Week 5 Flashcards
What is an ECG?
Electrocardiogram
Test to check rhythm and electrical activity of heart
What is a cardiac impulse?
the wave of cardiac excitation passing from the sinoatrial node to the atrioventricular node and along the bundle of His and initiating the cardiac cycle broadly
What are the parts of the cardiac conduction system?
SA node, AV node, bundle of His, bundle branches, and Purkinje fibers
Describe cardiac conduction system
Signal from sinoatrial node moves slowly to Atrioventricular node as ventricles begin to fill
From there signal moves through bundle of His, bundle branches, to Purkinje fibers which stimulate ventricles for ejection
Outline the properties of the ECG paper (speed, square size)
Speed: 25 mm/s
Large squares: .2 second, .5 mV
Small squares: .04 second, 0.1mV
What is positive/negative deflection?
Positive - energy coming towards the lead
Negative - energy travelling away from the lead
How many electrodes do you use for the ECG?
10
Leads are a misnomer (often called 12 lead ECG) - leads are not the cables, but the line between where you put the electrodeand where you are looking for
Describe Einthoven’s triangle
Right arm, left arm, left leg
aVR, aaVL, aVF
What is a chest lead vs limb lead?
Chest leads look at heart on horizontal transverse plane
Limb leads look at heart on coronal plane
What is the P wave? How long should it last? Where should it be positive (1) / negative (1) on ECG?
First positive deflection
Atrial depolarisation
Should no be more than 0.12 seconds
Positive in lead II (negative in AVR)
What is the T wave? What can changes indicate?
Rapid phase of ventricular repolarisation
Peaked or flattened can reflect changes in potassium, metabolic process
What is your QRS complex related to?
Ventricular depolarisation
If larger than 0.12 suggests defect in intraventricular conduction
Direction determine ‘electrical axis’
What is the PR interval?
Represents time for transmission of signal from atria to ventricles through AV node
0.12-.20 second duration (3-5 small squares)
What is the electrical axis? What is normal?
Direction of the mean vector of the wave of ventricular depolarisation in the limb leads
Lead 1 is arbitrarily defined as 0 degrees
Normal axis between -30 and +90 degrees
Define abnormal electrical axis readings
beyond -30 = left axis deviation
beyond 90 = right axis deviation
What is the ST segment?
In isoelectric line between QRS and T wave
Plateau phase of repolarisation
Should not deviate above/below isoelectric line by more than 1mm
Deviation = likely damage
STEMI!
What is the QT interval?
Measures polarisation process
Prolonged (>440ms in men, >460ms women)
Prolonged due to inherited conditions, drugs
Prolonged can cause arrhythmia
What is the structure for reading ECGs? (5)
Name / age of patient / current condition
Check heart rate
Check rhythm is regular (are R waves coming regularly)
P wave - duration and shape
T wave - should be positive in I, II, aVL, aVF, V2-6
How to check heart rate on ECG?
1 large square = 300 bpm
count number of squares between R waves (300 divided by this number)
What are the criteria for sinus rhythm? (3)
Positive 1, 2, aVF AND
Negative aVR AND
Each QRS preceded by P
What is left ventricle hypertrophy? How can you see it on ECG?
enlargement and thickening (hypertrophy) of the walls of your heart’s main pumping chamber (left ventricle)
Large QRS complex - various systems to add up
What are the changes on ECG during myocardial infarction?
ST elevation during STEMI
Maybe no changes during non-STEMI (or slight T inversion)
Pathological Q waves are long term effect
What are the clinical signs of shock?
Pale, sweaty, dizzy, cold/clammy skin
What is blood pressure? What maintains it? (4)
Pressure exerted by the circulating blood against the walls of the arteries Maintained by: 1. contraction of left ventricle 2. resistance of small blood vessels 3. elasticity of arterial walls 4. volume / viscosity of blood
What are the UK parameters for optimal, normal and high-normal blood pressure?
less than 120/80
less than 130/85
130-139/85-89
What are the parameters for grade 1-3 hypertension?
