Chapter 4: Exchange

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What are the properties of a good exchange surface?
A large Whdiffusion gradient, large surface area, thin, moist and blood supply.
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Describe the features of an exchange surface on a plant.
Branched leave (large surface area), few cells thick (thin), stomata can close to prevent movement of gases and waxy cuticle layer (moist)
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What provides an airtight, slippery covering that allows the lungs to inflate and deflate easily?
Lungs are inside the thorax surrounded by a pair of pleural membranes that secrete pleural fluid.
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Describe how the air travels from the mouth to the alveoli.
Air passes down into the lungs through the trachea, which branches into the left and right bronchus. Each bronchus branches repeatedly to form similar tubes called bronchioles, which end in bunches of tiny air sacs called alveoli.
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How do the lungs move if they have no muscle?
Movement is produced by the muscles in the diaphragm - a sheet of tissue containing muscle, that separates the thorax from the abdomen - and the muscles between the ribs, which are intercostal muscles.
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What do the ciliated cells and the goblet cells sit on?
The basement membrane, which contains fibres made from proteins that the cells beneath them have secreted.
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How do cilia move?
Each cilium contains microtubules which can slide past each other, causing the cilium to bend.
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What is the role of cartilage in the tissues of the airways?
Cartilage is a tough tissue that helps to support the walls of the trachea and bronchi. The cartilage is flexible, shaped in a c-ring to hold the trachea open, but in a irregular pattern in the bronchi.
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What is the role of the smooth muscle in the trachea, bronchi and bronchioles?
Its contracts slowly and steadily and can remain contracted for a long period of time.
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Why is smooth muscle an involuntary muscle?
You have no conscious control over its contraction. When the smooth muscle contracts, it narrows the airways.
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What is the role of elastic fibres in the walls of the airways?
They occur all round the alveoli. During breathing in, the alveoli expand, stretching the elastic fibres. During breathing out, the fibres recoil, helping to decrease the volume inside the lungs and forcing air out.
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What are macrophage?
A type of leucocyte. It is a large cell and it destroys bacteria and other foreign material by phagocytosis. Also known as a monocyte in the blood.
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In between the alveolar walls, elastic fibres provide ___ and ___, so that the alveolar ___ can easily increase during breathing and decrease when you breath out.
Strength, flexibility and volume
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What is the function of macrophage?
Patrol the alveolar surface. They scavenge for any harmful material that may have escaped the ciliated epithelium on the way to the lungs, such as bacteria, particulates of smoke or dust particles. Macrophages are phagocytes,will engulf and digest.
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_____ ___ can accumulate in the lungs despite the best efforts of macrophages and lead to a serious disease.
Asbestos fibres.
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What is the mechanism of inspiration?
Contraction of external intercostal muscles, rib cage moves upwards and out, increasing volume in the thorax, contraction of muscle is the diaphragm pulls it lower increasing v. in thorax. Pressure in T. falls with the increase in v. caused by r
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What is the mechanism of breathing out?
Diaphragm and intercostal muscles relax, the elastic fibres recoil causing the pressure in the thorax to rise.
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What s vital capacity?
The very greatest volume of air you can move into and out of your lungs with one breath.
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How do you calculate vital capacity?
Tidal volume + expiratory reserve volume + inspiratory reserve volume = vital capacity
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How does the spirometer work?
As you breathe in, the volume of air inside the chamber decreases, and the float drops down. As you breathe out, the volume of air inside the chamber increases, and the float is pushed up.The float is attached to a pen, recording movement.
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What is a surfactant?
Interfere with the intermolecular forces within water. Chemical found in the moisture lining in the alveoli, which reduces the cohesive forces between water molecules, preventing the collapse of the alveoli.
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What is ventilation?
Air pressure causing the air to move in and out the lungs.
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What are goblet cells?
Found in the ciliated epithelium layer they secrete a sticky mucus that traps harmful substances that are breathed in.
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Whats are elastic fibres?
When smooth muscle contracts to reduce the diameter of the lumen the elastic fibres stretch. When the smooth muscle relates the elastic fibres recoils to increase the diameter of the lumen.
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What does a spirometer measure?
Lung capacity.
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Why are capillaries in close contact with the alveoli?
For short diffusion.
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What is the definition of inspiratory reserve volume?
The maximum volume of air over and above the tidal volume that can be breathed in in one breath.
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What is you breathing rate?
The mean number of breaths per minute.
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What is your ventilation rate?
The volum of air moved into and out of the lungs per minute. no. breaths per min x mean tidal volume = ventilation rate.
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What is tidal volume?
The volume of air breathed in and out in one breath.
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What is meant by the term tissue?
A layer or a group of cells of which together preform a particular function.
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What are the precautions of using a spirometer?
Disinfect mouth piece and check if the person has asthma.
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Why can the lung be considered an organ?
It is a collection of tissues working together to enable gas exchange.
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What are the reasons for specialised exchange surfaces?
Surfaces thin for efficient gas exchange(reduced diffusion distance), large organisms have a small SA:V ratio, special area to increase that area and are also more active, greater requirement.
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What are the reasons for a specialised transport system?
Large organisms tend to be more active, so substances need to be moved to the body cells that require them. Distance over which substances need to be moved are large in larger organisms.
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What type of epithelium makes up the wall of an alveolus?
Squamous epithelium (because its one cell thick)
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What is the function of smooth muscle fibres?
To constrict the bronchus.
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What are three features in the alveolus which make it efficient for gas exchange?
Large SA:V, One cell thick, short distance for diffusion
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Why is squamous epithelium described as a tissue?
Made up of one type of cell.
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What are the features of a gas exchange surface?
Large surface area, permeable, short diffusion path, moist, good blood supply, well ventilated.
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Other cards in this set

Card 2

Front

Describe the features of an exchange surface on a plant.

Back

Branched leave (large surface area), few cells thick (thin), stomata can close to prevent movement of gases and waxy cuticle layer (moist)

Card 3

Front

What provides an airtight, slippery covering that allows the lungs to inflate and deflate easily?

Back

Preview of the front of card 3

Card 4

Front

Describe how the air travels from the mouth to the alveoli.

Back

Preview of the front of card 4

Card 5

Front

How do the lungs move if they have no muscle?

Back

Preview of the front of card 5
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