Science Focus 4.5 Flashcards
(27 cards)
A ________ system is needed to provide oxygen to, and remove carbon dioxide from cells.
respiratory
Although air can sometimes enter the respiratory system through the mouth, most inhaled air enters via the nose. Here it is ________, ______ and ________.
filtered; warmed; moistened
Nostril hairs filter out larger particles, and tiny hairlike _____ on the inside of the nose trap fine particles.
cilia
The nose is lined with _____ ______ that produce sticky _____ to trap dust particles.
mucus glands; mucus
The mucus and trapped particles move to the back of your nose and into the ______. We swallow around ___ millilitres of this mucus per day without usually being aware of it.
pharynx; 600
From the pharynx, air enters the ______ (windpipe), a thin-walled tube with about the same diameter as a garden hose.
trachea
At the top of the trachea is the ________, a flap of tissue, stops food entering the trachea. The _____ (voice box) also helps stop food entering.
epiglottis; larynx
________ and ________ are both reflexes to further protect the trachea.
Coughing; sneezing
The trachea branches into two main ______, which branch successively into smaller and smaller tubes.
bronchi
At the end of the smallest of these tubes (________), air enters clusters of sacs, the _______. Gas exchange in and out of the blood takes place here.
bronchioles; alveoli
The entire system of tubes is lined with _____, which beat upwards to send foreign material back to the pharynx to be coughed out or swallowed.
cilia; pharynx
Alveoli are sacs with walls only one cell thick. There are around _________ of these in your lungs, with a total surface of about __ square metres.
500 million; 80
Each alveolus lies close to the wall of a _______. These are also one cell thick, so there is only a short distance for gases to travel between the lungs and the bloodstream.
capillary
The network of capillaries in the lung is so large that at any one time __ per cent of the total blood volume is in the lungs.
20
Inside the alveoli, oxygen moves across through the thin walls of the tiny capillaries and into the blood. Once in the blood, oxygen is carried by red blood cells in a special carrier called _______.
haemoglobin
Haemoglobin allows much more ______ to be carried in blood than if it was simply dissolved.
oxygen
Dissolved waste gas - ____________ - comes out of the capillaries back into the alveoli, ready to be breathed out.
carbon dioxide
Replacement of the air is the result of ________ which is a physical process and is clearly different from respiration, which is a chemical reaction.
breathing
Normally, you breathe without thinking about it, but you can alter the rate and depth of breathing with ______ ______.
conscious effort
Take a deep breath. Notice that your ribs move up and out. This occurs due to the action of muscles in the chest (the ________) and the ________.
intercostals; diaphragm
The diaphragm is the sheet of muscular tissue that separates the chest from the _____.
abdomen
Simple single-celled (unicellular) organisms can exchange _____ directly with their watery surroundings through their cell walls or membranes.
gases
Many aquatic animals use _____.
gills
Flattened, worm-like animals often use their ____ _______ for gas exchange.
body surface
