1.5 The Respiratory System 🫁

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51 Terms

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Respiratory system

System of organs to maintain gas exchange

<p>System of organs to maintain gas exchange</p>
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Gaseous exchange

oxygen is taken in for respiration and exchanged for carbon dioxide (waste product)

<p>oxygen is taken in for respiration and exchanged for carbon dioxide (waste product)</p>
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Trachea

allows air to pass through and supported by rings of cartilage to prevent collapsing

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Sites of respiration

respiring cells around body

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Nasal cavity

hollow space behind nose to warm and filter air

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Lungs

main organs responsible for gas exchange

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Bronchus

Two short branches off trachea to carry air into lungs

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Bronchioles

Airways made up of multiple branches, leading to alveoli

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Thorax

between neck and abdomen

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Alveoli

Tiny sacs of lung tissue where gas exchange takes place

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Effective exchange surface

  • Has a large surface area

  • Good blood supply

  • Well ventilated for gas exchange

  • Thin, permeable membrane for diffusion

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Capillaries

Small and thin blood vessels where gas exchange occurs, single layer of cells

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Diaphragm

thin sheet of muscle to help control breathing, pulls down and contracts to become flat so air can easily enter

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Intercostal muscles

between ribs, moving rib cage during breathing

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Pleural membrane

double layered membrane that encloses and protects each lung to reduce friction

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Pleural fluid
Fluid necessary to prevent friction between the pleural membranes
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Mucus

particles and bacteria stick and move out towards back of throat

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Cilia

ciliated epithelial cells, fine hairs that beat to move mucus

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Diffusion

movement of particles from region of high concentration to region of low concentration

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Adaptations of the respiratory system

  • large surface area due to multiple branches of bronchioles and many alveolar sacs

  • good blood supply for quick diffusion

  • well ventilated, optimised by effective involuntary muscular action

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Need for transport and exchange systems

large organisms have smaller sa:v ratios so are unable to directly obtain substances from environment

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Large surface area to volume ratio

faster diffusion rates as more room to diffuse through membrane

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Alveoli adaptations

  • Large surface area as many alveoli are present

  • Good blood supply

  • Thin, moist and permeable walls

  • large diffusion gradient due to lower concentration in capillaries

<ul><li><p>Large surface area as many alveoli are present</p></li><li><p>Good blood supply</p></li><li><p>Thin, moist and permeable walls</p></li><li><p>large diffusion gradient due to lower concentration in capillaries</p></li></ul><p></p>
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Moist lining of alveolus

gases dissolve in moisture helping them to pass across

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Wall of capillary

one cell thick to optimise diffusion between alveoli and blood

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Permeable walls

allows gasses to pass through easily

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Many blood vessels surrounding alveoli

maintain a constant diffusion gradient for gas exchange

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Site of gas exchange

alveoli in mammals and stomata in plants

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Gas exchange in plants

carbon dioxide is taken in and exchanged for oxygen, regulated by guard cells

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Leaf adaptations as a respiratory surface

  • pores called stomata to open/close and regulate gas exchange

  • surrounded by air spaces to increase surface area

  • cell membranes are also thin, moist and permeable

  • occurs in spongy mesophyll

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Uses of energy

  • active uptake/ transport

  • movement

  • growth

  • reproduction

  • maintain constant body temp

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Aerobic respiration

  • happens in the presence of oxygen

  • occurs in mitochondria

  • produces lots of energy

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Fermentation (yeast)

  • can happen in presence or absence of oxygen

  • occurs in plant and yeast cells

  • boil and add layer of oil to remove oxygen

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Word equation for fermentation (yeast)

Glucose → carbon dioxide + ethanol + little energy

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Uses of fermentation (yeast)

making of bread and alcoholic drinks

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Enzymes in yeast

work at optimum temperatures and can become denatured

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Limewater test

CO2 bubbled in limewater causes change from colourless to milky (cloudy precipitate)

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Exothermic reaction

releases energy to its surroundings, usually heat

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Word equation for aerobic respiration

Glucose + oxygen → carbon dioxide + water + energy

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Balanced chemical equation for aerobic respiration

C6H12O6 + 6O2 6CO2 + 6H2O

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Anaerobic respiration

  • happens in the absence of oxygen (strenuous exercise)

  • occurs in cytoplasm

  • produces little energy

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Word equation for anaerobic respiration

Glucose lactic acid + little energy

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Oxygen debt

extra oxygen body needs after exercise to react with lactic acid

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Inhalation

  1. intercostal muscles contract, ribs move up and out

  2. thorax increases in volume and decreases in pressure, causing air to enter lungs

  3. diaphragm contracts, moving downwards

<ol><li><p>intercostal muscles contract, ribs move up and out</p></li><li><p>thorax increases in volume and decreases in pressure, causing air to enter lungs</p></li><li><p>diaphragm contracts, moving downwards</p></li></ol><p></p>
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Exhalation

  • intercostal muscles relax, ribs move down and in

  • thorax decreases in volume and increases in pressure, forcing air out of lungs

  • diaphragm relaxes, returning to domed shape

<ul><li><p>intercostal muscles relax, ribs move down and in</p></li><li><p>thorax decreases in volume and increases in pressure, forcing air out of lungs</p></li><li><p>diaphragm relaxes, returning to domed shape</p></li></ul><p></p>
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Bell jar model

  • rubber sheet moves down to increase volume inside glass jar

  • causes decrease in pressure

  • balloons inflate as air enters until pressures are equal

<ul><li><p>rubber sheet moves down to increase volume inside glass jar</p></li><li><p>causes decrease in pressure</p></li><li><p>balloons <span style="font-size: inherit; font-family: inherit">inflate</span> as air enters until pressures are equal</p></li></ul><p></p>
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Limitations of the bell jar model

  • ribs and intercostal muscles are not represented

  • diaphragm shape is flat and pulled down rather than domed

  • balloons contain open space instead of many alveoli

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Composition of inhaled air

21% Oxygen, 0.04% Carbon Dioxide, 78% Nitrogen, water vapor varies

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Composition of exhaled air

16% Oxygen, 4% Carbon Dioxide, 78% Nitrogen, saturated with water vapour
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Effects of exercising

  • muscles require more energy (increased respiration)

  • larger volume of air needed for gas exchange

  • body increases rate and depth of breathing (+ heart rate)

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Recovery time

time taken for breathing rate to return to normal after exercise