6.4 Gas Exchange Flashcards
What does physiological respiration involve?
The transport of oxygen to cells within the tissues
What does physiological respiration involve?
The transport of oxygen to cells within the tissues
What are the three processes in physiological respiration?
Ventilation
Gas exchange
Cell respiration
What is ventilation?
The exchange of air between the atmosphere and the lungs
What is gas exchange?
The exchange of oxygen and carbon dioxide between the alveoli and bloodstream
What is cell respiration?
The release of energy from organic molecules?
What is needed to maintain a concentration gradient in alveoli?
A ventilation system
Why is a ventilation system needed to maintain a concentration gradient in alveoli?
Because gas exchange is a passive process
What is consumed by cells during cell respiration?
Oxygen
What is a waste product of cellular respiration?
Carbon dioxide
Where is oxygen being removed from and into where?
Removed from the alveoli and into the bloodstream
How do the lungs function as a ventilation system?
By continually cycling fresh air into the alveoli from the atmosphere
What levels stay high in the alveoli?
O2 levels
What levels stay low in the alveoli?
Carbon dioxide
What diffuses into the blood?
Oxygen
What diffuses from the blood?
Carbon dioxide
How are the lungs structured to increase the overall rate of gas exchange?
A very large surface area
How does air enter the respiratory system?
Through the nose or mouth
What does air pass through after entering the nose/mouth?
Pharynx to the trachea
What does the trachea divide into?
Two bronchi
What are bronchi connected to?
the lungs and the trachea
How many lobes is the right lung composed of?
Three lobes
How many lobes in the left lung?
Two
Why is the left lung smaller than the right?
Due to the position of the heart
In each lung, what do the bronchi divide into?
Smaller airways called bronchioles
What do bronchioles increase?
Surface area
What do each bronchioles terminate with?
A cluster of air sacs called alveoli
What occurs in the alveoli?
Gas exchange with the bloodstream
What is the function of the alveoli?
The site of gas exchanged
What does the thin epithelial layer do?
Minimises diffusion distances for respiratory gases
What are alveoli surrounded by?
A rich capillary network
What does the rich capillary network around the alveoli increase?
The capacity for gas exchange
What is the internal surface of the alveoli covered with?
A layer of fluid
Why is there a layer of fluid in the internal surface of the alveoli?
As dissolved gases are better able to diffuse into the bloodstream
What are pneumocytes?
The cells that line the alveoli and comprise the majority of the inner surface of the lungs
What are the two types of alveolar cells?
Type I pneumocytes and Type II pneumocytes
What are type I pneumocytes involved in?
The process of gas exchange between te alveoli and the capillaries
What is the shape of the type I pneumocytes?
Squamous and extremely thin
Why are type I pneumocytes extremely thin?
To minimise the diffusion distance for respiratory gases
How are type I pneumocytes connected?
By occluding junctions
What do occluding junctions prevent?
The leakage of tissue fluid into the alveolar air space
What are type I pneumocytes unable to do?
Replicate
What can type II cells differentiate into?
Type I cells if required
What can type II cells differentiate into?
Type I cells if required
What are type II pneumocytes responsible for?
The secretion of pulmonary surfactant
What does pulmonary surfactant reduce?
Surface tension in the alveoli
What is the structure of type II pneumocytes?
Cuboidal and possess many granules
What do type II pneumocytes only comprise a fraction of?
The alveolar surface
What is the bad thing about the moist lining in alveoli?
It creates a tendency for the alveoli to collapse and resist inflation
What is the surface tension?
The elastic force created by a fluid surface that minimises the surface area
What happens to the surfactant as an alveoli expands with gas intake?
It becomes more spread out across the moist alveolar lining
What slows the rate of expansion?
The increase in surface tension
What does the surfactant ensure all alveoli do?
Inflate at roughly the same time
What does the surfactant ensure all alveoli do?
Inflate at roughly the same time
What is breathing?
The active movement of respiratory muscles that enables the passage of air into and out of the lung
What does the contraction of respirator muscles change?
The volume of the thoracic cavity
What law does the mechanism of breathing follow?
Boyles law
When the volume of the thoracic cavity increases what happens to the pressure in the thorax?
It decreases
When the volume of the thoracic cavity decreases what happens to the pressure in the thorax?
It increases
In general where will gases move from?
A region of high pressure to a region of lower pressure
When will air move into the lungs?
When the pressure in the chest is less than the atmospheric pressure
When will the air move out of the lungs?
When the pressure in the chest is greater than the atmospheric pressure
What do respiratory muscles contract to change?
