Respiratory System Flashcards
Structure, organs, process, etc.
What is the purpose of the nasal cavity?
The nasal cavity is convoluted and lined by mucous membranes. As air passes over membranes, it is warmed and humidified. There is also hairs and mucus lining in the nose, trapping debris and preventing it from reaching the lungs.
What is the pharynx?
The region from the nasal cavity to the top of the trachea and oesophagus.
What is the purpose of epiglottis?
The epiglottis diverts air and food into different pathways. During inhalation, the epiglottis covers the oesophagus, guiding the air into the trachea. When swallowing, the epiglottis covers the larynx, preventing food from entering it.
What is the larynx?
A cartilage structure joining the pharynx and the trachea. Contains vocal cords, which are mucous membranes that are able to vibrate as air passes over them.
Trachea:
Carries air into and out of the lungs.
- made up of C-shaped cartilage to hold structure open, ensure air can always pass through it even when inhaling.
- Epithelial lining of trachea produce mucus which is able to trap dust and debris, preventing from enter lungs.
- This is done through cilia, that line trachea, which move in wave-like motion to take mucus and debris up to the pharynx to be swallowed and digested.
Bronchi:
- at end of trachea, structure splits into two primary bronchi, which then split into secondary bronchi which take air into each lobe of the lungs. Secondary bronchi continue to divide to form tertiary bronchi.
- Bronchi also have C shaped cartilage rings.
- As bronchi get smaller, cartilage more spread out with smooth muscle and elastin forming more of the structure.
- There is also cilia in the bronchi as well.
Bronchioles:
- When tertiary bronchi divide, form bronchioles.
- Continue to split until they end in millions of terminal bronchioles.
- Made of smooth muscle and elastin rather than cartilage, allowing bronchioles to control flow of air in lungs, expand when need more oxygen.
- Cilia is also present.
Lungs:
2 lungs take up whole chest cavity, except space in between (mediastinum) that is occupied by heart + blood vessels.
- Left lung has 2 lobes, right has 3.
- Membrane called pleura covers surface of lungs (visceral pleura), and also lines inside of chest (parietal pleura).
- Btw 2 layers of membrane is thin layer of pleural fluid, hold lungs against inside of chest wall + allow to slide along wall when breathing.
- In lungs, terminal broncioles split into clusters of air sacs called alveoli.
- Alveolus has wall that is only one cell thick, surrounded by network of blood capillaries.
- This where gas move btwn blood in capillaries and air in alveolus.
Describe the Process of Inspiration.
During inspiration, the diaphragm and the intercostal muscles contract, causing the rib cage to move upwards and outwards. As the pleural fluid holds the lungs along the inner chest cavity, as the rib cage expands, the lungs also expand, increasing its volume. The increase in volume decreases the air pressure of the lungs. The difference in the air pressure between the atmosphere outside the body and inside the body within the lungs causes air to flow into the lungs through the nasal cavity and the trachea. Air continues to flow in until the air pressures between the outside and inside is equal. During normal breathing, the diaphragm is mainly responsible for the change in pressure of the lungs, and the rib cage becomes increasingly involved during heavy breathing.
Describe the Process of Expiration
During expiration the diaphragm and intercostal muscles relax, meaning that the diaphragm moves up into the lungs, and the rib cage moves down and inwards. This decrease in the volume of the lungs causes the air pressure to increase within the lungs. The air pressure within becomes higher than the air pressure outside the body. This causes air to flow out of the lungs through the trachea and nasal/oral cavity to the atmosphere outside the body, until the air pressure becomes equal. During normal breathing, expiration is a passive process, involving the relaxing of the muscles which have contracted during inspiration.
Why are the lungs well suited to their main function of gas exchange?
- The Alveoli provide a large internal surface area, meaning that gas exchange occurs at a faster rate as there are more surfaces for the gas exchange to occur.
- The Alveoli are well supplied with blood vessels, meaning that they are in constant contact with blood. The continuous flow of blood helps maintain a difference in concentrations of oxygen and carbon dioxide between the blood and the air in the lungs.
- The membrane that forms the wall of the alveoli is only one cell thick, meaning that gases including oxygen and carbon dioxide only have to move a short distance between the blood capillaries and the alveoli.
Describe the process of Gas Exchange.
During gas exchange, the blood in teh capillaries surrounding the alveoli is brought to the lungs by the pulmonary arteries. This blood has been through the capillaries of the body, where oxygen has been used up by the body cells. The blood that flows through the capillaries around the alveoli are deoxygenated, and have a lower concentration of oxygen that in the alveoli. Oxygen then dissolves in the moisture on the inside of the alveolus, and diffuses through the membrane, the walls of the capillaries and into the blood.
The blood arriving at the capillaries surrounding the alveoli has come from body circulation where it has picked up carbon dioxide produced by respiration in the cells. The concentration of carbon dioxide in the blood in capillaries is higher than. in the alveoli, therefore, carbon dioxide diffuses out of the blood and into the air in the alveolus.
What must be present for gas exchange to occur?
A concentration gradient must be present for the diffusion of gases into and out of the blood. A difference in gas concentration btwn air in the alveoli and blood in capillaries. Concentration gradient is maintained by:
1. Constant flow of blood through the capillaries. As blood flowing thru capillaries around each alveolus picks up oxygen and loses co2, its replaced by more blood which is low in oxygen and high in Co2 so concentration gradient is maintained.
2. Movement of air into and out of the alveoli as we breathe in and out: The air that has picked up co2 from, and lost oxygen to, the blood is replaced by new air with each breath. New air is high in oxygen and low in co2.
What is Emphysema?
A disease usually cause dby long term exposure to irritating particles in the air taken into the lungs. These irritating particles cause damage to alveoli, causing them to lose their elasticity and are often replaced with fibrous tissue, and may break down reducing internal SA of lungs. Cos of the loss of elasticity of lung tissue, lungs are constantly inflated, and breathing out no longer occurs passively and required voluntary effort.
What is lung cancer?
Involves the development of a mass of cells that divides in an uncontrolled way - a tumour. Begins in walls of air passages, usually bronchi. Particles irritate mucous membranes that lines air passages, leading to excessive production of mucous.
