Gas exchange in humans Flashcards
What carry out gas exchange in the body?
Alveoli - the lungs contain millions of these little air sacs
What does the blood passing next to the alveoli contain lots of?
Lots of carbon dioxide and very little oxygen as it has just returned to the lungs from the rest of the body
Where does the oxygen diffuse out of?
The alveolus (high concentration) into the blood stream (low concentration)
Where does the carbon dioxide diffuse out?
The blood (high concentration) into the alveolus (low concentration)
What happens when blood reaches body cells?
Oxygen is released from the red blood cells (where there is a high concentration) and diffuses into the body cells (where the concentration is low)
What happens to the carbon dioxide?
It diffuses out of the body cells (where there is a high concentration) into the blood (where there is a low concentration). Its then carried back to the lungs
How are alveoli specialised for gas exchange?
- Huge number of microscopic alveoli - lungs have big sa - Moist lining - gasses can dissolve easily - Thin walls (one cell thick) - gasses do not have far to diffuse - Great blood supply - maintain a high conc gradient - Walls are permeable - gasses diffuse across easily
What can smoking tobacco do?
Severely affect your lungs and circulatory system
What are the results of damaging the walls inside the alveoli when smoking?
Reduce sa for gas exchange leading to diseases like emphysema
What does the tar in cigarettes do?
Damages the cilia (small hairs) in your lungs and trachea
Why is it bad if the cilia are damaged?
These hairs, along with mucus, catch a lot of dust and bacteria before they reach your lungs. They keep the trachea clear by sweeping mucus towards the mouth - when they are damaged they cannot do the above and so just infections are more likely to happen
What else can tar do?
Irritate the bronchi and bronchioles encouraging excess mucus to be produced which cant be cleared very well by the damaged cilia - this causes smokers cough and chronic bronchitis
Why is carbon monoxide in cigarette smoke bad?
It reduces the amount of oxygen red blood cells can carry - the heart rate increases because of that which leads to an increase in blood pressure
Why is high blood pressure not good?
It damages the artery walls making the formation of a blood clots more likely increasing the risk of coronary heat disease
What does tobacco smoke contain?
Carcinogens which are chemicals that can lead to cancer