Grade 1 - 140-159 / 90-99
Grade 2 - 160-179 / 100-109
Grade 3 - More than 180 / 110
What is blood pressure homeostasis?
Maintenance of steady state of blood pressure
What are the three factors that control blood pressure?
Contraction of left ventricle
Resistance of small blood vessels
Volume of the blood
Why do we need blood pressure?
To move blood through vascular system
What are the characteristics that contribute to blood pressure stability? (3)
The mechanism that contribute to BP stability are:
powerful (it has rapid and slow components)
highly redundant (if something happens, there is back-up)
Able to cope/adjust (e.g physical activity, threats, trauma)
What is cardiac output? How do you calculate it?
amount of blood pumped out by the heart per minute (=Stroke volume x Heart rate)
What are the markers of low BP? (3)
low stroke volume, slow or very fast heart rate, or reduced peripheral vascular resistance
What are the markers of high BP? (2)
High stroke volume
High peripheral vascular resistance
How do you calculate vascular resistance?
Poiseuille’s law
Resistance = 8 x length of blood vessel x viscosity divided by pi x the radius of blood vessel ^4
What is the distribution of blood volume?
Arteries 13%
Capillaries 6%
Veins 81%
Blood pressure regulation - which four systems work together?
CVS, Renal, nervous, endocrine
What is the most important factor in regulation of blood pressure?
Salt
Describe role of renal system in BP regulation
RAAS system responds to low blood pressure and stimulates increase
Kidney filters more than 170 L of plasma every day, filtering 23,000mmol of sodium
Types / percentages of Na absorption on nephron - what is being absorbed? (4 sections with approximate percents of absorption of sodium)
Proximal tubule: Na+/H+ exchanger = 60% absorption
Thick ascending limb of Henle: Na-K-2Cl co-transporter= 30%
Distal convoluted tubule: Na-Cl co-transporter = 7%
Cortical collecting tubule: ENaC = 2%
Describe (simply) the RAAS system? location, purpose, main elements
xxx
Drugs that act on different stages of the RAAS system?
ACE inhibitors (between Angiotensin I and II) Beta blockers and renin inhibitors (between angiotensinogen and angiotensin I)
What is malignant hypertension?
extremely high blood pressure that develops rapidly and causes some type of organ damage.
What is the role of the sympathetic nervous system on BP?
Short-term variations (stress, exercise, changes in posture)
What is pressure naturesis?
central component of the feedback system for long-term control of BP
When pressure is very high, kidney will lose salt
What was the result of renal sympathetic dennervation?
Blocking sympathetic nerve pathways helped to lower blood pressure if those resistant to treatment. Research ongoing
What are baroreceptors? What happens if you put pressure on the neck?
Pressure receptors
The carotid sinus and aortic arch sense high pressure and the hear and pulmonary artery sense low pressure
Cause bradycardia and low blood pressure
Describe (simply) the activity of endocrine control of BP
hormonal mechanism for the regulation of blood pressure by managing blood volume
Why don’t you give epinephrine during shock?
Worsens the vasoconstriction, tissues aren’t getting enough blood
What is atrial natriuretic peptide? What does it do (3)? and why?
It increases excretion via kidneys - 3 methods:
- Reducing water reabsorption in collecting ducts
- Relaxes renal arterioles
- Inhibits sodium reabsorption in DCT
Starts these processes in response to stimulation of atrial receptors
In what order will you organs shut down with high BP? (2 early)
Skin, kidney, etc.
What is convection?
Mass movement of fluid caused by pressure difference
Describe Darcy’s Law of flow states
Flow is equal to the pressure drop divided by resistance to flow
Relationship between blood flow and cardiac output
They are equal
How does heart beat? (source, 4 steps)
Generates its own electrical activity (does not need external nerves)
Starts at SA node, spread out via gap junctions
Spreads to AV node, delays conduction to allow ventricles to fill
Depolarisation rapidly through bundle of His into ventricles
How does the heart beat? (from what part of the heart)
From apex (bottom) to base (line between atria and ventricles)
What are the general principles of the cardiac cycle?
