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Exchange Flashcards

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Biology 101 flashcards
1
Q

What kind of SA:V ratio do small organism have

A

A large one

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2
Q

Gas echa he in single celled organisms

A

Substances just diffuse across body surface

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3
Q

What features does insects have for gas exchange

A
  • Trachea
  • Tracheoles w/ water in the ends
  • Spiracles
  • Muscle fibre
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4
Q

What supports the trachea

A

Rings of cartilage so it doesn’t collapse

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5
Q

Why are do the tracheoles allow quick diffusion

A

Because they are directly next to cells allowing air to be directly brought to the respiring tissue

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6
Q

What 3 ways are gases moved in the insect tracheal system

A
  • along a diffusion gradient
  • mass transport
  • the ends of the tracheoles are filled with water
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7
Q

How do gases move in the insect tracheal system along a diffusion gradient

A
  • when cells are repairing, oxygen is used up decreasing its concentration at the ends of tracheoles -> this creates a diffusion gradient causing oxygen to diffuse from the atmosphere to the tracheoles
  • carbon dioxide is produced in cells during respiration -> this creates a diffusion gradient in the opposite direction so it’s taken out into the atmosphere
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8
Q

How do gases move in the insect tracheal system by mass transport

A

The contraction of muscles in insects can squeeze the trachea -> this allows mass movements of air in and out of

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9
Q

How do gases move in the insect tracheal system due to tracheoles being water filled

A
  • when insects undergo major activity, some anaerobic respiration takes places producing lactate
  • this lactate is soluble and lowers the water potential of the muscle cells
  • so water moves into cells from tracheoles by osmosis
  • the water in tracheoles ends decreases in volume allowing more air to be drawn in
  • this increases rate of air moved in but leads to greater water evaporation
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10
Q

What are spiracles

A

Pores on the body surface of an insect which open and close by a valve to let substances in and out of the

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11
Q

What are the limitations of the insect tracheal system

A
  • relies mostly on diffusion for gas exchange
  • and for diffusion to be effective the diffusion pathway must be short
  • so insects have to be of a small size
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12
Q

Structure of the gills

A

They are made up of gill filaments which have gill lamellae at a right angle
-> these increase surface area

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13
Q

What is the countercurrent flow

A

The flow of water over the gill lamellae and the flow of blood within them are in opposite directions

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14
Q

Why is the countercurrent so important

A
  • it means that the blood is already full of oxygen when it meets water which has its maximum concentration of water
    -> therefore diffusion of oxygen from the water to the blood takes place
  • blood with little oxygen in it meets water which has had most of its oxygen removed
    -> so diffusion of oxygen from the water to blood takes place
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15
Q

What is flow in the same direction called

A

Parallel flow

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16
Q

Why is countercurrent flow better than parallel flow

A

Parallel flow would mean the diffusion gradient would okay be maintained across part of the length of the gill lamellae and only half the available oxygen would be absorbed by the blood

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17
Q

What adaptations do plant leaves have for gas exchange

A
  • many stomata
  • many air spaces throughout the mesophyll
  • large SA of mesophyll cells for rapid diffusion
18
Q

What do the stomata do

A
  • each stoma is surrounded by guard cells which can open and close the stomata and so can control the rate of gas exchange and control water loss
19
Q

What adaptations do insects have to reduce water loss

A
  • small SA:V ratio
  • waterproof cuticle
  • spiracles -> can open and close
20
Q

What are xerophytes

A

Plants that have many adaptations to limit water loss through transpiration

21
Q

Adaptations of xerophytes

A
  • thick cuticle -> waterproof barrier
  • rolling up of leaves -> protects lower epidermis of stomata + traps moist air with high water potential so there’s no movement of water
  • hairy leaves -> traps moist air so water potential gradient is decreased
  • stomata in pits -> traps moist air
  • small SA:V ratio
22
Q

