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Biology🔬🧬 > adaptations for gas exchange > Flashcards

adaptations for gas exchange Flashcards

1
Q

features for gas exchange

A
  • Large SA, relative to volume so that the rate of gas exchange satisfies organisms needs
  • thin, short diffusion pathway
  • Moist and permeable so that respiratory gases diffuse easily
  • Have a mechanism to produce a steep diffusion gradient across respiratory surface, by bringing in O2 or removing CO2 rapidly
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2
Q

Respiratory surface
definiion

A

Sites of gas exchange

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3
Q

Gas exchange

A

Diffusion of gases down a concentration gradient across a respiratory surface between an Organism and its environment

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4
Q

Unicellular organisms

A

eg. Protocistian, Amobea
- Single cells have large SA:V
- Cell membrane is thin so diffusion into cell is rapid
- single cell is thin so diffusion distances inside cell are short
Therefore:
- They can absorb enough oxygen across cell membrane to meet needs for respiration
- Remove CO2 fast enough to prevent building up a high conc and making cytoplasm too acidic for enzymes to function

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5
Q

multicellular animals

A

Larger organisms have a lower surface area to volume ratio than smaller organisms
So diffusion across their services is not efficient enough for their gas exchange

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6
Q

Flatworms

A

Much larger surface area than a spherical Organism of the same volume
High SA:V Overcomes problem of size increase because no parts of body is far from surface and diffusion paths are so short
Very thin surface
Cold blooded (lower metabolic rate) so lower energy demand

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7
Q

Terrestrial organism

A

organism the lives on land eg. Earthworm

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8
Q

Metabolic rate

A

Rate of energy exponenditure by the body

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9
Q

Earthworm

A
  • Cylindrical and so its SA:V is smaller than flatworm
  • Skin is respiratory surface which keeps moist by secreting mucus, need for a moist surface restricts earthworm to the damp environment of soil
  • No O2 requirement because it is slow moving and has a low metabolic rate. Enough oxygen diffuses across its skin into blood capillaries beneath
  • haemoglobin is present in its blood, carrying oxygen around the body in blood vessels. Carrying oxygen away from the surface maintains a diffusion gradient at respiratory surface
  • CO2 is also carried in the blood and it diffuses across the skin, down a conc gradient
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10
Q

Features in multicellular animals not seen in unicellular organisms

A
  • Generally have a higher metabolic rate and need to deliver more O2 to aspiring cells and remove more CO2
  • With an increase in size and specialisation of cells, tissues and organs become more interdependent
  • Ventilation mechanism
  • Respiratory surfaces must be thin to make diffusion pathways short, but then they are fragile and could be easily damaged. But as they are inside the organism they are protected
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11
Q

Ventilation mechanism in multi cellular animals

A

Definition- A mechanism enabling air or water to be transferred between the environment and a respiratory surface

In multicellular animals they must actively maintain a steep concentration gradient across their respiratory surfaces by moving the environment medium, air or water, and in larger animals the internal medium, the blood so they need ventilation mechanism

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12
Q

Problems for terrestrial organisms

A
  • Water evaporates from body surfaces which could result in dehydration
  • Gas exchange services must be thin and permeable with large surface area. Water molecules are very small and passed through gas exchange services so gas exchange services are always moist they are consequently likely to lose a lot of water
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13
Q

Adaptations in amphibians

A

EG. Frogs, toads, newts
Skin is moist and permeable, with a well developed capillary network just below the surface
Gas exchange just takes place through the skin and when the animal is active and the lungs also

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14
Q

Adaptations in reptiles

A

EG. crocs, lizards, snakes
Their lungs have a more complex internal structure than those of amphibians, increasing the surface area for gas exchange

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15
Q

adaptations in birds

A

Lungs of birds process large volumes of oxygen because flight requires a lot of energy. Bids do not have a diaphragm but their ribs and flight muscles ventilate their lungs more efficiently than the methods used by other vertebrates

