1. Chapter 15: Respiratory System
BIOLOGY 12
Chapter 15:
Respiratory System

2. Overview/Objectives 15.1 The Respiratory System
Two steps required for ventilation
Three steps that involve the circulatory system
How respiratory surfaces modify air
Path of air/ and functions of each organ
15.2 Mechanism of Breathing
Measurements of air in and out of our lungs
How breathing is achieved (pressure in lungs)
15.3 Gas Exchange in the body
Gas exchange: external vs internal respiration
Function of respiratory pigments in red blood cells
15.4 Respiration and Health
Common respiratory infections and disorders

3. 15.1 The Respiratory System
Function:
Gas exchange to support cellular respiration.
Two steps of ventilation (breathing):
Inspiration (inhalation) – fresh oxygen rich air brought to lungs
Expiration (exhalation)- stale, carbon dioxide rich air brought away from lungs

4. Types of Respiration
Notice that the respiratory system works with the cardiovascular system (types 2-4) 1. Breathing: mechanical movement of air in and out of lungs. No diffusion of gases across any membranes

5. 2. External Respiration: exchange of gases between the lungs and the blood stream * O2 in and * CO2 out.

6. 3. Internal Respiration: exchange of gases between the tissue capillaries and the cells of the body
*O2 from blood to cells and *CO2 returned to the blood from cells.

7. 4. Cellular Respiration: biochemical reactions (metabolism) in the cells in which glucose is oxidized and converted into ATP energy with CO2 as a by product .

8. Cellular Respiration Reaction

9. Anatomy

10. Path of Air & Functions a) Upper Respiratory Tract 1) Nasal cavity
Structure:
Nostrils= opening to cavity
Two nasal cavities=
Lined with mucous membrane
Function:
Main function is to filter, warm and moisten air as it enters the respiratory tract

11. 2) Pharynx Epiglottis Glottis Structure: connects nasal
and oral cavity to larynx
Function:
Connection to
surrounding regions
Epiglottis
flap of skin covering the
glottis prevents food from
going down the windpipe
Glottis
opening to the trachea
allows air to pass between the pharynx and larynx

12. 3) Larynx Structure: Cartilaginous; houses the vocal cords (voice box)
Function:
Sound protection

13. b) Lower Respiratory Tract 4) Trachea
Structure:
Flexible tube, connects
Larynx with bronchi
Function:
Passage of air to bronchi

14. 5) Bronchi
Structure:
Paired tubes below the trachea that enter the lungs
Function:
Passage of air
to the lungs

15. 6) Bronchioles Structure:
Branched tubes that lead from bronchi to alveoli
Function:
Passage of air to
each alveolus

16. 7) Lungs Structure: Soft, cone-shaped organs
that occupy thoracic cavity
Enclosed by double layer
membrane = pleura
Function:
Contains alveoli and blood vessels

17. 8) Alveoli Structure: Thin-walled microscopic air sacs in lungs
Function:
Gas exchange between air and blood

18. The structure of alveoli allow it to perform its function:
Large SA/V ratio  efficient exchange of gasses
Thin & Elastic walls  increase diffusion rate (gasses are close to blood)
Moist surface  gasses diffuse efficiently through a liquid environment (to a limit)
Surfactant (lipoprotein layer)  lowers surface tension so alveoli do not collapse
Highly Vascularized  each alveolus is surrounded by extensive blood supply

19. Blood Supply to and from Alveoli
pulmonary arteries carry deoxygenated blood back to lungs from the right ventricle
pulmonary venules carry oxygen rich blood back to the heart from the lungs

20. 15.2 Mechanisms of Breathing

21. Respiratory Volumes
Spirometer- used by physicians to measure breathing
Tidal volume- the amount of air normally moved in/out (~500mL)
Vital capacity- the maximum amount of air that can be moved in + out
Inspiratory reserve volume- volume of air that can be forcibly inhaled after normal inhalation
Expiratory reserve volume- volume of air that can be forcibly exhaled after normal exhalation
Residual volume- amount of air remaining in lungs after a forceful exhalation

23. Important Facts to Know about Ventilation
Normally, there is a continuous column of air from the pharynx to the alveoli
Lungs lie in the thoracic cavity;
rib cage = top/sides of thoracic cavity
diaphragm= flood of thoracic cavity
Pleura= surrounds the lungs
Functions:
allows lungs to move freely in thoracic cavity
reduces friction between lungs and ribs
seals thoracic cavity; creating a vaccum