- Electrical activity conducted from SA node to atria and then ventricles causing CONTRACTIONS, CHAMBER PRESSURE CHANGES, MOVEMENT OF BLOOD
- Blood flows from high pressure to low pressure (unless blocked)
- Valves open / close depending on pressure change
- Left and right side are doing the same thing but pressure on the right is lower
Movement of blood through right side of the heart (describe path, valves) - 6
Blood returns from superior and inferior vena cava Enters right atrium Flows throw tricuspid valve Gathers in right ventricle pushed through pulmonary semilunar valve into pulmonary arteries to lungs
Movement of blood through left side of the heart (describe path, valves) - 6
Blood from lungs is sent to heart by pulmonary veins Enters left atrium Flows through mitral (bicuspid) valve Gathers in left ventricle pushed through aortic semilunar valve into aorta to systemic circulation
Describe process of cardiac cycle (where is blood going, what is happening?) - 4 phases
- ventricular filling
- isovolumetric contraction
- ejection
- isovolumetric relaxation
What is ejection fraction? What are normal values and what does a lower value indicate?
Ensures blood that is coming into ventricles is being ejected
SV / EDV
Normal value is 2/3rd or more; lower indicates heart failure
Describe the pressure changes as blood moves into/through right atrium
Pressure is going up in the right atrium during diastole, until so high the tricuspid valve opens
Blood moves from the atrium to ventricle, tricuspid closes
Blood leaves ventricle as atrium starts filling again
Repeats
Why do you look at the jugular? What does normal look like?
Low at SCM, pulse may be visible put should not be elevated
Jugular pressure can indicate if pressure in right atrium is too high, possible right sided heart failure
Describe the 4 basic heart sounds and what you are hearing
S1 - lubb - tricuspid / mitral valves close - beginning of systole
S2 - dupp - aortic / pulmonary valves close - beginning of diastole
S3 - occasional - turbulent blood flow into ventricles (common in young people)
S4 - pathological in adults - forceful atrial contraction against stiff ventricle
Outline the role of the parasympathetic nervous system on the circulatory system (route, receptors, where)
Vagus nerve sends messages from CNS (brainstem cranial nerves) to muscarinic M2 receptors on SA and AV node through acetyl choline
Outline the role of the vagus nerve in heart control - which nervous system, origin, where does it connect with heart, what sort of receptors
Parasympathetic nervous system
Sends messages from CNS to SA and AV nodes
Originates in brain stem
Muscarinic M2 receptors
Outline the role of the sympathetic nervous system on the circulatory system
Act on heart and blood vessels
Adreniline and noradrenialine
a1 and b1 receptors SA and AV nodes and at ventricles
Origin - thoracic and lumbar regions
Role of adrenaline and noradrenaline
Both catecholamines, regulation
no
Noradrenaline (synonymous with norepinephrine), the main neurotransmitter of the sympathetic nervous system, maintain blood pressure
Adrenaline is a key determinant of responses to metabolic or global challenges to homeostasis, such as glucoprivation, and of manifestations of emotional distress
Effect of sympathetic on CVS - what does it do? Where?
Major effect of sympathetic system is to mediate increases in CO and TRP to increase in BP
Does this by increasing heart rate and contractility and by stimulating vasoconstriction
How does stimulation of B1 adrenoceptor induce an increase in HR?
Targeted activation of the beta-1 receptor in the heart increases sinoatrial (SA) nodal, atrioventricular (AV) nodal, and ventricular muscular firing, thus increasing heart rate and contractility. With these two increased values, the stroke volume and cardiac output will also increase
If channel allows sodium through, causes polarisation, transfer of calcium and potassium drives ongoing polarisation/depolarisation
How does stimulation of B1 adrenorecptors induce an increase in contractility?
Inotrophic effect??
More calcium, more contraction
Calcium stores within cells released when stimulated, Tropinin
Define chrono, dromo, ino, lusitrophic
chrono - heart rate
dromo - conduction
ino - contractility
lusi - relaxation
Drugs that stimulate or inhibit B1 receptors - what are they, examples, used for what conditions?
