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Biology > Chapter 7 - Exchange Surfaces and Breathing > Flashcards

Chapter 7 - Exchange Surfaces and Breathing Flashcards

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1
Q

Why is diffusion alone enough to supply the needs of unicellular organisms?

A
  • The metabolic activity is low, so oxygen demands and CO2 production is low
  • SA:VOL ratio is large
  • Diffusion distance is short
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2
Q

How do you calculate SA:VOL with a cube of 4cm3?

A

SA= 4x4
= 16 ( x 6 bc six sides)

VOL= 4 x 4 x 4
= 64

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3
Q

Does SA or VOL need to be 1?

A

SA

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4
Q

Name the key features of effective exchange surfaces

A
  1. Increased surface area (e.g. root hair cells)
  2. Thin layers, diffusion distance are short (e.g. alveoli in lungs)
  3. Good blood supply, ensures substance is delivered and taken away from site.
    - maintains steep concentration gradient (e.g. gills of fish)
  4. Ventilation to maintain diffusion gradient (e.g. gills of fish) helps to maintain steep conc gradients for fast diffusion of gas exchange
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5
Q

Why do multicellular organisms need exchange surfaces?

A
  1. Longer diffusion difference between where O2 needed and where is supplied, exchange surface needed
  2. Larger organisms, higher metabolic activity, more 02 needed and CO2 produced
  3. Small SA:VOL ,gases aren’t diffused fast enough for metabolic demand
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6
Q

Why are gaseous exchange surfaces moist?

A
  • So oxygen dissolves in water before diffusing into the body tissue
  • Humidity increases, therefore the conc gradient between oxygen going in and oxygen already in lungs, therefore decreases the evaporation from exchange surfaces
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7
Q

Why do mammals have a high metabolic rate?

A
  • Active
  • Maintain body temperate independent of the environment
  • larger diffusion distances
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8
Q

Suggest the features of the nasal cavity in gas exchange

A
  • Large SA:VOL
  • Good blood supply (warms the air to body temp)
  • Hairy lining, which secrets mucus (trapping dust and bacteria)
  • Moist surfaces, increased humidity, reducing evaporation from exchange surfaces
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9
Q

What is the trachea supported by? and describe structure

A

Incomplete rings of strong flexible cartilage to prevent trachea collapsing

Incomplete rings -> so food can move easily down oesophagus behind trachea, so no blockage

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10
Q

What are the trachea and its branches lined by and what is its function?

A

Ciliated epithelium
- Cilia beat in rhythmic manners to move mucus along with trapped dust away from lungs

Goblet cells between
-Secrete mucus onto lining of trachea, to trap dust and microorganisms

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11
Q

True or false:

Bronchi have similar structures to the trachea

A

True

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12
Q

Describe the structure of bronchioles?

A
  • No cartilage
  • Walls contain smooth muscle which contract to constrict, relax = dilate
  • Bronchioles can change the amount of air in lungs
  • Lined with thin layer of flattened epithelium, making some gas exchange possible
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13
Q

Describe the composition of Alveoli and how this is an advantage

A
  • Thin layers of flattened epithelial cells with some collagen and elastic fibres
  • Elastic tissue allow alveoli to stretch as air is drawn in and return to regular size to help air squeeze out
  • Stretch and recoil
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14
Q

Suggest the main adaptation of alveoli

A
  1. Large SA because there are a lot, allows for rapid diffusion of CO2 in and 02 out
  2. Thin layers, one cell thick
  3. Good blood supply, constant flow of blood through capillaries brings CO2 in and delivers O2, maintain high concentration gradient
  4. Large SA:VOL ratio
  5. Good ventilation, breathing moves air in and out, helps maintain steep conc gradient for O2 diffuse out and CO2 in
  6. Lung surfactant
  7. Elastic fibres which allow for stretch and recoi
    - Stretch and recoil helps ventilation
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15
Q

What is the substance that covers the inner surface of alveoli?

