Healthy Heart and Lungs Week 2 Flashcards
Explain the mechanism for matching ventilation and perfusion?
Define ventilation?
Define Perfusion?
What is ventilation perfusion matching ?
- Ventilation (V) is the amount of gas that can move into and out of the alveolus that can participate in gas exchange
- Perfusion (Q) is the amount of blood in the alveolar capillaries, moving past the alveolus that can participate in gas exchange
The efficiency of gas exchange concerns both ventilation and perfusion.
- Ventilation perfusion matching is also known as ventilation perfusion coupling or ventilation perfusion ratio. We want the V/V ratio to be as close to 1/1 as possible. Its called matching because if V goes up Q goes up.
What is the mean ventilation - perfusion ratio in a healthy individual ?
In a healthy resting adult 4 L of air ventilate the alveoli (V) and 5L of blood pass through the lungs (Q) each minute.
Hence the mean ventilation – perfusion ratio (V/Q) is 4/5 or 0.8
What is the minute volume ?
What is the equation to work out minute volume ?
Minute Volume: Volume of air entering and leaving the lungs each minute. This is the same as pulmonary ventilation
Minute Volume (MV) = Respiratory Rate (RR) x Tidal Volume (VT)
- The number does vary whether your female and male and whether you have respiratory conditions
What is Tidal Volume ?
Tidal volume is the amount of air that moves in or out of the lungs with each respiratory cycle. It measures around 500 mL in an average healthy adult male and approximately 400 mL in a healthy female.
So the amount of air that is taken in and out with each breath.
What is the respiratory rate ?
Respiratory rate: the number of breaths per minute.
As you go from baby to adult your respiratory rate decreases
What are the conducting zones and respiratory zones of the tracheobronchial tree?
Conductance zones: Bronchi, bronchioles, terminal bronchioles (1-16)
Respiratory zone: Respiratory bronchioles, alveolar ducts, alveolar sacs (17-23)
- Not all of the air we take into the lungs is available to be used for gas exchange. 1/3 of every breath is not used in humans
- we have something called dead space in the respiratory system and these are areas where gas exchange do not take place.
- we also have non-perfused alveolus were gas exchange does not take place this could be because of a lack of blood supply because of tissue damage. This is known as physiological dead space. This often increases in disease conditions
What is Tidal Volume ?
-Tidal volume: is the volume of air moved into or out of the lungs in one breath.
-Tidal Volume = dead space + volume of air entering alveoli (respiratory area).
-Pulmonary ventilation (minute volume) = Respiratory rate x Tidal Volume
Pulmonary ventilation is the amount of air we are getting into the lungs
- Alveolar ventilation = RR x ( VT- VD)
Alveolar ventilation is the amount of air we are getting into the alveoli for gas exchange.
How can ventilation be measured ?
- ventilation can be measured using spirometry.
You breathe into the tube. Air enters the drum. The drum rises and then the pen draws on the paper which gives our spirometer image.
- Inspiratory reserve volume: the amount above the tidal volume we can take in ( so when we ask patient to take a big breath in)
- Inspiratory capacity: is the inspiratory reserve volume and tidal volume.
Expiratory reserve volume: the amount of above the tidal volume we can breathe out. ( so when we ask patients to take a breathe out as fully as they can).
- We can never completely empty our lungs, not while we are still alive anyway.
Residual volume: is the volume of air that remains in a persons lungs after fully exhaling.. If we didn’t have residual volume we would have collapsed lungs.
Once you have lung damage or collapsed lungs and loss of alveoli the residual volume increases ( goes up and up) and the expiratory reserve volume decreases ( goes down and down).
- Vital capacity: Inspiratory capacity and Expiratory capacity. So the total amount of air we can forcefully inhale and exhale added together.
- Total lung capacity: if we fully emptied the lungs what the volume would be. ( theoretically no one can actually do this)
What is the capacity of air in the lung ?
Total lung capacity: Vital capacity ( forcefully inhale + forcefully exhale) + Residual Volume
Vital Capacity = Tidal volume + inspiratory reserve volume and expiratory reserve volume
Inspiratory Capacity: Tidal volume + Inspiratory reserve volume
Functional Residual Capacity: Expiratory Reserve Volume + Residual Volume
What is another way of measuring the amount of inhaled and exhaled air besides spirometry ?
- Another way of measuring the amount of inhaled and exhaled air is using Helium Dilution Method.
