1. Chapter 9
Respiratory System

2. Points to Ponder
What are the parts and function of the upper and lower respiratory system?
What is the mechanism for expiration and inspiration?
How is breathing controlled by the nervous system and through chemicals?
Where and how is exchange of gases accomplished?
What are some common respiratory infections and disorders?
What do you know about tobacco and health?
What is your opinion about bans and legislation on smoking?

3. 9.1 The respiratory system

4. Respiratory Pathway Air Flow
8.1 Overview of digestion
Respiratory Pathway Air Flow
nose
pharynx
larynx
trachea
bronchus
bronchioles
alveoli

5. What constitutes the upper respiratory tract?
Nose
Pharynx
Larynx

6. The Nose Opens at the nostrils/nares and leads into the nasal cavities
9.2 The upper respiratory tract
The Nose
Opens at the nostrils/nares and leads into the nasal cavities
Hairs and mucus in the nose filters the air
Mucus  helps trap dust and move it to the pharynx to be swallowed
The nasal cavity has lot of capillaries that warm and moisten the air
Specialized ciliated cells act as odor receptors
Nerve impulses generated by the receptors are interpreted as smell
Tear (lacrimal) glands drain into the nasal cavities that can lead to a runny nose

7. The Pharynx Funnel-shaped cavity commonly called the “throat”
9.2 The upper respiratory tract
The Pharynx
Funnel-shaped cavity commonly called the “throat”
Connects the nasal and oral cavities to the larynx
3 portions based on location:
Nasopharynx  where the Nasal cavity opens
Auditory tubes empty into this location
Oropharynx  where the Oral cavity opens
Laryngopharynx  opens into the larynx
Tonsils provide a lymphatic defense during breathing at the junction of the oral cavity and pharynx
Contain lymphocytes that protect against invasion of foreign antigens that are inhaled
Respiratory tract assists the immune system in maintaining homeostasis

8. 9.2 The upper respiratory tract
The Larynx
Triangular, cartilaginous structure that passes air between the pharynx and trachea
Called the voice box and houses vocal cords
Vocal Cords
2 mucosal folds that make up the vocal cords with an opening in the middle called the glottis
Creation of Sound
Air is expelled through glottis forcing the vocal cords to vibrate
Pitch
High  greater the tension, glottis becomes narrower
Lower  glottis is wider
Amplitude (volume): degree of vocal cord vibrations

9. The Larynx Creation of Sound Pitch
Air is expelled through glottis forcing the vocal cords to vibrate
Pitch
High  greater the tension, glottis becomes narrower
Lower  glottis is wider
Amplitude (volume): degree of vocal cord vibrations

10. Lower Respiratory Tract
9.3 The lower respiratory tract
Lower Respiratory Tract
Trachea
Bronchial tree
Lungs

11. 9.3 The lower respiratory tract
The Trachea
A tube, often called the windpipe, that connects the larynx with the 1° bronchi
Made of connective tissue, smooth muscle and C-shaped cartilaginous rings
Lined with cilia and mucus that help to keep the lungs clean
Mucus membrane line trachea
Pseudostratified ciliated columnar epithelium
Mucus from goblet cells

12. The Trachea
Coughing
1. Tracheal wall contracts, narrowing the diameter
2. Air moves more rapidly through the trachea
3. Expels mucus and foreign objects

13. 9.3 The lower respiratory tract
The bronchial tree
Starts with two primary bronchi that lead from the trachea into the lungs
The bronchi continue to branch into secondary bronchi until they are small bronchioles about 1mm in diameter with thinner walls
Bronchioles eventually lead to elongated sacs called alveoli
Asthma Attach
smooth muscle of bronchioles contract  wheezing

14. 9.3 The lower respiratory tract
The Lungs
The bronchi, bronchioles and alveoli beyond the 1° bronchi make up the lungs
Right lung has 3 lobes Left lung has 2 lobes
Lobes are divided into lobules
Each lobule has a bronchiole serving many alveoli
Each lung is enclosed by membranes called pleura
Double layer of serous membrane that produces serous fluid
Parietal Pleura – adhere to thoracic cavity wall
Visceral Pleura – adhere to surface of lungs
Surface tension holds the two pleural layers together, therefore lungs follow the movement of the thorax when breathing
Surface tension: tendency of water molecules to cling to one another due to hydrogen bonding between molecules

