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Biology A1 > 4: Gas Exchange > Flashcards

4: Gas Exchange Flashcards

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1
Q

What is the rate of which substances can enter and exit a cell/organism dependant on?

A
  • Surface Area
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2
Q

What is the rate of which gases are used or produced dependant on?

A
  • Volume
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3
Q

Why does Volume affect the rate of gas production?

A
  • bigger/more cells, so a higher O2 and CO2 intake for respiration
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4
Q

Why do small organisms such as Amoeba meet gas exchange requirements solely through diffusion via cell surface membrane?

A
  • small organism, so will have a high SA:Vol ratio, which means they have a big enough surface for diffusion of gases by Fick’s law
  • Has a “short diffusion pathway” since very little distance from outside the organism to the middle of organism’s cells
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5
Q

Why do larger organisms such as Fish and Mammals need specialised Gas Exchange Systems?

A
  • smaller SA:Vol ratio, inefficient for respiration across whole body, so require specialised gas exchange systems
  • larger diffusion pathway, so diffusion alone for small SA:Vol ratio organisms are too slow
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6
Q

What is Metabolic Rate?

A
  • rate of which all chemicals reactions in the body occur
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7
Q

Mammals + Birds body temperature is _____ than surroundings so ____ ____ occurs.

A
  1. higher
  2. heat loss
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8
Q

Do Small Mammals have higher or lower metabolic rates than Large Mammals?

A
  1. higher
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9
Q

What is the amount of heat released related to?
What is the amount of heat loss related to?

A
  1. volume
  2. Surface Area
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10
Q

Why do smaller mammals have a larger metabolic rate?

A
  • smaller mammals have a higher SA:Vol ratio, therefore will lose heat faster
  • so they therefore need a higher Metabolic Rate, to respire faster releasing heat, to replace the lost heat
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11
Q

Why do Living Cells need to respire?

A
  • to produce ATP to survive
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12
Q

Aerobic Respiration Word Equation:

A

Glucose + Oxygen –> Carbon Dioxide + Water

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13
Q

Fick’s Law:

A

Rate of Diffusion is proportional to:
SA x concentration gradient / length of diffusion pathway

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14
Q

Do single-celled organisms have special gas exchange systems?
What do they rely on?

A
  • no
  • simple diffusion of gases across their outer surface membrane
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15
Q

How are single-celled organisms adapted for Gas Exchange?
(hint-Fick’s Law)

A
  1. Large SA:Vol ratio, due to small size
  2. short diffusion pathway, due to small size
  3. Concentration gradients maintained for O2 and CO2, due to continuous aerobic respiration
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16
Q

Why do Fish require a specialised Gas Exchange System?

A
  • small SA:Vol
  • longer diffusion pathway
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17
Q

Describe the Fish Gas Exchange Anatomy:

A
  1. 4 layers of “Gills” on fish
  2. “Gills” are made up of stacks of “Gill Filaments”
  3. “Gill Filaments” are covered with “Gill Lamellae”
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18
Q

How does Water enter fish?

A
  1. water enters through mouth, and rushes in over the gills and out through the operculum
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19
Q

How are Fish adapted to Gas Exchange?

A
  1. Large Surface Area:
    - each gill contains many filaments which are covered in many lamellae, which gives a large surface area for diffusion
    - many capillaries increase SA for diffusion of Oxygen from water into blood
  2. Short Diffusion Pathway:
    - there are many capillaries with a “single layer of thin epithelium”, close to “thin walled lamellae”, ensuring short diffusion pathway between blood and water
  3. Concentration Gradient:
    - continuous flow of blood through capillaries ensures that freshly oxygenated blood is quickly removed from gills and replaced deoxygenated blood ready for gas exchange
    - water flows over gill plates in opposite direction to the flow of blood in capillaries, “counter-current mechanism”
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20
Q

Explain the Counter Current Mechanism:

A
  1. Water flows over the gills in an opposite direction to the flow of blood in capillaries
  2. this ensures that the blood always meets water with a higher concentration of oxygen
  3. therefore equilibrium from diffusion is not met
  4. this ensures that constant diffusion can occur across the whole length of the Lamellae, due to the concentration gradient maintained across the whole length of the lamellae
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21
Q

How is the constant flow of Water to the Gills in Fish’s maintained?
Why is this important?