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16
Q

gas exchange in fish

A

Gas exchange takes place across the gills, they have:
- One way current of water keeping flow by ventilation mechanism
- Many folds, providing a large service area over which water can flow and over which gases can be exchanged
- Large surface area maintained as a density of water flowing through prevents gills from collapsing on top of each other

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17
Q

cartilaginous fish

A

Have girls in five spaces on each site called Gill pouches open to the outside at Gill slits

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18
Q

Ventilation of cartilaginous fish is less efficient than bony fish

A
  • Don’t have special mechanisms to force water over the gills and many must keep swimming for ventilation to happen
  • parallel flow
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19
Q

parallel flow

A

Blood and water flow in the same direction at the Gill lamellae maintaining the concentration gradient for oxygen to diffuse into the blood only up to the points where its concentration in the blood and water is equal

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20
Q

parallel flow in cartilaginous fish

A

Blood travels through gill capillaries in the same direction as the water travels- parallel flow
Oxygen diffuses from where it is more concentrated in the water to where it’s less concentrated in blood
This division can only continue until concs are equal, after this the blood cannot pick up any more oxygen from water because there is no more conc gradient so blood oxygen conc is limited to 50% of its possible maximum value- max water a 100% so Max saturation of blood is 50%
Gas exchange in parallel flow does not occur continuously across the whole gill lamella, it occurs only until oxygen conc in the blood and water is equal

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21
Q

Bony fish

A

Have an internal skeleton made of bone and gills are covered with a flap called operculum rather than opening directly on the side of the fish

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22
Q

Operculum

A

Covering over the gills of a bony fish

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23
Q

ventilation in bony fish

A

To maintain a continuous and directional flow, water is forced over the gill filaments by pressure differences
water pressure in mouth cavity is higher than in opercular cavity.
Operculum acts as both a valve (letting water out) and pump (moving water past Gill filaments) mouth also acts as a pump

24
Q

Ventilation mechanism - to take in water

A
  1. Mouth opens
  2. operculum closes
  3. Floor of the mouth is lowered
  4. Volume inside mouth cavity increases
  5. Pressure inside mouth cavity decreases
  6. Water flows in, as the external pressure is higher than the pressure inside the mouth
25
Q

Ventilation mechanism - to force water out over the hills

A
  1. Mouth closes
  2. Operculum opens
  3. Floor of the mouth is raised
  4. Volume inside the mouth cavity decreases
  5. Pressure inside the mouth cavity increases
  6. Water flows out over the girls because pressure in the mouth cavity is higher than in the opercular cavity and outside
26
Q

Counter current flow

A

Blood and water flow in opposite directions at the Gill Lamellae, maintaining conc gradient and oxygen diffusion into blood, along the entire length

27
Q

Bony fish have four pairs of gills

A
  • Each gill is supported by a gill arch made of a bone
  • Along each Gill Arch are many thin projections- gill filaments
  • On the gill filaments are gas exchange surfaces, gill lamellae/ Gill plates. Held apart by water flowing between them and provide a large surface area for gas exchange. out of water they stick together and girls collapse.
    much less area is exposed so not enough gas exchange can take place.
28
Q

At every point along the gill lamella

A

Water has a higher oxygen concentration than the blood, so oxygen diffuses into the blood along the whole length of the gill lamellae
This is a more efficient system than the parallel flow of cartilaginous fish. Girls of a bony fish remove about 80% of oxygen from the water
This level of extraction is important to fish as water contains much less oxygen than air

29
Q

Carbon dioxide exchange

A

As in cartilaginous fish, CO2 diffuses from the blood to the water. In Bony fish, because of counter current system, CO2 diffusion out of the blood along the whole length of the Gill lamellae
This is more efficient than the carbon dioxide loss from the gills of cartilaginous fish

