Unit 4: Respiratory System Flashcards
What are the three main functions of the respiratory system?
Supply O2 to the blood
Remove CO2 from the blood
Regulate blood pH (acid-base balance)
External vs Internal respiration
External respiration: The processes that occur within the lungs involving the exchange of oxygen and carbon dioxide.
Internal respiration: The exchange of gases at the tissue level, where O2 is delivered and CO2 is removed.
Trace the route of air from the external nares to an alveoli.
Nasal cavity Epiglottis Larynx Trachea Bronchi Lung Terminal bronchiole Alveoli Alveolar sac
Where in the respiratory tract is air filtered, warmed and moistened?
Nasal cavity
By the mucus secretions and hairs in the nose
How do the lungs maximize the rate of gas exchange?
Both the walls of the alveolar sacs and the capillary surrounding these sacs are only one cell thick
A very short distance for gas to diffuse
Therefore, the structure of the lungs provides a large surface area and a minimal distance for the diffusion of gases to occur
This maximizes the rate of gas exchange
What begins inspiration?
The contraction of the diaphragm and the external intercostal muscles begins inspiration
What causes expiration?
During expiration, the diaphragm and intercostal muscles relax, causing the thorax and lungs to recoil
The air pressure within the lungs increases to above the pressure of the atmosphere, causing air to be forced out of the lungs
What is ventilation?
Ventilation (VE):
To combination of inspiration and expiration together
VE is influenced by two factors:
The volume of air in each breath (tidal volume, VT)
The number of breaths taken per minute (respiratory frequency, f)
What is tidal volume?
Tidal volume (VT):
The volume of air in each breath
At rest, the typical VT is about 0.5L/breath
During exercise, the typical VT can increase up to 3 to 4L/breath
What is respiratory frequency?
Respiratory frequency (f):
The number of breaths taken per minute
At rest, a typical frequency of respiration is about 12 breaths/min
During exercise, frequency can increase up to 30 to 40 breaths/min
Name two major brain areas involved in the nervous control of breathing.
The areas of the brain stem that are important in the regulation of ventilation are:
- The medulla oblongata
- The pons
What is within the medulla olongata?
Within the medulla oblongata are:
The inspiratory center (the nerves located here generate rhythmic signals sent to the respiratory muscles, the diaphragm, and the intercostals) and the expiratory center
What is within the pons?
Within the pons are:
Pneumotaxic center
Apneustic center
These centers act to ensure that the transition from inhalation to exhalation is smooth
What is diffusion?
Diffusion: The movement of a gas, liquid, or solid from a region of high concentration to a region of low concentration through random movement.
When can diffusion occur?
Diffusion can only occur if a difference in concentration exists, and such difference is called a concentration gradient
What are the three factors that affect the rate of diffusion?
- The size of the concentration gradient:
As the size of the gradient increases, greater rates of diffusion are observed - The thickness of the barrier between the two areas where diffusion occurs:
Within the lungs, the distance between the alveoli and the capillaries that surround each alveoli is extremely small, essentially only 1-2 cells thick, optimizing the diffusion distance. - The surface area between the two areas where diffusion occurs:
The anatomy of the lung provides a huge surface area for diffusion
What ways are oxygen and carbon dioxide transported in the blood?
Oxygen transport (O2 transport) Carbon dioxide transport (CO2 transport) bicarbonate system (70-75%)
What is oxygen transport?
Oxygen transport (O2 transport): The process by which oxygen is absorbed in the lungs by the hemoglobin in circulating deoxygenated red blood cells and carried to the peripheral tissues.
How can oxygen transport be achieved?
O2 transport is achieved in two ways:
First a small amount of oxygen is actually dissolved within the plasma (the fluid component of blood)
This only represents 2% of the oxygen found in blood
The other way is by binding to a specialized protein found in erythrocytes, called hemoglobin
The majority of oxygen transported in the blood is bound to hemoglobin
What is carbon dioxide transport?
Carbon dioxide transport (CO2 transport): The process by which carbon dioxide in the blood is moved into the alveoli and then exhaled from the body
How can carbon dioxide transport be achieved?
Carbon dioxide must be moved from body tissues, where it is produced, back to the lungs where it can be moved into the alveoli and then exhaled and removed
CO2 transport is achieved in three ways:
First, a small amount of carbon dioxide is dissolved in the plasma
Only 5-10% of carbon dioxide is transported dissolved in plasma
The remaining 90-95% diffuses into erythrocytes
It can also bind to hemoglobin to form carbaminohemoglobin when there are low concentrations of oxygen (20%)
Having arrived in the lung, the elevated concentrations of oxygen stimulate the hemoglobin to release carbon dioxide, which then diffuses out of the alveoli and is exhaled
How can be bicarbonate system be achieved?
It diffuses into the erythrocytes, but undergoes a chemical reaction with water, forming a weak enzyme found in erythrocytes called carbonic acid
This carbonic acid then dissociates forming a hydrogen ion and a bicarbonate ion
The resulting hydrogen ion binds to the hemoglobin while the bicarbonate ion diffuses into the plasma
At the lungs, the partial pressure of carbon dioxide is low and this process is reversed
The higher partial pressure of oxygen mediates the release of the hydrogen ion from the carbon dioxide
Once the carbon dioxide is returned back to its original form , it can diffuse out of the blood and into the alveoli, and then exhaled.
What is the normal blood pH level?
Generally blood pH is maintained very close to a pH of 6.4
In situations where large amounts of acid are released into the blood, such as during exercise (lactic acid), results in a decline in blood pH
Decreased pH means an increase in acidity and hydrogen ions in the blood
What is blood pH?
Blood pH: The measure of how acidic or how basic the blood is.
