gas exchange

Question 1

How does high surface area affect diffusion?

Answer 1

These organisms have a large surface area of relative to their volume so the diffusion is fast

Question 2

How does low surface area affect diffusion?

Answer 2

These organisms have a small surface area relative to their volume so the diffusion of substances is slower

Question 3

What type of surface area to volume ratio do smaller organisms have?

Answer 3

A high surface area to volume ratio

Question 4

What type of surface area to volume ratio do larger organisms have?

Answer 4

A lower surface area to volume ratio

Question 5

How do you work out the surface area of a cube?

Answer 5

Length x width x 6

Question 6

How do you work out the volume of a cube?

Answer 6

Length x Width x depth

Question 7

How does substances diffuse in single cell organisms?

Answer 7

Substances diffuse directly across the cell membrane

Question 8

Why can’t substances diffuse directly across the cell membrane in multicellular organisms?

Answer 8

– Cells are not indirect contact with the external environment
– Diffusion distances between cells and the environmental are large
– Larger organisms have higher metabolic rate, so they need more oxygen and glucose

So multicellular organisms have evolved specialised exchange surfaces

Question 9

What are the key features of specialised exchange surfaces?

Answer 9

– A large surface area
– Thin walls, to minimise the diffusion distance
– An extensive blood supply and/or ventilation, maintain steep concentration gradients
– Being surrounded by selectively permeable plasma membranes, controls what substances are exchanged

Question 10

Why is the gas exchange system located inside the body?

Answer 10

– There is not enough to support and protect these delicate structures
– The body would otherwise lose water and dry out

Question 11

What is the pathway of air?

Answer 11

– Air first enters the trachea
– Air travels into the two bronchi, with one bronchus going to each lung
– A travels into smaller airways called bronchioles
– A travels into clusters of air sacs called alveoli at the end of the bronchioles

Question 12

what is the role of the ciliated epithelium and where is it located?

Answer 12

Located throughout most of the airways

Goblet cells – produce and secrete mucus that traps dust and microbes

Cilia on ciliated cells – these were mucus upwards to the mouth so it can be swallowed

Question 13

What is the role of the trachea and what are its adaptations?

Answer 13

Large tube that carries air from the throat down to the lungs

– Rings of cartilage to keep the airway open
– Smooth muscle can contract or relax to constrict or dilate the airway and change airflow
– Elastic tissue contains elastic fibres with the elastin that allows stretching and recoiling
– Lined with ciliated epithelial cells and goblet cells

Question 14

What is the role of the bronchi and what are its adaptations?

Answer 14

Carrier into each lung

– Reinforce of cartilage to keep the airway open
– Smooth muscle can contract or relax to construct or dilate the airway and change airflow
– Elastic tissue contains elastic fibres with elastin that allows stretching and recoiling
– Lined with ciliated epithelial and goblet cells

Question 15

What is the role of the bronchioles and what are its adaptations?

Answer 15

Smaller airways branching from the bronchi

– No cartilage, can change shape
– Smooth muscle contract/relax to constrict/dilate
– Elastic tissue
– Simple squamous epithelium (only larger bronchioles have ciliated epithelium)

Question 16

What are the adaptation of lungs for gas exchange?

Answer 16

– Wall consists of one layer of squamous epithelial cells
– Large surface area
– Partially permeable
– Surrounded by dense network of capillaries
– Ventilation of air, steep diffusion gradient
– Elastic fibres, stretching and recoiling
– Collagen fibres, limiting overstretching
– Moist in a surface, gases to dissolve, alveoli remain inflated

Question 17

What are the pulmonary blood vessels?

Answer 17

Pulmonary artery – deoxygenated blood from heart to pulmonary capillaries

Pulmonary vein – oxygenated blood from capillaries to heart

Pulmonary capillaries – site of gas exchange

Question 18

What are the adaptations of the pulmonary capillaries?

Answer 18

– Thin walls
– Red blood cells pressed against capillary walls
– Large surface area
– Movement of blood is slow

Question 19

What is ventilation?

