Lo2 Flashcards
Structure of the respiratory system
Nasal cavity, nose, mouth, epiglottis, throat, oesophagus, larynx, trachea, bronchus,pleural membrane, diaphragm.
Structure of respiratory system
- larynx: connects back of nose and the trachea: forming air passage to the lungs
- trachea, bronchi and bronchioles: trachea is also known as the windpipe. It stats at the back of throat and divides into 2 bronchi, each leads into one lung, where they continue to divide into bronchioles.
- alveoli: at the end of bronchioles: tiny sacs that are called alveolus: each alveolus has a capillary network.
- diaphragm: muscle anchored to the lower ribs that separates the chest from abdomen.
- intercostal muscles are found between ribs
- pleural membrane: covers the outside of the lungs and line the inside of the chest wall.
Role of pleural membranes
- Consists of two layers of thin membrane
- moist and slippery
- lubricates the surface so that 2 pleural layers will slide over each other, allowing lungs to move easily within chest cavity.
Role of diaphragm and intercostal muscles in inspiration and expiration
Inspiration:
- External intercostal muscles contract, internal intercostal muscles relax (antagonistic) → ribcage moves up / out
- Diaphragm muscles contract → flattens
- Increasing volume in thoracic cavity (chest)
- Decreasing pressure in thoracic cavity
- Atmospheric pressure higher than pressure in
lungs → air moves down pressure gradient into lungs
Expiration:
1. Internal intercostal muscles can contract, external intercostal muscles relax → ribcage moves down / in
2. Diaphragm relaxes → moves upwards
3. Decreasing volume in thoracic cavity
4. Increasing pressure in thoracic cavity
5. Atmospheric pressure lower than pressure in
lungs → air moves down pressure gradient out of lungs
Gaseous exchange: role and structure of alveoli walls
- exchange of oxygen and carbon dioxide takes place in alveoli.
- the wall os alveoli are very thin (one cell thick): short diffusion distance.
- surrounded by many capillaries: faster diffusion of gases to and from blood.
- many alveoli: large surface area to volume ratio: maximum diffusion
- oxygen moves into capillaries and co2 moves out of capillaries.
Diffusion gradient
- diffusion refers to movement of air particles from a high concentration to an area of low concentration: down concentration gradient.
- capillaries have a lower concentration of oxygen: oxygen diffuses from alveoli ( area o high conc) to capillary (area of low conc)
Erythrocytes and plasma
Inspiration- exchange of gases from lungs to blood- transport of oxygen and co2 in the blood- exchange of gases from blood to tissues- metabolism- expiration.
Cellular respiration
- ATP is a high-energy molecule found in every cell
- it is a store and supply of energy
- cellular respiration takes place in mitochondria
- two types of respiration: aerobic (uses oxygen)
Anaerobic(doesn’t need oxygen)
Aerobic respiration
- oxygen and glucose are required for aerobic respiration to take place
- produces waste carbon dioxide and water as well as providing energy
Anaerobic respiration
- glycolysis is the process that takes place in cell cytoplasm that breaks down glucose and forms pyruvate.
-pyruvic acid supplies energy to cells through citric acid cycles (kerbs cycle) - lactic acid needs to be oxidised later to carbon dioxide and water to prevent it building up
Asthma symptoms
- Recurring episodes of breathlessness, tightness of the chest and wheezing.
- Asthma ‘attacks’ - episodes of wheezing that require the use of an inhaler to open the airway.
Asthma biological explanations
- Inflammation of the bronchi, which carry air in and out of the lungs, causing the bronchi to be more sensitive than normal.
- Contact with allergens, something that irritates the lungs - known as a trigger (e.g. cigarette smoke, dust or pollen) - makes airways become narrow, the muscles around them tighten, and there is an increase in the production of sticky mucus (phlegm).
Asthma cause
The exact cause of asthma is not known and is likely to be a combination of factors.
It may be genetic, as it often runs in families and people who have allergies are at higher risk. A number of environmental and social factors are thought to play a role in the development of asthma and allergies, however. These include:
- exposure to tobacco smoke as a child
- triggers such as dust, air pollution and chemicals such as chlorine in swimming pools
- exposure to smoking while in the womb
- being born prematurely (before 37 weeks) or with a low birthweight.
Modern hygiene standards - ‘too hygienic’, don’t build up resistance.
emphysema symptoms
- Shortness of breath, wheezing
- Yellow sputum
- Persistent cough that never seems to go away
- Frequent chest infections
- Symptoms get worse over time.
Emphysema biological explanations
- The airways of the lungs become inflamed and narrowed. As the air sacs (alveoli) get permanently damaged, it becomes increasingly difficult to breathe out.
- There is currently no cure for COPD, but the sooner the condition is diagnosed and appropriate treatment begins, the less chance there is of
severe lung damage.
