View
215
Download
0
Category
Tags:
Preview:
Citation preview
Topic 2: Gas Exchange
Introduction• What is our atmosphere made
of?– Nitrogen (78%), oxygen (21%),
traces of carbon dioxide (<1%)• Why is breathing important?
– Allows for the exchange of O2 and CO2 between the environment and our bodies
• What is the O2 used for?– All cells require O2 for cellular respiration (for energy)
• What is the fate of the other gases?– CO2 + H2O: Expelled as waste
Topic 2-1: Anatomy of the Respiratory System
General Functions– Intake of
oxygen– Exhale carbon
dioxide– All for the
preservation of life
1. External gas exchangeBrings air into the lungs O2 diffuses into capillaries, CO2 diffuses from blood to the air
2. The circulatory system Transports blood high in O2 and low in CO2 from the lungs to the tissues
3. Internal gas exchange Diffusion of O2 from capillaries into the body
Cellular respiration occurs: C6H12O6 + 602 ―>6CO2 + 6H2O + 36 ATP
4. The circulatory system Transports blood high in CO2 and low in O2 to the lungs
The 4 steps to breathing:
Label the following diagram
Pulmonary Vein
Aorta/ArteriesInferior Vena Cava / Veins
Pulmonary artery
CO2
O2
Direction of the flow of blood
CO2O2
The Relationship between the Circulatory and Respiratory System
• Carbon dioxide diffuses from:a body cell circulatory system OUT the lungs
• Oxygen diffuses from: IN from lungs circulatory system a body cell
Breathing vs. RespirationBreathing Respiration
Intake of O2
Exhale CO2
Gases exchanged in alveoli in lungs
C6H12O6 + 6O2 = 6CO2 + 6H2O + energy
Breakdown of sugar into energy
Takes place in all cells
1. Nasal Cavity2. Pharynx (throat)
3. Epiglottis
4. Esophagus
5. Trachea
6. Bronchus (i)
7. Lung
8. Heart
9. Pleural Membranes
10. Diaphragm
11. Alveoli
12. Pleural Membranes
13. Bronchioles
14. Intercostal muscles
15. Rib
16. Cartilage Ring
17. Larynx (voice box)
Thoracic cavity (chest)
Right Lung = 3 lobes
Left Lung = 2 lobes
Abdominal cavity (below diaphragm)
http://www.youtube.com/watch?v=MrDbiKQOtlUBozeman respiratory system 8:46
Trace the flow of air as it
moves from the nose to the lungs
Nostrils
Larynx
Nasal Cavity
Bronchioles
Alveoli
Pharynx
Epiglottis
2 bronchi
Trachea
Capillaries http://www.youtube.com/watch?v=MrDbiKQOtlU
Bozeman respiratory system 8:46
Functions of the Respiratory System• Mouth and nostrils
– Air enters respiratory system• Nasal cavity
– Provides MOISTURE (allows gases to dissolve and diffuse)
– WARMS the air– Filters and traps particles
• via hair and mucous
• Pharynx (throat)– Passage for food and air
Epiglottis• Flap covering trachea during swallowing• If food enters trachea,
– Reflex: cough
•“Voicebox”•Contains 2 ligaments (vocal cords)•Air passes, vibrate ligaments and sound is produced•Cartilage protects larynx
Larynx
https://www.youtube.com/watch?v=Q-PZlj0UH0c
Trachea• Windpipe • Lined with cilia
– Mucus traps particles – Cilia act like a broom
carrying particles to the mouth
• Surrounded by rings of cartilage and smooth muscles
• Provide support – Keep trachea open
Trachea cut open (do you see the cartilage rings?)
Cilia in the trachea
Bronchi• Two branches of the trachea (left and right)• Contain cartilage
Bronchioles• Smaller branches• No cartilage• Rings of muscle –
change diameter to dilate or constrict
Trachea
Bronchi
Bronchioles
Alveoli• Tiny air sacs • Each lung - ~ 150 million
alveoli• Very thin; one cell thick• Surrounded by capillaries• Site of gas diffusion
– Diffusion occurs with the concentration gradient
• Film of lipoprotein – prevents alveoli from sticking together
Pleural Membranes• Membranes on the outer
surface of lungs and inner wall of chest cavity
• Between the two membranes is lubricant which reduces friction
Diaphragm– Dome shaped band of
muscle– Separates thoracic cavity
from abdominal cavity– Helps in inhalation and
exhalation
• Muscles attached to the ribcage
• Helps with inhalation and exhalation
Intercostal Muscles
Answer the questions on page 34 of your workbook.
Have you ever eaten ribs before? If you
have, you’re eating the intercostal muscles!
Intercostals
Exhalation PathwayAlveoli
Bronchioles
Bronchi
Trachea
Larynx
Epiglottis
Pharynx
Nasal Passage
Topic Two: BreathingGas Exchange in the Lungs
• O2 moves from atmosphere to alveoli then blood and body tissues
• Erythrocytes contain Hemoglobin (Hb) which picks up O2 in the lungs and carries it to body cells
• When hemoglobin reaches tissues with low concentration of oxygen, it releases O2
• Then O2 diffuses into the cells
Gas Exchange: Oxygen
Gas Exchange: Oxygen• Hb greatly increases the carrying capacity of
blood oxygen• Hb + O2 = oxyhemoglobin
Gas Exchange: Carbon Dioxide• Carbon dioxide (CO2) is produced in the cells by
cellular respiration• CO2 then diffuses into the blood
Gas Exchange: Carbon Dioxide
• Carbon dioxide diffuses OUT of a capillary into an alveolus
• Oxygen diffuses OUT of the alveolus into the capillary
Gas Exchange: Carbon DioxideCO2 can be transported in 3 ways:
1. ~10% of CO2 is dissolved in blood plasma
2. ~20% joins with Hb (CO2 + Hb = carbaminohemoglobin)
3. Remaining 70% of CO2 form carbonic acid• Carbonic acid = H2CO3
• This lowers blood pH• Buffered to prevent the blood from becoming too
acidic - H2CO3 changes to bicarbonate ions and H+ ions
Gas Exchange: Carbon Dioxide
Tissue Cells
CO2
diffusion
Blood Lungs
CO2+ H2O
Carbonic Acid(very
acidic)
Bicarbonate ions
(less acidic)
Exhaled CO2
Mechanism of Breathing
• Air always moves from areas of HIGH pressure to areas of LOW pressure.– This is similar to diffusion
If both of these containers have the same number of air molecules, which has higher air pressure?
