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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

Processes:

  • 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.
  • EXPLAIN EACH OF THE ADAPTATIONS IN THE TABLE:
Diaphragm
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

Assessment

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.

Memorandum

EXPLAIN EACH OF THE ADAPTATIONS LISTED IN THE TABLE:

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

CLASS ASSIGNMENT: DRAWING

  • Labels: alveoli

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Source:  OpenStax, Natural sciences grade 9. OpenStax CNX. Sep 15, 2009 Download for free at http://cnx.org/content/col11069/1.1
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