BIOL 273 - Unit 5.1 + 5.2 Flashcards
What does the respiratory system allow for (4)
- Exchange of gases between atmosphere and blood
- Homeostatic regulation of body pH
- Protection from inhaled pathogens and irritating substances
- Vocalization
4 main processes of the respiratory system
- Gas exchange between atmosphere and lungs (ventilation)
- Gas exchange between lungs and blood - CO2 and )2
- Transport of gases by blood - CO2 and O2
- Exchange of gases between blood and tissues
What structures/systems exist in the respiratory system that is involved in both ventilation and gas exchange
- Conducting system - airways
- Exchange surface - alveoli
- Pumping system - bones and muscles of the thorax
Describe the conducting system
passages or airways - lead from environment to the exchange surface of the lungs
What two parts can the conducting system divide into and what strucutres are involved
- Upper respiratory tract
- Mouth, nasal cavity, pharynx, larynx - Lower respiratory tract
- Trachea, bronchi, bronchioles, lungs
Describe the exchange surface
- sites of gas exchange - the alveoli
- tiny hollow sacs found at the ends of the terminal bronchiole
- wrapped with an extensive capillary network which covers 80-90% of the alveolar surface
Gas exchange occurs by diffusion between…
alveoli and capillary
What are the types of alveoli cells
- Type I alveolar cells - large but thin
- Type II alveolar cells - smaller but thicker
Function of Type I alveolar cells
rapid gas diffusion
Function of Type II alveolar cells
synthesize and secrete surfactant (used to decrease surface tension to keep lung inflated)
What allows exchange with alveoli
blood vessels of the pulmonary circulation
Why is rate of blood flow high
becuse all the output of the right ventricle goes to the lungs vs. whole body for the blood leaving the left ventricle
Describe the pumping system
bones and muscle of the thorax allow for ventilation (inspiration and expiration)
What are the two lungs surrounded by
the pleural sac - forms a double membrane around each lung
- pleura is filled with fluid
- Acts as a lubricant
Describe the relationship between volume and pressure of a gas
inversely related
Amount of gas will dissolve in a liquid is determined by…
- Partial pressure of the gas
- Solubility of the gas in the liquid
Partial pressure of an atmospheric gas equation
Pressure of atmosphere x % of gas in atmosphere
Pressure volume relationships: Boyle’s Law
P1V1 = P2V2
What is critical for ventilation
pressure-volume relationship
- during inspiration and expiration, the volume of the thoracic cavity changes
- this causes changes in the alveolar pressure
How does volume change occur in the lungs
- lungs do not have muscles so they cannot change volume on their own
- the muscles are in the chest wall - contraction will change thoracic volume
What does the volume in the chest depend on
- The transpulmonary pressure - difference between alveolar pressure and intrapleural pressure
- Degree of elasticity of lungs
What is the pressure inside the lungs referred to as
the alveolar pressure
What is the pressure outside the lungs referred to as
pressure in the intrapleural fluid
Importance of airways in ventilation and their requirements
- Airways serve an important role in conditioning the air before it reaches the lungs
- Warm air to 37 degrees to maintain core body temp and protect alveoli
- Add water vapour to air to prevent drying of epithelia
- Filter out foreign material
Describe the process of filtering foreign material in the airways using watery saline solution
- cells move Cl from ECF into the cell via the NKCC - Cl transported to lumen of airway via apical anion channel
- Na+ moves between cells from ECF to lumen
- concentration gradient of NaCl draws water towards the lumen creating the watery saline solution
What type of cells located in ciliated epithelia secretes mucous
goblet cells
Describes how mucous is involved in the filtering of foreign material in the airways
- Mucous contains immune cells that kill invaders
- Mucus is moved up to the pharynx (mucus escalator)
- Transferred to the digestive tract where additional bacteria are destroyed
- transported by cilia
Describe the steps of inspiration
- Somatic motor neurons trigger contraction of diaphragm and inspiratory muscles (external intercostals contract)
- Thorax expands - thoracic volume up
- Alveolar and intrapleural pressure decreases
- Lungs expand resulting in air flowing into lungs
Describe the steps of Expiration
- Impulses from somatic motor neurons stop
- Diaphragm and thoracic muscles relax which returns thorax to their original positions - volume down
- Alveolar and intrapleural pressure increases
- Elastic recoil of the lungs decreases lung volume - air flows out of the lungs
Describe expiration during quiet breathing
expiration is a passive process
- depends on elastic recoil of the thoracic muscles and the lungs
Describe expiration during heavy breathing
expiration is an active process
- depends on contraction of internal intercostals and abdominal muscles
Which muscles contract during inspiration?
Which muscles are active during expiration?
Inspiration - external intercostals
Expiration - internal intercostals
Describe the Intrapleural pressure in the lung and explain why is it this way
sub- atmospheric: having lower pressure in the pleural fluid (outside lung) than inside lung helps keep lung expanded and open
What happens to intrapleural pressure when air gets into pleural cavity
pressure increases
Pneumothorax
when pressure difference between in and outside of the lungs is abolished (lung collapse)
What are the two factors for breathing
- Compliance (stretchability) of the lungs
- The resistance to air flow in the airways
