Physiology notes
Respiratory system
4 primary functions
1. exchange of O2 and CO2
2. pH homeostasis
3. protection from inhaled pathogens and irritating substances
4. vocalization
Left side: superior and inferior lobe
Right side: superior, middle, and inferior lobe
- Surface area for gas exchange: size of a squash hall
- Lung arteries: only arteries in the body with higher CO2 than O2
c0ncentrations.
Gas exchange
External respiration (lungs)
Exchange 1: atmosphere to lung (ventilation). Via the alveoli. CO2 leaves,
O2 enters
Exchange 2: lung to blood. Via pulmonary circulation (veins) the O2
travels.
- Pulmonary circulation moves blood between heart and lungs.
- Systemic circulation moves blood between body tissues and
heart.
Cellular respiration
Exchange 3: blood to cells.
O2 (4 molecules) binds to hemoglobin in red blood cells. CO2 is the
waste product out of the citric acid cycle (Krebs cycle). Hemoglobin gives
the blood the colour red.
Anatomy of lungs
- Larynx: high, close to the mouth. Entry of the trachea.
- Trachea: branches into 2 primary bronchi. Cartilage rings which you
can feel.
- Right and left primary bronchus: divides in bronchi
bronchioles alveoli
- Alveoli exchanges O2 and CO2 with blood vessels. They do not
have muscles, so elastic fibres are important, woven between 2
alveoli. Contraction by elasticity and pressure.
o Type 1 alveolar cells are the thin layers over the alveoli =
gas exchange
o Type 2 alveolar cells synthesizes surfactant (soap)
- O2 rich blood travels through the pulmonary vein to the left
chamber of the heart.
- Pulmonary artery brings CO2 rich blood to alveoli, which
exchanges it with O2.
- 2 pleural membranes enclose the lungs.
, - Pleural cavity covered by 2 membranes (inner and outer), in
between your chest wall and your lung. Filled with fluid. Lung can’t
get loose because it is attached to the cavity (cohesive force), so
they must follow the chest wall.
- Pericardial cavity around the heart.
Airway functions
- Filtering: airway can catch dust particles. The cilia move the mucus
(dust) towards the pharynx so it can be swallowed.
o Goblet cells secrete mucus.
o Mucociliary escalator is the system that moves the mucus
up.
- Airways humidify air and warm up the air for the alveoli
Watery saline layer allows cilia to push mucus toward the pharynx.
Ion channels bring chloride ions to the outside of the cell (airway) saline
layer. Osmotic pressure water and sodium go in between the cells into
the airway.
CFTR channel (cystic fibrosis) = the ion channel. If the channel does not
work CF
Pulmonary circulation
- 5 liter blood / min
- Low pressure = 25/8 mm Hg (systemic = 120/70 mm Hg)
- low hydrostatic pressure (= pressure from blood vessels to
extracellular fluid of cells). Low, so no fluid comes into lungs.
- Congestive heart failure = left chamber (ventricle) is weak, not
enough blood pumped higher pressure in right chamber higher
hydrostatic pressure fluid in lungs.
- Edema in lungs = fluid gets into lungs
- Boyle’s law = P1V1 = P2V2. Smaller volume higher pressure
air flows out
Higher volume lower pressure air flows in
- Pleural pressure < lung pressure
- External intercostal muscles can increase lung capacity
- Thoracic wall = chest wall
- Negative intrapleural pressure due to
o Surface tension of alveolar fluid
o Elasticity of lugs
o Elasticity of thoracic wall
- Parietal pleura = thoracic wall membrane
- Visceral pleura = lung membrane
- Transpulmonary pressure = intrapulmonary (lungs) minus
intrapleural pressure (±4 mm Hg). Transpulmonary pressure is
always positive!
Spirometer
Subject inserts a mouthpiece attached to an inverted bell filled with air or
oxygen.
The volume of the bell and volume off the subject’s respiratory tract
create a closed system because the bell is suspended in water.
When the subject inhales, air moves into the lungs.
