5 Lungs and heart

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  • Created by: Naana
  • Created on: 10-02-15 10:36
What is ventilation?
The process of breathing in and out. Air must be constantly moved in and out of the lungs to maintain diffusion of gases across the alveolar epithelium
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Describe the process of breathing in- inspiration
External intercostal muscles contract,internal intercostal muscles relax. Ribs pulled upwards and outwards- increase thorax volume. Diaphragm muscles contract (flatten) - increase thorax volume. Increased volume of thorax decreases pulmonary pressure
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When does air move into the lungs?
When atmospheric pressure is greater than pulmonary pressure air is forced into the lungs (alveoli)
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Describe the process of breathing out -expiration
Internal intercostal muscles contract,external intercostal muscles relax. Ribs move downwards and inwards- decrease thorax volume. Diaphragm muscles relax (return to domed positon)- decrease thorax volume. Decreased volume of thorax increases pulmona
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When does air move out of the lungs
When the pulmonary pressure is greater than the atmospheric pressure. The recoil of the elastic lungs is the main cause of air being forced out of lungs
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What is meant by pulmonary ventilation?
The total volume of air that is moved into the lungs during one minute
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How do we calculate pulmonary ventilation?
Tidal volume × ventilation rate. Tidal volume= volume of air normally taking in at each breath when body is at rest. Ventilation rate= the number of breaths taking in one minute
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What are the essential features of an exchange surfaces?
Surface: volume ratio has to large- speed up rate of diffusion, thin wall- short pathway to diffusion, partially permeable membrane-allow certain materials to diffuse easily, movement of internal and environmental medium- maintain diffusion gradient
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What is meant by cardiac output?
The volume of blood pumped by one ventricle of the heart in one minute
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How do we calculate cardiac output?
Heart rate (rate at which the heart beats) × stroke volume (volume of blood pumped out of each beat)
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What are the essential features of exchange surfaces?
Large surface area to volume ratio-speeds exchange, very thin- short diffusion pathway, partially permeable- allow selected materials to diffuse easily, movement of internal and environmental medium- to maintain steep concentration gradient
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What is the cause of pulmonary tuberculosis?
It is caused by a bacterium called Mycobacterium tuberculosis
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What are the symptoms of pulmonary tuberculosis?
Initially persistent cough, tiredness, loss of appetite- leads to weight loss. After, fever and coughing up blood
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How is pulmonary tuberculosis transmitted between individuals in the population?
It is spread through the air by droplets, released into the air when infected person coughs or sneezes. It tends to be more widespread in areas where people live in crowded conditions or there is poor hygiene
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How does the TB disease develop within the body?
When Mtb bacteria is inhaled by someone who is not immune to it, the bacteria is ingested by phagocytes and then encased in tubercle. The bacteria remains dormant however if person becomes immunosuppressed then the bacteria starts to replicate. The b
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What is pulmonary fibrosis?
This is the formation of scar tissue on the epithelium of the lung. The scarring is a result of exposure to asbestos or dust
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How does pulmonary fibrosis reduce the efficiency of gas exchange in the lungs?
Oxygen can’t diffuse into the blood as efficiently because the pathway to diffusion increases as scar tissues are thicker. Also, the volume of air that the lung is able to contain reduces as the lungs are less likely to expand and recoil, due to the
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What is asthma?
This is when the linings of the airways become inflamed and irritated, (as the allergen causes the white blood cells on the lining of the bronchi and bronchioles to release a chemical called histamine)
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How does asthma reduce the efficiency of gas exchange in the lungs?
During an asthma attack, the smooth muscle linings of the bronchioles contract and large amounts of mucus is produced and secreted. This constricts the airways. As a result the air flow in and out of the lungs is greatly reduced - less o2 enters the
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What is emphysema?
This is when the elastin in lungs has become permanently stretched, as a result to smoking or long time exposure to air pollution.
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How does emphysema reduce the efficiency of gas exchange in the lungs?
When the foreign particles from smoke or the air become trapped in the alveoli, it causes inflammation, which then attracts phagocytes. The phagocytes produce enzyme which break down the protein elastin. Loss of elastin means that the alveoli can’t r
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What is the first stage of the cardiac cycle? Outline the process
Diastole- both the atria and the ventricles are relaxed. The atria start to fill up which blood which increases the pressure in the atria so that it is higher than the ventricles. As a result the AV valves open and the ventricles also fill up with bl
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What is the second stage of the cardiac cycle? Outline the process
Atrial systole (contraction of the atria) - the ventricles are relaxed whereas the atria contracts which increases the pressure inside the atria. The blood pressure is now greater in the atria than the ventricles so the AV valves open and blood is fo
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What is the third stage of the cardiac cycle? Outline the process
Ventricular systole (contraction of the ventricles) – After a short delay to allow the ventricles to fill up with blood, the ventricles contract which increases the blood pressure within them. The pressure in the ventricles is now higher than the atr
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What is the role of the atrioventricular valves?
They prevent the back flow of blood when the ventricular pressure is greater than the atrial pressure. They ensure that when the ventricles contract, blood within them moves to the aorta and the pulmonary artery rather than back to the atria.
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What is the role of the semi lunar valves?
They prevent the backflow of blood into the ventricles when the pressure inside the pulmonary artery or the aorta is greater than the ventricular pressure
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What do the pocket valves in the veins ensure?
They ensure that when the veins are squeezed, blood flows back to the heart rather than away from the heart.
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What is an atheroma?
This is the fatty deposits that form within the walls of an artery. They begin as fatty streaks that are accumulations of white blood cells that have taken up low density lipoproteins. These streaks enlarge to form an atheromatous plaque (atheroma).
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How does atheroma increase the risk of thrombosis? Explain what thrombosis is?
If the atheroma breaks through the inner lining (endothelium) of an artery, it forms a rough surface that disrupts the smooth flow of blood. This may result in platelets and fibrin accumulating at the site of damage and forming of a blood clot (throm
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How does atheroma increase the risk of aneurysm? Explain what aneurysm is?
Atheroma’s that lead to the formation of a thrombus weaken the artery walls. These weakened points swell to form a balloon -like blood filled structure called an aneurysm. Aneurysms often burst and cause hemorrhage (bleeding) and as a result there is
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What is a myocardial infarction (heart attack)?
When the coronary arteries that supply blood to the heart muscles become completely blocked. As a result an area of the heart muscle becomes totally cut off from its blood supply, receiving no oxygen. A heart attack can cause damage (if blockage is f
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What factors increase the risk of coronary heart disease?
Smoking, high blood pressure, high cholesterol and poor diet
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Other cards in this set

Card 2

Front

Describe the process of breathing in- inspiration

Back

External intercostal muscles contract,internal intercostal muscles relax. Ribs pulled upwards and outwards- increase thorax volume. Diaphragm muscles contract (flatten) - increase thorax volume. Increased volume of thorax decreases pulmonary pressure

Card 3

Front

When does air move into the lungs?

Back

Preview of the front of card 3

Card 4

Front

Describe the process of breathing out -expiration

Back

Preview of the front of card 4

Card 5

Front

When does air move out of the lungs

Back

Preview of the front of card 5
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