Biology B3 - pulmonary system Flashcards
what is the structure and function of lungs ( 6 marks )
Aerobic respiration breaks down the chemicals we eat . This requires oxygen.
Small organisms take in oxygen by diffusion because they have a large surface area to volume ratio. Large organisms have a small surface area to volume ratio so need a respiration surface - lungs
Lungs are protected by the ribs . Below the lungs is the diaphragm
Diaphragm is a large muscle that divides the thorax from the abdomen.
Each lung is made up of lobes . The left lung has 2 lobes and the right lung has 3 lobes. A thin membrane called the pleura surrounds the lungs.
In the lungs oxygen diffuses into the blood and carbon dioxide diffuses out of the blood - gas exchange.
The sequence of breathing processes is called ventilation.
The lungs are surrounded by the pleural membranes . When the chest expands the membrane sticks to the chest wall making the alveoli open , internal air pressure in the lungs and air flow into the lungs. The alveoli secrete a surfactant to stop the internal walls sticking together. Breathing is called inspiration , breathing out is called expiration. During inspiration the intercostal muscles pull the ribs upwards and outwards.
What happens to the diaphragm before we inhale and where is it found ?
Before we inhale , it is found in a dome shape. As we inhale it contracts and flattens
what happens in expiration ?
- Ribs move down and in
- Internal / intercoastal muscles contract and external muscles relax.
- Diaphragm relaxes
- volume inside the chest cavity decreases
- Pressure inside the lungs increases which pushes out carbon dioxide
what happens to the lungs when inhaling ?
Lungs become inflated
what happens to the lungs when exhaling ?
Deflated
How does oxygen get into the blood ( 6 marks )
Millions of alveoli fill with air each time you inhale and deflate each time you exhale.
Squamous epithelial tissue is very thin and elastic.
Each alveolus surrounded by a network of tiny blood vessels. Thin walls . Short diffusion pathway.
Gas exchange needs a concentration gradient. This is maintained by constant flow of blood and the ventilation in the lungs.
Oxygen and carbon dioxide can only cross cell membranes when they are dissolved in water or an aqueous solution , thus respiratory surfaces must be moist.
what is pulmonary ventilation ?
Pulmonary ventilation is the total volume of air that is moved into the lungs during one minute
what is tidal volume ?
Tidal volume is the volume of air normally taken in at each breath when the body is at rest
what is the ventilation rate ?
Ventilation rate is the number of breaths taken in one minute.
how do you calculate pulmonary ventilation ?
pulmonary ventilation = tidal volume x ventilation rate
what is spirometer?
A spirometer measures the volume of air breathed in and out.
What volumes are measured on a spirometer ?
Tidal volume
Vital capacity
Residual volume
what is tidal volume ?
Tidal volume is the volume of air inhaled and exhaled.
What is vital capacity ?
Vital capacity is the maximum volume of air exhaled after ihalation
what is Residual volume ?
Residual volume is amount of air left in lungs after exhalation.
