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Biology A-Level -James > Chapter 3.1-Exchange surfaces and breathing > Flashcards

Chapter 3.1-Exchange surfaces and breathing Flashcards

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1
Q

What are the 3 main factors that affect the need for an exchange system?

A
  • size
  • surface area to volume ratio
  • level of activity
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2
Q

What is the equation for working out the surface area of a sphere?

A

4nr^2

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3
Q

What is the equation for working out the volume of a sphere?

A

4/3nr^3

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4
Q

As an organism gets bigger what happens to the surface area to volume ratio?

A

surface area to volume ratio gets smaller

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5
Q

What are the common features of a good exchange system?

A
  • large surface area to provide more space for molecules to pass through
  • thin barrier to reduce the diffusion distance- and that barrier must be permeable to the substances being exchanged
  • good blood supply:this can bring fresh supplies of molecules to one side (supply side), keeping the concentration high, or it may move molecules from the demand side to keep the concentration low. This is important to maintain a steep concentration gradient so that diffusion can occur rapidly.
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6
Q

What is the trachea?

A

the main airway leading from the back of the mouth to the lungs

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7
Q

What are the bronchi and bronchioles?

A

smaller airways leading into the lungs

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8
Q

What are the alveoli?

A

tiny folds of the lung epithelium to increase the surface area

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9
Q

What are the muscles called that hold together the ribcage?

A

intercostal muscles

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10
Q

What is the layer of muscle tissue beneath the lungs?

A

diaphragm

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11
Q

What is meant by ventilation?

A

the refreshing of the air in the lungs, so that there is a higher oxygen concentration than in the blood, and a lower carbon dioxide concentration

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12
Q

What are the ways in which the alveoli are adapted to carry out efficient gaseous exchange?

A
  • large surface area to provide more space for molecules to pass through
  • barrier to exchange is permeable to oxygen and carbon dioxide
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13
Q

What are the adaptations in the gaseous exchange system which reduces the diffusion distance?

A
  • the alveolus wall is one cell thick
  • the capillary wall is one cell thick
  • both walls consist of squamous cells-this means flattened or very thin
  • the capillaries are in close contact with the alveolus walls
  • the capillaries are so narrow that the red blood cells are squeezed against the capillary wall- making them closer to the air in the alveoli and reducing their rate of flow
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14
Q

What is the total barrier to diffusion in terms of cells and what is this in thickness (micrometers)?

A
  • two flattened cells thick

- 1 micrometre

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15
Q

How does the blood ensure that the gaseous exchange system in mammals is efficient?

A
  • blood transports carbon dioxide away from the tissues and to the lungs. This ensures that the concentration of carbon dioxide in the blood is higher that that in the air of the alveoli
  • the blood also transports oxygen away from the lungs. This ensures that the concentration of oxygen in the blood is kept lower than that in the alveoli-so that oxygen diffuses into the blood
  • therefore the blood helps to keep the steep concentration gradient of both oxygen and carbon dioxide
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16
Q

Why is ventilation important in the mammalian gaseous exchange?

A
  • the concentration of oxygen in the air of the alveolus remains higher than that in the blood
  • the conc of carbon dioxide in the alveoli remains lower than that in the blood
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17
Q

What are the steps in inspiration(inhaling)?

A
  1. diaphragm contracts to move down and become flatter-this displaces the digestive organs downwards
  2. the external intercostal muscles contract to raise the ribs
  3. the volume of the chest cavity is increased
  4. the pressure in the chest cavity drops below the atmospheric pressure
  5. air is moved into the lungs
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18
Q

What are the steps in expiration (exhaling)?

A
  1. diaphragm relaxes and is pushed up by the displaced organs underneath
  2. external intercostal muscles relax and the ribs fall; the internal intercostal muscles can contract to help push air out more forcefully-this usually only happens during exercise or coughing and sneezing
    3.volume of the chest cavity is decreased
    4pressure inside the lungs increases and rises above the pressure in the surrounding atmosphere
  3. air is moved out of the lungs
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19
Q

What is a spirometer?

A

a device that can measure the movement of air into and out of the lungs

20
Q

What are the precautions that must be taken when using a spirometer?

A
  • subject should be healthy and free from asthma
  • soda lime should be fresh and functioning
  • there should be no air leaks in the apparatus, as this would give invalid or inaccurate results
  • mouthpiece should be sterilised
  • water chamber must not be overfilled (or water may enter the air tubes)
21
Q

What is the vital capacity and whats its typical value in humans?

