Biology 11

1
The Respiratory System

• Biology 11
• A. Allen
• Cow lungs ?

2
Activate your prior knowledge!

• What is respiration?
• What organs/structures make up the respiratory
  system?
• Draw a sketch of a human respiratory system.
• What are the lungs for?
• How does air get in and out your lungs?

3
Interesting facts

• There are 150 million alveoli in each lung. Total
  surface area in both lung 40 m2 (1/2 tennis
  court). diameter of alveoli 0.1 0.2 mm.
• Laryngitis is the swelling of the vocal cords in
  the larynx (voice box). Can cause your voice to
  sound hoarse. Some smokers have permanent
  hoarseness from chronic inflammation.
• You automatically cough when food heads down your
  trachea. Coughing brings the food back up to the
  mouth.
• Your epiglottis closes off the trachea as you
  swallow. Why?
• Tuberculosis (TB) is caused by bacteria that
  destroys the air sacs in the lungs.
• An estimated 1.7 million people died from TB in
  2009. The highest number of deaths was in Africa.

4
Interesting facts

• you lose about ½ litre of water a day through
  breathing
• The stuff that comes out of your mouth when you
  cough travels at about 160 km/hr.
• One acre of trees produces enough oxygen to keep
  18 people alive for one year.
• Cigarettes and cigarette smoke contain over 4,000
  chemicals, including 43 known to cause cancer. 
• Every cigarette shortens your life by 14
  minutes.
• Lizards cant breathe when they are running.
  Their breathing depends on the muscles between
  their ribs. These muscles must be used during
  running.  
• Some animals such as certain frogs can breathe
  through their skin.

5
Importance of Gas Exchange

• Composition of Atmosphere
• ? 78 Nitrogen
• ? 21 Oxygen
• ? 0.03 Carbon Dioxide
•  
• Cells obtain energy by breaking down sugars. O2
  is the required.
• Humans need oxygen to survive (250 mL/min)
• Humans may live several days without water, weeks
  without food, only minutes without oxygen.

6
Human Respiratory System
7
Components of the Upper Respiratory Tract

• Passageway for respiration
• Receptors for smell
• Nose lined with mucus, cilia and long hairs to
  filter incoming air.
• Moistens and warms incoming air
• Resonating chambers for voice

8
Components of the Lower Respiratory Tract

• Larynx maintains an open airway, routes food and
  air appropriately, assists in sound production
• Trachea transports air to and from lungs
• Bronchi branch into lungs
• Bronchioles small branches that lead to alveoli
  fr bronchi
• Lungs transport air to alveoli for gas exchange
• Diaphragm essential for breathing
• contraction ? ? chest volume ?
• ? pressure ? inspiration!

9
Summary of Air Movement

• air from environment
• into nasal cavity/mouth (hair and mucus filter
  particles -boogers!)air get moistened and
  warmed.
• into pharynx
• pharynx branches into trachea (mucus and cilia
  sweeping hair-like structures- filter air in
  trachea ..debris goes to pharnyxswallow it!
• pharynx branches into 2 bronchi (one in each
  lung)
• bronchi branch off into bronchioles (smaller)
• bronchioles end in air sacs, made of alveoli, the
  site of gas exchange between blood and air!

Respiration
10
THE RESPIRATORY SYSTEM

• Like the nasal passages, the trachea is lined
  with a cilia a mucous membrane for trapping
  foreign particles. The cilia constantly move to
  sweep debris up towards the pharynxspit it out
  or swallow!
• The smoke from one cigarette will paralyze the
  cilia for 20 minutes and increase the production
  of mucus in the air passages resulting in
  smokers cough.
• The trachea is about 12 centimeters long and
  about 2.5 centimeters wide and is lined by rings
  of cartilage which help maintain its shape and
  prevent it from collapsing when air is exhaled.

11
Boogers!

• When dust, dirt, germs, and pollen get stuck
  inside the nose, the mucus surrounds it and tiny
  hairs inside the nose called cilia help move the
  mucus and the trapped stuff toward the front of
  the nose or the back of the throat. When the
  mucus, dirt and other debris dry and clump
  together, you're left with a booger!

12
THE RESPIRATORY SYSTEM

• As with the blood vessels, as the air passages
  subdivide into more branches, their diameter
  decreases.
• As the bronchial tubes divide and subdivide,
  their diameter decreases, their walls become
  thinner and they eventually lose their cartilage
  rings.
• Finally, they form a network of tiny tubes called
  BRONCHIOLES.

13
THE RESPIRATORY SYSTEM

• The bronchioles end in little air sacs called
  ALVEOLI.
• Alveoli are surrounded by capillaries and are the
  site of gas exchange (oxygen and carbon dioxide)
  with the circulatory system.
• Inhaled oxygen diffuses into the blood and binds
  with hemoglobin - carbon dioxide diffuses from
  the blood into the alveoli and is exhaled.

