module 3 - Exchange Surfaces and Breathing

Question 1

what are the needs for a specialised exchange surface?

Answer 1

multi-cellular organism:
SA:V ratio is small
metabolic activity is much higher
distance between cells is too far for diffusion alone

Question 2

how is SA:V calculated?

Answer 2

SA = 4Pir2
V = 4Pir3 / 3

Question 3

what features do specialised exchange surfaces have to make them so efficient?

Answer 3

• increased surface area - provides larger surface for exchange
• thin layers - distances substances have to diffuse is shorter
• good blood supply - steeper conc radient = faster diffusion and ensures substances are constantly delivered
• ventilation to maintain diffusion gradient - helps maintain conc grad

Question 4

what are the key structures of the human exchange system?

Answer 4

• nasal cavity
• trachea
• bronchus
• bronchioles
• alvioli

Question 5

features of the nasal cavity?

Answer 5

large surface area with a good blood supply - warms air to body temp
hairy lining that secretes mucus
moist surfaces - increases humidity reduces chance of eveapouration from exchange surfaces

Question 6

features of the trachea?

Answer 6

main airway carrying clean moist air
incomplet rings of strong flexible cartilage (c shape)
lined with cilliated epithelium and goblet cells - secret mucus
lined with cillia

Question 7

features of the bronchus?

Answer 7

trachea dicides into right and left bronchus which leads to the lungs
similar structure to trachea with c shaped cartilage but are smaller

Question 8

features of the bronchioles?

Answer 8

no cartilage rings
walls contain smooth muscle
lined with thin layer of flattened epithelium

Question 9

feautures of the alvioli?

Answer 9

tiny air sacs
consistes of a thin layer of flattened epithelium allong with collages and elastic fibres
elastic fibres allow elastic recoil = alvioli streaches but can return to its original shape

Question 10

what are the main adaptations of the alvioli? (4)

Answer 10

1.large surface area - increases gaseous exchange and diffusion
2.thin layers - decreases difusion pathway
3.good blood supply - maintains steep conc gradient of O2 and CO2
4.good ventilation - helps maintains steep diffusion gradient

Question 11

what happens during inspiration?

Answer 11

domed shaped diaphram contracts = lowers
external intercostl mucles co ntract moving ribs upwards
volume of thorax increases and pressure decreases

Question 12

what happens during expiration?

Answer 12

diaphram relaxes moving upwards
external intercostal muscles relax
ribs move bnack inwards
elastic fibres in alvioli return to normal
volume of thorax decreases

Question 13

how can you measure the breathing capacity of the lungs?

Answer 13

• a peak flow metre - measures rate at which air can be expelled from lungs
• vitalograms - paciet breathes out quickly in a mouthpiece and intruments record this on a graph
• spirometer - pacient breathes in and out until all O2 used up canister of soda lime removes CO2 bulid up a trace will be drawn by revolving drum as its lid moves up and down

Question 14

what is tidal volume?

Answer 14

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

Question 15

what is vital capacity?

Answer 15

volume of air that can be inhailed when strong exhilation is followed by strong inhailation

Question 16

what is the inspiratory reverse volume?

Answer 16

max vol of air you can inhail

Question 17

what is the expiratory reverse volume?

Answer 17

extra amount of air you can force out your lungs

Question 18

what is the residual volume?

Answer 18

amount of air lef tin your lungs after youve breathed out as much as possible

Question 19

how do you calculate the total lung capacity?

Answer 19

vital vol + residual vol

Question 20

how do you calculate ventilation rate?

Answer 20

tidal volume x breathing rate (per min)