HAP
Chapter 16
“THE RESPIRATORY SYSTEM”
Why breathe???
I. Introduction
A. Why Breathe?
1. break down nutrients
2. produce ATP
3. excrete carbon
B. What is the respiratory system?
1. Obtaining O2 and removing CO2
II. Organs of the Respiratory System
A. Upper Tract
1. nose
2. nasal cavity
3. paranasal cavity
4. pharynx
B. Lower Tract
1. larynx
2. trachea
3. bronchial tree
4. lungs
C. The Nose
1. comprised of bone and cartilage
2. nostrils (2)
D. The Nasal Cavity
1. space behind nose
a. Nasal septum – divides into right and left halves
b. Nasal conchea – bones that give structure
c. Goblet cells – produce mucous
-swallow particles (why?)
E. Paranasal Sinuses
1. air filled spaces
a. Lighten skull
b. Resonant chambers used for voice
F. Pharynx (Throat)
1. passageway for air and food
2. used for speech
3. parts…
a. Nasopharynx
b. Oropharynx
c. Laryngopharynx
G. Larynx
1. enlargement above trachea
2. allows air in and out
a. Home of the vocal cords
3. 3 cartilages
a. Thyroid – “Adam’s apple”
b. Cricoid
c. Epiglottic
H. Trachea
1. aka  windpipe
2. flexible tube (2.5 cm diameter / 12.5 cm length)
3. splits into r/l bronchi
4. goblet cells
5. cartilage rings – C-shaped
prevent collapsing
I. Bronchial Tree
1. Primary Bronchi
a. Initial split from trachea/5th thoracic vertebra
2. Secondary Bronchi
3. Tertiary Bronchi
4. Bronchioles
5. Alveolar ducts
6. Alveolar sacs
7. Alveoli – tiny air sacs which are surrounded by capillary
networks
a. Increase surface area
b. 300 million
c. 1000 feet2
J. Lungs
1. pink, soft, spongy organs…
2. found in thoracic cage
3. Pleura – sac that lines the lungs…
a. Visceral pleura – inner sac that connects to
lungs
b. Parietal pleura – outer sac that holds lungs to
the thoracic cavity
4. right lobe (3) > left lobe (2)
III. Breathing Mechanism (Boyle’s Law)
A. Def – air into and out of the body.
1. Inspiration – inhaling
2. Expiration – exhaling
B. Inspiration
1. Atmospheric pressure = 760 mm Hg
2. How does air get into the lungs?
 Diaphragm moves downward / ribs move out
 lung volume increases
 pressure decreases
*Result…Outside air moves into the lungs
C. Expiration
1. How do we get air out of the lungs?
Elastic recoil of muscular and connective tissue
Diaphragm pushes upward
Pressure inside thoracic cavity increases
Air is forced outside of the body
Diaphragm is moving up
thus the internal pressure
increases causing the air to
move out of the body
D. Respiratory Air Volumes and Capacities
tidal volume = amount that enters or leaves lungs
-500 mL
inspiratory reserve volume = extra air that can be breathed in
- 3,000 mL (past tidal volume)
expiratory reserve volume = extra air that can be breathed out
- 1,100 mL (past tidal volume)
residual volume = amount that stays in the lungs permanently
- 1,200 mL
total lung capacity = total amount of air that could be found in
lungs.
-5,800 mL
vital capacity = maximum amount a person can exhale after taking
in a full breath.
-4,600 mL
Respiratory Volumes and Capacities
IV. Control of Breathing
A. The Respiratory Center (involuntary and voluntary)
1. Location – Brainstem
a. Pons
b. Medulla Oblongata
2. Special Areas
a. Medullary Rhythmicity Area
dorsal respiratory group
-basic inspiration rhythm (at rest)
-send signals to diaphragm and other small muscles
ventral respiratory group
-dormant at resting levels
-activated during forceful breathing
-send impulse to larger muscles used in breathing
b. Pneumotaxic Area
transmit impulses that inhibit inspiratory
bursts from the dorsal respiratory group
controls the overall breathing rate
-when transmitting = slow breathing
-when not transmitting = fast breathing
B. Factors that Affect Breathing
1. High CO2 levels (primary)
2. High H+ ion levels
3. Low blood O2 levels (minor)
4. Emotions (fear, pain, stress)
V. Alveolar Gas Exhange
A. Respiratory Membrane
1. Simple Squamous Epithelial Cells
2. Covered in a capillary network
3. O2 and CO2 easily exchanged
B. Diffusion (HL)
1. Partial pressure – amount of pressure for each gas
according to concentration.
Gas
Lung (alveoli)
Capillary
O2
104 mmHg
40 mmHg
CO2
40 mmHg
45 mmHg
VI. Gas Transport
A. Oxygen Transport
1. hemoglobin
a. 98% of all O2
Hypoxia – O2 deficiency
b. Forms oxyhemoglobin
-bond is unstable
-O2 is released
-O2 diffuses into nearby cells
c. Factors which cause oxyhemoglobin to release O2
-CO2 levels, acids, increase in blood temp
*Explains why working muscles get more O2
B. CO2 Transport (3 methods)
1. CO2 dissolved in plasma
a. Based on partial pressure
b. Approx. 7%
2. Part of a compound formed with hemoglobin
a. Binds with globulin (-NH2)
-carbaminohemoglobin
b. Approx. 23%
3. Converted to Bicarbonate ion (HCO3-)
a. CO2 + H2O  H2CO3 (carbonic acid)
-carbonic anhydrase (enzyme)
b. Approx. 70%