Respiratory system Flashcards
What is the main function of the respiratory system?
Main function: to exchange CO2 and O2 between the body and the external environment
Gaseous exchange occurs in the respiratory division of the lungs
Nose → ________ → larynx → trachea → ______ → bronchioles (passageways for air to pass
in and out and known as conducting division)
pharynx
bronchi
What is the nasal cavity lined with?
Nasal cavity is lined with a ciliated mucous membrane → sticky mucous traps inhaled particles + beating of cilia drives mucous to throat to be swallowed
Bacteria that are inhaled are destroyed by lysozymes in the mucous + lymphocytes + antibodies
3 folds of tissue arising from wall of nasal cavity (nasal conchae/turbinate’s) → increase _____ _______ with inhaled air enabling nose to rapidly warm, moisten and cleanse it.
content surface
Roof of nasal lining has ________ nerve cells which bring sense of smell
The inhaled air moves at a ___-degree angle down as soon as it reaches the pharynx. Also, another method of trapping large particles, that due to their inertia, crash and stick to the wall of the throat and stick to _______.
olfactory
90
mucosa
Pharynx has several _____ (immune competent) + pharynx also passes food down the oesophagus
tonsils
How do we prevent food from going down the wrong pipe?
In order to prevent food from going down the wrong pipe, the larynx is covered by a flap called the epiglottis. During swallowing, the larynx is pulled up and the flap flips over, directing food and drink to oesophagus.
Vocal folds are closed protecting airway. From the larynx, air passes to _______.
trachea
The bronchi split into multiple bronchi until making ______ (smooth muscles allow to constrict (to decrease air flow) /dilate (to increase air flow)
Larynx, trachea, bronchiole tree are lined by ciliated columnar epithelium which act as ______ _______ (mucous traps dust and moves up into throat to get swallowed).
bronchioles
mucocillary escalator
What are terminal branches?
→ branch into respiratory bronchioles begins which mark beginning of respiratory division
The terminal bronchioles ned with alveoli. These are surrounded by blood capillaries where gaseous exchange occurs. The Alveoli is surrounded by a Type I squamous cells which allows rapid diffusion.
What is the function of the Type II (cuboidal cell)?
Type II (cuboidal cell) acts as surfactant to lower ST at air-liquid interface + prevents alveolus from exploding ate need of each exhalation.
Alveoli have ______ so as to dissolve any unwanted large particles
Macrophages ride the mucocillary escalator so they can be digested.
macrophage
Alveoli have ______ so as to dissolve any unwanted large particles
Macrophages ride the mucocillary escalator so they can be digested.
macrophage
What is the conducting zone?
nose/mouth → pharynx –> larynx → trachea → primary bronchus → bronchi → bronchioles
- no gaseous exchange
- contribute to anatomical space
- act as pathway for air
What are the functions of the conducting zone?
- warm and humidify the air
- filter air via cilia (move particles) + mucous (trap particles) and the mucocillary escalator (expel particles)
What happens as air moves down the trachea? (3)
As air moves down our trachea, low resistance of air flow, because trachea is open by cartilaginous rings.
The air then moves into 2 bronchi, one to each lung. Bronchi has cartilaginous rings to keep them open. When we don’t have the cartilaginous rings, we term them bronchioles.
Bronchioles form bronchiole tree. Further split into terminal bronchioles (16000)
What happens in the respiratory zone? (4)
- As air flows down terminal bronchioles, they will branch again into respiratory bronchioles (500 000)
- Respiratory bronchioles have tiny air sacs (alveolar sacs – 8 million) where gaseous exchange takes place. The alveoli form the start of the respiratory zone.
- Respiratory bronchioles split into alveolar sacs which are made by individual alveoli (singular: alveolus – 300 million) bunched together.
- The alveoli increase the surface area of the lungs to facilitate gaseous exchange.
What is needed for gaseous exchange to occur? (3)
In order for gaseous exchange to occur, alveoli need to be associated with a blood supply. Around each alveoli air sac, is a capillary bed.
Branch of pulmonary artery does not thick muscles to lower the pressure with which blood flows to the lungs. The pulmonary artery carriers deoxygenated blood down the artery into arterioles into small capillaries which surround the alveolar sacs.
In capillary beds, O2 is picked up and CO2 is offloaded.
The oxygenated blood is then collected via the pulmonary vein and returned to the heart to pump to the rest of the body.
What happens when air moves into the alveoli?
The O2 moves down a concentration gradient from the high concentrated alveoli into the low concentrated alveoli and the CO2 is high in the deoxygenated blood in the capillary and moves into the alveolar air space moving down its concentration gradient. CO2 is then exhaled. Oxygenated blood is then returned to heart via pulmonary vein. When you inhale, sacs expand.
This gaseous exchange takes place across this ________ membrane – 0.2 um
respiratory
What are the 5 layers of the alveoli?
- First layer = surfactant
- Second layer = Type I epithelial cells
- Alveolar basement membrane
- Capillary basement membrane
- Endothelial cell lining capillary lumen
What is the first layer?
Surfactant
Need a moist surface, if the moisture was from water, the water molecules would come together and collapse the tiny alveoli. Instead, the membrane is kept moist via the surfactant – phospho-lipoprotein – to reduce ST to prevent collapse with each exhale.
What is the second layer?
Type I epithelial cells
Flattened squamous epithelial cells in the alveolar
walls, which help to keep respiratory membrane thin.
What are the third and fourth layers?
