chapter 7 - exchange surfaces

Question 1

features of the perfect exchange surface

Answer 1

• large surface area
• thin
• maintains concentration gradient
• protected from drying out

Question 2

how is an alveolus adapted to fulfil its role?

Answer 2

• many alveoli allows for a large surface area
• has thin layers
• capillaries surrounding alveolus allows for a good blood supply

Question 3

role of macrophages in the lungs

Answer 3

• patrol alveolar surfaces
• scavenge for any harmful material
• engulf anything they find

Question 4

cartilage

Answer 4

found in trachea and bronchi for support and prevents from collapsing

Question 5

smooth muscle

Answer 5

found in walls of trachea, bronchi and bronchioles involuntary muscle that contracts to narrow the lumen

Question 6

elastic fibres

Answer 6

found in walls of all airways and alveoli recoil of elastic tissue widens airways and forces air out

Question 7

goblet cells

Answer 7

found throughout ciliated epithelium secrete mucus to trap particles and prevent drying out

Question 8

ciliated epithelium

Answer 8

found in trachea, bronchi and bronchioles waft mucus up the airway to the back of the throat

Question 9

inspiration

Answer 9

• contraction of external intercostal muscles causes rib cage to move up and out
• contraction of muscles in diaphragm causes it to go downwards
• increases the volume of the thoratic cavity
• pressure within thoratic cavity is lowered
• air flows down pressure gradient into thorax

Question 10

expiration

Answer 10

• external intercostal and diaphragm muscles relax
• elastic fibres between alveoli recoil to normal length
• volume decreases and pressure increases forcing air out
• more air forced out by contraction of internal intercostal muscles moving rib cage down and in
• contraction of abdominal muscles raises diaphragm

Question 11

breathing out normally vs forced breathing out

Answer 11

forced breathing out involves contraction of internal intercostal and abdominal muscles whereas normal breathing out does not

Question 12

tidal volume

Answer 12

the volume of air moved in and out of the lungs with each breath when you are at rest

Question 13

vital capacity

Answer 13

the largest possible volume of air that can be moved into and out of the lungs in one breath

Question 14

inspiratory reserve volume

Answer 14

how much more air can be breathed in over and above tidal volume

Question 15

expiratory reserve volume

Answer 15

how much more air can be breathed out over and above tidal volume

Question 16

vital capacity equation

Answer 16

inspiratory reserve volume + tidal volume + expiratory reserve volume

Question 17

residual volume

Answer 17

the volume of air that always remains in the lungs, even after the biggest possible exhalation

Question 18

dead space

Answer 18

the air in the bronchioles, bronchi and trachea; no gas exchange between air and blood

Question 19

breathing rate

Answer 19

number of breaths per minute

Question 20

ventilation rate

Answer 20

total volume of air breathed in or out in one minute (number of breaths per minute x volume of air in each breath)

Question 21

calculating oxygen consumption

Answer 21

• chamber must be filled with oxygen not air
• soda lime must be in container
• each time you breath out, CO2 is absorbed by soda lime
• total volume of air going into container is less
• traces drawn by pen go down
• measure how much they go down over time; this tells oxygen consumption

Question 22

adaptations of gills

Answer 22

many filaments and lamellae - large surface area
rich blood supply - maintains concentration gradient
thin layers - short diffusion distance

Question 23

buccal - opercular pump

Answer 23

• the mouth is opened and operculum is closed
• the floor of the buccal cavity is lowered
• volume in the buccal cavitiy increases; pressure compared to outside decreases
• water moves into the buccal cavity down a pressure gradient
• the opercular cavity expands
• the mouth closes and the floor of the buccal cavity is gradually raised
• the pressure inside the buccal cavity is now higher than in the opercular cavity pushing water over the gills
• the operculum opens - the sides of the operculum cavity move inwards, increasing the pressure
• water flows out of the fish through the opercular

Question 24

trachael system in insects

Answer 24

• air enters the trachea through holes called spiracles in the thorax and abdomen of the insect
• trachea branches into many microscopic tubes called tracheoles which are freely permeable to gases
• gas exchange takes place directly between cells and the tracheoles

Question 25

chitin

Answer 25

spirals which keep the trachea open to allow air to move through them

Question 26

tracheal fluid

Answer 26

fluid found in the tracheoles to limit the penetration of air

Question 27

mechanical ventilation

Answer 27

some large insects have adaptations to increase gas exchange, eg movement of wings alters the volume of the thorax

Question 28

collapsible air sacs

Answer 28

store a reserve of air which can be squeezed to push air through the tracheal system