Gas Exchange Flashcards
0
Q
Cellular respiration
A
- A chemical process taking place inside cells
- Glucose reacts with oxygen to produce carbon dioxide, water and energy (ATP and heat)
1
Q
Breathing
A
- Mechanically ventilating the lungs
- Inhaling oxygen rich air and exhaling carbon dioxide rich air
2
Q
Gas exchange
A
- A physical process taking place by diffusion
- Between air in the alveoli and blood
- Between the blood and tissues of the body
3
Q
Diffusion
A
- Movement of a substance from a high to a low concentration until equilibrium
- No energy input required
4
Q
Requirements for efficient gas exchange surface
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- thin surface
- moist surface
- large surface area
- protected surface
- transport system close to surface
- adequate ventilation
5
Q
Plant large surface for gas exchange
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- Spongy mesophyl inside leaves
- Leaves themselves have a large surface area
6
Q
Earthworm large surface for gas exchange
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- Entire body surface can exchange gases
7
Q
Insect large surface for gas exchange
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- Tracheal system of branching tubes
- Ending in tiny channels called tracheoles
8
Q
Fish large surface for gas exchange
A
- Gills with filaments and lamellae (folds)
9
Q
Plant thin surface for gas exchange
A
- Gases exchanged directly into leaf cells
10
Q
Earthworm thin surface for gas exchange
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- Gases exchanged across columnar epithelium (short distance)
11
Q
Insect thin surface for gas exchange
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- Tracheoles very thin permeable walls in close contact with cells
12
Q
Fish thin surface for gas exchange
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- Very finely structured gills, water and blood in close contact
13
Q
Moist surface for gas exchange in plants
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- Water moves through xylem into the leaf and evaporates by transpiration
14
Q
Moist surface for gas exchange in earthworm
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- Epithelium secretes mucus
15
Q
Moist surface for gas exchange in insects
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- Exoskeleton prevents insect from drying out
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Q
Moist surface for gas exchange in fish
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- Fish lives in water
17
Q
Ventilated surface for gas exchange in plants
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- Leaves exposed, constantly ventilated by air movement
18
Q
Ventilated surface for gas exchange in earthworm
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- Surface of worm exposed to air trapped between soil particles
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Q
Ventilated surface for gas exchange in insects
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- Air sacs in tracheal system close to muscles
- When muscles contract and relax air is drawn into the tubes
20
Q
Ventilated surface for gas exchange in fish
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- As fish swim, water flows over gills
- Operculum also acts as a pump
21
Q
Transport system for efficient gas exchange in plants
A
- Gases exchanged directly with cells in the leaf
22
Q
Transport system for efficient gas exchange in earthworm
A
- Worm has a closed blood system with haemoglobin
- Capillaries close to surface of the skin
23
Q
Transport system for efficient gas exchange in insects
A
- Oxygen diffuses directly from tracheoles to cells
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Transport system for efficient gas exchange in fish
* Blood flows in vessels in opposite direction to water flow
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Protection of gas exchange surface in plants
* Stoma and waxy cuticle protect the inside layers of the leaf
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Protection of gas exchange surface in earthworm
* Protective layer of skin called cuticle
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Protection of gas exchange surface in insects
* Exoskeleton of insects protects system
* Openings protected by valves called spiracles
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Protection of gas exchange surface in fish
* Bony flap called operculum covers gills
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Efficient gas exchange in humans
* Thin: walls of alveoli and capillaries single celled, flattened squamous epithelium
* Moist: lining of epithelium in alveoli covered in a thin layer of moisture
* Surface area: millions of alveoli air sacs add up to a large surface area
* Protection: thoracic cage made up of rib bones and muscles
* Transport: alveoli supplied by capillaries containing blood
* Ventilation: breathing system by muscles and rib bones
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Function of nostrils
* Opening to air passages
* Lined with hairs to remove dust from inhaled air
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Function of nasal passages
* Lined with ciliated columnar epithelium which secretes mucus
* Mucus moisten air and filters dust and germs by trapping these
* Turbinate bones slow air flow so it can be warmed by nearby blood
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Function of pharynx
* Common to both air and food.
* Leads to trachea via valve called the glottis
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Function of the larynx
* Also called the voice box as this contains vocal cords
* Guards the entrance to the trachea
* When food swallowed the glottis is closed by the epiglottis to prevent food entering trachea
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Function of the trachea
* Held open by c-shaped rings of cartilage
* Lined with ciliated epithelium to remove dust etc.
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Functions of bronchi and bronchioles
* Trachea divides into bronchi also with cartilage to hold them open
* Bronchi divide into numerous bronchioles
* These branch until ending in the alveoli
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External structure of the lungs
* Cone shaped
* Base touches diaphragm
* Pleural membranes (pleura) line the inside of thoracic cavity and the outside of each lung
* Between pleura is pleural fluid that reduces friction during breathing
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Internal structure of lungs
* Bronchi subdivide to form bronchioles
* Smallest bronchioles end in alveoli
* Walls of alveoli made of flattened squamous epithelium
* Each alveolus surrounded by a network of capillaries
* Walls of capillaries have a single layer of endothelium.
* Pulmonary artery (deoxygenated blood) enters the lung
* Pulmonary vein (oxygen rich) leaves the lungs
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Mechanism of inhalation
* Diaphragm contracts and flattens
* External intercostal muscles contract
* Internal intercostal muscles relax
* Rib cage is lifted
* Internal volume of thoracic cavity increases
* Internal pressure decreases
* Air rushes into lungs
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Mechanism of exhalation
* Diaphragm relaxes and moves up
* External intercostal muscles relax
* Internal intercostal muscles contract
* Rib cage is dropped
* Internal volume of thoracic cavity decreases
* Internal pressure increases
* Air rushes out of lungs
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How is oxygen transported
* Oxyhaemoglobin (98,5%)
* Dissolved in blood plasma (1,5%)
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How is carbon dioxide transported?
* Bicarbonate ions (70%)
* Carbaminohaemoglobin (23%)
* Dissolved in blood plasma (7%)
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Gas exchange in the lungs after inhalation
* Alveolus has a high concentration of oxygen and a low concentration of carbon dioxide
* Blood capillaries have a high concentration of carbon dioxide and a low concentration of oxygen
* The oxygen diffuses from the alveolus into the blood
* The carbon dioxide diffuses in the opposite direction from the blood into the alveolus
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Gas exchange in the tissues
* Blood arriving at the tissues has a high concentration of oxygen.
* The tissues have a high concentration of carbon dioxide.
* The oxygen diffuses from the blood into the tissues.
* The carbon dioxide diffuses in the opposite direction from the tissues into the blood.
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Composition of inhaled vs exhaled air
* Inhaled oxygen 21% vs. exhaled oxygen 16%
* Inhaled carbon dioxide 0,04% vs. exhaled carbon dioxide 4%
* Nitrogen stays the same at about 79%
* Water vapour increases
45
To be continued...
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