9. Human Respiratory System Flashcards

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1
Q

Nostrils

Function

A

Entrance to respiratory tract

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2
Q

Nasal Cavity

Function + Features

A

Function:

  • Cleaning, moistening and warming the incoming air

Features:

  • Hairs on walls of nostrils: filters dust and bacteria from the inhaled air
  • Mucus-secreting cells/goblet cells: secrete mucus that traps dust and bacteria
  • Blood capillaries: close to the surface of the cavity, warms inhaled air
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3
Q

Larynx

Function

A

Contains vocal cords

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4
Q

Trachea

Feature

A

Supported by C-shaped rings of cartilage:

  • Prevents trachea from collapsing during breathing due to change in air pressure (keeps lumen of trachea open)
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5
Q

Bronchus, Bronchioles, Alveoli

Features

A

The trachea divides into two tubes, bronchi (plural of bronchus).
Each bronchus divides into numerous fine tubes, bronchioles.
Each bronchiole ends in a cluster of alveoli (singular: alveolus).

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6
Q

Inner walls of the trachea and bronchi

Features + Functions

A

The inner walls of the trachea and bronchi are lined with ciliated cells and gland cells.

  • Gland cells secrete mucus that traps dust particles and bacteria
  • Ciliated cells have hair-like structures, cilia, on their surface. They sweep the dust-trapped mucus up the bronchi and trachea away from the lungs into the pharynx, where they can be swallowed or expelled.
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7
Q

Describe the role of diaphragm, ribs, and intercostal muscles in breathing.

A

Breathing (ventilation) is achieved by changing the volume of the chest cavity and it is done by the movement of the ribs and diaphragm.

The movement of the ribs is controlled by the intercostal muscles. There are two sets of intercostal muscles, internal and external intercostal muscles. They are antagonistic.

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8
Q

Diaphragm

Structure + Function

A

Structure:

  • A sheet of muscular and elastic tissue, which separates the thorax from the abdomen.

Function:

  • It contracts to expand the chest cavity and relaxes to allow the chest cavity to return to its original volume.
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9
Q

What happens during inhalation?

Process

A

During inhalation:

  1. The diaphragm contracts and flattens.
  2. External intercostal muscles contract and internal intercostal muscles relax.
  3. Ribcage moves upwards and outwards.
  4. Lung expands, as volume of lung increases, air pressure within the lung decreases.
  5. Air is drawn into lungs as air moves from higher atmospheric pressure to lower air pressure in lungs.
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10
Q

What happens during exhalation?

Process

A

During exhalation:

  1. The diaphragm relaxes and arches upwards (to form a dome shape).
  2. External intercostal muscles relax and internal intercostal muscles contract.
  3. Ribcage moves downwards and inwards.
  4. Lungs are compressed, as volume of lung decreases, air pressure within the lung increases.
  5. Air is expelled out of lungs as air moves from higher air pressure in lungs to lower atmospheric pressure.
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11
Q

Adaptations of Alveoli

A
  1. Alveolar walls are one-cell thick: Provide shorter distance for faster rate of diffusion of gases into the blood
  2. Each alveolus is covered with a thin film of moisture: Enable gases to dissolve, increasing rate of diffusion
  3. Each alveolus is surrounded by numerous blood capillaries: Blood capillarties transport diffused oxygen away from lungs and carbon dioxide from bloodstream to the lungs for removal. The continuous transport of gases maintains the concentration gradient of the gases for a faster rate of diffusion
  4. Alveoli present in large quantities: Provide a large surface area to volume ratio to increase rate of diffusion of gases
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12
Q

Oxygen transport from lungs

Process

A
  1. Alveolar air contains a higher concentration of oxygen than blood.
  2. Oxygen dissolves in the thin film of moisture on the surface of the alveoli.
  3. Oxygen then diffuses through the walls of the alveoli and blood capillaries into blood, where it diffuses into the red blood cell.
  4. Oxygen binds with haemoglobin in red blood cells to form oxyhaemoglobin (reaction is reversible, direction is dependent on concentration of oxygen in surroundings).
  5. When blood passes through oxygen-poor tissues, the oxyhaemoglobin releases oxygen which will then diffuse through the walls of the capillaries into the tissue cells.
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13
Q