- Another name for helium dilution method is Plethysmography.
How it works:
- instead of air in the drum there is helium.
- We ask the patient to breathe in and out. The helium enters the lungs and we measure the change in the volume of helium.
How it works in practice ( Plethysmography):
- the patient sits in the chamber, which is then sealed.
- they breathe through the pneumotach.
- they first breathe normally so we can get their tidal volume.
- then we close the shutter so they cant breathe any air in (seems cruel but allows us to calculate key values).
- you then ask the patients to breathe in fully and measure the change in gas in the chamber. (this is possible because the chamber is sealed).
Why do we do Plethysmography? :
- Accessing the values (RV + FRC) for our lungs can tell us about chronic respiratory conditions such as emphysema and COPD.
Why does increased Residual Volume (RV) occur in patients with emphysema and COPD and asthma ?
- In the image you can see healthy and unhealthy alveoli.
-You can see the total lung capacity for both of the ECG have remained the same.
- However in the damaged alveoli (COPD) the Residual Volume has increased.
- Because of this the Vital Capacity (Tidal volume + inspiratory reserve volume and expiratory reserve volume) has decreased.
- Also the gradient of the graph has changed. In both healthy and damages alveoli patients the amount of time taken to take air in is relatively the same.
- However in the patient with damaged alveoli you can see it takes them much longer to breathe out compared to the healthy patient.
Another way we can test ventilatory function is using a Peak Flow Meter.
This is used to see if airways are obstructed. It’s very useful in monitoring asthma.
Useful measures:
- Forced Expiratory Volume in 1 second (FEV1)
- Forced Vital Capacity ( FVC)
The ratio of both of these FEV1 and FVC is commonly used and it is expressed as a percentage (%).
- FEV1 and FVC are measured against predicted values
Normal PEFR is 75% - 80%
This does decrease significantly with an underlying condition.
Obstruction condition:
- could be emphysema or cystic fibrosis
- you can see the total lung capacity does not change much, however it takes a lot longer to reach this point of air in the lungs dur to the obstruction.
- So FEV1 is significantly reduced in patients with obstruction compared to normal patients.
Restricted condition:
- could be due to idiopathic pulmonary fibrosis or interstitial lung disease or motor neuron disease or obesity.
- we can see maximum inhalation is much lower ( take in a lot less air)
- FVC is significantly lower
What is a flow volume loop
What is the flow volume loop?
The flow-volume loop is a plot of inspiratory and expiratory flow (on the Y-axis) against volume (on the X-axis) during the performance of maximally forced inspiratory and expiratory maneuvers.
Changes in the contour of the loop can aid in the diagnosis and localization of airway obstruction.
First graph:
Obstruction curve -
Expiration curve: has shifted slightly to the left and has stretched significantly. So it takes a long time for expiration to complete compared to normal expiration
Restrictive-
Expiration curve: has shifted to the right. The flow volume loop is much narrower.
Our inspiratory has massively decreased
What is Boyle’s Law ?
Is a gas law that describes the relationship between pressure and volume of a confined gas.
Boyles Law: At a constant temperature (T) the volume (V) of a given quantity of gas is 1/ (inversely proportional) to the pressure (P) it exerts .
Inversely proportional is when one value increases the other decreases.
So in this case as the volume decreases the pressure increases.
- We use the equation (P1 x V1) = (P2 x V2). This is the equation we use when solving volume and pressure problems.
Boyles law graph shape ?
A question answered using Boyles law
What is Avogadro’s Law ?
Equal volume of gas at the same temperature and pressure contains the same number of molecules.
All 3 balloons contain exactly the same amount of molecules.
The number of molecules in one mole of gas is 6.02 x 10 (23)
What is Charles law ?
Charles Law is an experimental gas law that describes how gases tend to expand when heated.
At a constant pressure the volume of gas is proportional to its absolute temperature.
When we heat a gas the volume of the gas expands because the particles move away from each other
What is the Ideal Gas Law ?
We can use this equation to work out:
- pressure
- temperature
- Volume
- moles
( R = gas constant)
What is Grahams Law ?
- The rate of diffusion of a gas is inversely proportional to the square root of its molecular weight.
- This means a gas with a lower molecular weigh will diffuse more quickly than a gas with a higher molecular weight.
What is Henrys Law?
- The quantity of a gas that can dissolve in a fluid is equal to the partial pressure of the gas multiplied by the solubility coefficient.