30
Q

What do gills provide

A
  • specialised respiratory surface, rather than using the whole body surface
  • Launch surface area extended by the gill filaments and Gill Lamellae
  • Extensive network of blood capillaries, with blood carrieng haemoglobin, allowing efficient diffusion of oxygen into the blood and carbon dioxide out
31
Q

Structure of the human breathing system

A
  • Lungs are enclosed in thorax
  • Surrounding each lung and lining the thorax are pleural membranes. Between the membranes is the pleural cavity containing few pleural fluid
  • Base of Thorax: Dome shaped sheet of muscle (diaphragm) Separating thorax from abdomen
  • Ribs surround thorax
  • Intercoastal muscles are between the ribs
  • trachea is flexible airway bringing air to lungs
  • Two bronchi are branches of the trachea/ bronchus
  • Lungs consist of branching network of tubes called bronchioles, arise from the bronchus
  • Ends of the bronchioles are air sacs: Alveoli
32
Q

Pleural fluid

A

Lubricant, preventing friction between the lungs and inner wall of the thorax when they move during ventilation

33
Q

Ventilation of the lungs

A

Mammals ventilate their lungs by negative pressure breathing meaning that for air to enter the lungs the pressure inside lungs must be below atmospheric pressure

34
Q

Inspiration- inhalation

A
  1. External intercostal muscles contract
  2. Ribs are pulled upwards and outwards
  3. At the same time the diaphragm muscles contract so diaphragm flattens
  4. Outer pleural membrane is attached to the thoracic cavity wall so it is pulled up and out with the ribs, and lower part is pulled down with the diaphragm. In a membrane follows and so lungs expand increasing volume inside the alveoli
  5. Reduces pressure in the lungs
  6. Atmospheric air pressure is now greater than the pressure in the lungs so air is forced into the lungs
35
Q

expiration- exhalation

A
  1. External intercostal muscles relax
  2. Ribs move downwards and inwards
  3. At the same time the diaphragm muscles relax so diaphragm domes upwards
  4. The pleural membrane move down and in with the ribs, and the lower parts move up with the diaphragm. Elastic properties of the lungs allow their volume to decrease, decrease in the volume inside the alveoli
  5. Increases the pressure in the lungs
  6. Air pressure in the lungs is now greater than atmospheric pressure so air is forced out of the lungs
    Lungs recoil and regain their original shape when not being actively expanded. The recoil plays a massive part in pushing air out of the lungs
36
Q

Inside surfaces of Alveoli - Surfactant

A

Surfactant can be thought as an anti sticking mixture
Made of moist secretions containing phospholipid and proteins and has a low surface tension, preventing alveoli collapsing during exhalation, when a pressure inside them is low
Also allows gases to dissolve, before they diffuse in or out

37
Q

Gas exchange in the Alveolus

A
  • Provide a large SA:V and more molecules can diffuse in a given time
  • Gas is dissolved in the surfactant moisture lining the alveoli
  • Alveoli have walls made of squamous epiphyllum, only one cell thick, so the diffusion pathway for gases is short
  • An extensive capillary network surrounds the alveoli and maintains diffusion gradients, as O2 is rapidly bought to the alveoli and CO2 is rapidly carried away
  • Capillary walls are also one cell thick, contributing to the short diffusion pathway for gases
38
Q

Process of gas exchange in Alveoli

A

The oxygenated blood enters the capillary surrounding the alveoli
Oxygen diffuses out of the air in the alveoli into the red blood cells in the capillary
CO2 diffuses out of the plasma in the capillary into the air in the alveoli from where it is exhaled

39
Q

inspired and expired air- oxygen

A

inspired- 20%
Expired- 16%
Oxygen is absorbed into the blood at the alveoli and used in aerobic respiration

40
Q

inspired and expired air- water vapour

A

i- variable
E- saturated
Water content of the atmosphere varies. The alveoli are permanently lined with moisture, water evaporates from them and is exhaled

41
Q

Inspired and expired air- carbon dioxide

A

I- 0.04%
E- 4%
carbon dioxide produced by aerobic respiration diffuses from the plasma into the alveoli

