exchange surfaces- exchange surfaces and breathing(mammalian gas exchange system and measuring the process)

Question 1

what are the two main reasons to why diffusion alone if enough to supply the needs of single celled organisms?

Answer 1

1)metabolic activity of single celled organism is low so oxygen demands are low
2)surface area to volume ratio is large

Question 2

how do you calculate the surface area and volume of a sphere?

Answer 2

surface area: 4(pi)r squared
volume: 4/3(pi)r cubed

Question 3

give features of an effective exchange surface

Answer 3

-large surface area: large surface area to volume ratio
-thin layer: short diffusion path, quick
-good blood supply: steep concentration gradient
-ventilation to maintain diffusion gradient

Question 4

Describe the important features of the nasal cavity

Answer 4

-large surface area with good blood supply, which warms the air to body temperature
-a hairy lining which secretes mucus to trap dust and bacteria, protecting delicate lung tissue from infection
-moist surfaces which increase the humidity of incoming air, reducing evaporation from exchange surfaces.

Question 5

Describe the important features of the trachea

Answer 5

-wide tube supported by rings of cartilage to prevent collapsing
-lined with ciliated epithelium and goblet cells. Goblet cells secrete mucus to trap dust and microorganisms. Cilia moves mucus away from lungs.

Question 6

trachea branch off into what?

Answer 6

bronchus which has cartilage rings but is smaller. Bronchus branches into bronchioles which have no cartilage, only smooth muscle.

Question 7

Describe the important features of alveoli

Answer 7

-tiny air sacs where gas exchange occurs
-flattened epithelial cells composed of collagen and elastin fibres. Elastin allows alveoli to stretch when air is pulled in and relax when air is pulled out which is called elastic recoil.

Question 8

Describe the important adaptations of alveoli for gas exchange

Answer 8

-large surface area
-thin layers: one cell thick
-good blood supply: steep concentration gradient
-good ventilation: steep concentration gradient

Question 9

the inner surface of the alveoli is covered in a thin layer of solution of water, salts and lung surfactant. How does this help?

Answer 9

surfactant allows the alveoli to remain inflated. Oxygen dissolves in the water before diffusing into the blood but water can also evaporate into the air of the alveoli

Question 10

what is ventilation?

Answer 10

the movement of air

Question 11

describe how the process of inhalation takes place

Answer 11

-diaphragm contracts, lowering
-external intercostal muscles contract, moving ribs outwards
-volume of thorax increases so pressure is reduced lower than atmospheric air. So air rushes into the lungs to equalise the pressure in and outside the chest.

Question 12

how is inspiration (inhalation) different from expiration?

Answer 12

inspiration is a energy using process but expiration is a passive process.

Question 13

describe the process of expiration

Answer 13

-diaphragm relaxes, domed shape
-external intercostal muscles relaxes moving ribs inwards
-volume in thorax decreases so pressure increases in lungs higher than atmospheric pressure so air moves out of lungs so pressure is equal.
-elastic fibres of alveoli return to normal

Question 14

describe the process of expiration forcibly using energy

Answer 14

-internal intercostal muscles contract pulling ribs down hard and fast
-abdominal muscles contract forcing diaphragm up to increase pressure in lungs rapidly

Question 15

how can the volume of air drawn in an out of the lungs be measured?

Answer 15

-a peak flow meter: device that measures the rate at which air can be expelled from the lungs. These are often used for people with asthma.
-vitalographs: sophisticated version of peak flow meter. Patient breaths out as quickly as they can through mouth piece and the instrument produces a graph
-spirometer: measures different aspects of the lung volume and breathing patterns.

Question 16

what is tidal volume?

Answer 16

the amount of air that moves into and out of lungs with each resting breath. It is around 500cm cubed in adults and uses around 15 percent of vital capacity of lungs.

Question 17

what is vital capacity?

Answer 17

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

Question 18

what is the inspiratory reserve volume?

Answer 18

the maximum volume of air you can breath in over and above a normal inhalation.

Question 19

what is expiratory reserve volume?

Answer 19

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

Question 20

what is residual volume?

Answer 20

the volume of air that is left in your lungs when you have exhaled as hard as possible. This cannot be measured directly.

Question 21

what is total lung capacity?

Answer 21

sum of vital capacity and residual volume

Question 22

what is breathing rate and ventilation rate?

Answer 22

breathing rate is the number of breaths taken per minute. Ventilation rate is the total volume of air inhaled in one minute.

Question 23

what is the ventilation rate equation?

Answer 23

ventilation rate= tidal volume times breathing rate (per minute)

Question 24

state ways in which the bronchus in a long term smoker would be different?

Answer 24

-damaged cilia
-smooth muscle become thicker
-more mucus secreted
-more goblet cells

Question 25

what are the effects of inelastic alveoli?

Answer 25

-less tidal volume
-alveoli may burst

Question 26

definition of degenerative disease?

Answer 26

disease which causes progressive deterioration of part of the body

Question 27

Explain why cartilage is necessary to the trachea? (3marks)

Answer 27

-provides strength from collapse
-during inspiration
-as volume in lungs increases, decreasing pressure

Question 28

which part of the intercostal muscles contracts to force air out of the lungs?

Answer 28

internal