14
Oxygen Transport

• Oxygen enters the blood stream from the lungs.
• Oxygen itself is not very soluble. There is only
  0.3 mL of oxygen/100 mL of blood.
• After 0.3 mL of oxygen enters 100 mL of blood, no
  more oxygen will diffuse into the blood.
• Hemoglobin acts to disguise the oxygen.
• Hemoglobin and oxygen bond together to form
  oxyhemoglobin.
• When this happens, more oxygen can come into the
  blood.
• (When oxygen is formed as oxyhemoglobin, it does
  not count towards the 0.3mL.)
• When oxygen is disguised as hemoglobin, blood
  can transfer 20 mL of oxygen for every 100 mL of
  blood.
• Oxygen does not split from hemoglobin until
  partial pressure drops to 5.3kPa. This happens
  in the capillaries next to the body tissues.

hmcgraw-hill.movement_of oxygen_and_carbon_dioxide

alveolar_pressure_changes_McGraw Hill
15
Carbon Dioxide Transport

• Carbon Dioxide is 20 X more stable than Oxygen.
• In the blood
• 9 is in the plasma (liquid portion of blood).
• 27 is combined with hemoglobin to form
  carbaminohemoglobin.
• 64 combines with water from plasma to form
  carbonic acid. (H2CO3)
• The enzyme carbonic anhydrase causes this
  reaction to increase by 250x.
• When carbon dioxide is in the form of carbonic
  acid it is in disguise.
• This saves room for more carbon dioxide to enter
  the blood.
• Remember carbon dioxide travels from areas of
  greater partial pressure to areas of lesser
  partial pressure .
• If it seems like there is less carbon dioxide in
  the blood, more will leave the tissues.
• If some of the carbon dioxide is in disguise in
  the blood stream, then more carbon dioxide will
  leave the tissues.

16
Mechanics of Breathing

• Inspiration (breathing in)
• requires chest cavity to increase in volume to
  create low pressure.
• Accomplished when
• diaphragm contracts and moves down (abdominal
  breathing)
• External intercostal muscles contract (only
  during forced inspiration)

17
Mechanics of Breathing

• Expiration (breathing out)
• requires chest cavity to decrease in volume to
  create high pressure.
• Accomplished when
• diaphragm relaxes and moves up (abdominal organs
  help with thisthey were squished during
  inspiration)
• Internal intercostal muscles contract (only
  during forced expiration)
• Diaphragm youtube
• 3D breathing youtube

Gas exchange youtube
18
Mechanics of Breathing

• When the external intercostals contract, the ribs
  swing up and out like bucket handles. This
  increases the chest volume to create the low
  pressure required for air to enter the lungs.

19
Measurement of Lung Function

• Tidal volume volume of air inhaled and exhaled
  in a single breath
• Residual Volume the air that remains in the
  airways and does not participate in gas exchange
• Vital capacity the maximal volume that can be
  exhaled after maximal inhalation
• Inspiratory reserve volume the amount of air
  that can be inhaled beyond the tidal volume
• Expiratory reserve volume the amount of air that
  can be forcibly exhaled beyond the tidal volume
• Residual volume the amount of air remaining in
  the lungs, even after a forceful maximal
  expiration

20
Regulation of Breathing
Figure 10.13
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Breathing rate is monitored by Blood CO2 levels
- increase as more CO2 is produced as a waste
product Blood O2 levels - decrease as O2 is used
up in respiration to produce ATP Rate is more
sensitive to changes in CO2 levels. In the blood,
carbon dioxide dissolves into hydrogen and
bicarbonate ions (HCO3-) CO2 H2O ? H
HCO3- Fall of CO2 Equation shifts to the
left More CO2 is produced by removing hydrogen
ions This increases blood pH (more
alkaline) Excess CO2 (exercise) Equation shifts
to the right More CO2 dissolves in blood to
produce more hydrogen ions This reduces blood pH
(more acidic) Chemoreceptors Located in the
aorta (aortic bodies) and common carotid arteries
(carotid bodies) Monitor pH and CO2 levels Send
impulses to the medulla Aortic bodies monitor CO2
and O2 levels, and BP but NOT pH! Carotid bodies
monitors CO2 and O2 levels, and pH Exercise
Increases CO2 / blood becomes more
acidic Chemoreceptors detect low pH and stimulate
respiratory centres in the medulla
oblongata. Respiratory centres send more impulses
to diaphragm and intercostals muscles Increases
breathing rate and depth
22
Disorders of Respiratory System

• Reduced air flow asthma, emphysema, bronchitis
• Infections pneumonia, tuberculosis, botulism
• Lung cancer
• Congestive heart failure
• Cystic fibrosis

23
Gas Exchange Transport A Passive Process

• Gases diffuse according to their partial
  pressures
• External respiration gases exchanged between air
  and blood
• Internal respiration gases exchanged with tissue
  fluids
• Oxygen transport bound to hemoglobin in red
  blood cells or dissolved in blood plasma
• Carbon dioxide transport dissolved in blood
  plasma, bound to hemoglobin, or in the form of
  plasma bicarbonate

24
Regulation of Breathing Nervous System
Involvement

• Respiratory center in the medulla oblongata
  establishes basic breathing pattern
• Chemical receptors monitor carbon dioxide,
  hydrogen ions, and oxygen levels
• Medulla sensitive to hydrogen ions in
  cerebrospinal fluid resulting from carbon dioxide
  in blood