Answer 19

Ventilation or breathing is the constant movement of air into or out of the lungs

Question 20

What is inspiration?

Answer 20

Breathing in

Question 21

What is expiration?

Answer 21

Breathing out

Question 22

What are the muscles involved in ventilation?

Answer 22

– The rib cage is made up of bones called ribs that enclose the thorax – the cavity where the lungs are located (Thoracic cavity)

– The diaphragm – a sheet of muscle that moves the rib cage up and out when it contracts

– the external intercostal muscles – these are found between the ribs and pull the rib cage up and out when they contract

– The internal and coastal muscles – these are found between the ribs but pull the rib cage down and in when they contract

– When the muscles attached to the rib cage contract and relax, they move the ribs to change the volume of the Thoracic cavity

The internal and external intercostal muscles have opposite effects on the rib cage

Question 23

What is the process of inspiration?

Answer 23

An active process requiring energy for muscle contraction

1. The external intercostal muscles contract while the internal intercostal muscles relax, moving the rib cage up and out.
2. The volume of the thoracic cavity increases
3. The diaphragm contracts and flattens, further increase in the volume of the thoracic cavity
4. The lung pressure decreases below atmospheric pressure.
5. Air flows into the lungs and down the pressure gradient.

Question 24

What is the process of expiration?

Answer 24

At Rest is a passive process, doesn’t require energy

1. The external intercostal muscles relax, moving the rib cage down and in
2. The volume of the thoracic cavity decreases
3. The diaphragm relaxes and flattened, further decrease in the volume of the thoracic cavity
4. The lung pressure increases above atmospheric pressure.
5. Is forced out of the lungs down the pressure gradient.

Question 25

What is a spirometer?

Answer 25

This calculates different lung volumes using a chamber containing unknown volume of gas connected to a mouthpiece and recorder

Question 26

What is breathing rate?

Answer 26

Number of breaths taken per minute

Question 27

What is tidal volume?

Answer 27

Volume of air in or out in an average breath during rest

Question 28

What is vital capacity?

Answer 28

This is the maximum volume of air that can be inhaled or exiled in one deep breath

Question 29

What is inspiratory reserve volume?

Answer 29

The maximum volume of air that can be inhaled above a normal inhalation

Question 30

What is expiratory reserve volume?

Answer 30

The maximum volume of air that can be expelled above a normal exhalation

Question 31

What is residual volume?

Answer 31

The volume of air that remains in the lungs after the largest possible exhalation

Question 32

What is total lung capacity?

Answer 32

Vital capacity added to residual volume

Question 33

What is oxygen consumption?

Answer 33

The volume of oxygen used per minute The changing volume of gas in the spirometer over a period of time and divide this value by the time taken

Question 34

How do you calculate ventilation rate?

Answer 34

Ventilation rate = tidal volume x breathing rate

Question 35

Why do insects need efficient systems for exchanging gases?

Answer 35

To deliver oxygen to cells – allows aerobic respiration to occur to release energy for cellular processes To remove carbon dioxide from cells – the buildup of carbon dioxide produced as a waste product of respiration reduces pH, which can denature enzymes

Question 36

Why have insects gas exchange adapted to balance conflicting needs?

Answer 36

– Maximising gas exchange efficiently – Minimising water loss

Question 37

What are the structures of the insects gas exchange system?

Answer 37

Open respiratory system Trachea – airfield tubes branching throughout the body Tracheoles – find branches of trachea that deliver gases to cells Spiracles – external openings of the tracheal system on the exoskeleton along the abdomen and thorax

Question 38

How is the tracheae adapted in insects?

Answer 38

– Reinforce with spirals of chitin, prevents collapsing – Multiple tracheae, increases surface area

Question 39

How are the tracheoles adapted in insects?