The volume of the thoracic cavity and the pressure in the chest
What are different groups of muscles required to do because muscles only do work via contraction?
Expand and contract chest volume
What does changing chest volume create?
A pressure differential between the chest and the atmosphere
What equalises the pressure differential?
Air moving
What do muscles that increase the volume of the chest cause?
Inspiration
What do muscles that decrease the volume of the chest cause?
Expiration
When is atmospheric pressure lower?
At high altitudes
Why is it harder to breathe at high altitudes?
As a greater increase in chest volume is required before a pressure differential is formed
What are inspiration and expiration controlled by?
Two sets of antagonistic muscle groups
What does antagonistic mean?
WOrking oppositely
What are the muscles responsible for inspiration?
The diaphragm and external intercostals
What happens when the diaphragm muscles contract?
The diaphragm flattens and increase the volume of the thoracic cavity
What contracts during inspiration?
Diaphragm and external intercostals
What happens when the external intercostals contract?
Ribs are pulled upwards and outwards
What also may help pull the ribs up and out?
Additional muscle groups
What are the muscles responsible for expiration?
The abdominale muscles and internal intercostals
What do the diaphragm muscles do during expiration?
Relax
What happens when the diaphragm muscles contract during expiration?
The diaphragm curves upwards and reduces the volume of the thoracic cavity
What do the internal intercostals muscles do during expiration?
Contract
What happens when the internal intercostal muscles contract?
The ribs are pulled inwards an downwards
What happens when the internal intercostal muscles contract?
The ribs are pulled inwards an downwards
What do abdominal muscles do during forced exhalation?
Contract and push the diaphragm upwards
What else may help pull the ribs downwards?
Additional muscle groups
What is lung cancer?
The uncontrolled proliferation of lung cells leading to the abnormal growth of lung tissue
What can the abnormal growth of lung tissue impact?
Normal tissue function, leading to a variety of symptoms according to size and location
What are the two main reasons lung cancers are the most common cause of cancer related death worldwide?
- lungs are vital and the abrogation of their normal function is detrimental to health
- lungs possess a rich blood supply increasing the likelihood of metastasis
What are common causes of lung cancer?
Radiation
Ageing
Pollution
Environment
Diseases
Genetics
Occupation
Asbestos
Tobacco
Smoking
What is emphysema?
A lung condition where the walls of the alveoli lose their elasticity due to damage to the alveolar walls
What does the loss of elasticity in alveoli result in?
The abnormal enlargement of the alveoli
What does the abnormal enlargement of the alveoli lead to?
A lower total surface area for gas exchange
What can the degradation of the alveolar walls cause?
Holes to develop and alveoli to merge into huge air spaces
What is the major cause of emphysema?
Smoking
Why is the major cause of emphysema smoking?
As the chemical irritants in cigarette smoke damage the alveolar walls
What does damage to the lung tissue lead to the recruitment of?
Phagocytes to the region
In damaged lung tissue what does the recruitment of phagocytes produce?
An enzyme called elastase
What does elastase do?
Breaks down the elastic fibres in the alveolar wall
What can elastase activity be blocked by?
An enzyme inhibitor but only when elastase concentrations are increased
What is a small proportion of emphysema cases caused by?
A hereditary deficiency in the enzyme inhibitor due to a gene mutation
When does ventilation in humans change in response to?
Levels of physical activity
Why doe ventilation change in response to physical activity?
As the bodys energy demands are increased
What does ATP production produce as a waste product?
Carbon dioxide
What detects changes in bloodCO2 levels?
Chemosensors in the walls of the arteries
Where does chemosensors send signals to?
The brain stem
What increases as energy intensity increases?
Demand for gas exchange
What are the two ways exercise will influence ventilation?
- increase ventilation rate
- increase tidal volume
How does an increased ventilation rate help when exercise intensifies?
A greater frequency of breaths allows for a more continuous exchange of gases
How does an increased tidal volume help when exercise intensity is increased?
Increasing the volume of air taken in and out per breath allows for more air in the lungs to be exchanged
What are the three ways ventilation in humans can be monitored?
- simple observation
- chest belt and pressure meter
- spirometer
How does simple observation work?
Counting the number of breaths per minute
How does chest belt and pressure meter work?
Records the rise and fall of the chest
What is spirometry?
The measuring o the amount/speed at which air can be inhaled or exhaled
What is a spirometer?
A device that detects the changes in ventilation and presents the data on a digital display
What is a more simplistic method of a spirometer?
Breathing into a balloon and measuring the volume of air in a single breath
How can the volume of air in a balloon be determined?
By submerging the balloon in water and measuring the volume displaced
