<< Chapter < Page Chapter >> Page >

Natural sciences

Grade 9

Life processes: healthy life

Module 4

The human respiratory system

Structure of the respiratory system:

  • You have air passages that consist of nasal passages, an oral cavity, throat (pharynx), a trachea and two bronchi .
  • You have two lungs consisting of thousands of air sacs called alveoli . This increases the area of the lungs to the size of a badminton court.
  • The diaphragm and intercostal muscles.

Class activity: study of the lungs of a sheep or a pig

  • If possible, your educator should have the lungs of a sheep or a pig in the classroom for you to examine while working through this unit.

the human respiratory system


  • There are other systems besides the digestive system that are important for the effective functioning of the body. We will examine the systems for respiration, excretion, propulsion and reproduction, as well as the skeleton.
  • Every cell in the body of a living organism needs oxygen for RESPIRATION . It is the ENERGY-GIVING PROCESS during which glucose is “burned” in the presence of oxygen. The waste product of this process is carbon dioxide.
  • The part of the cell where this occurs, is the mitochondria .
  • These substances get to and from the cells by means of the bloodstream.
  • BREATHING and EXCHANGE OF GASES are the processes by which oxygen arrives in the blood and carbon dioxide leaves the blood.
  • BREATHING: the process by which air moves into and out of the lungs with the help of muscle action. The process of breathing in, or inhalation, is also known as INSPIRATION and breathing out, or exhalation, is known as EXPIRATION .
  • EXCHANGE OF GASES : The process by which gases such as carbon dioxide in the blood and oxygen that is in the air in the lungs are exchanged to get oxygen into the blood and to the cells.
  • RESPIRATION : the energy-giving process that occurs in the mitochondria in cells. Often people use the term Respiration incorrectly when they mean breathing.

Adaptations that facilitate these processes:

  • for BREATHING , we have a DIAPHRAGM, a muscular partition below the lungs that separates the thoracic and abdominal cavities and contracts and relaxes to alter pressure in the thoracic cavity. There are also INTERCOSTAL MUSCLES that raise and lower the ribcage.
  • for GASEOUS EXCHANGE in the lungs, there are thousands of air sacs, or ALVEOLI, with very thin, moist walls filled with blood vessels.
  • for GASEOUS EXCHANGE in the tissues there are fine blood capillaries that extend to each cell, and tissue fluids that surround the cells and the mitochondria.
Intercostal muscles
Thousands of alveoli
Thin-walled blood capillaries
Alveoli with single-layer epithelia
Mucus membrane with cilia

Class assignment: DRAWING

  • Make a sketch to illustrate the alveoli and the blood capillaries that facilitate the movement of gases.

Assessment: DRAWING

Could you draw the sketch correctly?

LO 2.3


Learning Outcomes 2 : Constructing Science knowledge

The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

We know this when the learner:

  • interprets information.



Increases/decreases the thoracic cavity (chest cavity)
Raise/lower the ribcage
Enlarge the surface
Short distance for diffusion
Thin layer for fast diffusion
Mucus layer traps particles, cilia remove particles and dust


  • Labels: alveoli

Questions & Answers

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
QuizOver.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Natural sciences grade 9. OpenStax CNX. Sep 15, 2009 Download for free at http://cnx.org/content/col11069/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Natural sciences grade 9' conversation and receive update notifications?