TOPIC 7 : EXCHANGE AND TRANSPORT Flashcards

Question

3.2.3 VENTILATION IN MAMMALS How does expiration work?

Answer 1

the external intercostal and diaphragm muscles relax the ribcage moves downwards and inwards and the diaphragm becomes curved again the thorax volume decreases, causing the air pressure to increase air is forced out of the lungs normal expiration is a passive process - it doesn't require energy The internal intercostal muscles contract, pulling the ribs down hard and fast, the abdominal muscles contract, forcing the diaphragm up to increase the pressure in the lungs rapidly ^^ textbook notes pressure in the thorax increases air brishe out of lungs as atmospheric pressure now lower than pressure in thorax diaphragm relaxes diaphragm bulges upwards volume of thorax decreases ^^ class notes

Answer 2

ensure the spirometer is airtight use medical grade oxygen and sufficient volume in chamber check health of the subject disinfect mouthpiece between each subject

Answer 3

the volume of gas exchanged during one breath

Answer 4

maximum volume of air that can be exchanged during on breath

Answer 5

the volume of gas remaining in the lungs after forced expiration this cannot be expelled

Answer 6

number of breaths taken per unit time (usually per minute)

Answer 7

the rate at which a person uses up oxygen (dm3/minute)

Answer 8

chamber filled with medical grade oxygen floats on tank of water subject wears a nose clip to ensure breathing through mouth only so exhaled gas returns to tank only and not to be atmosphere subject breaths in, takesin gas from chambers so chamber volume decreases and chamber moves down - pen on kymograph moves down with chamber subject breathes out exhales gas into chamber so chamber volumes increases chamber moves up - pen on kymograph moves upwith chamber kymograph turns slowly to give spirometer trace soda lime absorbs carbon dioxide from exhaled air over time overall volume in chamber decreases as subject takes up oxygen and carbon dioxide absorbed traces falls over time

Answer 9

the alveoli are the gas exchange surface in the lungs each alveolus is made from a single layer of thin, flatt cells called the alveolar epithelium O2 diffuses out of the alveolar space into the blood CO2 diffuses in the opposite direction the thin alveolar epithelium helps to decrease the distance over which O2 and CO2 diffusion takes place, which increases the rate of diffusion

Answer 10

the alveoli are surrounded by a large capillary network, giving each alveolus its own blood supply the lungs are also ventilated so the air in each alveolus is constantly replaced good blood suppy to maintain a steep diffusion gradient capillary wall is only one cell thick, so short diffusion distance spherical shape of alveolus gives larger surface area to volume ratio = increases rate of diffusion good ventilation system to maintain a steep diffusion gradient layer of surfactant enables gases to dissolve which ^ rate of diffusion many alveoli gives a large surface area

Answer 11

contains a large network of capillaries - this keeps them well - supplied with blood they're also well-ventilated - fresh water constantly passes over them these features help to maintain a concentration gradient of O2 - increasing the rate at which O2 diffuses into the blood

Answer 12

some cells are deep within the body - there's a big distance between them and the outside environment larger animals have a low surface area to volume ratio - its difficult to exchnage enough substances to supply a large volume of animal through a relatively small outer surface multicelluar organism have a higher metabolic rate than single-celled organisms, so they use up oxygen and glucose faster

Answer 13

substances can diffuse directly into the cell across the cell surface membrane the diffusion rate is quick because of the short distances the substance have to travel and because single-celled organisms have relatively high surface are : volume ratio

Answer 14

the cylce of gill irrigation strats by the fish opening it's mouth which lowers the floor of it's buccal cavity water flows into the buccal cavity the fish closes it's mouth which raises the floor if it's buccal cavity this makes the volume of its buccal cavity smaller so therefore the pressure increases this forces the water over the gills the fish opens its mouth again and the sides of the operculum bulge out this increases the volume of the opercula cavity which decreases the pressure so water is drawn over the gills the opercula flaps open and the water passes out the flaps then closes again the fish opens it's mouth and the cycle begins again

Answer 15

respiratory system is not linked to the circulatory system insects have an open circulatory system - fluid is not in vessels cells are bathed by haemolymph gases obtained by diffusion

Answer 16

air enters insect body via spiracle - valve like openings in exoskeleton air flow can be regulated by small muscles which can open or close the spiracle each spiracle leads into a network of TRANCHEA the trancheae subdivide leading to tracheoles gases diffuse through the network of tubes

Answer 17

tracheoles are the site of exchange between the respiratory system and the cells tracheoles are filled with fluid so oxygen dissolves and then diffuses into the cytoplasm of cells whilst carbon dioxide diffuses from the cell into the tracheole air sacs in the system provide a reserve of air useful to conserve water as spiracles can be closed under high evaporation stress to reduce water loss

Answer 18

small insects rely on diffusion large insects use their abdominal muscles to flush air through the tracheal system whilst opening some spiracles and closing others

Answer 19

water containing oxygen, enters the fish through its mouth and passes out through the gills each gill is made of lots of thin plates called gill filaments or primary lamellae which gives a big surface area for exchange of gases = ^ the rate of diffusion the gill filaments are covered in lots of tiny structures called gill plates or secondary lamellae = ^ surface area even more each gill is supported by a gill arch the gill plates have lots of blood capillaries and a thin surface layer of cells to speed up diffusion between the water and the blood

Answer 20

in the gills of a fish, blood flows through the gills plates in one direction and water flows over in the opposite direction

Answer 21

means water with a relatively high oxygen concentration always flows next to blood with a lower concentration of oxygen this in turn means that a steep concentration gradient is maintained between the water and the blood - so as much oxygen as possible diffuses from the water into the blood

TOPIC 7 : EXCHANGE AND TRANSPORT Flashcards

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