The Structure And Function Of The Cardio - Respiratory System Flashcards
Movement of air in the respiratory system
When we breathe in air moves through the mouth and nose and then travels into the trachea. The trachea carries air from the throat to the lungs. The trachea is also covered in cilia which catch particles of dust which are removed when coughing. The trachea divides into two tubes called bronchi, one entering the left and the other entering the right lung. The bronchi several ways into smaller bronchi called bronchioles inside the lungs. At the end of each bronchiole are openings to the alveoli where the air travels into for gas exchange to occur.
Explain gaseous exchange
Gas exchange occurs at the alveoli, where there are networks of blood capillaries surrounding each alveolus.
Carbon dioxide and oxygen move down a concentration gradient from high to low concentration. This means that the oxygen in the alveoli that is at a relatively high concentration diffused into the blood capillaries where the oxygen concentration is lower. The oxygen that diffuses out of the alveoli is replaced by the air that we continue to breathe in.
The same thing happens with carbon dioxide, where there is a higher concentration of it in the blood capillaries, causing it to diffuse into the alveoli where the concentration is lower. This carbon dioxide is eventually breathed out.
The respiratory system definition
The process of breathing in order to maintain the body with oxygen to function.
Factors assisting the process of diffusion in the alveoli during gaseous exchange
- The alveoli are very small in size and large in number so they provide a large surface area for the exchange of gases.
- The surface of the alveoli and the walls of the blood capillaries are very thin and moist which helps with the exchange of gases.
- The levelling and capillaries are touching each other so there is a very short distance for diffusion to occur.
- Each alveolus is surrounded by a network of blood capillaries so there is a rich supply of blood for the gases to diffuse into/from.
Inspiration + expiration
Inspiration - the intake of air into the lungs
Expiration - the expulsion of air from the lungs
Explain what happens during inspiration
- During inspiration, the intercostal muscles contract and pull the rib cage up and out.
- This contraction causes the diaphragm to flatten, also enlarging the chest cavity.
- When the chest cavity expands, its volume increases, causing pressure in the lungs to fall.
- Air moves from the higher pressure outside the lungs to the lower pressure inside the lungs
Explain what happens during expiration
- During exhalation, the intercostal muscles relax and so the rib cage moves inwards and downwards returning to normal.
- Due to the muscles relaxing the diaphragm also curves and returns to its dome shape, causing the chest cavity to get smaller.
- The chest cavity gets smaller means the volume also decreases, so pressure in the lungs increase.
- Expiration is passive so the breathing muscles simply relax.
- Air moves from the high pressure in the lungs to the low pressure in the bronchi and trachea.
What happens with inspiration during exercise?
During exercise, inspiration process is assisted by the contraction of the pectoral and the sternocleidomastoid muscles which increase the chest cavity even further to allow more air into the lungs.
What happens with expiration during exercise?
During exercise, the passive expiration process is supported by the contraction of the abdominal muscles which helps to force out the air of the lungs, speeding up the process.
What is a spirometer and how does it work?
A spirometer is a piece of apparatus designed to measure lung volumes. Ir consists of a chamber filled with oxygen that floats on a tank of water. A person breathes from a mouthpiece attached to a tube which is connected to the chamber. Breathing in talkies oxygen away from the chamber, which then sinks down. Breathing it then pushes air into the chamber, casing it to float. The lung volumes may be seen and measured during these movements.
Four lung volumes and explanations
Tidal volume - the amount of air that enters the lungs during normal inspiration at rest. (Average is 500ml)
Inspiratory reserve volume - the amount of extra air inspired during a deep breath in. (Can be as high as 3000ml)
Expiratory reserve volume - the amount of extra air expired during a forceful breath out.
Residual volume - the amount of air left in the lungs following a maximal expiration.
Arteries
- Arteries carry blood away from the heat under high pressure.
- They have thick, muscular, elastic walls, and maintain the blood pressure by recoiling and narrowing when the heart is relaxing.
- Small arteries can adjust their diameter to increase or restrict blood flow to certain parts of the body.
- Vasoconstriction is where the rings of muscle in the small arteries contract, making the diameter smaller and reducing blood flow to tissues.
- Vasodilation is where the diameter of the small arteries increase to allow more blood to flow through them to the tissues. This occurs during exercise to send more blood to the exercising muscles.
Veins
- Veins carry blood towards the heart.
- Veins have much thinner walls than arteries because the blood pressure in veins is much lower.
- They have a large internal diameter called lumen, and they valves to prevent blood from flowing backwards.
Capillaries
- Tiny, thin walled blood vessels that join arteries and veins.
- They facilitate gas exchange by allowing oxygen to transfer from the blood into tissues, and carbon dioxide to pass from tissues into the blood.
- Nutrients also diffuse from blood into the capillaries and onto the surrounding tissues, and waste products from the tissues unto the blood.
Cardiac cycle
The cardiac cycle is the sequence events that occur when the heart beats. There are two phases of the cardiac cycle which are diastole and systole. In diastole, the heart relaxes and the chambers fill with blood. In systole, the heart contracts and the chambers empty.