A
  • Made of water, salts and lung surfactant
  • Lung surfactant ensures that the alveoli remain inflated, lowering surface tension so prevent alveoli from collapsing
  • Oxygen dissolves in the water before diffusing into the blood, but water can also evaporate into air in the alveoli (minimise water loss)
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16
Q

What is the thorax lined by?

A

Pleural membrane

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17
Q

What lies in the space between the thorax and the pleural membrane?

A

Pleural cavity

- Filled w thin layer of lubricating fluid so membranes can slide easily over each other

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18
Q

Inhalation is energy using process or non- energy using process?

A

Energy using

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19
Q

Describe the process of inhalation1

A
  1. Diaphragm contracts, flattening and lowering
  2. External intercostal muscles contract, moving ribs upwards and outwards
  3. Volume of the thorax increases so the pressure is reduced
  4. Pressure now lower than pressure of the surrounding air so air drawn in to equalise the pressure
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20
Q

Why can expiration be a passive process?

A

Because the muscles relaxing doesn’t require energy

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21
Q

Describe the process of expiration

A
  1. Muscles of the diaphragm relax so moves up into rested dome shape
  2. External intercostal muscles relax so ribs move down and inwards w gravity
  3. Elastic fibres in alveoli return to normal length
  4. The volume in the thorax decreases so pressure inside the thorax is greater than the surrounding air
  5. Air moves out of lungs until the pressure inside and outside is equal
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22
Q

What happens when you forcefully exhale?

A
  • Energy using
  • Internal intercostal muscles contract
  • Ribs pulled down hard and fast
  • Abdominal muscles contract forcing diaphragm up to increase pressure in the lungs rapidly
23
Q

Suggest how the volume of air drawn in and out of lungs can be measured

A
  • peak flow meter, measures the rate at which air can be exhaled from lungs
  • Vitalographs, patient breaths out as quickly as they can through a mouthpiece, produces a graph of amount of air breathed out and how quickly (forced expiratory volume in 1 sec)
  • Spirometer
24
Q

Define Tidal volume

A

The volume of air that moves into and out of the lungs with each resting breath

-Usually 15% of vital capacity

25
Q

What is the vital capacity?

A

The volume of air that can be breathed in when strongest possible exhalation is followed by the deepest possible intake of breath

26
Q

What is the inspiratory reserve volume?

A

The max volume of air you can breath in over and above your normal

27
Q

What is the expiratory reserve volume?

A

The extra amount of air you can force out of your lungs over and above the normal tidal volume of air you breath out

28
Q

Define residual volume

A

The volume of air that is left in your lung when you have exhaled as hard as possible

29
Q

Define the total lung capacity

A

The sum of the vital capacity and the residual volume

30
Q

What is the breathing rate?

A

The n. of breaths taken per minute

31
Q

What is the ventilation rate? and how calc?

A

The total volume of air inhaled in one min

tidal volume x breathing rate

32
Q

When exercising what happens to the tidal volume and breathing rate?

A
  • tidal volume increases with each breath
  • breathing rate also increases
  • So oxygen uptake during gaseous exchange can be increased to meet demands of the tissue
33
Q

Suggest the effects that muscle contractions have on ventilation ( 3 marks )

A
  • Smooth muscle of bronchioles contract volume of O2 entering lungs decreases
  • CO2 leaving lungs decreases
  • Lumen of bronchioles decreasing making it harder to ventilate
34
Q

Do insects have blood pigments that carry oxygen?

A

No, they have systems that deliver the oxygen directly to the cells and to remove the CO2

35
Q

What are the small openings along the thorax of insects called and what do they do?

A

Spiracles
Air enters and leaves, but water is also lost
-can be opened or closed by the sphincters

36
Q

What happens to the spiracles when the insect is inactive?

