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Gas exchange Flashcards

1
Q

What is the gas exchange surface in fish and why do they require it?

A

Gills, because fish have a small surface area to volume ratio.

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2
Q

Explain the fish gill anatomy

A
  • There are 4 layers of gills on both sides of the head
  • The gills are made up of stacks of gill filaments.
  • Each gill is covered in gill lamellae which are positioned at right angles to the filaments
  • The gill lamellae create a large surface area
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3
Q

Where does water go when fish open their mouth?

A

When fish open their mouth, water rushes in and over the gills and then out through a hole in the sides of their heads

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4
Q

What are the 3 adaptations in fish gills?

A
  • Many gill filaments have many gill lamellae which provide a large surface area to volume ratio
  • Gas exchange only occurs in gill lamellae which are very thin so they provide a short diffusion distance. Inside every gill lamellae there is a capillary network which also provide a short diffusion distance
  • The countercurrent flow mechanism is used for maintaining concentration gradient.
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5
Q

Describe the countercurrent exchange principle.

A
  • Countercurrent flow is when water flows over the gills in the opposite direction to the flow of blood in the capillaries. This ensures that equilibrium is not reached which creates a diffusion gradient across the entire length of the gill lamellae
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6
Q

Explain the process of gas exchange in fish

A
  • The fish opens its mouth to allow water to enter the gills and then closes its mouth to increase pressure.
  • Water passes over the gill lamellae which allows oxygen to diffuse into the bloodstream.
  • Carbon dioxide diffuses into the water and flows back out of the gills.
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7
Q

What is the difference between breathing and respiration?

A

Breathing: Movement of air in and out of the lungs
Respiration: Chemical reaction that releases energy in the form of ATP

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8
Q

What is ventilation?

A

Scientific word for breathing

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9
Q

Why are there rings around the trachea and why are they C-shaped?

A

To support the trachea and keep it open. C-shape allows our necks to be flexible

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10
Q

Explain inspiration.

A

During inspiration:
- External intercostal muscles contract which causes the ribs to go upwards and outwards
- Internal intercostal muscles relax
- Diaphragm contracts downwards into a flattened shape
- The air pressure in lungs drops because there is an increase in lung volume
- Air moves down a pressure gradient from atmospheric pressure to lower pressure.

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11
Q

Explain expiration.

A

During expiration:
- External intercostal muscles relax
- Internal intercostal muscles contract to pull the ribs downwards and inwards
- Diaphragm relaxes into its dome position
- The air pressure in the lungs is greater than the atmospheric pressure.
- The lung volume decreases to increase pressure in the lungs
- Air moves out of the lungs, from high pressure in lungs and out to atmospheric pressure.

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12
Q

What are alveoli?

A

Tiny air sacs at the end of the bronchioles.

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13
Q

What are alveoli’s surrounded by?

A

Capillaries

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14
Q

What are alveoli and capillaries made up of?

A

Single layer of cells

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15
Q

How does oxygen and carbon dioxide diffuse in and out of alveoli and capillaries?

A

The alveoili contains highly oxygenated air so oxygen diffuses from the alveoli, through the epithelium and into the capillaries and bloodstream.
There’s a high concentration of carbon dioxide in the bloodstream so it diffuses out from the capillaries, through the epithelium and into the alveoli.

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16
Q

How does oxygen in the air reach capillaries surrounding alveoli in the lungs

A

Air travels through the trachea, bronchi and bronchioles and reaches the alveoli down a pressure gradient. Then oxygen travels down a diffusion gradient through the alveolar epithelium.

17
Q

What are the adaptations of the alveoli?

A
  • There are many alveoli which increases the surface area for gas exchange
  • The alveoli epithelium cells are very thin which prodivdes a short diffusion pathway
  • Each alveolus is surrounded by a network of capillaries to remove exchanged gases and maintain the concentration gradient.
18
Q

Why can’t insects use their bodies as an exchange surfaces?