A
  1. a ventilation mechanism ensures water enters the fish’s mouth and flows over gills, leaving via the operculum, so a constant flow of water over the gills is maintained
    2.
    - ensures water with a higher oxygen concentration passes over gills to diffuse into blood capillaries, and low O2 concentration are removed
    - thus, concentration gradient maintained
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22
Q

What is the body of an Insect protected by?

A
  • an exoskeleton, made up of a rigid substance “chitin”
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23
Q

What minimises water loss across body surface for insects?

A
  • outermost layer is waxy and waterproof
24
Q

Why do insects require specialised gas exchange system?

A
  • tough exoskeleton prevents simply using their body surface for diffusion
25
Q

What is the gas exchange system for insects called?

A
  • tracheal system
26
Q

How does the Tracheal System work?

A
  1. running along the length of the abdomen, there are round, valve like openings called “Spiracles”
    - O2 and CO2 enter + exit via spiracles
  2. These spiracles are attached to “trachea” which are a network of internal, air-filled tubes
  3. These “trachea” subdivide to smaller and smaller tubes, with the finer tubes called “tracheoles”, which penetrate into and between all cells
    - these are the sites of gas exchange
    - O2 diffuses directly into the cells and CO2 diffuses out
27
Q

Why does “trachea” contain rings of chitin?

A
  • Support: strengthens tubes by keeping airways open even when pressure inside decreases, or body is moving
28
Q

How are Insects adapted for Fast Rates of Diffusion?

A
  1. Large Surface Area:
    - large number of small “tracheoles” give a large S.A for diffusion
  2. Short Diffusion Pathway:
    - tracheoles have “thin walls”, and “extensive branching”, with close proximity to the cells providing the Short Diffusion Pathway
  3. Concentration Gradient:
    - in smaller and large, inactive insects; respiring cells use up O2 and produce CO2, which means there’s always a lower level of O2 inside cells than outside, providing a steep concentration gradient for diffusion
29
Q

Why do Insects require more O2 during flight?

A
  • insect flights require more ATP for increased muscle contraction
  • O2 is required to produce ATP via aerobic respiration, and since more ATP is required a higher rate of respiration needs to occur
30
Q

How are insects adapted to maximise ATP production during flight?

A
  • Abdominal Pumping: ventilation by contractions of the muscles in the abdomen, forces air in and out of the spiracles and tracheae to maintain greater air flow and steeper concentration gradients for diffusion of O2, for aerobic respiration
31
Q

How are insects adapted to minimise water loss?

A
  1. waterproof, waxy cuticle all over body
  2. spiracles surrounded by hairs which can trap layers of moist air to minimise water loss
  3. small SA:Vol ratio decreases surface area of which water can evaporate
  4. spiracles guarded by “spiracle valves” which can close spiracles
    - ALL OF THESE PREVENT/REDUCE EVAPORATION OF WATER
32
Q

Where is the Gas Exchange Site for Plants?
How does this work?

A
  • spongy mesophyll layer of the leaf (containing large air spaces, and thin walls)
  • contact with with stomata, across which gases enter and leave via diffusion down steep conc. gradients
33
Q

How are Plants adapted to Gas Exchange?

A
  1. Large Surface Area:
    - numerous air spaces in spongy mesophyll, large S.A for gas exchange
    - large number of Stomata, so more gases can enter so higher rate of diffusion
  2. Short Diffusion Pathway:
    - spongy mesophyll cells have thin cell walls, in direct contact with air
  3. Concentration Gradient:
    - CO2 low in the leaf by day as it is used by photosynthesis, O2 will be high
    - O2 low in the leaf at night, used by aerobic respiration, Co2 will be high
34
Q

How do plants minimise water loss?

A
  • thick, waxy cuticle on upper epidermis reducing evaporation of water
  • stomata mainly on underside, less evaporation of water
  • guard cells can close stomata if temperatures too high
35
Q

Why do humans need to carry out Gas Exchange?

A
  • we require a constant supply of O2, to release energy in the form of ATP via Aerobic Respiration
  • to remove CO2, to prevent dangerous lowering of pH in the body
36
Q

Why are volumes of gases in mammals exchanged, in large quantities?