15. The Alveoli ~ 300 million in lungs that increase surface area
9.3 The lower respiratory tract
The Alveoli
~ 300 million in lungs that increase surface area
Alveoli are enveloped by blood capillaries
The alveoli and capillaries are simple squamous epithelium to allow exchange of gases
Oxygen: diffuse across alveolar wall to bloodstream
CO2: diffuse from blood across the alveolar wall to the aveoli
Alveoli lined with surfactant that act to keep alveoli open
Decrease surface tension of water

16. Two Phases of Breathing/Ventilation
9.4 Mechanism of breathing
Two Phases of Breathing/Ventilation
1. Inspiration – an active process of inhalation that brings air into the lungs
2. Expiration – usually a passive process of exhalation that expels air from the lungs

17. Thoracic Cavity Lungs in thoracic cavity
Rib cage joined to vertebral column and sternum
Intercostal muscles line between the ribs
Diaphragm and connective tissue

18. Inspiration – Active Phase
9.4 Mechanism of breathing
Inspiration – Active Phase
1. The diaphragm and external intercostal muscles contract
The diaphragm flattens and the rib cage moves upward and outward (active phase)
2. Volume of the thoracic cavity and lungs increase
The air pressure within the lungs decrease
- creating partial vacuum
Air flows into the lungs
- Actual flow of air into the alveoli is passive

19. Expiration – Passive Phase
9.4 Mechanism of breathing
1. The diaphragm and external intercostal muscles relax
2. The diaphragm moves upward and becomes dome-shape
The rib cage moves downward and inward
3. Volume of the thoracic cavity and lungs decrease
4. The air pressure within the lungs increases
5. Air flows out of the lungs

20. Maximum Inspiratory Effort and Forced Expiration
Maximum inspiratory effort involves Back, chest, and neck
Increases the size of the thoracic cavity
Maximize expansion of the lungs
Maximum Expiration effort
Contraction of the internal intercostal muscles
Force rib cage to move downward and inward
Abdominal wall muscles contract and push against the diaphragm
Increased pressure in the thoracic cavity expels air

21. Different volumes of air during breathing
9.4 Mechanism of breathing
Different volumes of air during breathing
Tidal volume –
the small amount of air that usually moves in and out with each breath (500 mL)
Vital capacity –
the maximum volume of air that can be moved in plus the maximum amount that can be moved out during one breath
Inspiratory and expiratory reserve volume –
the increased volume of air moving in or out of the body (2,900 mL)
Residual volume –
the air remaining in the lungs after exhalation
Air is no longer useful for gas exchange

22. Visualizing the Vital Capacity
9.4 Mechanism of breathing
Visualizing the Vital Capacity

23. Breathing controlled by the nervous system
9.5 Control of ventilation
Breathing controlled by the nervous system
Breathing = 12 – 20 ventilations/min
Rhythm of ventilation controlled by nervous system
Nervous control (involuntary):
Inspiration
Respiratory control center in the brain (medulla oblongata) sends out nerve impulses to contract muscle for inspiration
Expiration
Respiratory control center stops sending neuronal signals to the diaphragm and rib cage
Sudden infant death syndrome (SIDS) is thought to occur when this center stops sending out nerve signals
Can voluntarily control breathing to force inspiration
1. Stretch receptors in alveolar walls initiate inhibitory nerve impulses
2. Stops respiratory center from sending out nerve impulses temporarily

25. Breathing is chemically controlled
9.5 Control of ventilation
Breathing is chemically controlled
Chemical control:
2 sets of chemoreceptors sense the change in chemical composition in body fluids (blood pH)
1. Brain (medulla oblongata)
2. Circulatory system (carotid bodies and aortic bodies)
Sensitive (stimulated by) carbon dioxide levels that change blood pH due to metabolism
Decrease pH (below 7, increase in H+ ions)
Respiratory center increases rate and depth of breathing
More CO2 is removed from blood