Respiratory system
4 primary functions
1. exchange of O2 and CO2
2. pH homeostasis
3. protection from inhaled pathogens and irritating substances
4. vocalization
Left side: superior and inferior lobe
Right side: superior, middle, and inferior lobe
- Surface area for gas exchange: size of a squash hall
- Lung arteries: only arteries in the body with higher CO2 than O2
c0ncentrations.
Gas exchange
External respiration (lungs)
Exchange 1: atmosphere to lung (ventilation). Via the alveoli. CO2 leaves,
O2 enters
Exchange 2: lung to blood. Via pulmonary circulation (veins) the O2
travels.
- Pulmonary circulation moves blood between heart and lungs.
- Systemic circulation moves blood between body tissues and
heart.
Cellular respiration
Exchange 3: blood to cells.
O2 (4 molecules) binds to hemoglobin in red blood cells. CO2 is the
waste product out of the citric acid cycle (Krebs cycle). Hemoglobin gives
the blood the colour red.
Anatomy of lungs
- Larynx: high, close to the mouth. Entry of the trachea.
- Trachea: branches into 2 primary bronchi. Cartilage rings which you
can feel.
- Right and left primary bronchus: divides in bronchi
bronchioles alveoli
- Alveoli exchanges O2 and CO2 with blood vessels. They do not
have muscles, so elastic fibres are important, woven between 2
alveoli. Contraction by elasticity and pressure.
o Type 1 alveolar cells are the thin layers over the alveoli =
gas exchange
o Type 2 alveolar cells synthesizes surfactant (soap)
- O2 rich blood travels through the pulmonary vein to the left
chamber of the heart.
- Pulmonary artery brings CO2 rich blood to alveoli, which
exchanges it with O2.
- 2 pleural membranes enclose the lungs.
, - Pleural cavity covered by 2 membranes (inner and outer), in
between your chest wall and your lung. Filled with fluid. Lung can’t
get loose because it is attached to the cavity (cohesive force), so
they must follow the chest wall.
- Pericardial cavity around the heart.
Airway functions
- Filtering: airway can catch dust particles. The cilia move the mucus
(dust) towards the pharynx so it can be swallowed.
o Goblet cells secrete mucus.
o Mucociliary escalator is the system that moves the mucus
up.
- Airways humidify air and warm up the air for the alveoli
Watery saline layer allows cilia to push mucus toward the pharynx.
Ion channels bring chloride ions to the outside of the cell (airway) saline
layer. Osmotic pressure water and sodium go in between the cells into
the airway.
CFTR channel (cystic fibrosis) = the ion channel. If the channel does not
work CF
Pulmonary circulation
- 5 liter blood / min
- Low pressure = 25/8 mm Hg (systemic = 120/70 mm Hg)
- low hydrostatic pressure (= pressure from blood vessels to
extracellular fluid of cells). Low, so no fluid comes into lungs.
- Congestive heart failure = left chamber (ventricle) is weak, not
enough blood pumped higher pressure in right chamber higher
hydrostatic pressure fluid in lungs.
- Edema in lungs = fluid gets into lungs
- Boyle’s law = P1V1 = P2V2. Smaller volume higher pressure
air flows out
Higher volume lower pressure air flows in
- Pleural pressure < lung pressure
- External intercostal muscles can increase lung capacity
- Thoracic wall = chest wall
- Negative intrapleural pressure due to
o Surface tension of alveolar fluid
o Elasticity of lugs
o Elasticity of thoracic wall
- Parietal pleura = thoracic wall membrane
- Visceral pleura = lung membrane
- Transpulmonary pressure = intrapulmonary (lungs) minus
intrapleural pressure (±4 mm Hg). Transpulmonary pressure is
always positive!
Spirometer
Subject inserts a mouthpiece attached to an inverted bell filled with air or
oxygen.
The volume of the bell and volume off the subject’s respiratory tract
create a closed system because the bell is suspended in water.
When the subject inhales, air moves into the lungs.
