2G- humans gas exchange Flashcards
How do we breathe (ventilation)
- Air enters our nose/mouth and passes down the trachea
- When you breathe in your ribs move upwards and outwards by the intercostal muscles. The outer (external) intercostals contract, pulling the ribs up.
- At the same time, the muscles of the diaphragm contract, pulling the diaphragm down into a more flattened shape.
- Both these movements increase the volume of the chest and cause a slight drop in pressure inside the thorax compared with the air outside. Air then enters the lungs (inhalation).
- The opposite happens when you breathe out deeply. The external intercostals relax, and the internal intercostals contract, pulling the ribs down and in.
- At the same time, the diaphragm muscles relax and the diaphragm goes back to its normal dome shape.
- The volume of the thorax decreases, and the pressure in the thorax is raised slightly above atmospheric pressure. This time the difference in pressure forces air out of the lungs.
- Exhalation is helped by the fact that the lungs are elastic, so that they have a tendency to collapse and empty like a balloon.
What does the trachea split into? Then what?
Two tubes called the bronchi, one leading to each lung. Then it splits in smaller tubes, called bronchioles, eventually, ending at the alveoli.
What’s the thorax?
The thorax is the upper part of the body.
The inside of the thorax is separated from the lungs by two thin, moist membranes called the pleural membranes.
What is the pleural membranes and cavity?
They make up a continuous envelope around the lungs, forming an airtight seal. Between the two membranes is a space called the pleural cavity, filled with a thin layer of liquid called pleural fluid. This acts as lubrication, so that the surfaces of the lungs don’t stick to the inside of the chest wall when we breathe.
What supports the airways?
(C-shaped) cartilage (The open part of the ring is at the back of the Chakya, next to where the oesophagus lies as it passes through the thorax. When food passes along the oesophagus by peristalsis the gaps, and the rings, allow the lumps of food to pass through more easily)
% Inhaled air:
Nitrogen 78%, oxygen, 21% carbon dioxide 0.04%, other gases (mainly argon) 1%
% Exhaled air:
Nitrogen 79%, oxygen, 16%, carbon dioxide, 4%, other gases (mainly argon), 1%
Alveoli process
- Deoxygenated blood is pumped from the heart to the lungs and passes through the capillaries surrounding the alveoli.
- The blood has come from the respiring tissues of the body, where it has given up some of its oxygen to the cells, and gained carbon dioxide.
- Around the lungs, the blood is separated from the air inside each alveolus by only two cell layers; the cells making up the wall of the alveolus, and the capillary wall itself. This is a distance of less than a thousandth of a millimetre. 4. Because the air in the alveolus has a higher concentration of oxygen than the blood entering the capillary network, oxygen diffuses from the air, across the wall of the alveolus and into the blood.
- At the same time there is more carbon dioxide in the blood than there is in the air in the lungs. This means that there is a diffusion gradient for carbon dioxide in the other direction, so carbon dioxide diffuses the other way, out of the blood and into the alveolus.
- The result is that the blood which leaves the capillaries and flows back to the heart has gained oxygen and lost carbon dioxide. The heart then pumps the oxygenated blood around the body again, to supply the respiring cells
How do ciliated cells and goblet cells keep their airways clean?
Ciliated cells have hair that wafts the mucus and pathogens up and out of the trachea. Goblet cells produce mucus to trap dust pathogens.
Three most harmful substances in cigarettes.
Tar- a black sticky substance, which contains carcinogens. It destroys the Celia and irritates our airway lining leading to inflammation and overproduction of mucus.
carbon monoxide – a poisonous gas. It binds to haemoglobin in preference, two and more tightly than oxygen forming carboxyhaemoglobin
nicotine – a highly addictive stimulant drug.
The heart and smoking
Carbon monoxide affects this organ by blocking its blood vessels when smoking. When someone smokes adrenaline causes organ to work harder to pump more oxygen around the bloodstream.
The brain and smoking
Smokers can be in danger of suffering a stroke whether this organs blood supply is cut off. Nicotine causes this organ to create adrenaline and make a person feel relaxed. 
The stomach and smoking
Chemicals with smoke can cause organs to look older. Smoking can cause ulcers, which can cause problems with digestion in this major organ.
The lungs and smoking
Smoking can cause condition, such as emphysema and cancer in these breathing organs. Smoking and caused tar to collect in this organ which causes breathing difficulties.
Bronchitis
Tar, destroys, Celia and irritates the airways, causing inflammation. This leads to the overproduction of mucus which accumulates in the airways leading to: smokers cough, increased risk of infection (bronchitis), reduced airflow -> reduced gas exchange
Emphysema
Alveoli walls, breakdown and fuse together, forming in large of regular airspaces. This causes: reduces surface area for gas exchange, less oxen delivered to cells for aerobic respiration, parson gets fatigue easily.
Lung cancer
Chemicals and taco carcinogens cause DNA in lung cells to mutate and divide rapidly and uncontrollably. This is a tumour which can spread to other organs via the blood.
Carbon monoxide poisoning
It binds to haemoglobin in preference to, and more tightly than oxygen, forming carboxyhaemoglobin, which reduces the oxygen carrying capacity of the blood, and it causes a reduced rate of aerobic respiration, which can lead to rapid death
Coronary heart disease
Nicotine increases blood pressure which damages arteries, leaving fatty deposits on artery walls. This means blood is more likely to clot increasing the risk of heart, heart attacks and strokes.