- So some gases are more soluble than others. This is because oxygen is less soluble in water than a lot of other gases including caron dioxide.
What is Daltons Law of partial pressure ?
What is the partial pressure of gasses in inspired air compared to alveolar air ?
What does the rate of diffusion ( O2 and CO2) from alvoli to blood depend on ?
CO2 is 20 x more soluble than oxygen
Area available for gas exchange - for example gas exchange cannot take place in ‘dead spaces’
- The ability of a gas to diffuse between alveolar air and blood is measured by its diffusing capacity.
- membrane surface area - the larger the surface area the faster diffusion.
What is CaO2 in terms of oxygen?
What is SaO2 in terms of oxygen ?
What is PaO2 in term of oxygen?
CaO2 (ml/100ml) - means the Arterial Oxygen Content (confusing because looks like calcium oxide). The CaO2 is the amount of oxygen bound to Hb plus the amount of oxygen dissolved in arterial blood.
SaO2 (%) - % saturation of Hb with O2
PaO2 (mmHg) - partial pressure of oxygen
The relationship of PaO2 to SaO2 and CaO2 is not linear but forms the O2 dissociation curve for Hb.
What are the pressures of oxygen and carbon dioxide when blood is being delivered to tissues ?
The partial pressure of oxygen being delivered to tissues is PO2 = 100mmHg
The partial pressure of carbon dioxide being delivered to tissues is PCO2 = 40mmHG
Describe hemoglobin ?
- has a quaternary structure
- made up of 2 alpha and 2 beta chains
- the chains surround a central heme group, each heme group binds to an oxygen
- Each heme group consist of a porphyrin ring with an iron atom in the center
How much oxygen can we carry in 1 liter of blood at 98% hemoglobin capacity ?
hemoglobin carrying 98% of their maximum load of oxygen (this is average. In patients with health conditions this number is lower).
- In addition to 3mL of O2 which diffuse across in the plasma
- We have 197mL of O2 in the blood
- So the total oxygen carrying capacity is 200ml O2 / Liter of blood
In some cases where there is reduced pO2 such as at a high altitude, red blood cells may only be able to carry 50% of their maximum load of oxygen.
Hemoglobin dissociation curve ?
Bind first oxygen which increases the affinity for the next two. Then its hard for the last oxygen to bind as their are less available spaces.
What factors cause a shift to the right in hemoglobin dissociation curve?
Shift in curve alters the affinity of Hb for oxygen.
Shift to right:
- Shift to the right is called Bohr’s effect.
- It caused by a decreased pH and increased CO2
- It reduces Hb affinity for O2.
What causes a shift to the right:
- Increase H+ ions
- Increased CO2
- Increased temperature
- Increased BPG
What factors cause a shift to the left in hemoglobin dissociation curve ?
Shift in curve alters the affinity of Hb for oxygen.
Shift to left:
- caused by a decrease in temperature, PCO2, 2-3-BPG and H+ ions
- These factors increase affinity for oxygen.
-
What is the Haldane effect ?
The Haldane effect explains how oxygen concentrations influence haemoglobin’s carbon dioxide affinity. The change in carbon dioxide levels is caused by oxygen in both cases. The Bohr effect, on the other hand, explains how carbon dioxide and hydrogen ions influence haemoglobin’s oxygen affinity.
The Haldane effect explains how oxygen concentrations influence haemoglobin’s carbon dioxide affinity. The change in carbon dioxide levels is caused by oxygen in both cases. The Bohr effect, on the other hand, explains how carbon dioxide and hydrogen ions influence haemoglobin’s oxygen affinity.
The key difference between the Bohr and Haldane effects is that the Bohr effect is the decrease of haemoglobin’s oxygen binding capacity with an increase in carbon dioxide concentration or a decrease in pH, while the Haldane effect is the decrease of haemoglobin’s carbon dioxide binding capacity with an increase in oxygen concentration.
Fetal hemoglobin has an increased affinity for oxygen, so its curve is more to the left compared to an adults.
Fetal hemoglobin has to take oxygen from the mothers hemoglobin so it has to have a higher affinity for oxygen.
- fetal hemoglobin lasts for the last 7 weeks of pregnancy and potentially up to 2 months after birth. If it stays too long it can cause issues because a high affinity for oxygen is great for fetal hemoglobin to steal oxygen from the mother but after birth this also means its harder for the hemoglobin to give up oxygen at the tissues.