What do all aerobic organisms require a constant supply of and why

A

Oxygen to release energy in the form of ATP in respiration

23
Q

What supports lungs

A

Ribcage

24
Q

Why are lungs inside the body opposed to outside

A
  • air isn’t dense enough to support and protect the delicate structures
  • the body would lose a lot of water and dry out
25
Q

Features of the lungs

A
  • trachea
  • tracheoles
  • bronchi
  • bronchioles
  • alveoli
26
Q

Structure of trachea

A
  • supported by rings of cartilage that prevents it from collapsing as air pressure inside falls when breathing in
  • tracheal walls are made up of muscle, lined with ciliated epithelium and goblet cells
27
Q

Structure of bronchi

A
  • 2 divisions of the trachea that each lead to one lung
  • produce mucus to trap dirt
  • have cilia to move mucus towards throat
  • larger bronchi are supported by cartilage -> but amount decreases as bronchi gets smaller
28
Q

Structure of bronchioles

A
  • walls are made of muscles lined with epithelial cells
    -> this muscles lets them construct so they can control the flow of air in and out of the alveoli
29
Q

Structure of alveoli

A
  • have collagen and elastic fibres between alveoli -> elastic fibres allow them to stretch as they fill with air and then spring back during exhalation to get rid of carbon dioxide rich air
  • lined with epithelium
30
Q

What is the scientific word for breathing

A

Ventilation

31
Q

What is the other word for inhalation and what is it

A

Inspiration
- when the atmospheric pressure is greater than pulmonary pressure and air is forced into the lungs

32
Q

What is the other word for exhalation and what is it

A

Expiration
- when pulmonary pressure is greater than atmospheric pressure and air is forced out of the lungs

33
Q

What muscles cause pressure changes in lungs

A
  • diaphragm
  • intercostal muscles
34
Q

What are the types of intercostal muscles

A
  • internal intercostal muscles -> contract during expiration
  • external intercostal muscles -> contract during inspiration
35
Q

Process of inspiration

A

• The external intercostal muscles contract, while the internal intercostal muscles relax

• The ribs are pulled upwards and outwards, increasing the volume of the thorax

• The diaphragm muscles contract, causing it to flatten, which also increases the volume of the thorax

• The increased volume of the thorax results in reduction of pressure in the lungs

• Atmospheric pressure is now greater than pulmonary pressure, and so air is forced into the lungs

36
Q

Process of expiration

A

• The internal intercostal muscles contract, while the external intercostal muscles relax

• The ribs move downwards and inwards, decreasing the volume of the thorax

• The diaphragm muscles relax and so it is pushed up again by the contents of the abdomen that were compressed during inspiration

The volume of the thorax is therefore further decreased

• The decreased volume of the thorax increases the pressure in the lungs

• The pulmonary pressure is now greater than that of the atmosphere, and so air is forced out of the lungs

37
Q

What types of processes are inspiration and expiration

A

Inspiration is an active process (uses energy)

Expiration is a largely passive process (doesn’t require much energy)

38
Q

What is the main cause of air being forced out during breathing

A

The recoil of elastic tissue
BUT under more strenuous conditions, various muscles start to play a major part

39
Q

Why is diffusion of gases between the alveoli and blood very rapid

A
  • RBCs are slowed as they pass through the pulmonary capillaries -> allowing more time for diffusion
  • the distance between the alveolar air and RBCs is reduced as the RBCs are flattened against the capillary walls
  • the walls of the alveoli and capillaries are very thin
  • large SA of alveoli and pulmonary capillaries
  • well ventilated + rich blood supply -> maintains steep concentration gradient
  • blood flow through the pulmonary capillaries maintains a concentration gradient
40
Q

Why is the diffusion pathway in alveoli short

A

Because the alveoli only have a single layer of epithelial cells and the blood capillaries only have one layer of cells

41
Q

What is a correlation

A

When a change in one of two variables is reflected by a change in the other variable

Bio Alevel (5 decks)

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