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Biology AS > Organisms Exchange Substances With Their Environment 3.3 > Flashcards

Organisms Exchange Substances With Their Environment 3.3 Flashcards

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1
Q

What is the rate of diffusion proportional to?

A

Surface Area x Concentration DIfference / Diffusion Distance

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2
Q

Why is the diffusion rate slow in single celled organisms?

A

There is a small distance for the substances to travel.

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3
Q

Why is the diffusion across the outer membrane of multi-cellular organism too slow?

A

Some cells are too deep inside the body which means that there is a big distance for the substances to travel and larger animals have a low surfac area to volume ratio which makes it difficult to exchange enough substances required.

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4
Q

What is meant by the term metabolic rate?

A

The amount of energy expended by that organism in a time period, usually daily.

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5
Q

What is meant by the term metabolic demand?

A

How much oxygen and nutrients an organism needs to take in daily to respire enough to maintain the metabolic rate.

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6
Q

What is the general rule for the correlation of metabolic rate and and mass of an organism?

A

The greater the mass of an organism the higher that organisms metabolic rate.

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7
Q

Why do unicellular organisms have a large surface area to volume ratio?

A

This means that the surface area is high enough to absorb the substances required.

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8
Q

Why is the diffusion distance in unicellular organisms short?

A

This means that diffusion could happen fast.

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9
Q

What can impact heat exchange?

A

Body size and body shape.

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10
Q

Where does gas exchange happen in mammals?

A

In the lungs.

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11
Q

What are the key steps in inspiration?

A

External intercostal and diaphragm muscles contract 🡨 requires energy

Rib cage moves upwards and outwards

Diaphragm flattens

Increased volume of the thoracic cavity

Lung pressure decreases to below atmospheric pressure

Air flows from a higher pressure to a lower pressure (pressure gradient)

Air flows into the lungs.

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12
Q

Is inspiration an active or passive process?

A

Active.

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13
Q

If a process requires energy is it active or passive?

A

Active.

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14
Q

What are the key steps in inspiration?

A

External intercostal and diaphragm muscles relax. (no energy needed).

Rib cage moves downwards and inwards

Diagram moves upwards

Decreased volume of the thoracic cavity

Air pressure increases to above atmospheric pressure.

Air is forced down the pressure gradient and out of the lungs.

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15
Q

What are the key steps of forced expiration?

A

External intercostal muscles relax

Internal intercostal muscles contract (Antagonistic)

Pulls the ribcage further down and in.

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16
Q

What are the alevoli surrounded by?

A

A network of capillaries.

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17
Q

What is the wall of each alveolus made up by?

A

The wall of each alveolus is made from a single layer of thin, flat cells called ‘alveolar epithelium’.

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18
Q

What do the walls of alevoli contain?

A

The walls contain a protein ‘elastin’ – which helps them recoil to their normal shape.

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19
Q

Describe the pathway of oxygen from the alveoli to the haemoglobin.

A

Oxygen diffuses from alveoli, across the alveolar epithelium
and capillary endothelium and into haemoglobin.

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20
Q

Where does the endothelium generally line?

A

Endothelium generally lines
fully internal pathways (such as the vascular system).

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21
Q

Where does the epithelium generally line?

A

Epithelium generally lines pathways that are open to the
external environment (such
as the respiratory and digestive systems).

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22
Q

What factors affect the rate of diffusion in alevoli?

A

Thin exchange surface
Large surface area
Steep concentration gradient maintained by constant blood flow and ventilation

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23
Q

What can tell you about how the lungs are functioning?

A

Ventilation rate (the volume of air
entering the lungs in a minute) and
tidal volume (the volume of air in
each breath) can tell you about how the lungs are functioning.

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24
Q

What is residual volume?

A

The certain volume of air that remains in the lungs to make
sure they never fully deflate.

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25
Q

What is breathing rate?

A

Breathing rate is the number of
breaths per minute.

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26
Q

What can you use to measure lung function?

A

A spirometer.

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27
Q

How does a sprioemeter measure lung function?

A

You work out breathing rate (number of breaths per minute), tidal volume and ventilation rate from a spirometer trace.

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28
Q

What is tidal volume?

A

The volume of air in each breath.

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29
Q

What is the ventilation rate?

A

The number of breaths per minute. Usually 15 for a healthy person resting.

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30
Q

What is the forced vital capacity?

A

The maximum volume of air it is possible to breathe forcefully out of the lungs after a really deep breath in.

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31
Q

What is the forced expiratory volume?

A

The maximum volume of air that can be breathed out in one second.

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32
Q

What does an airway disease do?

A

Affect the body’s ability to move air in and out of the lungs.

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33
Q

What are examples of airway diseases?

A

Asthma
COPD
Bronchitis

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34
Q

What is a lung tissue disease?

