Ch.8 Gas exchange in humans Flashcards
Most organisms obtain energy from the oxidation of food in a process called __________
respiration
What is gas exchange?
The exchange of respiratory gases between the cells of an organism and the environment is called gas exchange.
How does gas exchange take place in unicellular organisms?
Unicellular organisms are small and therefore have a large surface area to volume ratio. Gas exchange takes place effectively by diffusion across their cell surfaces, which is covered only by a cell membrane.
In other words, the cell membrane works as the respiratory surface.
Is diffusion over the body surface an adequate method for gas exchange in multicellular organisms?
No.
∵multicellular organisms are relatively large
∴ small surface area to volume ratio
Human have evolved a _________________ to move air into and out of the body for effective gas exchange.
breathing system
The breathing system works closely with the ______________________, which delivers oxygen to all the body cells and removes carbon dioxide from them
circulatory system
What features does nostrils and nasal cavity have to condition the incoming air?
- the nostrils are lined with hairs to filter out dust and other particles from the air
- the wall of the nasal cavity is lined with mucus-secreting cells, which secrete mucus. The mucus traps dust particles and bacteria. It moistens the incoming air as well
- The wall of the nasal cavity is also lined with ciliated epithelial cells. The cilia extending out from these cells beat in a wave like manner. This beating action sweeps the mucus towards the throat (pharynx). The mucus is then either swallowed or coughed out.
- the nasal cavity is well supplied with blood capillaries. The blood in the capillaries helps warm the incoming air.
What is the pharynx?
The pharynx is a part shared by the breathing system and the digestive system. Both food and respiratory gases pass through it. From the pharynx, air passes into the larynx of the breathing system, while food and drink enter the oesophagus of the digestive system.
What happen to the larynx when we swallow?
When we swallow, the larynx rises. A flap of tissue called the epiglottis automatically covers the entrance to the trachea (the glottis). This stops food and drink from entering the trachea, and thus prevents choking.
The larynx is also called the voice box. Within the larynx, there are two thin elastic membranes called the ____________________. When air is forced through the vocal cords, they vibrate to produce sound.
vocal cords
What’s the use of the C-shapes rings of cartilage in the wall of the trachea?
These cartilage rings keep the trachea open for air to pass through freely. Without the support of the cartilage, the trachea would collapse with the fall in air pressure when we bbreathe in.
The open side of the C-shaped rings is next to the oesophagus. This allows the oesophagus to expand when food passes down it.
How are bronchi supported?
By complete rings of cartilage.
Does the bronchioles have cartilage?
NO
What’s the use of the ciliated epithelial cells and mucus-secreting cells lined in the inner walls of the trachea, bronchi, and some larger bronchioles?
The inner walls of the trachea, bronchi and some larger bronchiles are also lined with ciliated epithelial cells and mucus-secreting cells. The secreted mucus traps dust particles and bacteria in the air. The beating action of the cilia sweeps the mucus upwards towards the phraynx, where the mucus is either swallowed or coughed out.
These is a dense network of _____________________ surrounding the air sacs. These capillaries are supplied with blood from the ________________________ and are drained by the ________________________. As blood flows through these capillaries, it exchanges respiratory gaes with air inside the air sacs.
blood capilarries
pulmanoary arteries
pulmonary veins