A
  • the greatest volume of air that can be expelled from the lungs after the deepest breath
  • 2.5-5dm^3
22
Q

What is the residual volume and whats its typical value?

A
  • volume of air that remains in the lungs even after forced expiration. This air remains in the airways and the alveoli
  • approximately 1.5dm^3
23
Q

What is the tidal volume and whats it typical value in humans at rest?

A
  • the volume of air inhaled or exhaled in one breath, usually measured at rest
  • 0.5dm^3
24
Q

What factors affect a persons vital capacity?

A
  • size of the person
  • age and gender
  • level of regular exercise
25
Q

Whats the job of the soda lime in a spirometer?

A

absorbs the carbon dioxide which is exhaled from the person

26
Q

How do you calculate oxygen uptake from a spirometer?

A
  • calculate the difference in time (seconds) between the two points e.g. 55 seconds
  • measure the difference in volume between points A and B e.g. 0.3dm^3
  • divide by the time taken to decrease 55 seconds
  • the unit will be dm^3s^-1
  • rate of oxygen uptake = 0.3/55= 0.0055dm^3 s^-1
27
Q

What is breathing rate and how can this be measured on a spirometer?

A
  • the number fo breaths per minute

- count the number of peaks in each minute (usually about 12-14 breaths per minute)

28
Q

What is meant by oxygen uptake?

A

the volume of oxygen absorbed by the lungs in one minute

29
Q

How can oxygen uptake be increased?

A
  • increased breathing rate

- deeper breaths

30
Q

What is the total lung capacity?

A

vital capacity + residual volume

31
Q

What are elastic fibres?

A

protein fibres that can deform and then recoil to their original size

32
Q

What are ciliated epithelium?

A

a layer of cells that have many hair-like extensions called cilia

33
Q

What are goblet cells?

A

cells that secrete mucus

34
Q

How do the goblet cells and ciliated epithelium work together in the airways?

A
  • goblet cells trap pathogens by the mucus they release

- cilia move the mucus to the top of the airway, where is is swallowed

35
Q

What is cartilage and why is it important in the airways?

A
  • a form of connective tissue
  • prevents the collapse during inspiration
  • they are C-shaped rather than a complete ring which allows flexibility and space for food to pass down the oesophagus
36
Q

Whats the job of the smooth muscle?

A
  • it can contract. The action of the smooth muscle will constrict the airway.
  • This makes the lumen of the airway narrower.
  • it is not a voluntary act and Amy occur as a result of an allergic reaction
37
Q

How is smooth muscle returned back to its elongated form?

A
  • when the smooth muscle contracts, not deforms the elastic fibres
  • as the muscle relaxes, the elastic fibres recoil to their original size and shape. this acts to dilate the airways
38
Q

What is the operculum?

A

a bony flap that covers and protects the gills

39
Q

What are gill filaments?

A

slender branches of tissue that make up the gill. They are often called primary lamellae

40
Q

What are lamellae?

A

(sometimes called secondary lamellae): folds of the filament to increase surface area. They are also called gill plates

41
Q

What is a countercurrent flow?

A

where two fluids flow in opposite directions

42
Q

What is the tracheal system in insects?

A

a system of fluid-filled tubes in insects

43
Q

What is a spiracle?

A

external opening or pore that allows air in or out of the tracheae

44
Q

What is the pathway of air starting at the spiracle?

A
  • air enters the spiracle
  • air flows down the body through a series of tubes called tracheae (singular trachea)
  • these divide into smaller and smaller tubes, called tracheoles
  • the ends of the tracheoles are open and filled with fluid called tracheal fluid
  • gaseous exchange occurs between the air in the tracheoles and the tracheal fluid.
45
Q

How can flight muscles be used to help ventilate an insect?

A

sections of the tracheal system are expanded and have flexible walls. these act as air sacs which can be squeezed by the action of the flight muscles repetitive expansion and contraction of these sacs ventilate the tracheal system

46
Q

How can movement of the wings in insects help ventilate themselves?

A
  • alters the volume of the thorax
  • as the thorax volume decreases, air in the tracheal system is put under pressure and is pushed out of the tracheal system
  • when the thorax increases in volume, the pressure inside drops and air is pushed into the tracheal system from outside
47
Q

How can locusts ventilate themselves?

A
  • they can alter the volume of their abdomen by specialised breathing movements. These are co-ordinated with opening and closing valves in the spiracles.
  • as the abdomen expands, spiracles at the front end of the. body open and air enters the tracheal system.
  • as the abdomen reduces in volume, the spiracles at the rear end of the body open and air can leave the trachea; system

Biology A-Level -James (18 decks)

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