A
  • high rates of respiration, so need to maintain a constant body temperature
37
Q

Describe the Airway of humans:

A
  1. air enters the airway through the nose/mouth
  2. mucus membranes line much of the airway, which contain goblet cells which secrete mucus and are lined with ciliated epithelium
  3. air passes into the trachea, which splits into 2 bronchi, one for each lung
  4. bronchi branch into many bronchioles
  5. these end in small air sacs called alveoli
  6. alveoli are in millions, and are made of a single layer of epithelium
38
Q

What is the function of the mucus and cilia?

A

Mucus: traps microorganisms and debris, helping to keep airways clear
Cilia: beat regularly to move microorganisms and dust particles along with the mucus

39
Q

Gas exchange only occurs between the _____ and the _____ ______

A
  1. alveoli
  2. blood capillaries
40
Q

How does Oxygen/CO2 diffuse from alveoli into blood?

A
  1. Oxygen diffuses through the epithelium of the alveoli and the endothelium of the blood capillaries into the blood
  2. it here combines with the haemoglobin in red blood cells
  3. carbon dioxide diffuses oppositely
41
Q

How is the human gas exchange system adapted for high rates of diffusion?

A
  1. Large Surface Area:
    - millions of alveoli + blood capillaries for diffusion
  2. Short Diffusion Pathway:
    - only 2 layers of cells between air in alveoli + blood in capillaries (both on cell thick)
  3. Large Concentration Gradient:
    - blood continuously circulates through capillaries, removing O2 high blood and delivering low O2 blood to be oxidised
    - ventilation ensures high O2 air is taken in, and low O2 air is removed
42
Q

What is inspiration?
What is expiration?

A

inspiration: taking air into the thorax
expiration: taking air out the thorax

43
Q

Both inspiration and expiration require breathing movements to alter the ____ of the thorax, which in turn creates ___ _____ differences between the thorax and atmosphere

A
  1. volume
  2. air pressure
44
Q

air moves _______ a __________

A
  1. down
  2. pressure gradient
45
Q

Since the thorax is airtight and the only opening is the ____, air is drawn ___ ____ ___ when pressure of the thorax is _____ than atmospheric pressure

A
  1. trachea
  2. into the lungs
  3. lower
46
Q

During Inspiration does volume and pressure increase or decrease?
During Expiration does volume and pressure increase or decrease?

A
  1. volume increases, pressure decreases
  2. volume decreases, pressure increases
47
Q

Inspiration is achieved through movements of what body parts/muscles?

A
  1. ribcage, diaphragm
  2. internal/external antagonistic muscles
48
Q

Define Antagonistic Muscles:

A
  • a pair of muscles, which on contraction, produces opposite effects to each other
49
Q

Describe how inspiration works:

A
  1. external intercoastal muscles contract
  2. ribcage moves up and outwards
  3. diaphragm muscles contract, and diaphragm flattens
  4. elastic tissue stretches, inflating lungs
  5. volume increases in thorax
  6. pressure decreases < atmospheric
  7. air enters down pressure gradient
50
Q

Describe “at rest” expiration:

A
  1. external intercoastal muscles relax
  2. ribcage moves down and in
  3. diaphragm muscles relax, and diaphragm returns to dome shape
  4. elastic tissue recoils
  5. volume of air in thorax decreases
  6. pressure increases > atmospheric
  7. air forced out down pressure gradient
51
Q

What is the difference between “at rest” expiration and “forced”?

A
  • forced is not passive
  • same process but as external intercoastal muscles relax, internal intercoastal muscles contract, pulling ribcage down and in
52
Q

What is elastin?
How does it effect breathing?

A
  • fibrous protein
  • when inspiration occurs, the elastic tissue stretches allowing lungs to inflate, but at expiration it recoils
53
Q

Tidal Volume Definition:
Ventilation Rate Definition:
Pulmonary Ventilation Definition:

A
  1. volume of air breathed in or out of lungs in a normal resting breath
  2. number of breaths in and out per minute
  3. the total volume of air moved into the lungs in one minute
54
Q

Pulmonary Ventilation Formula:
(include units)

A

= tidal volume (dm^3) x ventilation rate (min^-1)

55
Q

Casually Linked Defintion:

A
  • one variable causes the other to occur

Biology A1 (15 decks)

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