Carbon Dioxide Transport from the Body Cells

Process

A
  1. Tissue cells produce a large amount of carbon dioxide as a result of aerobic respiration.
  2. As blood passes through these tissues, carbon dioxide diffuses into the blood. Most carbon dioxide enters the red blood cells. A small amount is carried in the plasma as dissolved carbon dioxide.
  3. The carbon dioxide then reacts with water in the cytoplasm of red blood cells to form carbonic acid(H2CO3). This reaction is catalysed by carbonic anhydrase (enzyme).
  4. Carbonic acid then dissociates to form hydrogen ions (H+) and hydrogencarbonate ions(HCO3-).
  5. Hydrogen ions remain in the red blood cells, while hydrogencarbonate ions diffuse out of the red blood cell to be carried in the plasma.
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14
Q

Carbon Dioxide Transport at the Lungs

Process

A
  1. Hydrogencarbonate ions diffuse back into the red blood cell and combine with hydrogen ions to form carbonic acid.
  2. Carbonic anhydrase catalyse the conversion of carbonic acid to carbon dioxide and water.
  3. Carbon dioxide diffuses out of the red blood cell, into the blood, through the capillaries and alveolar wall to be removed to the environment during exhalation.
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15
Q

Stimulus for breathing

A

Stimulus for breathing is a high concentration of carbon dioxide in the blood or alveolar air. When there is too little carbon dioxide in the lungs, breathing movements do not occur.

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16
Q

Inhaled air vs Exhaled air

Composition of components in air

A

Inhaled air:

  • Oxygen: 21%
  • Carbon dioxide: 0.03%
  • Nitrogen: 78.0%
  • Water vapour: Variable (rarely saturated)
  • Temperature: Variable
  • Dust particles: Variable but usually present

Exhaled air:

  • Oxygen: 16%
  • Carbon dioxide: 4%
  • Nitrogen: 78.0%
  • Water vapour: Saturated
  • Temperature: about 37 degrees celcius
  • Dust particles: Little, if any
17
Q

Nicotine

Properties of chemicals and Effects on body

A

Properties:

  • Addictive stimulant drug that causes the release of adrenaline
  • Makes blood clot easily

Effects:

  • Increases heart rate and blood pressure
  • Increases risk of blood clots in the arteries. If blood clots in coronary arteries, it will result in coronary heart disease.
18
Q

Carbon Monoxide

Properties of chemicals and Effects on body

A

Properties:

  • Combines permanantly with haemoglobin to form carboxyhaemoglobin

Effects:

  • Reduces the ability of blood to carry oxygen
19
Q

Tar

Properties of chemicals and Effects on body

A

Properties:

  • Carcinogenic
  • Paralyses cilia lining air passage

Effects:

  • Increases the risk of cancer in lungs
  • Dust particles trapped in the mucus lining the air passages cannot be removed, increasing risks of chronic bronchitis and emphysema
20
Q

Irritant chemicals (hydrogen cyanide, formaldehyde)

Effects on body

A

Effects:

  • Causes the cells lining bronchi and bronchioles to increase production of mucus
  • Paralyses cilia lining air passages
  • Dust particles trapped in the mucus lining the air passages cannot be removed, increasing risks of chronic bronchitis and emphysema
21
Q

Chronic Bronchitis

Cause and Effects

A

Cause:

  • Prolonged exposure to irritants particles found in tobacco smoke can cause chronic bronchitis.

Effects:

  1. Epithelium lining of airways become inflamed.
  2. Excessive production of mucus by the epithelium.
  3. Cilia on the epithelium become paralysed, unable to remove mucus and foreign particles.
  4. Airflow becomes blocked, making breathing difficult.
  5. Decreases the efficiency of the gaseous exchange process.
  6. Persistent coughing to clear the air passages, in order to breathe.
22
Q

Emphysema

Cause and Effects

A

Cause:

  • Persistent and violent coughing due to bronchitis may lead to emphysema.

Effects:

  • Walls of the alveoli break down, due to persistent and violent coughing, this decreases surface area for gaseous exchange.
  • The lungs lose their elasticity and ability to effectively expel air, causing build-up of carbon dioxide.
  • Oxygen uptake and carbon dioxide removal is impaired, causing severe breathlessness.
23
Q

What is a person said to suffer from when he has both chronic bronchitis and emphysema?

A

Chronic obstructive lung disease