A

They have a waterproof exoskeleton and a small surface area to volume ratio in order to conserve water.

19
Q

What do insects have instead of lungs.

A

Tracheal system

20
Q

How do insects prevent water loss?

A
  • Spiracles are tiny holes on the body’s surface that can open and close to prevent water loss or gas exchange
  • Insects have a small surface area to volume ratio which prevents water loss
  • Insects have a waterproof exoskeleton
21
Q

What are the 3 structures in the tracheal system?

A

Spiracles
Trachea
Tracheoles

22
Q

Explain spiracles in relation to the tracheal system.

A

Round, valve like openings that run across the length of the insects abdomen. Oxygen and carbon dioxide enter and leave via the spiracles. The trachea attach to these openings.

23
Q

Explain trachea in relation to the tracheal system.

A

Trachea are a network of internal tubes within the insect that have rings to strengthen the tubes and prevent them from collapsing and to keep them open.

24
Q

Explain tracheoles in relation to the tracheal system.

A

The trachea branch into smaller tubes called tracheoles which are deeper into the abdomen of the insect. They extend to all the tissues in the insect to deliver oxygen.

25
Q

What are the three ways of moving gases in the tracheal system?

A
  1. Gases can exchange by simple diffusion. When cells respire they use oxygen and produce carbon dioxide which creates a concentration gradient from the tracheoles to the atmosphere.
  2. Gas exchange can occur in mass transport when an insect contracts and relaxes their abdominal muscles to move gases on mass.
  3. When insects are in flight, the muscle cells respire anaerobically to produce lactate. This lowers the water potential of the cell and causes water to move from the tracheoles into the cell via osmosis. This decreases the volume and pressure in the tracheoles which means more air from the atmosphere is drawn in.
26
Q

What are the adaptations for efficient gas exchange in the tracheal system?

A
  1. Use of oxygen and production of carbon dioxide from respiring cells creates a steep concentration gradient
  2. Large number of tracheoles creates a large surface area
  3. The walls of tracheoles are thin which provide a short diffusion pathway.
  4. The short distance between the spiracles and the tracheoles create a short diffusion pathway.
27
Q

What is the structure of a dicotyledonous leaf?

A
  • On the lower side of the leaf are the stomata. A stoma is a gap formed by 2 guard cells. It is the site of gas exchange since the gap allows carbon dioxide to diffuse into the spongy mesophyll.
  • Spongy mesophyll is the middle layer that contains gaps for carbon dioxide
  • Palisade mesophyll is the upper layer, most photosynthesis occurs here because it is closer to the leaf’s surface so it can receive more direct sunlight.
28
Q

How do plants reduce water loss by evaporation?

A
  • Stomata close at night when photosynthesis will not be occurring
29
Q

What are xerophytes?

A

plants that are adapted to dry and arid conditions

30
Q

What adaptations do xerophytes have to prevent water loss.

A
  • Hair on leaves, traps moisture and increases humidity
  • Curled leaves traps moisture and increases humidity
  • Thick cuticle increases the diffusion distance
  • Sunken stomata traps moisture and increases humidity.
31
Q

What are the adaptations of the alveolar epithelium that make it well adapted for gas exchange?

A
  • Single layer of cells which reduces the diffusion distance
  • Permeable which allows the diffusion of oxygen and carbon dioxide.
32
Q

Tidal volume is the volume of air inhaled and exhaled during a single
breath when a person is resting. The tidal volume in a person with
emphysema is reduced compared with the tidal volume in a healthy
person.
Suggest and explain how a reduced tidal volume affects the exchange of
carbon dioxide between the blood and the alveoli.

A
  • Less carbon dioxide is being exhaled
  • Which means there is a decrease in concentration gradient between blood and alveoli
  • This means more carbon dioxide stays in the blood.
33
Q

Describe the pathway taken by an oxygen molecule from an alveolus to the
blood.

A

Across alveolar epithelium and into the capillary of the epithelium

34
Q
A

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