Answer 39

– Penetrate directly into tissues, reduces gas diffusion distance – Thin walls, reduce gas diffusion distance – Highly branched, maximising the surface area – Not reinforced with chitin, allowing gas exchange to occur – Fluid at the end of tracheoles (tracheal fluid), allows oxygen to dissolve to a diffusion and reduces water loss

Question 40

How are the spiracles adapted in insects?

Answer 40

Open and close, control gas exchange with the atmosphere and minimise water loss

Question 41

How does gas exchange occur in insects?

Answer 41

1. Air enters the tracheal system through spiracles 2. Air moves into larger tracheae and diffusers into smaller tracheoles 3. Tracheoles brunch throughout the body, transporting directly to cells. 4. Oxygen dissolves in water in tracheal fluid and diffuses down its concentration gradient from tracheoles into body cells 5. Carbon dioxide diffuses down its concentration gradient out of body cells into the tracheoles 6. Air then carried back to the spiracles via the tracheae and released from the body

Question 42

How is the concentration gradient between the tissues and air in the tracheal system are maintained?

Answer 42

Cells using up oxygen for respiration – keeps oxygen concentration low in cells Cells producing carbon dioxide and respiration – keeps carbon dioxide concentration high in cells Continuous ventilation – fresh air is supplied to the tracheal system via spiracles

Question 43

What are the other ventilation mechanism?

Answer 43

More pics open – allows more oxygen to enter the tracheal system Mechanical active ventilation – when muscles around the tracheae contract and relax, changing the volume and pressure in the abdomen and squeezing the tracheae to pump air in and out of the spiracles Movement of tracheal fluid out into tissues – increases the diffusion rate and surface area for gas exchange Enlarged collapsible tracheae , accessory sacs and air reservoirs – inflate or deflate to ventilate the track your system and can increase the volume of air move through throughout the system Movement of wing muscles connected to sacs– pump air to ventilate the track your system Vibration of thoracic muscles – pumps air to ventilate the track your system

Question 44

What does lactic acid accumulation do?

Answer 44

Lactic acid accumulation reduces the water potential in the tracheal fluid at the end of tracheoles Water leaves the tracheoles via osmosis A higher surface area is exposed for gas exchange

Question 45

What are the challenges for gas exchange systems in fish?

Answer 45

– Water is dancer and more viscous than air, resulting in slower diffusion of oxygen – Water has less oxygen than air – Bonefish are very active so have high oxygen demands

Question 46

What is the structure of the gas exchange system in bony fish?

Answer 46

– Girls are covered by an operculum flap – Girls consist of stacked filaments containing gill lamellae – Gill lamellae are surrounded by extensive blood vessels

Question 47

What are the adaptation of gills?

Answer 47

– lamellae provide a large surface area – Lamellae membranes a thin to minimise diffusion distance – The girls have rich blood supply to maintain steep diffusion gradients – The countercurrent flow of blood and water creates even steeper concentration gradient – Overlapping filament tips increase resistance, slowing water flow over gills and allowing more time for gas exchange

Question 48

What is countercurrent flow?

Answer 48

More efficient than parallel flow 1. Blood and water flow over the lamellae in opposite directions 2. This means that oxygen rich blood meets water that is at its most oxygen rich when it first moves across the gills, maximising diffusion of oxygen into the blood 3. Oxygen poor blood returning from body tissues meets oxygen reduce water that has had most of its oxygen removed, still allowing diffusion of oxygen into the blood. 4. This maintains a steep concentration gradient across the entire gill

Question 49

What is parallel flow?

Answer 49

Parallel flow reduces the concentration gradient. The less oxygen can be absorbed.

Question 50

How does ventilation via the buccal cavity occur?

Answer 50

Bony fish ventilate their girls by opening and closing their mouths, changing the volume of the buccal cavity 1. When a fish opens its mouth, this increase the volume of the buccal cavity. 2. This decreases the pressure, which pulls water into the buccal cavity. 3. Water flows over the gills. 4. Water flows out through the operculum. This drives and directional water flow for ventilation, providing freshly oxygenated water and removing carbon dioxide