- There is pharmalogical drugs which can reactivate fetal hemoglobin which can help treat patients with sickle cell anemia.
Carbon monoxide can bind 200 x more readily than oxygen.
- When it bind to hemoglobin it forms carboxyhemoglobin
- this decreases the affinity of Hb for O2 ( competes with O2)
- It also impairs the release of O2 at tissues
Symptoms of CO poisoning vary depending on the COHb ( carboxyheamoglobin level)
At what levels are Carbon monoxide levels fatal ?
Carbon monoxide can bind 200 x more readily than oxygen.
- When it bind to hemoglobin it forms carboxyhemoglobin
- this decreases the affinity of Hb for O2 ( competes with O2)
- It also impairs the release of O2 at tissues
Symptoms of CO poisoning vary depending on the COHb ( carboxyheamoglobin level)
-Normally the amount of hemoglobin bound to carbon monoxide so carboxyhemoglobin is 2%. So we have low but constant levels of hemoglobin
- After a cigarette your carboxyhemoglobin levels are 10%
- A level of 2-6% carboxyhemoglobin can exacerbate an underlying cardiovascular condition.
- 3 - 24% can cause nausea and dizziness
- mean level of carbon monoxide that can cause a loss of consciousness is 24%
- Some people can survive up to 70% which is crazy
- The mean level of carbon monoxide which can be fatal is 32%
Describe where carbon dioxide which is released from the body comes from ? (carbon dioxide transport)
Carbon dioxide is much less toxic than carbon monoxide but still needs to be cleared from our bodies.
- When cells excrete CO2 some of it diffuses straight into the blood. This is about 7%.
- Most CO2 ends up in the blood as bicarbonate (HCO3-) and this makes up about 70% of CO2 in the body.
- The remaining 23% combines to hemoglobin and becomes carbaminohemoglobin. ( remember this is only 2% of total haemoglobin)
Describe the carbon dioxide dissociation curve ?
Carbon dioxide dissociation curve:
- has a more straight and less sigmoid shape than hemoglobin
Graph:
- A is showing content in venous blood. There is more CO2 in venous blood as we are taking it to the lungs to get rid of it.
- B is showing content in arterial blood.
What is the Haldane effect?
The Haldane effect and Bohr effect work together.
Gas exchange at the tissues ?
- We want oxygen in and CO2 out
- As oxygen leaves the blood it is exchanged for CO2
- Some CO2 dissolves in the plasma
- Some binds to the proteins
- Most of it enters the red blood cells
- An enzyme called CARBONIC ANHYDRASE is the enzyme which catalyzes the reaction of:
CO2 + H20 -> H2CO3 (carbonic acid)
Carbonic acid then breaks down into bicarbonate ion and hydrogen ion.
H2CO3 -> HCO3- + H+
CO2 is therefore leaving the cell as bicarbonate ion. A change called the chloride shift occurs at this point. This is where there is an influx of Cl- ions to replace the lost bicarbonate ions and balance the charges.
Describe gas exchange at the lungs ?
- rapid transfer of CO2 in the lungs for exchange of O2
- There is chloride shift occurring again. But this time Cl- ions are leaving and HCO3- ions are entering.
- The dissolved CO2 in the plasma also leaves but this is at a much slower rate.
Acid base balance recap
- Instead of using the concentration of H+ ions in this case we are using the concentration of CO2 because it will be the same
- To find the concentration of CO2 we times the partial pressure of CO2 by solubility coefficient for CO2.
What causes pH change in the blood ?
It could be due to:
- respiratory reasons
- metabolic reasons
Diabetic ketoacidosis : diabetic ketoacidosis (DKA) in people with diabetes, is a complication of diabetes that occurs when a person does not have enough insulin. The body responds by breaking down fat into ketones too rapidly, resulting in high levels of ketones in the blood (far more than the normal amount in people without type 1 diabetes).
Ketones are acidic molecules, so an increased level of ketones can cause the blood to become more acidic which prevents the body’s processes from working normally. By definition, ketone levels in DKA are too high, causing the blood to become dangerously acidic.
Renal failure: The buildup of acid in the body due to kidney disease or kidney failure is called metabolic acidosis. When your body fluids contain too much acid, it means that your body is either not getting rid of enough acid, is making too much acid, or cannot balance the acid in your body.