A

Damaged tissue in the lungs due to scarring or an injury.

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35
Q

What are examples of lung tissue disese?

A

Pulmonary fibrosis
Sarcoldosis

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36
Q

What does a lung circulation disease do?

A

It affects the circulation of blood to and from the lungs.

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37
Q

What are examples of lung circulation disease?

A

Pulmonary hypertension
Pulmonary edema

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38
Q

What are the two types of diseases that affect ventialtion in the lungs?

A

Restrictive and obstructive.

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39
Q

What do restricitve ventilation lung diseases do?

A

They make it difficult to breathe as they affect the elastic tissue and severely reduces FVC as breathing in is difficult but FEV is less affected because breathing out is still normal.

40
Q

What do obstructive ventilation lung diseases do?

A

They make it difficult to breathe out as airways are blocked, both FVC and FEV are much lower than normal.

41
Q

What happens when someone becomes infected with tuberculosis?

A

When someone becomes infected with tuberculosis bacteria, immune system cells build a wall around the bacteria in the lungs.

42
Q

What does tuberculosis cause?

A

Tubercules to form.

43
Q

What does tuberculosis causes?

A

Infected tissue to die and cause damage to the gaseous exchange surface.

44
Q

What happens to tidal volume to a person infected with tuberculosis?

A

It decreases, which means that less air can be inhaled with each breath.

45
Q

What happens to ventilation rate to a person infected with tuberculosis?

A

It increases.

46
Q

What is fibrosis?

A

Fibrosis is the formation of scar tissue in the lungs from infection or exposure to substances like asbestos or dust.

47
Q

Why is scar tissue bad in lungs?

A

Scar tissue is thicker and less elastic than normal lung tissue. This means that the lungs cant expand and can’t hold as much air as normal – tidal volume and FVC is reduced.

48
Q

Why is there a reduction in gas exchange in someone with fibrosis?

A

A reduction is the rate of gas exchange because diffusion is slower across a thicker scarred membrane.

49
Q

Why does fibrosis cause a larger ventilation rate?

A

Faster ventilation rate to get enough air into the lungs to oxygenate the blood.

50
Q

What is asthma?

A

A respiratory system when the airways become inflamed and irritated, usually due to an allergic reaction to dust or pollen.

51
Q

What happens during an asthma attack?

A

During an asthma attack, the smooth muscle lining the bronchioles contracts and a large amount of mucus is produced. This causes constriction of the airways, making it difficult to breath. Air flow in and out is severely reduced, so less oxygen enters the alveoli and moves into the blood.

52
Q

Why does asthma cause a significant FEV reduction?

A

Reduced air flow means FEV is severely reduced.

53
Q

What is emphysema?

A

Emphysema is a lung disease caused by smoking or long-term exposure to air pollution. Foreign particles in the smoke become trapped in the alveoli. This causes inflammation, which attracts phagocytes to the area.

The phagocytes produce an enzyme that breaks down elastin (protein) in the alveolar wall. Loss of elastin means the alveoli can’t recoil to expel air as well. It also destroys the walls which reduces the surface area.

54
Q

What is the ventilation rate?

A

The volume of air entering the lungs in a minute.

55
Q

Why does the ventilation rate increase during exercise?

A

Increased volume of air needed.

56
Q

What is tidal volume?

A

The volume of air in each breath

57
Q

What is total lung capacity?

A

VC + RV / total volume of air in the lungs.

58
Q

What is breathing rate?

A

The number of breaths per minute

59
Q

What is FVC?

A

The maximum volume of air it is possible to breathe forcefully out of the lungs in a single breath.

60
Q

A person with fibrosis scar tissue will have a reduced tidal volume, explain why.

A

Elasticity is reduced so lungs cannot expand and hold as much air as normal.

61
Q

Why is ventilation rate increased in a person with TB?

A

Damaged alveoli have a smaller surface area. Scar tissue is thicker, so diffusion rate is reduced as diffusion distance between alveoli and blood is increased. Less oxygen able to diffuse into the blood with each breath so have to breathe more.

62
Q

Explain why the rate of gas exchange in someone with fibrosis is lower than a healthy person.

A

Scar tissue is thicker so diffusion rate is reduced as diffusion distance between alveoli and blood is increased.

63
Q

Explain what happens to FEV1 during an asthma attack?

A

Airways constrict severely reducing air flow in and out of the lungs so FEV1 is severely reduced.

64
Q

What is a gill made up of?

A

Each gill is made of lots of
thin plates called gill filaments which are attached to a bony gill arch.

65
Q

Describe gill filaments.

A

Gill filaments are covered in lots of tiny folds called lamella which
further increase the surface area of the gills.

66
Q

What do the lamellae have lots of?

A

Blood capillaries and a thin
layer of cells.