26. Exchange of gases in the body
9.6 Gas exchanges in the body
Exchange of gases in the body
Oxygen and carbon dioxide are exchanged in the lungs and tissues
The exchange of gases is dependent on diffusion
Partial pressure is the amount of pressure each gas exerts (PCO2 or PO2)
Oxygen and carbon dioxide will diffuse from the area of higher to the area of lower partial pressure

27. 9.6 Gas exchanges in the body
External respiration
Exchange of gases between the lung alveoli and the blood capillaries
PCO2 is higher in the lung capillaries than the air thus CO2 diffuses out of the plasma into the lungs
CO2 carried in plasma as bicarbonate ions (HCO3-)
The partial pressure pattern for O2 is just the opposite so O2 diffuses the red blood cells in the lungs
O2 diffuses into plasma and into RBC in lungs
Carbon dioxide transport: carbonic
H+ + HCO H2CO3 anhydrase H2O + CO2
Oxygen transport:
Hb + O HbO2 (oxyhemoglobin)
(deoxyhemoglobin)

28. External respiration Hyperventilate (breathe at a high rate)
Push reaction to the right
Fewer hydrogen ions  alkalosis
High blood pH
Solution: Inhibit breathing
Hypoventilate (breathe at a low rate)
Hydrogen ions build up in the blood  acidosis
Buffer compensate for low pH
Solution: Increase breathing

29. 9.6 Gas exchanges in the body
Internal respiration
The exchange of gases between the blood in the capillaries outside of the lungs and the tissue fluid
PO2 is higher in the capillaries than the tissue fluid therefore, O2 diffuses out of the blood into the tissues
Oxyhemoglobin gives up oxygen:
HbO Hb + O2
Most CO2 is carried as a bicarbonate ion:
carbonic
CO2 + H2O anhydrase H2CO H3 + HCO3-

30. Internal respiration Oxygen diffuses out of the blood into tissues
- PO2 of tissue fluid is lower than that of blood because cells use up oxygen in cellular respiration
CO2 diffuses into the blood from tissues
PCO2 of tissue fluid is higher than the blood because CO2 is produced by cells and collected in tissue fluid
CO2 enters the RBCs and plasma to be either
Taken up by hemoglobin in RBC to from HbCO2
Taken up by RBC and formed into HCO3-
Excess H+ from this reaction combines with Hemoglobin to form HHb, reduced hemoglobin

32. Upper respiratory tract infections
9.7 Respiration and health
Upper respiratory tract infections
Sinusitis – blockage of sinuses
Otitis media – infection of the middle ear
Tubes placed in the eardrums to prevent buildup of pressure in the middle ear
Tonsillitis – inflammation of the tonsils
Laryngitis – infection of the larynx that leads to loss of voice

33. Lower respiratory tract disorders
9.7 Respiration and health
Lower respiratory tract disorders
Pneumonia –
infection of the lungs with thick, fluid build up
Tuberculosis –
bacterial infection that leads to tubercles (capsules)
Pulmonary fibrosis –
lungs lose elasticity because fibrous connective tissue builds up in the lungs usually because of inhaled particles
Emphysema –
chronic, incurable disorder in which alveoli are damaged and thus the surface area for gas exchange is reduced
Asthma –
bronchial tree becomes irritated causing breathlessness, wheezing and coughing
Lung cancer –
uncontrolled cell division in the lungs that is often caused by smoking and can lead to death

34. Health focus: Things you should know about tobacco and health
9.7 Respiration and health
Health focus: Things you should know about tobacco and health
All forms of tobacco can cause damage
Smoking increases a person’s chance of lung, mouth, larynx, esophagus, bladder, kidney, pancreas, stomach and cervix
The 5-year survival rate for people with lung cancer is only 13%
Smoking also increases the chance of chronic bronchitis emphysema, heart disease, stillbirths and harm to an unborn child
Passive smoke can increase a nonsmokers chance of pneumonia, bronchitis and lung cancer