B agonists increase cardiac activity - used for cardiac arrest anaphylaxis, cardiogenic shock (during sepsis)
Non-selective - Adrenaline, dobutamine
B antagonists reduce cardiac activity - used for angina, hypertension, arrhythmia, HF
B1 - atenolol
B1 & 2 (non selective) - propranolol
Describe sympathetic nerve activity on blood vessels - what does it control?
Radius of blood vessels (so important for TPR)
Affected by release of NA from sympathetic nerves and adrenaline / NA from adrenal medulla
Acts at Ai adrenoreceptors on smooth muscle cells in arterioles
Describe activity of alpha adrenoceptor agonists (and 2 examples)
A agonists increase vasoconstriction
Adrenaline (in high doses)
NORAD / noradrenaline (non-selective a agonist)
Phenylephrine (selective a1 agonist)
Describe activity of alpha adrenoceptor antagonists (and 2 examples, for what treatment)
A antagonists reduce vasoconstriction
Prazosin, phenoxybenamine (a1 selective antagonists) - hypertension and Phaeochromocytoma (adrenal gland tumour)
What happens if you give beta and alpha blockers together? And example combo
Very strong treatment for hypertension, cardiac protective
Carvedilol and metoprolol
What is the effect of the parasympathetic nerve activity on the heart?
Stimulation of vagus nerve decreases cardiac output
Vagus nerve releases acetyl choline which acts on M2 receptors on the heart
Reduces frequency at SA node, reduction in heart rate
How does stimulation of M2 muscarinic induce a decrease in HR?
Vagus nerve releases acetyl choline which acts on M2 receptors on the heart. Reduces frequency at SA node, reduction in heart rate
Outline Mus receptor agonist and antagonist and examples of each
Mus agonists decrease cardiac activity
Pilocarpine (relieves intraocular pressure in glaucoma), bethanechol
Mus antagonists increase cardiac activity
Atropine, hyocine - used to address sinus bradycardia post myocardial infarction
What is the exception to the rule (that parasympathetic activity generally doesn’t effect blood vessels)?
Blood vessels to penis, arousal stimulates CNS to drive release of NO, which produces cycle that increases blood flow which causes an erection
What is a risk factor?
Aspect of personal behaviour or lifestyle, environmental exposure, inborn or inherited characteristic ASSOCIATED with particular disease or condition.
What is the healthy entrant effect?
People who are unhealthy may be excluded from study which makes the pool of entrants healthier than the general population
How can we quantify risk?
Probability event will occur
Compare risk of those who are exposed, to those who aren’t
How do you calculate a relative risk (RR)?
Ratio of absolute risks
Exposed : unexposed group
What are confounding factors? Provide examples
A confounding factor is one that is associated with the risk factor, without being a consequence of it. Furthermore, it is associated with the disease (independently of the risk factor).
What are the limitations of cohort studies? (6)
there are unknown (and therefore not measured) risk factors. Confounding factors Time / expense Bias due to loss of follow up Behaviour change Doesn't work if diseases are rare
Why / how do you calculate incidence rate?
In cohort studies, people have been studied for different numbers of years (varying length of exposure)
Incidence rate: Total number occurrences of outcome divided by total number of years at risk.
What are the advantages to cohort studies? (2)
Prospective designs help establish when people are exposed to risk and when they develop the disease
Population based samples can make findings very helpful
What is a prospective vs retrospective study?
xxx
Retrospective - using past data from electronic databases - introduces different bias such as missing data
What are the challenges explaining findings from a cohort study to a patient?
Study looks at risks in a mixed group with varying demographics - not at their specific situation
What are the four phases of drug movement in the body?
Administration/Absorption
Distribution
Metabolism
Excretion
What factors effect whether a drug can exert its actions? (3)
- must reach target
- correct concentration
- correct duration
What does pharmacokinetics mean?
Drug movement
How body handles drug
What are the routes of administration? (3) How is each route absorbed?