Vomiting: Loss of stomach acids. This is the most common cause of metabolic alkalosis. It’s usually brought on by vomiting or suction through a nose-feeding tube.
The gastric juices have a high content of hydrochloric acid, a strong acid. Its loss causes an increase in the alkalinity of the blood.
The vomiting can result from any number of stomach disorders. By figuring out and treating the cause of the vomiting, your doctor will cure the metabolic alkalosis
What is the physiological response to changes in blood Ph away from the optimum?
- We can buffer the change the change in Ph with chemicals including HCO3- , Hb and other blood proteins. This happens very rapidly but it doesn’t make much difference its quite limited in capacity.
- We can also change ventilation, this would cause a rapid response. The only scenario in which this may not work is if the primary cause of acidosis or alkalosis is already respiratory.
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What is the physiological response to changes in blood Ph away from the optimum?
- We can buffer the change the change in Ph with chemicals including HCO3- , Hb and other blood proteins. This happens very rapidly but it doesn’t make much difference its quite limited in capacity.
- We can also change ventilation, this would cause a rapid response. The only scenario in which this may not work is if the primary cause of acidosis or alkalosis is already respiratory.
- We can change how much H+ and HCO3- we excrete from our urine. This will change the pH of the blood. Its a slower response and can have a significant buffering effect if the primary cause is renal its very limited.
What are the physiological responses to respiratory acidosis ?
Caused by low pH because of high pCO2. ( lungs retain CO2)
- The kidneys compensate by increasing plasma HCO3-
- We excrete more H+ ion in the urine
- This process takes 3-5 days ( so is quite slow)
- This restores pH towards normal.
- But HCO3- and pCO2 remain high ( we have counteracted the high pH but we still have high CO2 and bicarbonate levels)
What are the physiological responses to respiratory alkalosis ?
Caused by high pH and low pCO2 (lungs lose excessive CO2)
- The kidneys compensate by retaining H+
- And also excreting HCO3- in the urine.
- This process takes 3-5days ( so is quite slow)
- This HCO3- and pH will fall and the pH will restore to normal
- But HCO3- and pCO2 will remain low ( we have counteracted the change in pH however the pCO2 and HCO3- will remain low)
Describe and explain a Davenport Diagram ?
- pH on x -axis
- Bicarbonate ion on y - axis
We have 4 quadrants which indicate a condition
- respiratory acidosis (A) - increased CO2
- respiratory alkalosis (B) - decreased CO2
- metabolic acidosis (C) - increased non-volatile acid and low HCO3- levels
- metabolic alkalosis (D) - increased non- volatile base and high HCO3-
Summary of acid base disturbances .
Which veins bring deoxygenated blood to the right atrium ?
- Superior and inferior vena cava bring deoxygenated blood to the right atrium
- pulmonary arteries carry deoxygenated blood to the lungs
- pulmonary veins carry oxygenated blood to the heart
At which position does the heart sit ?
Inferolateral: Below and to one side
The left lung is smaller than the right lung to accommodate the heart
Right hand side of lung:
- runs from the 3rd costal cartilage to the 6th costal cartilage
- Only 1/3 of the heart is right of the midline
Left side of the lung:
- runs from 2nd costal cartilage to the 5th intercostal space going outward from the midclavicular line
- 2/3 of the heart is right of the midline
If we look from the back of the heart. The posterior surface of the heart runs from the T5 to T8 (5tha and 8th thoracic vertebrae)
Describe the pericardium of the heart ?
Visceral pericardium = Epicardium
- parietal and visceral pericardium are continuous. Visceral pericardium is the area around the heart and parietal pericardium is the next layer.
- The pericardial cavity lies between the visceral and parietal pericardium. This contains serous fluid which reduces friction between the visceral and parietal pericardium.
- Around the parietal pericardium we have the fibrous pericardium.
- The heart muscle itself is made up of:
- Epicardium (visceral pericardium)
- Myocardium
- Endocardium
The bottom of the heart is connected to the diaphragm via the fibrous pericardium and the central tendon to the diaphragm. There is connection between the heart and diaphragm.
What are pericardial sinuses ?
Explaining diagrams. On the right hand image we are looking at the thorax in an anatomical view but the heart has been removed. It is as if the heart has been removed and placed on the left hand side. The image on the left shows the posterior view of the heart.
