the respiratory system

Question 1

nasal cavity

Answer 1

hairs filter out dust, pollen and other particles
air is warmed and moistened

Question 2

pharynx

Answer 2

throat
connects nasal cavity to larynx
pathway for food and air

Question 3

larynx

Answer 3

voice box
contains vocal chords
rigid walls of cartilage
connects pharynx with trachea

Question 4

trachea

Answer 4

windpipe
12cm long
surrounded by rings of cartilage to prevent collapse
branches into left and right bronchi

Question 5

epiglottis

Answer 5

small flap of cartilage closes over top of trachea when swallowing food
prevents food from travelling into lungs

Question 6

lungs

Answer 6

organs that allow oxygen to be drawn into the body
paired right and left lungs occupy most of the thoracic activity
extends down to diaphragm

Question 7

bronchi

Answer 7

branch off the trachea
carry air into the lungs

Question 8

bronchioles

Answer 8

small airways that extend from bronchi
connect the bronchi to small clusters of thin walled air sacs, known as alveoli

Question 9

alveoli

Answer 9

site of gaseous exchange
oxygen is diffused through the alveoli into the blood capillary
carbon dioxide is diffused from the blood capillary into the alveoli

Question 10

characteristics of alveoli

Answer 10

one cell thick
short diffusion pathway
semi-permeable membrane
good blood supply
small in size, large in amount
big surface area

Question 11

diaphragm

Answer 11

flat muscle beneath the lungs
supports the mechanics of breathing
drawing in air (oxygen)
breathing out air (carbon dioxide)
inspire = contracts and pulls flat
expire= relaxes and rises into a dome shape

Question 12

thoracic cavity

Answer 12

chamber in the chest that is protected by the ribs and sternum

Question 13

internal intercostal muscles

Answer 13

lie inside the rib cage
draw ribs downward and inwards
decreasing volume of chest cavity, forcing air out of lungs when breathing out

Question 14

external intercostal muscules

Answer 14

muscles lie outside rib cage
pull ribs upwards and outwards
increasing the vulume of the chest cavity and drawing air into the lungs when breathing in

Question 15

mechanism of breathing

Answer 15

breathing or pulmonary ventilation is the process by which air is transported in and out of the lungs.
this has two phases:
it requires the thorax to increase in size to allow air to be taken in, followed by a decrease to allow air to be forced out

Question 16

phase 1: inspiration

Answer 16

• the diaphragm contracts and pulls flat
• external intercostal muscles move the ribs upwards and outwards
• this increases the area of thoracic cavity, reducing the pressure from inside the lungs compared to the outside
• air then moves from high concentration (atmosphere) to low concentration (lungs)

Question 17

phase 2: expiration

Answer 17

• the diaphragm and external intercostal muscles relax, while the internal intercostal muscles contract
• the diaphragm rises into a dome shape and the internal intercostal muscles move the ribs downwards and inwards
• this decreases the area of thoracic cavity, increasing the pressure inside the lungs
• air then moves from a high concentration (lungs) to a low concentration (atmosphere)

Question 18

process of gaseous exchange

Answer 18

• process by which one gas is exchanged for another
• in lungs, gaseous exchange by diffusion of the air in the alveoli and the blood in the capillaries surrounding their walls
• it delivers oxygen from the lungs to the bloodstream, and removes carbon dioxide from the bloodstream to the lungs
• the alveolar and capillary walls form a respiratory membrane which has gas on one side and blood flowing past the other
• gaseous exchange occurs more readily by simple diffusion across the respiratory membrane
• blood entering the capillaries has a lower oxygen concentration and a high carbon dioxide concentration than the air in the alveoli
• oxygen diffuses into the blood via the surface of the alveoli, through thin walls of the capillaries, through the red blood cell membrane and finally latches onto haemoglobin
• carbon dioxide diffuses in the opposite direction, from the blood plasma into the alveoli

Question 19

tidal volume

Answer 19

volume of air breathed in and out per breath. on average 0.5 litres per breath
- increases during exercise

Question 20

vital capacity

Answer 20

maximum amount of air that can be breathed out after breathing in as much air as possible. can be as much as 4.8 litres
- stays the same during exercise

Question 21

residual volume

Answer 21

volume of air that remains in the lungs after a maximal expiration. this air cannot be breathed out. average 1.2 litres
- stays the same during exercise

Question 22

total lung capacity

Answer 22

total lung capacity after you have inhaled as deeply as you can. this is total capacity + residual volume. approx 6 litres
- stays the same during exercise

Question 23

pulmonary ventilation

Answer 23

process of moving air in and out of lungs
- increase during exercise

Question 24

minute volume

Answer 24

the passing of air through the lungs in one minute
- increases during exercise

Question 25

inspiratory reserve volume

Answer 25

amount of additional air you can breathe in after normal tidal volume
- decreases during exercise

Question 26

expiratory reserve volume

Answer 26

amount of additional air that can be breathed out after normal expiration
- decreases during exercise

Question 27

two types of control of breathing

Answer 27

neural
chemical

Question 28

neural control

Answer 28

• inspiration at rest is an active process (diaphragm contracts) while expiration at rest is a passive process (diaphragm relaxes)
• this process is not possible without neurones in the brainstem, which exist in two area of our medulla oblongata
• when we exercise the medulla oblongata sends impulses to the diaphragm and the intercostal muscles to contract, speeding up breathing

Question 29

chemical control

Answer 29

• another factor that controls breathing is the changing levels of oxygen and carbon dioxide (acidity) in the blood
• the sensors that respond to these chemical fluctuations are called chemoreceptors, found in the aortic arch and carotid artery
• when we exercise carbon dioxide levels increase. these chemical changes are picked up by the chemoreceptors in the heart
• they will send signals to the medulla oblongata, speeding up the heart through neural control