Enteral - absorbed via GI tract
Parenteral - bypasses GI tract
Topical - for local action (can also be systemic)
What are the types of enteral administration?
Absorbed vial GI tract
Oral
Buccal, sublingual
Rectal
What are the types of parenteral administration?
Bypasses GI tract Injection: Intradermal Subcutaneous Intramuscular Intravenous Injected into other body cavity
What are the types of topical administration?
For local action (or systemic effect)
Eye drops, inhalers, cream/ointments/patches, nose/ear/eye drops
How do drugs move between fluid compartments, across physiological barriers?
Across cell membrane (lipid soluble by passive diffusion, water soluble by protein transporters)
Between cells - some can pass between cells depending on nature of epithelia
What is bioavailability?
How else can you measure/define this?
The proportion of the drug administered that is available for therapeutic effect
Look at proportion that reaches systemic circulation
Biggest risk for oral treatments
What are the factors affecting bioavailability? (4)
Pharmaceutical formulation
Absorption
Metabolism / elimination
Local factors - disease / interactions
Why is sublingual better than oral for bioavailability?
Treatment goes into capillaries under tongue
Considerations when choosing rate of administration (5)
Administration - Convenience, acceptability
Absorption -Bioavailability and Speed
Site of action
Local effects/ side effects
Effect of disease on route of administration
Advantages (3) / disadvantages (4) of IV administration
Excellent bioavailability
Ensure patient gets medicine
Can be used when enteral route not available (e.g. vomiting)
Usually needs input from healthcare professional
Risk of cannula infections
High concentrations from bolus may cause side effects
Expensive
Advantage (4) / disadvantages (5) of transdermal
Acceptable to patients
Easy to administer
May aid adherence to treatment
Can be stopped easily
Local side effects Many drugs not absorbed Patches may come off Affected by skin disease Slow to initiate effect
What happens during drug distribution? (3 steps)
- dissolved in body water
- bound to plasma proteins
- distributed to tissues
Calculating volume of distribution
total amount of drug in the body / plasma concentration of the drug
What is the significance of a high volume of distribution?
Need loading dose before maintenance dose
In body, which drug molecules are active vs inactive?
Free state drugs are active, protein bound are inactive
Why are albumin levels in patients important before starting treatment?
If high levels, will inactivate more of the drug
If low, more of the drug will be active
What is the significance of a drug being protein bound?
Protein-bound drugs act as a reservoir when free-state drugs are removed by metabolism or excretion
Protein-bound drugs therefore have a longer half-life
What are the characteristics of drugs that bind to tissues? (2) Examples (3)
Extensive binding to tissue delays elimination and increases the drug half life.
These include many lipid-soluble drugs, which may enter fat stores
E.g. benzodiazepines, verapamil, lidocaine.
What happens during systole?
ventricles contract and atria relax
What happens during diastole?
ventricles relax and atria contract
What are the three components that drive the cardiac cycle?
Pacemaker
Conduction system
Contractile element
Describe cardiac muscle tissue
Striated cells containing numerous mitochondria joined at intercalated discs
Describe intercalated discs
Come together through physical connection (desmosomes) and xxx gap junctions
What are the characteristics of a cardiac myocyte? (4)
Automaticity: ability to spontaneously initiate an impulse.
Excitability: indicates how well a cell responds to electrical stimuli.
Conductivity: ability of cell to transmit an impulse to another cell.
Contractility: ability to contract after receiving an impulse
What is resting potential?
Net balance of ions inside/out of cell
Na moving in, K moving out
Ca Na exchanger
Describe what happens during depolarisation and repolarisation
Depolarisation
Voltage-gated activation
Triggers release of sarcoplasmic reticular Ca++
Sarcomeric contraction
Repolarisation
Restoration of resting membrane potential
Sarcomeric relaxation
What are the two main cell types in the heart?
