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Unit 1: Breathing and respiration

GRADE 7 – Unit 1: Breathing and respiration — HIA International - Grade 7 Revision Notes & Topical Questions

5 min read 9 parts Lesson 1 of 6 1 quiz

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Lesson summary

GRADE 7 - Unit 1: Breathing and respiration — HIA INTERNATIONAL notes: Describe the respiratory system, gas exchange, breathing, respiration and the role of blood.Path of air — nose or mouth, larynx, trachea, two bronchi, bronchioles and air sacs.Trachea and bronchi — held open b…

  • Mucus and cilia
  • Air sacs (alveoli)
  • Blood in the capillary
  • Many small air sacs
  • Carbon dioxide
  • Energy source

Section 1 of 9Respiratory system

Respiratory system
Path of air
  • Path of air nose or mouth, larynx, trachea, two bronchi, bronchioles and air sacs.
Trachea and bronchi
  • Trachea and bronchi held open by rings of cartilage.
Chest
  • Chest ribs protect the lungs, intercostal muscles lie between the ribs and the diaphragm is a muscle beneath the lungs.
Mucus and cilia
  • Mucus and cilia trap and sweep out dust and microorganisms.

Section 2 of 9Gas exchange

Gas exchange
Gas exchange oxygen passing from the air into the blood and carbon dioxide passing from the blood into the air.
Air sacs (alveoli)
  • Air sacs (alveoli) have walls one cell thick and are wrapped in capillaries with walls one cell thick.
Diffusion
Diffusion movement of particles from where there are many to where there are fewer.
Blood in the capillary
  • Blood in the capillary arrives with little oxygen and a lot of carbon dioxide, so oxygen diffuses in and carbon dioxide diffuses out.
Many small air sacs
  • Many small air sacs give a larger surface area than a few big ones.

Section 3 of 9Inspired and expired air

Carbon dioxide
  • Carbon dioxide expired air contains more carbon dioxide than inspired air.
Test
  • Test breathe through limewater, which turns cloudy first with expired air.
Oxygen
  • Oxygen about 21% in inspired air and about 16% in expired air.

Section 4 of 9Breathing

FeatureBreathing inBreathing out
Intercostal musclesContract; ribs move up and outRelax; ribs move down
DiaphragmContracts and moves downRelaxes and domes up
Chest volumeIncreasesDecreases
Pressure in chestDecreasesIncreases
Air movementMoves into the lungsSqueezed out of the lungs

Section 5 of 9Respiration

Respiration
Energy source
  • Energy source all energy comes from food, and carbohydrates are broken down to glucose.
Mitochondria
  • Mitochondria structures in cells that release energy from glucose in a controlled way.
Word equation
  • Word equation glucose + oxygen gives carbon dioxide + water.
Heat
  • Heat some energy released is changed to heat, so respiring cells are slightly warmer than their surroundings.
Breathing and respiration
  • Breathing and respiration breathing moves air, while respiration is a chemical reaction in cells.

Section 6 of 9Blood

Plasma
  • Plasma the pale yellow liquid part that carries dissolved glucose and carbon dioxide.
Red blood cells
  • Red blood cells the most numerous cells; they have no nucleus, contain haemoglobin and carry oxygen.
White blood cells
  • White blood cells have a nucleus and defend against pathogens.
Haemoglobin
  • Haemoglobin combines with oxygen to form bright red oxyhaemoglobin in the lungs and releases it in the body cells.
White blood cell defence
  • White blood cell defence phagocytosis engulfs and digests pathogens, and antibodies stick to pathogens.

Section 7 of 9Models and investigations

Models and investigations
Syringe and balloon model
  • Syringe and balloon model pulling the plunger out increases the volume and makes the balloon inflate like lungs.
Measuring lung volume
  • Measuring lung volume breathe out into an upturned water-filled bottle with a marked scale.
Respiration in peas
  • Respiration in peas germinating peas give out heat that dead peas do not.

Section 8 of 9Key terms

TermMeaning
Aerobic respirationRespiration using oxygen to release energy from glucose.
AlveolusA tiny air sac in the lungs where gas exchange occurs.
DiffusionThe movement of particles from a high to a low concentration.
MitochondriaCell structures where aerobic respiration takes place.
HaemoglobinA red pigment in red blood cells that carries oxygen.
PlasmaThe liquid part of the blood.
PathogenA microorganism that causes disease.
AntibodyA chemical made by white blood cells that attaches to pathogens.

Section 9 of 9Exam technique

1
Saying breathing and respiration mean the same — respiration is a chemical reaction in cells.
2
Saying expired air has no oxygen — it still contains about 16%.
3
Saying the lungs pull air in — the chest volume increases and air moves in because the pressure falls.
4
Thinking red blood cells have nuclei — they do not.
5
Saying plasma is red — it is pale yellow.

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