The Respiratory System
The Respiratory System
Section 1
5 Functions
1. Respiration
Exchange of gases: O2 & CO2 O2 is needed for cellular respiration (ATP)
2. Regulates blood pH
3. Contains receptors for smell
4. Filters inspired air
5. Sound Production
3 Stages of Respiration
1. Pulmonary Ventilation
Gas exchange between atmosphere and lungs
2. External Respiration
Gas exchange between lungs and pulmonary
capillaries
3. Internal Respiration
Gas exchange between systemic capillaries and
body cells
Structures of the Respiratory System
The Nose
Warms, moistens & filters air
Detects odor
Modifies speech vibrations
Conchae & meatuses
increase surface area
trap exhaled water droplets
prevent dehydration
Nasal Membranes
Goblet cells secrete mucus:
Moistens air
Traps debris
Cilia: tiny hairs trap debris
Blood capillaries: warm inhaled air
Sneezing:
Stimulus irritates nasal mucosa
Spasmodic contraction of respiratory
muscles occurs
Air forcefully expelled out nose & mouth
Sneezes can travel up to 200 mph
Sputum can spread 2-3 meters
The Pharynx
part of both GI Tract & Respiratory Tract
passageway for air & food
resonating chamber for speech sounds
houses the tonsils
3 regions of Pharynx:
1. Nasopharynx
2. Oropharynx
3. Laryngopharynx
Larygopharynx contains epiglottis:
flap of cartilage, covers glottis during
swallowing
glottis: opening to larynx/trachea
The Larynx
“Voice Box”
anterior to C4-C6
composed of cartilage
air passing across vocal folds & the vibration of
folds creates sound
pharynx, mouth, nasal cavity:
act as resonating chambers to give sound
human quality
muscles of face, mouth & tongue allow for
enunciation
Pitch of voice controlled by
tension on vocal cords:
Tension = Pitch
Tension = Pitch
Men have longer, thicker vocal cords:
- Vibrate more slowly: creates lower pitch
- d/t testosterone
The Trachea
“windpipe”
12 cm in length, 2.5 cm in diameter
Anterior to the esophagus
Contain 16-20 arcs of cartilage – prevents
collapse
Divides at Carina (T-5) into right & left
bronchi
Respiratory Tract
Nose
Nasal Cavity
Pharynx
Trachea
Primary Bronchi
Secondary Bronchi
Tertiary Bronchi
Lungs
Bronchioles
Terminal Bronchioles
Respiratory Bronchioles
Alveolar Ducts
Alveoli
Lungs
The Lungs Right lung: 3 lobes
Left lung: 2 lobes
Pleural membrane (2 layers) covers each lung
Pleural cavity: space between layers, contains lubricating fluid
Hilus: region where primary bronchi, blood & lymph vessels, & nerves enter or exit lung
Alveoli
Tiny air sacs
300 million!
Very thin tissue - 0.5 µm
Diffusion of gases occurs here
Contain macrophages – cells that remove
dust/debris
Alveoli secrete fluid for moisture
Contains Surfactant: lowers surface tension
of alveolar fluid to prevent alveolar collapse
Blood Supply to Lungs
Pulmonary arteries
Bring O2–poor blood to lungs from body (via heart)
Pulmonary veins
Bring O2-rich blood to heart from lungs
Bronchial arteries
Bring O2-rich blood from heart to lungs (feeds
lung tissue)
Section 2
PULMONARY VENTILATION
gases are exchanged between atmosphere
& lung alveoli
O2 in or CO
2 out
due to differences in pressure
Boyle’s Law explains how this occurs
BOYLE’S LAW
pressure of a gas varies inversely with volume
If pressure then volume
If pressure then volume
Boyle's Law at Work:
1. Diaphragm contracts (flattens)
2. Volume of lungs increases
3. Pressure in the lungs decreases
4. Air moves into lungs
After inhalation occurs...
1. Diaphragm relaxes - returns to dome shape
2. Volume of lungs decreases
3. Pressure in the lungs increases
4. Air moves out of lungs
Inhalation is an active process:
It requires muscle contraction & ATP
Exhalation is a passive process:
It does not require muscle contraction & ATP
External Respiration
exchange of O2 and CO2 between alveoli
and blood in pulmonary capillaries
occurs by passive diffusion
controlled by 2 gas laws:
1. Dalton’s Law
2. Henry’s Law
Dalton’s Law
each gas in a mixture of gases exerts its own pressure as if all the other gases were not present
This is its partial pressure (Px)
ex: atmospheric air is made of N2, O2, H2O, CO2, & other gases
PN2 + PO2 + PH2O + PCO2 + Pother = 760 mm Hg
760 mm Hg = total atmospheric pressure
How does this relate to respiration?
**The gases will diffuse from the area of higher
pressure to the area of lower pressure
ex: if O2 is in alveoli & in blood:
O2 will diffuse across the alveoli and into
the blood
Henry’s Law
the quantity of a gas that will dissolve in a liquid is
proportional to the partial pressure of the gas and its
solubility coefficient
partial pressure, solubility = gas in solution
How does this relate to respiration?
Oxygen crosses into blood because:
PO2 (alveolar air) = 105 mmHg
PO2 (deoxygenated blood in pulmonary capillaries) = 40 mmHg
So O2 moves from alveoli to blood
Carbon Dioxide crosses into alveoli because:
PCO2 (deoxygenated blood in pulmonary capillaries) = 45 mm Hg
PCO2 of alveolar air is 40 mm Hg
So CO2 moves from blood to the alveoli
The RATE of Gas Exchange depends on:
1. Partial pressures of gases
2. Surface area for gas exchange
area = rate of exchange
3. Diffusion distance
distance = rate of exchange
INTERNAL RESPIRATION
exchange of gases at the cellular level
(Dalton’s Law applies)
O2 leaves blood and diffuses into cell
CO2 leaves cells and diffuses into blood
O2 Transport
O2 does not dissolve well in water
Transportation requires Hemoglobin
Hemoglobin = iron-rich protein that turns
bright red when combined w/ O2
1 Hemoglobin + 4 O2 = Oxyhemoglobin
CO2 Transport Dissolves well in water
most found in blood as bicarbonate ions
blood detects this & transports it to lungs to be
exhaled
controls rate of breathing:
ions = resp. rate
ions = resp. rate
Medulla oblongata – part of brain that controls
respiratory rate
Lung Volumes
Adult = 12 breaths/min
Tidal volume: volume of one breath, ~ 500 ml
Spirometer: device used to measure volume of
respiration
Residual Volume: air that remains in lungs after maximum exhalation (~1200 ml)
Prevents lung collapse
Can’t be measured w/ spirometer