressure, high compliance. High elastin:smooth muscle ratio




Muscular: medium and small arteries. Higher smooth muscle quotient.

Normal BP, marginal and interventional hypertension

120/80


140/90


160/100

Cardiac output in healthy resting male

70ml SV * 70bpm pulse = ~5L/m

Theories of hypertension aetiology


x3

Increased sympathetic tone due to increased baroreceptor sensitivity (eg. plaques in carotid sinus


Arteriolar endothelial damage, increasing SVR


RAAS malfunction, due to renal artery plaques

Capillary types

Continuous - only water and ions may diffuse in or out. May contain caveoli for transport of large molecules




Fenestrated - endothelial pores with continuous basal lamina, permitting free water, salt exchange eg. glands, intestine, glomerulus




Sinusoidal (discontinuous) - large pores, discontinuous basal lamina. Permits blood cell, protein movement. eg. spleen, liver, bone marrow

Capillary bed filtration

Constant higher vascular than oncotic pressure throughout, encouraging influx


High hydrostatic pressure at arterial end produces net pressure out


Lower hydrostatic pressure at venous end produces net pressure in

Autonomic control of blood pressure

Parasympathetic afferents in carotid and aortic sinuses -> medullary vasomotor centre


Sympathetic output to arteriolar smooth muscle (α-1 receptors) + systemic adrenaline acting on myocytes (β1 receptors) --- in inverse relation to baroreceptor activation




Baroreceptor afferents also excite cardioinhibitory centre, increasing vagal depression of heart rate



High GFR and Low GFR responses

High GFR -> high sodium in distal tubule -> macula densa secretes adenosine -> afferent arteriole vasoconstriction




Low GFR -> low sodium in distal tubule -> juxtaglomerular cells secrete renin -> RAAS acts systemically

Angiotensin ii effects

Stimulates aldosterone secretion (+expression of sodium/potassium exchangers in distal tubule)


Arteriolar constriction


Glomerular efferent arteriole constriction


Increased pituitary ADH secretion


Increased thirst

ADH regulation

Osmoreceptors in hypothalamus increase expression in response to dehydration




(increases expression of aquaporin in renal collecting ducts)

Principle muscles of inspiration




+accessory muscles of inspiration+expiration

Diaphragm (phrenic nerve)


External intercostals


Interchondral portion of internal intercostals




In: SCM, scalenus


Ex: Internal intercostals, abdominal muscles

Thoracic wall circulation (inc. drainage)

Posterior IC muscles: IC arteries from descending aorta


Anterior IC muscles: branches of internal thoracic artery (from subclavian)


IC arteries anastomose




Drainage into azygous (right) and hemiazygous (left) systems, then into inferior vena cava

Pleural nerve supply

Visceral pleurae: pulmonary branches of vagus nerve (no somatosensory endings)




Thoracic parietal pleurae: IC nerves


Diaphragmatic and mediastinal parietal pleurae: phrenic nerve

Autonomic control of lungs

Parasympathetic: pulmonary branches of vagus nerve via lung roots. Bronchoconstriction and vasodilation




Sympathetic: β-2 receptors respond to systemic adrenaline. Bronchodilation (and vasoconstriction)

Important cartilage structures of the larynx


x3

Thyroid cartilage: 'Adam's apple', large


Cricoid cartilage: a complete ring inferior to the thyroid cartilage


Epiglottis: spoon-shaped, protracts to close trachea during swallowing

Innervation of larynx

Motor to cricothyroid: external laryngeal nerve (lesion: monotonous speech)


All other motor: recurrent laryngeal nerve (lesion: hoarse speech - unilateral vocal fold paralysis)


Sensory: internal laryngeal nerve (lesion: loss of choke reflex - very disabling)

Effect of pulmonary vascular oxygen pressure on vascular tone

Pulmonary hypoxia -> vasoconstriction


High pulmonary oxygenation -> vasodilation

Normal spirometry values in healthy young people




Tidal volume, Residual volume, vital capacity

Tidal volume - 0.5L


Residual volume - 1.2L


Vital capacity - 3-5L

Vitalograph (pneumoniachograph) measures

Forced vital capacity in total (FVC)


Forced expiratory volume in 1 second (FEV1)


FVC1/FVC (FEV1%) - proportion of vital capacity which can be expired in 1 second

Anatomical vs. physiological dead space

Anatomical: volume of air in the URT and conducting portions of respiratory tree




Physiological: anatomical + gas trapped in damaged alveoli

Function of peak flow measurement

Assesses radius of conducting airways

Types of nitric oxide synthase


+tissue

bNOS - neurones


iNOS - most cells, but especially macrophage. Activated by inflammatory cytokines


eNOS - endothelium. Calcium-dependent

Classes of respiratory failure

Type 1: hypoxaemia with normocapnia


Type 2: hypercapnia + hypoxia ie. decompensated (failure of respiratory drive)

Cortical vs. juxtamedullary nephrons

Cortical: entirely in renal cortex




Juxtamedullary: loop of Henle descends into renal medulla. Role is to produce concentrated urine.

Renal circulation

Renal artery -> Arcuate arteries


-> Interlobular arteries


-> Afferent arteriole, glomerulus, efferent arteriole


-> Peritubular capillaries


-> Interlobular vein


-> Arcuate vein


-> Renal vein

Atrial natiuretic peptide

Inhibits sodium pumps in the DCT and collecting ducts of the nephron




Secreted by atrial myocytes in response to stretch, indicating hypervolaemia

Basis of creatine measurement of GFR

Creatine is freely filtered in the glomerulus and not reabsorbed and only slightly secreted. Therefore creatine in urine provides an index of GFR when compared to plasma creatine.

Normal pH, PCO2 and bicarbonate levels

pH 7.35-7.45


PCO2 35-45mmHg


HCO3 22-28mMol/L

Use of anion gap

Proportion of unmeasured anions


Helps determine origin of metabolic acidosis




If gap is increased, increased acid production eg. keto-acidosis


If gap is normal, increased bicarbonate excretion eg. diarrhoea (chloride is retained, maintaining gap)

Sites of renal calculi lodging

Pelvo-uteric junction


Pelvic brim


Cysto-uteric junction

Diagnostic tree in acidosis/alkalosis

Acidosis or alkalosis (based on blood pH)


Respiratory or metabolic (is bicarbonate or carbon dioxide causative of pH imbalance)


Compensated or uncompensated (is other chemical adjusted)

Acidosis vs. acidaemia

Acidaemia = blood pH<7.35. It is a sign


Acidosis refers to syndromes involving acidaemia

Normal ABG values for oxygen and carbon dioxide (kPa)

PaO2: 11-13kPa


PaCO2: 4.7-6kPa

Determinants of cardiac output

Heart rate * stroke volume

Determinants of stroke volume

Contractility * preload

Determinants of preload

Intravascular volume * vascular tone

Structures normally perfused by right coronary artery

Right atrium (including SA node)


AV node


Most of right ventricle


Posterior interventricular septum


Posterior left ventricle

Structures normally perfused by left coronary artery

Left atrium


Most of interventricular septum (via LAD perforating branches)


Most of left ventricle