Gas exchange

Flashcards by HollyFanshawe , updated more than 1 year ago
Created by HollyFanshawe about 5 years ago


IB Biology Flashcards on Gas exchange, created by HollyFanshawe on 02/05/2015.

Resource summary

Question Answer
Definition of ventilation The flow of air in and out of the alveoli
Gas exchange The exchange of oxygen and carbon dioxide between the alveoli and the bloodstream
Call respiration The release of ATP from organic molecules
What is the trachea? The main airway to the lungs
What is the function of cartilaginous rings in the trachea? They prevent collapse of air passages as pressure falls to draw in air.
Speacial features of trachea and bronchi Lined with ciliated epithelium. This tissue is made from goblet cells and columnar ciliated epithelial cells.
What is the role of goblet cells and mucus Goblet cells make and secrete mucus. Mucus contains glycoproteins , that are slimy and sticky. This forms a protective covering over the epithelial trapping dust and bacteria.
Label the ventilation system also need pleural layers a70586a7-f06a-4520-8f97-21de625b41b8.jpg (image/jpg)
What are the roles of cilia? Cilia move mucus along with any trapped dust and bacteria up out of airways, helping to prevent infections. Each cilium contains microtubules which can slide past each other causing the cilium to bend. They act in a coordinated fashion like a Mexican wave.
Describe the structure of alveoli Thin epithelial cells line the alveolus. Thin endothelial cells form the capillaries so that gives a short diffusion pathway. Millions of alveoli give a SA of about 100cm3. Many capillaries surround alveoli. Some cells produce surfactant. This prevents alveolus sticking together by preventing cohesion.
Explain which factors cause the diffusion gradient to remain high. The fact that the alveolus is ventilated and blood flows. Incoming air is high in oxygen and low in CO2. Incoming blood is high in CO2 and low in O2.
Explain how the oxygen diffusion gradient is maintained. Oxygen binds readily with haemoglobin in red blood cells. This means that that it is not free to diffuse back so a gradient is created. Flow of blood removes oxygenated red blood cells so new ones can bind with oxygen. Ventilation of the alveolus maintains a fresh supply of O2. Thus a concentration gradient from high in the alveolus to low in the capillary is maintained.
Explain how the CO2 diffusion gradient is maintained. Ventilation removes high levels of CO2 in the alveolus. Incoming blood has high levels of CO2. Diffusion gradient to leave blood and enter alveolus for removal. Blood in the capillary as it leaves the alveolus has low levels of CO2.
Do lungs have any muscles themselves, and what does this mean? Lungs have no muscles themselves. Breathing movements are caused by the diaphragm and intercostal muscles.
What is asthma? A common chronic inflammation of the airways to the lungs.
Describe the features of asthma. Inflammation leads to swelling and increased mucus production, resulting in reduced airflow and bronchospasms. During an asthma attack, constriction of the bronchi smooth muscle may cause significant airflow obstruction, which may be life threatening. This reduces gas exchange.
What are the symptoms of asthma? Shortness of breath, chest tightness, wheezing and coughing,
What causes asthma? It is an allergic response to a variety of antigens e.g. dust mites, pollen, animal tissues, smoke and foods.
Describe the processes in breathing in? Diaphragm contracts - goes from domed to flattened this increases the volume of the thorax. External intercostal muscles contract - rib cage moves upwards and outwards - increasing the volume of the thorax. Pressure in the pleural cavity falls causing lung pressure to decrease below atmospheric pressure. Air flows in down a pressure gradient.
Describe the process of breathing out. Diaphragm and intercostal muscles relax, the elastic fibres in the lungs recoil causing the pressure in the thorax to rise. Pressure in the lungs increases above atmosphere pressure so air leaves the lungs.
What happens when you breathe out heavily e.g. exercise ? Your internal intercostal muscles contract. Also your abdominal muscles contract and press the diaphragm further up.
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