42
Q

inspired and expired air- nitrogen

A

i- 79%
E-79%
Nitrogen is neither absorbed nor use so all that is inhaled gets exhaled

43
Q

Gas exchange in insects- Reducing water loss

A

Reduce water loss with a waterproof layer covering the body surface EG. The insects exoskeleton is rigid and comprises a thin waxy layer over thicker layer of chitin and protein

44
Q

Gas exchange process in insects

A

Insects have relatively small SA:V so without an impermeable exoskeleton, they could not use their body surface to exchange enough gases by Diffusion
Gas exchange occurs through spiracles, running along the side of their body
spiracles lead into a system of branched, chitin lined air tubes - tracheae ( branch into tracheoles)
The spiracles can open and close so gas exchange can take place and water loss can be reduced. Covering spiracles in some insects contribute to water loss preventation and they prevent solid particles getting in

45
Q

When insects are resting

A

rely on diffusion through spiracles, tracheae and tracheoles to take an O2 and to remove CO2
During acive like flight, movements of the abdomen ventilate the tracheae.
ends of the tracheoles are fluid-filled and extend into muscle fibres
This interface between tracheoles and muscle fibres is where gas exchange takes place; oxygen diffuses in the fluid and diffuses directly into the muscle cells so no respiratory pigment or blood circulation is needed. CO2 diffuses out by reverse process

46
Q

Cuticle

A

Waxy covering on a leaf, secreted by epidermal cells which reduce water loss

47
Q

Stomata definition

A

Pores on the lower leaf surface, and other aerial parts of a plant, bounded by two guard cells through which gases and water vapour diffuse

48
Q

Photosynthesis in the day and night

A

Day:
Respiration - oxygen in, carbon dioxide out
Photosynthesis - oxygen out, carbon dioxide in
Rate of photosynthesis is faster than rates of respiration, more oxygen produced, gas released oxygen

Night:
Respiration - oxygen in, carbon dioxide out
No photosynthesis as there’s no sufficient light
No oxygen produced, gas released carbon dioxide

49
Q

Leaf structure

A

Cuticle, upper epidermis, palisade mesophyll, spongy meysophyll, airspace, lower epidermis, cuticle, sub stomotal air chamber, stoma, Guard cell

50
Q

Guard cells

A

Only epidermal cells with chloroplasts and have unevenly thickened walls, with the inner wall, next to the pore in many species, being thicker than the outer wall

51
Q

Function of the stomata

A

Ask the width of the stoma can change, the stomata can control the exchange of gases between the atmosphere and the internal tissues of the leaf
control of water loss

52
Q

Mechanism of opening and closing

A

During the day:
- If water enters the guard cells, they become turgid and swell and the pore opens
- If water leaves the guard cells they become flaccid and the pore closes

53
Q

Process of an open stoma

A
  1. In the light chloroplasts in the guard cells photosynthesise, producing ATP
  2. This ATP provides energy for active transport of K+ ions into the guard cells from the surrounding epidermal cells
  3. Stored starch is converted to malate ions
  4. The K+ and Malate ions lower the water potential in the guard cells, making it more negative and water enters by osmosis
  5. Guard cells expand as they absorb water but less in thicker cell wall areas. As guard cell stretch a pore appears between the area w less stretching- stoma
  6. Guard cell becomes turgid and inner wall is inelastic so guard cells curve and bend away from each other
54
Q

Process of closed stoma

A
  1. Guard cell actively pumps out K+ ions raising water potential
  2. Water moves out by osmosis to adjacent cells
  3. Vacuum shrink and guard cells become flaccid
  4. Stoma closes
55
Q

When does the stomata close

A
  • At night to prevent water loss when there’s insufficient lights for photosynthesis
  • In a very bright light as it is accompanied by intense heat which which would increase evaporation
  • If there’s excessive water loss

Biology🔬🧬 (11 decks)

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