- There is a couple of spaces that sit within the pericardial cavity called pericardial sinuses
- There are three sinuses in the pericardial space: superior, transverse, and oblique. The two pericardial space sinuses that can be accessed in electrophysiological (EP) procedures are the transverse and oblique sinuses.
Oblique pericardial sinus - at the back of the heart where the asteriks are
Transverse pericardial sinus - runs above the pulmonary veins between the aorta and superior vena cava. This is a continuous passage. A cardiac surgeon will often
What are pericardial sinuses ?
Explaining diagrams. On the right hand image we are looking at the thorax in an anatomical view but the heart has been removed. It is as if the heart has been removed and placed on the left hand side. The image on the left shows the posterior view of the heart.
- There is a couple of spaces that sit within the pericardial cavity called pericardial sinuses
- There are three sinuses in the pericardial space: superior, transverse, and oblique. The two pericardial space sinuses that can be accessed in electrophysiological (EP) procedures are the transverse and oblique sinuses.
Oblique pericardial sinus - at the back of the heart where the asteriks are. Oblique pericardial sinus has less of a function clinically but is a space you may need to know about.
Transverse pericardial sinus - runs above the pulmonary veins between the aorta and superior vena cava. This is a continuous passage. A cardiac surgeon will often feed a ligature through here to the of the aorta and pulmonary trunk whilst performing surgery on the heart.
What are the cardiac surfaces of the heart ?
What are the borders of the heart ?
- Diaphragmatic surface
- Sternocostal surface
- Posterior surface (base)
- Right pulmonary surface
- Left pulmonary surface
Borders of the heart:
- inferior border ( runs along right ventricle)
- right border ( runs along right atrium )
- superior border ( runs from the top of the right atrium, ventricles along the base of the aorta and pulmonary trunk)
- Left border ( runs down the side of the left ventricle)
- Apex (left inferior most part of the heart)
We can trace cardiac borders on a x -ray of the heart ?
Left -
- right atrium
- Vertical border on top of that is the superior vena cava
Right
- bigger bulge which is the left ventricle
- left auricle is the dip ontop of that
- vertical border on top of that is the pulmonary trunk and left artery
- smaller bump on top of that is what we call the aortic ‘knuckle’
What are the chambers of the heart ?
Left and Right Atrium
Left and Right Ventricle
- Atria are important in maintaining the cardiac pace at about 60bpm
- If we only had ventricles the cardiac pace would be abouut 40bpm. But since we have atria they set the cardiac pace at about 60bpm
Describe the Right Atrium ?
Smooth wall of atrium = sinus venarum
Rough wall of atrium = covered in pectinate muscles (muscculi pectinati)
-Between the smooth and rough wall is a ridge called the crista terminalis.
The outside of the heart has a corresponding groove called the sulcus terminalis
Sinoatrial node - in the right atrium top corner. This is teh pacemaker of the heart.
Fossa Ovalis - depression left after foramen ovale closes
Coronary sinus - coronary (heart) circulation drains into the coronary sinus
Blood leaves the right atrium onto the right ventricle via the tricuspid valve
Describe the left atrium ?
Left atrium receives blood from the 4 pulmonary veins
Left atrium drains into the left ventricle via the mitral valve (bicuspid).
Valve of the foramen ovale which would of allowed the embryo to communicate between the right atrium and left atrium. This has now closed.
Describe the right ventricle ?
- Receives blood rom right atrium through tricuspid valve
- pumps blood through the pulmonary trunk which splits into the two pulmonary arteries which enter each hilum of the lungs
- intraventricular septum is the wall between the left and right ventricle. Within that we have the moderator band ( septomarginal trabecula)
What is trabeculae carneae ?
What is pectinate muscle ?
- trabeculae carneae is present in both ventricles
- pectinate muscle is present in both atria
Describe the left ventricle ?
- Bicuspid valve ( mitral valve).
- Blood travels across the infundibulum towards the aortic valve
Comparing right and left ventricle ?
- The left ventricle walls are much thicker than the right.
Describe the atrioventricular valves ?
- Bicuspid valve
- tricuspid valve
You can see chordae tendinea (heart strings) and the papillary muscles
Describe the semilunar valves ?
- Aortic
- pulmonary vales
They have no chordae tendinea and no papillary muscles. These work entirely by the pressure in different chambers of the heart. Contraction of the ventricles causes these valves to open and relaxation causes the valves to shut so there can be no backflow of blood.