Contractile cells - atrial and ventricular tissue in layers, low automaticity, highly contractile/excitable
Automatic / auto-rhythmic cells - pacemaker and conduction tissue
High automaticity and conductivity
Describe contractile cell action potential (0-4 phase)
Phase 0: rapid depoliarisation - Na rapidly into cell, Ca slowly into cell Phase 1: early repolarisation - Na channels close Phase 2: plateau phase - Ca continues in, K flows out Phase 3: rapid repolarisation - Ca channels close, K flows out rapidly Phase 4: resting potential - Active transport through Na-K pump, cell impermeable to Na, K may leave cell
Describe the autorhythmic cell action potential
Phase 4: Pacemaker potentials – the ‘ funny current – If ’Inward diffusion of sodium ions
Phase 0: Depolarisation due to inward diffusion of calcium. Concludes when fast calcium channels open.
Phase 3: Repolarisation due to outward diffusion of potassium
Where is there non-conductive tissue in the tissue?
Between atria and ventricles
What is ‘re-entry’? What is the circus movement?
Reentry can be subdivided into three subcategories: (1) circus movement, (2) reflection, and (3) Phase 2 reentry. Reentry occurs when a propagating impulse fails to die out after normal activation of the heart and persists to re-excite the heart after expiration of the refractory period
Scar and fibrosis can form slow component of re-entry circuit
Factors that can affect blood pressure measurements
anxiety, technique, personality of taker, instrument characteristics, cuff size, environment, number of readings
What tends to happen to someone’s blood pressure after repeated readings?
Regression to the mean - they will tend to return towards normal after multiple readings
Why is high blood pressure an important problem? (2)
- Strongly associated with higher risks of CVD, especially CHD and stroke
- Common in general population
If these complications (3) are present it’s particular important to control BP to reduce risk of CVD
- left ventricular hypertrophy
- proteinuria or renal impairment
- hypertensive retinopathy
What makes blood pressure quantitative rather than qualitative?
It is the value that matters, not just the existence of high blood pressure
How do we define hypertension / high blood pressure?
The level at which treatment becomes beneficial - where it is better to treat than leave it
What are the causes of high blood pressure?
Small number have specific medical cause (secondary hypertension)
Most have no specific medical cause (primary hypertension)
Common causes of secondary hypertension (5)
-Coarctation of aorta
-Renal and renal vascular disease
-Adrenal disease
cortical 1 hyperaldosteronism,
Cushing’s syndrome
medulla phaeochromocytoma
-Pregnancy
-Drugs esp OCP, HRT
Other factors that may cause ‘essential’ hypertension
high BMI, high alcohol intake, high salt intake, low potassium intake, low fibre / high fat diet, physical inactivity, stress
What do migration studies show in studies about high blood pressure?
People who move to a higher blood pressure population will generally have their BP increase to match host population within 6 months
What is attributable risk?
Excess risk
Risk in the ‘exposed’ group (those with high blood pressure) - risk in ‘unexposed’ (those w/o high blood pressure)
How do you lower blood pressure (non pharma)? (6)
Weight loss, reduce alcohol, reduce salt, increase fruit/vegetable, increase exercise, reduce saturated fat intake
What are main pharmacological tools used to lower blood pressure? (6)
(A) ACE inhibitors
(B) beta blockers
(C) calcium-channel blockers
(D) diuretics
How has the view on who needs their blood pressure lowered changed?
People who are at high CVD risk should be treated, others maybe not (old view was that everyone with high BP should be treated)
What is relative risk vs attributable risk?
Attributable risk is the excess risk (difference in risk between exposes and unexposed groups) whereas the relative risk is a ratio
Advantages (3) / disadvantages (3) of oral
Acceptable to patients
Easy to administer
Cheapest route
Interrupted by vomiting, GI problems Bioavailability may be limited by: Poor absorption First pass metabolism Interactions in GI lumen GI upset common side effect
Advantages (1) / disadvantages (3) of rectal
Can be used for people who can’t swallow
Socially undesirable
Local factors influence absorption
Local irritation
Advantages (4) / disadvantages (4) of IM
Easier than IV
Bioavaliability better than oral
Depot of drug absorbed slowly may be useful e.g. in contraception/antipsychotic, for administration at monthly or longer intervals.