Air Pressure
http://www.youtube.com/watch?v=mA_fNMe9hoQ&safety_mode=true&persist_safety_mode=1&safe=active
Bill Nye 2:05 – 3:30 Lung balloon demo6:25 – 7:23 Lung SA7:24 – 7:58 R side bigger than L
Inspiration (Inhalation)1. Intercostal muscles
contract, pulling ribs up and out
2. Diaphragm contracts, straightening (flattens)
3. Abdominal muscles relax, allowing compression by diaphragm
4. Volume increases, air pressure in lungs decreases, air rushes in
Expiration (Exhalation)1. Intercostal muscles relax,
ribs spring back (down and in)
2. Diaphragm relaxes, rising to ORIGINAL position
3. Abdominal muscles contract, pushing abdominal organs up against the diaphragm
4. Elastic fibers in lungs shrink, helping force air out
5. Volume decreases, air pressure in lungs increases, air rushes out
Inspiration and ExhalationNotice what’s happening
to the diaphragm and lung volume when you
inhale and exhale
Inspiration Expiration
Intercostals contract = ribs up and out
Intercostals relax = ribs down and in
diaphragm contracts = moves down = pulls air in
diaphragm relaxes = moves up = pushes air out
• The amount of air that moves in and out of the lungs with each breath can be measured with a spirograph
Respiratory Volume
Normal breath
Forceful inhalation
Forceful exhalationAmount of air that remains in lungs
Total amount of air that can be inhaled and exhaled
• Tidal volume: volume of air that can be inhaled and exhaled in a normal breath
• Inspiratory reserve volume: Additional volume of air that can be taken into the lung
• Expiratory reserve volume: Additional volume of air that can be forced out of lungs
• Vital capacity (aka total lung volume): total volume of air that can be moved in and out of the lungs
• Residual volume: amount of air that remains in the lungs
Respiratory Volume
Regulation of Breathing• Breathing controlled by nerves
– The medulla oblongata = in the brain– The medulla contains chemoreceptors – test amount of CO2 in the blood
• If chemoreceptors stimulated by an increase in CO2, the medulla causes the
– Diaphragm to move– Increased breathing
rates, lowers CO2 levels
• Can be controlled – Medulla will take
over if CO2 builds up
Control of Breathing
1. Carbon dioxide rises in the cells during cell activity.
Carbon dioxide rises in the blood
2. Increased blood carbon dioxide stimulates chemoreceptors in the medulla.
3. Stimulation of the rib and diaphragm muscles increases the breathing rate. Carbon dioxide is removed from the blood.
Breathing rate is MOSTLY influenced by Carbon Dioxide!
Factors Affecting Breathing RateCondition Effect on Breathing Rate
High blood carbon dioxideLow blood oxygenCarbon monoxide
High blood adrenaline levels
Increases (to remove CO2)Increases
Increases
Increases
Exercise increases breathing rate!
Carbon monoxide competes with
Oxygen for hemoglobin
Adrenaline rushes cause an increase in breathing rate!
• Inflammation of bronchioles
• Air passages get smaller• Excess mucus• Harder to exhale than
inhale• Can lead to asthma and
emphysema
Disorders: Bronchitis
Disorders: Bronchial Asthma• Reversible
narrowing of the bronchial passage.
• Tissues that line the walls of the bronchioles swell and may cause bronchiole spasms.
Emphysema• Increased resistance to
airflow• Over-inflation of the
lungs• Alveoli cannot handle
pressure– Rupture– Less SA for gas exchange– Lowers O2 levels
Lung Cancer• Uncontrolled growth of cells =
tumour• Less surface area for diffusion• Blockages may occur• People have smoked tobacco for
centuries• How is related to this class?• Canadian Council for Tobacco
Control
• Lung cancer– Most common type of death from cancer– 50% OF SMOKERS WILL DIE FROM SMOKING RELATED CAUSES
Healthy vs. Unhealthy
The effects of chewing tobacco
1. hair loss 2. cataracts 3. wrinkling 4. hearing loss6. tooth decay7. lung ailments9. heart disease16. cancer:
a) of the lungs b)of the tongue c) of the mouth, salivary
glands and pharynx
Other Effects of Smoking
Lung Cancer
http://www.youtube.com/watch?v=gGcsBltFkds&safety_mode=true&safe=active
Bill Nye Respiration Start – 3:00 and 6:40 – 7:57
Stop smoking video: http://www.youtube.com/watch?v=wUSWXzHi0GE&safety_mode=true&safe=active
Other Disorders...• Pneumothorax
– a collapsed lung
• Laryngitis– swelling of the larynx
• Respiratory Distress Syndrome– when the lipoprotein on the alveoli is
missing in some newborns (especially premature babies) so extreme force is required to overcome the surface tension of the alveoli – different breathing patterns, often results in death
Recommended