24. Inspiration
The medula oblongata detects CO2, O2, (H+) levels and sends signals to the diaphragm and rib muscles by the phrenic nerve
Diaphragm goes down (contracts) and ribs come up and out
This enlarges thoracic chest cavity creating negative pressure compared to atmospheric pressure  air rushes in
Stretch receptors in alveoli are stimulated  message sent by vagus nerve to brain for expiration

25. Inspiration

26. Expiration The diaphragm relaxes and the rib cage moves down & in
Lungs recoil
Positive pressure in lungs
Air forced out
Talking occurs as air moves over vocal cords in larynx

27. Expiration

28. Mechanics of Breathing
Medulla senses decrease in pH and increase in CO2 and sends a message to the diaphragm and intercostal muscles via the phrenic nerve causing inhalation
When the lungs are stretched receptors send a message via the vagus nerve back to brain and exhalation occurs

29. Control of Breathing Rate
Our breathing rate must be able to respond to various energy demands of the body.
The medulla in our brain contains our breathing center - it sets the basic rate.

30. Control of Breathing By Carbon Dioxide CO2 levels rise in blood
Medulla oblongata detects this
Nerve impulses sent to diaphragm and rib muscles
Breathing rate increases to get rid of CO2

31. Control of Breathing Continued
B) By Oxygen
Low oxygen levels measured by chemoreceptors in aorta and carotid arteries
Message sent to medulla oblongata
Nerve impulses sent to the diaphragm and rib muscles to increase breathing rate to obtain oxygen

32. Of the two mechanisms, the control of breathing by carbon dioxide is the most important

33. 15.3 Gas Exchange

34. 1. External Respiration
External respiration = exchange of gasses between air (alveoli) and blood (pulmonary capillaries) Partial pressure= pressure exerted by a gas (PCO2 and PO2)

35. EXTERNAL RESPIRATION

36. External Respiration CO2
Blood in pulmonary capillaries has higher PCO2 than atmospheric air CO2 diffuses out of plasma and into lungs
Most CO2 is carried as bicarbonate ions (HCO3-)
Enzyme carbonic anhydrase in red blood cells speeds breakdown of carbonic acid (H2CO3)
carbonic
anhydrase
H HCO  H2CO3  H2O + CO2
Hydrogen Bicarbonate carbonic water carbon
Ion ion acid dioxide

37. External Respiration  O2
Reverse pattern of that for CO2
Blood in pulmonary capillaries is low in O2
and alveolar air has higher PO2  O2 diffuses into plasma and into red blood cells in the lungs
Hemoglobin takes up oxygen and becomes oxyhemoglobin (HbO2)
Hb O  HbO2
Deoxyhemoglobin oxygen oxyhemoglobin

39. 2. Internal Respiration Internal Respiration=
the exchange of gasses between the blood in the systemic capillaries and the tissue fluid

40. Internal Respiration  O2
O2 diffuses out of the blood and into the tissues because PO2 of tissue is lower than that of blood
PO2 of tissue is lower because cells are continuously using O2 in cellular respiration
HbO2  Hb O2
oxyhemoglobin Deoxyhemoglobin oxygen

41. Internal Respiration  CO2
Carbon dioxide diffuses into the blood from the tissues because PCO2 of tissue fluid is higher than that of blood
PCO2 of tissue fluid is higher because cells continuously produce CO2
CO2 enters red blood cells three ways:
dissolved in plasma (small amount)
transported as bicarbonate ion (most)
attached to hemoglobin (some) carbaminohemoglobin
carbonic
anhydrase
H2O + CO2  H2CO3  H HCO3-
water carbon carbonic Hydrogen Bicarbonate
dioxide acid ion ion

43. 15.4 Respiration and Health
The respiratory tract is constantly exposed to environmental air, which means air quality affects our health

44. Upper Respiratory Tract Infections
Sinusitis- infection of the cranial sinuses
Otitis Media- bacterial infection of middle ear (caused by nasal infection
Tonsillitis- tonsils in the pharynx become inflamed and enlarged
Laryngitis- infection of the larynx (hoarseness of voice)

45. Lower Respiratory Tract Infections
Acute bronchitis- infection of primary and secondary bronchi
Pneumonia- viral or bacterial infection of the lungs (bronchi and alveoli fill with thick fluid)
Pulmonary tuberculosis- tuburcle bacillus (bacteria) invade lung tissue
Pulmonary fibrosis (restrictive pulmonary disorder)- connective tissue build up in lungs
Chronic bronchitis- airways inflamed and filled with mucous
Emphysema- chronic, incurable disorder, alveoli damaged, less SA for gas exchange
Asthma- disease of bronchi and bronchioles

46. Lung Cancer