Axial view of the heart
MRI of heart
Axial view feet upwards
Auscultating valves
The valves of the heart can be dissected out of the heart together. All 4 cardiac valves lie in the same plane.
As Docters we want to listen to these valves in patients as it will tell you how healthy a patients hart is. The valves are located behind the sternum so cannot be directly auscultated.
Instead we auscultate the valve in the chamber receiving the blood from those valves.
Auscultation points for the heart valves ?
Atrioventricular valves (both) auscultation point: 5th intercostal space on the left hand side.
- tricuspid valve (green) : close to the sternum
- bicuspid valve (purple): apex of the heart
Semilunar valves (both auscultation point): 2nd intercostal space on either side of the sternum.
- pulmonary valve ( blue) : on left of the sternum
- aortic valve (orange): on the right of the sternum
What are the sinuses of the semilunar valves ?
Semilunar valves:
aortic ( right)
Pulmonary ( left
What are the sinuses of the semilunar valves ?
Semilunar valves:
aortic ( right)
Pulmonary ( left)
There are 3 sinuses of the aortic valve. And 2 of the sinuses have a coronary artery coming out from them
Describe coronary artery filling.
Coronary arteries supply blood to the heart muscle.
Coronary arteries are the only arteries that fill during diastole.
Describe coronary arterial supply ?
- There is a lot of variation in the position of the coronary arteries but we are going to learn where everything generally is.
- We have 2 main coronary arteries the right and left. These branch into smaller coronae arteries to supply different parts of the heart.
Describe the right coronary artery?
- important branch called the Marginal artery. Together they form an L shape
What form of imaging lets us see coronary arteries?
Coronary arteriogram
Described the left coronary artery ?
- Left coronary artery is larger but shorter than the right coronary artery
Coronary artery distribution ?
How much of the coronary arteries are supplied by the right and left coronary arteries varies.
- you could have the entire heart supplied by the left coronary artery
- or 1/3 from the right and 2/3 from the left
- “/3 from the right and 1/3 from the left
Describe coronary veins ?
- drain deoxygenated blood from coronary distribution and return it to the right atrium so it can be reoxygenated.
- A number of cardiac veins run alongside the cardiac arteries
e.g the great cardiac veins runs along the left anterior descending - All of the cardiac veins drain into the coronary sinus which then takes the blood to the coronary sinus in the right atrium.
- Some veins carry deoxygenated blood back to the right atrium without going through the coronary sinus such as the smallest cardiac vein (thebesian vein) and the anterior cardiac vein
What 3 compartments make up the thoracic cavity ?
Mediastinum: is the middle part of thoracic cavity which contains your heart and other structures.
Where do the pleauraof the lungs meet?
At the hilum.
There is different parts of the pleura:
- diaphragmatic pleura
- mediastinal pleura
- cervical pleura
What is the space between the visceral and parietal pleura called?
-The potential pleural spaces that are formed are called pleural recesses.
-There are two pleural recesses. The costodiaphragmatic recesses (also called costophrenic angles) are the larger of the recesses located between the costal and diaphragmatic pleura of right and left pleural cavities.
- Costomediastinal recesses - between the ribs and the mediastinum
Describe the surfaces of the lungs ?
The apex of the lung extends beyond the clavicle into the root of the neck
Describe the surfaces of the lungs ?
What is lobar pnemonia?
Chest radiograph with lobar pneumonia
- left lung is healthy, its black and full of air
- right lung - superior lobe is black and healthy
- inferior lobe is black and healthy
- middle lobe is not healthy ( its filled with fluid). We have
pneumonia of the right middle lobe
Surface marking of oblique fissure
To find the oblique fissure get the patient to hold both hands up behind their head. This will swing the scapulae to the side. The margin of the scapulae are in line with the oblique fissure.
- Mid axillary line. Going down from the armpit (axilla).
- The horizonal fissure crosses mid axillary line at 5th rib
- The oblique fissure crosses the mid axillary line at the 6th rib
- The mid axillary line crosses the base of the inferior lobe at rib 8
- The pleaura crosses the mid axillary line at the 10th rib
Where do you assultate the lung ?
4 places you should assultate the lungs:
Anterior
- Apex of the lung - just above the clavicle
- superior lobe (between ribs 2 and 3 )
- middle lobe (between ribs 4 and 5, medial to the nipple)
- inferior lobe (between ribs 6 and 7)
Relationship of ribs and lungs.
