7.1 The human breathing system (Book 1B, p. 7-3)
Ø Cells carry out
(1) respiration to release
energy for cellular activities.
Ø
To ensure the supply
of (2) oxygen to cells and the removal of (3) carbon dioxide
from cells, gas
exchange (氣體交換) takes place continuously between the cells and the
external environment.
Ø
Gas exchange in microorganisms can
take place by (4) diffusion
|
Ø
Organisms with larger size like human
need (5) breathing system (呼吸系統) to carry out gas
exchange effectively
|
|
(a)
|
(b)
|
(c)
|
Total surface
area = height X width X no. of sides X no. of boxes
|
6
|
150
|
750
|
Total volume = height X width X length X no. of boxes
|
1
|
125
|
125
|
Surface-to-volume-ratio
= Surface area / Volume
|
6
|
1.2
|
6
|
Conclusion: Volume è Surface-to-volume-ratio
¯ è Efficiency of
diffusion (6) increases / decreases
Ø In organisms with
larger size like humans,
n
a (7) breathing system (呼吸系統) is developed for efficient gas exchange.
n
a (8) transport system (運送系統) is also developed
to carry gases between the sites of gas exchange and other body cells.
Ø The human breathing
system consists of: CE-2008-I-A Q.3
n
the (9) respiratory tract (呼吸道) and
n structures that
aid breathing.
Structure
|
Feature
|
Function
|
Nostril
|
With (17) hair
|
filter larger dust particles from the air
|
nasal cavity
(鼻腔)
|
Lined with: èFig 1: mucus-secreting
cells and ciliated epithelial cells
|
|
(18) mucus-secreting cells
(黏膜分泌細胞)
|
n trap dust particles and bacteria
n
moisten the
incoming air
|
|
ciliated
epithelial cells
(纖毛上皮細胞)
|
have (19) cilia
(纖毛) to sweep the mucus towards pharynx
for being coughed out or swallowed
|
|
capillaries
|
carry
blood to warm up the incoming air
|
|
(20)larynx (咽)
|
Where the respiratory tract and the alimentary
canal meet
|
|
(21) epiglottis
(會咽軟骨)
|
Covers the opening of larynx during (22) swallowing to prevent choking
|
|
Larynx
|
n Mainly made of (23) cartilage èFig 2: Trachea & larynx
n Contains vocal
cords (聲帶) which vibrate to produce sound
|
|
Trachea
|
(24) C-shaped cartilages
|
Support and prevent trachea
from being collapsed
|
Lined with mucus-secreting cells, ciliated epithelial cells and capillaries
|
as above
|
|
(25) bronchus (bronchi)
(支氣管)
|
circular
rings of cartilages
|
Support and prevent bronchus
from being collapsed
|
Lined with mucus-secreting cells, ciliated epithelial cells and capillaries
|
as above
|
|
(26) bronchiole
(小支氣管)
|
n No cartilages
n Larger
ones lined with mucus-secreting cells and ciliated epithelial cells
|
|
Lung
|
Mainly composed of bronchioles and air
sacs
|
|
(27) air
sac
(氣囊)
|
numerous
|
Provides a large respiratory
surface (呼吸表面) for efficient gas exchange
|
Surrounded by a network of
(28) capillaries
|
To maintain a steep concentration gradient for
diffusion of gases
|
|
(29) ribs
|
Makes up the (30) rib
cage (肋骨籃)
with sternum (胸骨) and vertebral column (脊柱)
|
Protect the lungs
|
(31) intercostal
muscles
|
n Located between each pair of ribs
n Alternate contraction and relaxation
|
Involved in breathing actions
èFig
3: ribs, intercostal
muscles & pleural membrane
|
(32) pleural
membrane
(胸膜)
|
n Located between thoracic cavity and the
lungs
n enclose the lungs
|
Secrete (33) pleural
fluid (胸膜液)
|
(34) pleural
cavity
(胸膜腔)
|
n enclosed by the pleural membranes
|
Contains pleural fluid which acts as a
(35) lubricant to reduce friction during breathing
movement
|
(36) diaphragm
|
n
A sheet of muscle (fibre?) lying at
the bottom of the rib cage
|
Involved in breathing actions
èFig 4: diaphragm
|
Ø The path of air flowing through the respiratory tract into the
lungs:
Nasal cavity à (37) pharynx à larynx à (39) trachea à bronchus
à bronchiole (in lungs) → (40) air sac (in lungs)
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