Can be used when enteral route not available (e.g. vomiting)
Painful
Risk of infection
Drug may not be absorbed if blood pressure low
Usually needs to be done by healthcare professional
Advantages (1) / disadvantages (2) of subcutaneous
Useful to self-administer drugs
Absorption may be slow and unreliable
Local side effects e.g. repeat insulin injections can cause lipoatrophy
Advantages (3) / disadvantages (3) of topical
Straight to site of action
Limits systemic exposure and side effects
Acceptable to patients
Local side effects
May be messy/inconvenient
Rapid clearance may need regular administration
What are you hearing during ‘lub’ and ‘dub’?
“lub” is the first heart sound, commonly termed S1, and is caused by turbulence caused by the closure of mitral and tricuspid valves at the start of systole
The second sound,” dub” or S2, is caused by the closure of aortic and pulmonic valves, marking the end of systole
What are the branches of the aorta and what do they supply?
Coronary arteries - heart
Brachiocephalic trunk - head and right arm (through right common carotid and right subclavian)
Left common carotid - head
Left subclavian - head and left arm
What are the branches of the descending thoracic aorta? Where does it start? end?
Descending starts at about T3, ends at aortic hiatus through diaphragm T12 Paired posterior intercostal Bronchial Oesophageal Mediastinal
Common variations of aortic branches (2) & clinical significance
Double - splitting of the ascending aorta into two limbs that pass to either side of the trachea and oesophagus. May result in trachael or oeosphageal obstruction
Right-sided - aorta courses to right of trachea, three different types with varying complications
What is the azygous system? How does it relate to caval system?
azygos vein serves to drain most of the posterior intercostal veins on the right side of the body, and the hemiazygos vein and the accessory hemiazygos vein drain most of the posterior intercostal veins on the left side of the body.
Blood can circumvent vena cava if there is a blockage through the azygous system
What is the thoracic duct? where?
The thoracic duct is the largest lymphatic vessel within the human body
A large portion of the body’s lymph is collected by this duct and then drained into the bloodstream near the brachiocephalic vein between the internal jugular and the left subclavian veins.
Starts at T12 (and extends to the root of the neck)
What is the relationship of the ligamentum arteriosum to the left vagus nerve?
ligamentum arteriosum is closely related to the left recurrent laryngeal nerve, a branch of the left vagus nerve. After splitting from the left vagus nerve, the left recurrent laryngeal loops around the aortic arch behind the ligamentum arteriosum, after which it ascends to the larynx
What are the locations of the oesophageal and pulmonary plexuses and superficial and deep cardiac plexuses?
Pulmonary about T3
Oesophageal about T7
Cardiac between bifurcation of trachea (carina) and arch of aorta
How does the heart actually sit in the body? What is anterior/posterior?
Right ventricle to the anterior, left posterior
apex pointing to left side of chest
What are the remnants of foetal structures present in the adult heart and great vessels? (3 terms)
foramen ovale - passage between left/right atrium
fossa ovalis - indentation where passage used to be
ligamentum arteriosum - small ligament that is the remnant of the ductus arteriosus formed within three weeks after birth. At the superior end, the ligamentum attaches to the aorta
What are the valves of the heart?
Tricuspid valve
Pulmonary valve
Mitral (bicuspid valve)
Aortic valve
Significance and location of coronary sinuses
Above aortic valve provide pooling spot for entrance to coronary arteries which provide blood to heart Left - left coronary artery Right - right coronary artery Posterior - non-coronary sinus
How do the valves work?
Pulmonary and aortic are semilunar and close when back flowing blood starts to put pressure of them
Mitral and Tricuspid have chordae tendineae - blood moves into ventricles down pressure gradient, chrodae tendineae hold them closed as blood moves from ventricles through the semilunar valves
What is the role of the lymphatic system? What are the key lymphatic organs?
Tonsils, spleen, liver, thymus
the lymphatics that drain fluid from the tissue (only move in one direction - from periphery to neck)
(2) one of the most important functions of the lymphatic system is in host defence as it houses most of the immune system.