- Alveolar basement membrane
- Capillary basement membrane
3 and 4 can be fused together to help keep respiratory
membrane thin
What is the fifth layer?
- Endothelial cell lining capillary lumen
What is Fick’s law?
Factors affecting the rate of gas exchange
Rate of diffusion = k × A × P2 − P1/D
K = diffusion constant depends on solubility of gas + temperature
A = area for gaseous exchange (increase SA, increases rate of diffusion)
P2 – P1 = partial pressure gradient (works like a concentration gradient → if you exercise
rigorously, you take in more oxygen therefore rate of diffusion increases as the oxygen will
try to move to an area of low concentration.)
D = thickness of respiratory membrane (thin membrane increases rate of diffusion)
What changes the factors in Fick’s law?
Diseases change these factors.
Pneumonia → increase in fluid membrane of respiratory membrane which increases D which then decreases rate of diffusion.
Emphysema → breakdown of cells decreasing A which decreases surface area
The rate of diffusion across the respiratory membrane is going to be severely compromised in diseases such and emphysema and chronic bronchitis, which together make up Chronic Obstructive Pulmonary Disease (COPD).
What is COPD and what is its cause?
COPD – gradual loss of ability to breathe effectively
Cause: smoking, air pollution, chemical fumes, dust
What is Emphysema? (2)
- Air sacs lose flexibility making it hard for them expand and contract
- Air sacs joint, lowering the SA therefore rate of diffusion decreases
What are the symptoms of emphysema?
Symptoms of emphysema:
Wheezing + shortness of breath + tightness in your chest
What are the Steps of respiration?
- Ventilation – exchange of air between atmosphere
and alveoli - Gas exchange – exchange of O2 and CO2
between alveolar air and blood - Gas transport – transport of O2 and CO2 through
pulmonary and systemic circulation - Gas exchange – exchange of O2 and CO2
between blood in capillaries and cells in tissue - Cellular respiration – cellular utilisation of O2
and production of CO2
What is Boyle’s law?
The pressure and volume of a gas have an inverse
relationship when temperature is held constant.
What is negative pressure breathing?
- Humans use this method of breathing
- Force air into the lungs
- Positive pressure breathing → ventilator + CPR
Lungs do not have muscles attached to them. They are passive elastic structures.
What are the layers of the pleural sac? (3)
- Visceral pleura (inner) → attached to lungs
- Parietal pleura (outer) → attached to thoracic cavity (intercostal muscles, ribs, diaphragm, mediastinum)
- Pleural cavity is between the 2 pleurae → have lubricating intrapleural fluid which helps lungs move more smoothly + create interpleural pressures to keep lungs + alveoli sacs open
What happens during inspiration?
Breathing in *
Increase volume of thoracic cavity, which pulls the parietal pleura which further decreases the intra-pleural pressures. Due to the surface tension of the pleural fluids, its going to pull on the visceral pleura. This will increase the volume of the lungs therefore the pressure in the inter-alveola will decrease.
Air moves into lungs until no pressure gradient remains.
During expiration:
Breathing out * (passive)
Decrease volume of _____ cavity, volume of lungs decreases. Decreasing volume will increase the pressure of the alveoli. Air flows out of lungs.
Transpulmonary pressure = intra-alveolar pressure – intra-pleural pressure = __ mmHg
__________ pressure helps keep lungs open
thoracic
4
Transpulmonary
Healthy lungs have low resistance, high ______
Lung compliance decreases when lung tissue hardens/stiffens → harder to ______ lung
Asthma causes airways to block, therefore air has difficulty flowing.
Parasympathetic stimulation + ______→ constrict airways which increases resistance and decreases airflow
Epinephrine → _______ bronchioles which increases air flow
compliance
inflate
histamine
dilates
What is Pulmonary (minute) ventilation?
Volume of air moved into and out of lungs per unit time
= Tidal volume* (L/breath) x respiratory rate (breaths/min)
= 0.5 L/breath x 10 breaths/min
= 5 L/min
(Normal is 5L to 12L per minute)
Composition of inspired and expired air:
As gas moves from gas to liquid, concentrations change as well.
Partial pressure of gas (air we breathe) = Partial pressure of _____ (blood)
Gases move from high partial pressure to a low partial pressure, down a partial pressure gradient.
liquid
Partial pressures in alveoli =
Factors that determine alveolar PO2 and PCO2: (3)
- Rate of alveolar ventilation and perfusion
Increase alveolar ventilation, increase amt of O2
Decrease alveolar ventilation, decrease amt of CO2 - Rate of cellular oxygen consumption and carbon dioxide production
If tissues use a lot of O2 and produce a lot of CO2s, creates partial pressure gradient
O2 moves out of alveoli into blood, CO2 moves out of blood in the alveoli - PO2 of atmospheric air
What can we deduce from this table?
From the above table, we can tell that as we go higher up, our atmospheric pressure decreases which ultimately decreases the partial pressure of O2, making it difficult to breath.
At sea level:
O2 starts at 160 but drops to about 140 in the
trachea, due to the humidification of inspired air
by the nasal mucosa. Further drops to 100 in alveolar air due to small Tidal volume relative to the large functional
residual capacity, stale air that stays. Further declines as it is goes down arteries into the capillaries and further drops into venous blood.
At 4540 m: (highest permanent human settlement)
O2 starts at a lower pressure from the beginning. There is a low partial pressure gradient at both the lung and tissue levels. People that live at high altitudes adapt to those conditions. Body produces more RBCs to carry more oxygen to the body cells