67
Q

Where does gas exchange happen in fish?

A

Gas exchange happens at the lamellae. Water flows over them
in an opposite direction to the blood (countercurrent flow).

68
Q

What is meant by concurrent flow?

A

Water and blood flow over and through the lamellae in the
same direction.

69
Q

Describe the trend in concentration during concurrent flow.

A

At first there is a very large concentration gradient as water
has a much higher oxygen concentration, so diffusion occurs.

As they flow along the lamellae the concentration gradient
decreases until equilibrium is reached and no more oxygen
diffuses into the blood

70
Q

What is meant by countercurrent flow?

A

Water and blood flow over and through the lamellae in opposite directions to each other.

71
Q

Describe the trend in concentration during countercurrent flow.

A

Blood always flows next to water that has a higher oxygen concentration, so diffusion happens along the full length of the lamellae.

The blood absorbs more and more oxygen as it moves along.

72
Q

How do gases move in and out of leaves?

A

Through stomata which are controlled by guard cells.

73
Q

What happens when plants have enough water?

A

When plants have enough water guard cells are turgid which keep the pores open.

74
Q

What happens when plants are dehydrated?

A

When plants are dehydrated the guard cells become flaccid because water moves out of vacuoles by osmosis causing the pore to close.

75
Q

What do insects use for gas exchange?

A

Insects use microscopic air-filled pipes called tracheae for gas exchange.

76
Q

How does air move into the tracheae in insects?

A

Air moves into the tracheae through pores on the surface called spiracles.

77
Q

What do the tracheae branch off into in insects?

A

The tracheae branch off into smaller tracheoles which have thin, permeable walls leading to individual cells.

78
Q

What do insects use to move air into and out of their spiracles?

A

Insects used rhythmic abdominal movements to move air into and out of the spiracles.

79
Q

What covers an insects body surface?

A

A rigid outer skeleton covers the insects body surface.

80
Q

What covers an insects exoskeleton?

A

A waterproof cuticle.

81
Q

What forms a waterproof barrier on insects?

A

Layers of a material called Chitin form a waterproof barrier on the surface of an insect.

82
Q

What is the tracheole in insects stiffened with and why?

A

The tracheole is stiffened with bands of chitin to prevent
collapse. (like cartilage in our own trachea)

83
Q

What is tissue fluid and how is it formed?

A

Tissue fluid is formed by blood plasma (carrying dissolved
substances) leaking from the capillaries. It surrounds the
cells in the tissue and provides them with oxygen and
nutrients.

84
Q

What is lymph?

A

Lymph is a colourless/pale yellow fluid like tissue fluid but
containing more lipids. Lymph
passes through the lymphatic
system and drains back into the
blood via the vena cava.

85
Q

State the cell types that are most likely to be found in blood plasma, tissue fluid and lymph

A

Blood plasma - red blood cells, white blood cells; tissue fluid
– white blood cells only during infection; lymph - lymphocytes

86
Q

Why can proteins known as plasma proteins not leave the blood plasma?

A

They are too large to pass between the cells of the capillary
wall.

87
Q

Describe the role of the lymphatic system

A

A system of tubes that returns excess tissue fluid to the
blood system. Transports lymphocytes.

88
Q

How does exchange of substances from tissue fluid to body cells occur?

A

Tissue fluid surrounds body cells so exchange occurs via diffusion, facilitated diffusion and active transport across plasma membranes

89
Q

Where is hydrostatic pressure the highest?

A

The arteriole end.

90
Q

Explain the movement of tissue fluid at the arteriole end of a capillary

A

At the arteriole end of the capillary hydrostatic pressure is greater than the osmotic pressure of the tissue fluid. This forces fluid containing small
molecules out of the blood through tiny gaps between the cells in the capillary walls.

91
Q

What substances move out of the capillary due to pressure filtration?

A

Oxygen, products of digestion

92
Q

Why does hydrostatic pressure
decrease along the capillary?

A

Because fluid is lost/ water leaves the capillary – reduces the volume of blood

93
Q

Why does osmotic pressure increase along the capillary?

A

Because fluid/water is lost from the capillary but large plasma proteins and other cells remain as they are too large to leave lowering the water potential compared to the tissue fluid

94
Q

Explain the movement of tissue fluid at the venule end of a capillary

A

Loss of water lowers the water potential and hydrostatic pressure of the blood. Hydrostatic pressure and water potential in tissue fluid is then higher at the venule end so water returns to capillaries by osmosis.

95
Q

What substances return to the capillary at the venule end?

A

Carbon dioxide, urea, lactate.

96
Q

How does excess tissue fluid get returned to the blood?

A

Any excess tissue fluid that is not reabsorbed is returned is collected into the lymphatic capillaries which returns it to the circulatory system.

97
Q
A

Biology AS (12 decks)

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