10th rib at mid scapular line at the back
Describe th hilum of the lung ?
Hilum of the lung is the only place in the lung where structures can exit and enter.
-pulmonary artery
- pulmnary vein
- bronchus
- Bronchial artery (provide blood supply to the bronchioles)
- Bronchial vein ( provide blood supply to the bronchioles)
- pulmonary nerves
- lymphatic vessels
Describe the left and right hila ?
Right hilum: we have the esophagus running next to it. We have the superior vena cava ( above it) and the inferior vena cava ( below).
Right lung = Relationship between pulmonary artery and bronchus: Right Anterior (so Infront of the bronchus). Inferior to the bronchus and arteries is the pulmonary veins
Left lung = Relationship between the pulmonary artery and bronchus: Left superior ( pulmonary artery is superior to the bronchus). The pulmonary veins are inferior again.
Left hilum: aortic arch is looping around the hilum (leaves an impression on the left lung)
The reason we use RALS to identify structures in the hilum is because the bronchus the walls are reinforced with cartilage so is much tougher than arteries and veins.
Describe the left and right hila ?
Right hilum: we have the esophagus running next to it. We have the superior vena cava ( above it) and the inferior vena cava ( below).
Right lung = Relationship between pulmonary artery and bronchus: Right Anterior (so Infront of the bronchus). Inferior to the bronchus and arteries is the pulmonary veins
Left lung = Relationship between the pulmonary artery and bronchus: Left superior ( pulmonary artery is superior to the bronchus). The pulmonary veins are inferior again.
Left hilum: aortic arch is looping around the hilum (leaves an impression on the left lung)
The reason we use RALS to identify structures in the hilum is because the bronchus the walls are reinforced with cartilage so is much tougher than arteries and veins.
What does the mediastinum contain ?
- Heart and its vessels
- Oesophagus
- Trachea
- Phrenic and cardiac nerves
- Thoracic duct
- Thymus
- Lymph nodes of the central chest
What does the mediastinum contain ?
- Heart and its vessels
- Oesophagus
- Trachea
- Phrenic and cardiac nerves
- Thoracic duct
- Thymus (only in infants)
- Lymph nodes of the central chest
Divisions of the mediastinum ?
What is in the superior mediastinum ?
- aortic arch and its branches is in the superior mediastinum
- some things pass through such as the esophagus, thoracic duct, vagus and phrenic nerve.
-
What is the contents of inferior mediastinum ?
- The thymus gland is replaced with fibrofatty connective tissue in adults.
Middle mediastinum:
- deep cardiac plexus (nerves which supply the heart)
Posterior mediastinum ( behind the heart):
- vagus nerves (vagi) which run alongside the oesophagus
The function of the thoracic duct is to transport lymph back into the circulatory system
- azygous vein provides an alternative route to return deoxygenatd blood to the heart. Links up with superior inferior vena cava. Azygous vein is not paired it is on the right hand side of the body only.
Label the cadaver of the mediastinum ?
Mediastinum - axial CT with contract
Describe the aorta ?
What are the vagus nerves ?
The vagus nerve, also known as the vagal nerves, are the main nerves of your parasympathetic nervous system. This system controls specific body functions such as your digestion, heart rate and immune system. These functions are involuntary, meaning you can’t consciously control them.
The vagus nerve is the 10th cranial nerve (CN X)
- The vagus nerve originates from the medulla of the brainstem
he right vagus nerve passes anterior to the subclavian artery and posterior to the sternoclavicular joint, entering the thorax.
The left vagus nerve passes inferiorly between the left common carotid and left subclavian arteries, posterior to the sternoclavicular joint, entering the thorax.
What are the vagus nerves ?
The vagus nerve, also known as the vagal nerves, are the main nerves of your parasympathetic nervous system. This system controls specific body functions such as your digestion, heart rate and immune system. These functions are involuntary, meaning you can’t consciously control them.
The vagus nerve is the 10th cranial nerve (CN X)
- The vagus nerve originates from the medulla of the brainstem
he right vagus nerve passes anterior to the subclavian artery and posterior to the sternoclavicular joint, entering the thorax.
The left vagus nerve passes inferiorly between the left common carotid and left subclavian arteries, posterior to the sternoclavicular joint, entering the thorax.
Where are the subcarinal lymph nodes found ?
Subcarnial lymph nodes are located around the divison of the trachea and main bronchi.
