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Unit 1: Breathing and respiration

The human respiratory system — HIA International - Grade 7 Revision Notes & Topical Questions

5 min read 9 parts Lesson 2 of 6 3 quizzes

📚 HIA International - Grade 7 Hub / Topical Revision
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Lesson summary

1.1 The human respiratory system — HIA INTERNATIONAL notes: Name the structures of the respiratory system and describe the route air takes into the lungs.Respiration = a series of chemical reactions in every living cell that releases energy.Aerobic respiration — the usual kind in…

  • Oxygen supply
  • Carbon dioxide
  • Air leaving the body
  • Rings of cartilage
  • Bronchioles
  • Intercostal muscles

Section 1 of 9Why we need oxygen

Why we need oxygen
Respiration
Respiration a series of chemical reactions in every living cell that releases energy.
Aerobic respiration
  • Aerobic respiration the usual kind in our cells;
    • it uses oxygen and produces carbon dioxide as a waste product.
Oxygen supply
  • Oxygen supply air is breathed into the lungs, some oxygen enters the blood, and the blood delivers it to every cell.
Carbon dioxide
  • Carbon dioxide the blood collects it from the cells and takes it back to the lungs.
Respiratory system
Respiratory system the organs that take oxygen from the air and get rid of carbon dioxide.

Section 2 of 9Path of air into the lungs

1
Air enters through the nose or mouth.
2
It passes the larynx (voice box).
3
It travels down the trachea (windpipe).
4
The trachea divides into two bronchi, one to each lung.
5
Each bronchus divides into smaller bronchioles.
6
The bronchioles end in tiny air sacs (alveoli).
  • Air leaving the body
    • travels the same structures in the reverse order.

Section 3 of 9Trachea and bronchi

Trachea
  • Trachea the windpipe, which connects the mouth and nose to the lungs.
Rings of cartilage
  • Rings of cartilage they keep the trachea open so that it cannot collapse and air keeps moving.
Bronchi
  • Bronchi the two branches of the trachea, also supported by cartilage.
Bronchioles
  • Bronchioles smaller tubes that carry air deeper into the lungs.
Air sacs
  • Air sacs where oxygen goes into the blood and carbon dioxide comes out.

Section 4 of 9Protective and moving parts of the chest

Protective and moving parts of the chest
Ribs
  • Ribs protect the lungs.
Intercostal muscles
  • Intercostal muscles lie between the ribs and help move them.
Diaphragm
  • Diaphragm a sheet of muscle beneath the lungs.
Lungs
  • Lungs soft and spongy to the touch because they are made mostly of air tubes and air sacs.

Section 5 of 9Larynx and vocal cords

Larynx
  • Larynx the voice box at the top of the trachea.
Vocal cords
  • Vocal cords bands of muscle that stretch across the larynx.
Making sound
  • Making sound the cords vibrate like guitar strings.
Pitch
  • Pitch the larynx changes as higher or lower sounds are made.

Section 6 of 9Cleaning the airways

Mucus
  • Mucus cells lining the airways make mucus that traps dust and microorganisms.
Cilia
  • Cilia tiny hairs that sweep the mucus up to the throat.
Smoking
  • Smoking tar damages the cilia and can cause cancer;
    • smoke can destroy the alveoli walls (emphysema) and reduce the surface for gas exchange.

Section 7 of 9Examining real lungs

1
Make a risk assessment and plan how to reduce the risks.
2
Look at the lungs and describe or draw them.
3
Touch them and note how they feel.
4
Find the trachea and feel the cartilage rings.
5
Follow it to where it divides into two bronchi.

Section 8 of 9Key terms

TermMeaning
RespirationChemical reactions in cells that release energy from food.
Aerobic respirationRespiration that uses oxygen.
TracheaThe windpipe that carries air to the lungs.
BronchusOne of the two tubes branching from the trachea to the lungs.
BronchioleA small air tube in the lungs.
Air sacA tiny sac in the lungs where gas exchange takes place.
CartilageA firm flexible tissue that supports the trachea.
LarynxThe voice box containing the vocal cords.

Section 9 of 9Exam technique

1
Saying air goes straight from the mouth to the lungs — it passes down the trachea and bronchi first.
2
Mixing up breathing and respiration — respiration is the chemical reaction in cells.
3
Saying the trachea is soft — it is held open by rings of cartilage.
4
Thinking oxygen enters the blood in the trachea — it enters in the air sacs.

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