A

Spiracles will be closed because the oxygen demands are low

37
Q

Where is the trachea found in insects? and how adapted

A

Leading away from the spiracles

Run along the body of the insect

Lined with spirals of chitin, keeping them open if they are bent or pressed

-Chitin is relatively impermeable to gases * little gas exchange in trachea

38
Q

Describe the structure of the tracheolus

A

Elongated cell with no chitin lining so freely permeable to gases

Small in size they run in between individual cells, where most of GE takes place

Large n. of tiny tracheoles give large SA for GE

39
Q

Describe the process of GE in insects

A
  • Air moves long trachea and tracheoles by diffusion alone, reaching all tissues
  • Oxygen dissolves in moisture on the walls of the tracheoles and diffuses into surrounding cells
40
Q

What is the function of tracheal fluid?

A

Fluid found at the ends of tracheoles

Helps control the surface area available for GE and water loss

41
Q

What happens to the tracheal fluid when the insect becomes more active?

A
  • Oxygen demands increase
  • Lactic acid build up in the tissues
  • Water moves out of tracheoles by osmosis because the water potential in the tissues is lower than that of the tracheoles
  • Exposes more SA for GE
42
Q

Suggest other methods of increasing the level of gaseous exchange

A

Mechanical ventilation of tracheal system

- Air is pumped by muscular contractions of thorax/abdom. changing

43
Q

What happens in Mechanical ventilation?

A

Mechanical ventilation of tracheal system

  • Air is pumped by muscular contractions of thorax/abdom. changing the volume of body and pressure in the tracheoles & trachea
44
Q

What is the function of collapsible enlarged trachea or air sacs?

A

Air reservoirs

-Used to increase the amount of air moved through the GE system

45
Q

What features of trout combat its high metabolic demands?

A
  • Diffuse alone not enough
  • Have unidirectional flow of water over the gills
  • Gills have large SA:VOL
  • Good blood supply
  • Thin layers to maximise GE
46
Q

What is the function of the operculum?

A

Contained in the gill cavity, covers gills actively maintaining the flow of water over the gills

47
Q

What is the gill lamellae and how is it adapted?

A

The individual lats (e.g. blinds)

Rich blood supply and large SA

48
Q

What are the gill filaments?

A

The 2 sections of filaments stacked

Need a flow of water to keep them apart, exposing large SA for GE

49
Q

Why does the mouth and operculum open?

A

To keep a current of water flowing over their gills

50
Q

What is ram ventilation?

A

fish (e.g. sharks) that rely on continual movement to ventilate the gills

51
Q

Describe the process of gas exchange in fish

A
  1. Mouth is opened and flood of buccal cavity is lowered
  2. Increases volume of the buccal cavity -> pressure in the cavity drops and water moves into buccal cavity
  3. Opercular valve is shut and opercular cavity containing the gills expands
  4. Lowers the pressure in the opercular cavity containing gills
  5. Floor of the buccal cavity starts to move up, increasing the pressure there so water moves from the buccal cavity over the gills
52
Q

Describe what happens when the fish closes its mouth

A
  1. Mouth closes = operculum opens and the sides of the opercular cavity move inwards
  2. Therefore increase in pressure in the opercular cavity and force of water over the gills and out of operculum
  3. Floor of the buccal cavity is steadily moved up to maintain flow of water
53
Q

Suggest how gills of fish are adapted for gaseous exchange

A
  • large SA for diffusion because of the gill filaments and lamellae
  • Rich blood supply to maintain steep conc gradient for diffusion
  • Thin layers
  • Tips of adjacent gill filaments overlap , increases the resistance to the flow of water over the gill surfaces and slows down movement of water -> more time for GE
  • Water moving over the gills and the blood in the gills flow in different directions providing counter current
  • An oxygen concentration gradient between water and blood maintained
  • steeper conc gradient are maintained than if blood and water flowed in same direction
  • More gaseous exchange
54
Q

Explain why bone is described as a tissue and gills are described as organs

A

Tissue= one type of cell that preforms a specific function

Organ= different tissues working together doing one function

Gills have 2 or more different types of tissues (e.g. epithelium cells)

Biology (15 decks)

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