exchange surfaces

Question 1

what do cells obtain

Answer 1

glucose (energy), AA (growth/repair), fatty acids and glycerol (membrane structure), water, mineral ions, vitamins, oxygen (AR), carbon dioxide (photosynthesis)

Question 2

what do cells remove

Answer 2

carbon dioxide from respiration, oxygen from photosynthesis, excess nitrogen in form of urea from AA, excess heat

Question 3

what is the SA:V in a large organism

Answer 3

small SA:V

Question 4

what is the SA:V in a small organism

Answer 4

large SA:V

Question 5

lung structures

Answer 5

nasal cavity, trachea, bronchi, bronchioles, alveoli, pleural membranes, intercostal muscles, diaphragm

Question 6

feature/function of nasal cavity

Answer 6

hairs/mucus membrane, warms/cleans/humidifies inhaled air

Question 7

feature/function of trachea and bronchi

Answer 7

cartilage tissue (rings) - support, prevents collapse when low air pressure after expiration, C shape for flexibility

smooth muscle tissue - contracts, relaxes during exercise so more air flow

elastic tissue/fibres - stretch/recoil to change lumen

glandular tissue goblet cells - secrete mucus to trap dirt

ciliated epithelial tissue - sweep mucus to back of throat

Question 8

feature/function of bronchioles

Answer 8

less cartilage, smooth muscle tissue, elastic fibres, ciliated epithelium with glandular tissue - goblet cells

Question 9

feature/function of alveoli

Answer 9

air sacs - large SA:V

squamous epithelial tissue - thin so short diffusion distance

surfactant cells - phospholipids, lowers surface tensions so alveoli don’t stick together

surrounded by capillaries - maintains conc gradient

Question 10

feature/function of pleural membrane

Answer 10

smooth surface and secrete pleural fluid - allows lungs to move freely

Question 11

feature function of intercostal muscles

Answer 11

2 sets, internal and external - move rib cage up/out (inspiration) and down/in (expiration)

Question 12

feature/function of diaphragm

Answer 12

sheet of muscle and fibrous tissue - contracts, flattens, increases volume of thorax, inhalation

Question 13

buccal-opercular pump

Answer 13

1. mouth opens and water enters buccal cavity
2. buccal cavity constricts and mouth closes increasing pressure inside buccal cavity
3. water forced into gill cavity and increases pressure there
4. increased pressure forces opercular valve to open and water moves out over gills
5. pressure outside fish is greater than in gill cavity so opercular valve shuts
6. pressure in buccal cavity dropped and buccal cavity expands as mouth opens

Question 14

gill lamellae features

Answer 14

rich blood supply and large SA, main site of gaseous exchange in fish

Question 15

gill filaments features

Answer 15

occur in large stacks (gill plates) and need a flow of water to keep apart, exposing large SA

Question 16

afferent blood vessel fish

Answer 16

brings blood into system

Question 17

efferent blood vessel fish

Answer 17

carries blood leaving gills in opposite direction to incoming water, maintaining steep concentration gradient

Question 18

limitations to gas exchange in insects

Answer 18

tough waterproof exoskeleton does not allow for gas exchange, insects rarely have blood pigment to carry oxygen and usually have open circulatory systems so can’t direct blood to where it is needed

Question 19

gas exchange in insects

Answer 19

1. air enters via pore in each segment (spiracle)
2. spiracle leads into system of branching tubes called trachea (supported by rings of chitin) and tracheoles
3. gas exchange occurs between moist lining of tracheoles and tissues by diffusion
4. AT REST tracheal fluid seeps into ends of tracheoles from surrounding tissues
5. WHEN ACTIVE muscles contract and draw up tracheal fluid, gas exchange occurs with respiring tissue, pressure in tracheoles lowers so more air drawn in, SA of tracheole walls increase so more oxygen diffuse directly to tissues
6. fluid moves back into tracheole when muscle relaxes

Question 20

inhalation

Answer 20

1. diaphragm contracts (flat)
2. contraction of external intercostal muscles (ribs up and out
3. internal intercostal muscles relax
4. increase in volume of thorax
5. decrease in pressure of thorax
6. pressure gradient established from atmosphere to alveoli
7. inhalation equalises pressure

Question 21

exhalation

Answer 21

1. relaxation of diaphragm (dome shaped)
2. relaxation of external intercostal muscles
3. contraction of internal intercostal muscles
4. elastic fibres of alveoli and return to normal length
5. decrease in volume and increase in pressure in thorax, pressure gradient established from alveoli to atmosphere
6. pressure equalises from exhalation

Question 21

forced breathing

Answer 21

1. contraction of internal intercostal muscles (pull ribs down and in hard and fast)
2. contraction of abdominal muscles (increase upward pressure on diaphragm)
3. forced expiration

Question 22

tidal volume meaning

Answer 22

volume of air in and out of lungs at rest (dm3)

Question 23

forced expiration meaning

Answer 23

most air moved out of lungs

Question 24

vital capacity meaning

Answer 24

most that can be breathed in and out in one go

Question 25

ventilation rate meaning

Answer 25

total volume of air breathed in or out per minute (dm3/min) = breathing rate x mean tidal volume

Question 26

breathing rate meaning

Answer 26

the number of peaks per minute (breaths/min)

Question 27

oxygen consumption meaning

Answer 27

decrease in peaks over 1 min (dm3/min)