Unit 4: Respiratory System

Question 1

What are the three main functions of the respiratory system?

Answer 1

Supply O2 to the blood
Remove CO2 from the blood
Regulate blood pH (acid-base balance)

Question 2

External vs Internal respiration

Answer 2

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.

Question 3

Trace the route of air from the external nares to an alveoli.

Answer 3

Nasal cavity
Epiglottis
Larynx
Trachea
Bronchi
Lung
Terminal bronchiole
Alveoli
Alveolar sac

Question 4

Where in the respiratory tract is air filtered, warmed and moistened?

Answer 4

Nasal cavity

By the mucus secretions and hairs in the nose

Question 5

How do the lungs maximize the rate of gas exchange?

Answer 5

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

Question 6

What begins inspiration?

Answer 6

The contraction of the diaphragm and the external intercostal muscles begins inspiration

Question 7

What causes expiration?

Answer 7

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

Question 8

What is ventilation?

Answer 8

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)

Question 9

What is tidal volume?

Answer 9

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

Question 10

What is respiratory frequency?

Answer 10

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

Question 11

Name two major brain areas involved in the nervous control of breathing.

Answer 11

The areas of the brain stem that are important in the regulation of ventilation are:

• The medulla oblongata
• The pons

Question 12

What is within the medulla olongata?

Answer 12

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

Question 13

What is within the pons?

Answer 13

Within the pons are:
Pneumotaxic center
Apneustic center
These centers act to ensure that the transition from inhalation to exhalation is smooth

Question 14

What is diffusion?

Answer 14

Diffusion: The movement of a gas, liquid, or solid from a region of high concentration to a region of low concentration through random movement.

Question 15

When can diffusion occur?

Answer 15

Diffusion can only occur if a difference in concentration exists, and such difference is called a concentration gradient

Question 16

What are the three factors that affect the rate of diffusion?

Answer 16

1. The size of the concentration gradient:
   As the size of the gradient increases, greater rates of diffusion are observed
2. 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.
3. The surface area between the two areas where diffusion occurs:
   The anatomy of the lung provides a huge surface area for diffusion

Question 17

What ways are oxygen and carbon dioxide transported in the blood?

Answer 17

Oxygen transport (O2 transport) 
Carbon dioxide transport (CO2 transport)
bicarbonate system (70-75%)

Question 18

What is oxygen transport?

Answer 18

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.

Question 19

How can oxygen transport be achieved?

Answer 19

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

Question 20

What is carbon dioxide transport?

Answer 20

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

Question 21

How can carbon dioxide transport be achieved?

Answer 21

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

Question 22

How can be bicarbonate system be achieved?

Answer 22

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.

Question 23

What is the normal blood pH level?

Answer 23

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

Question 24

What is blood pH?

Answer 24

Blood pH: The measure of how acidic or how basic the blood is.

Question 25

What are the four main factors that affect internal respiration?

Answer 25

An increase in the PO2 gradient
An increase in PCO2
A decrease in pH
An increase in temperature

Question 26

What is a-vO2 difference?

Answer 26

a-vO2 difference (a-vO2 diff): The difference between the amount of O2 in the artery and vein reflects the amount of O2 delivered to the muscle.

Question 27

Are there changes to respiratory function with training?

Answer 27

VE at rest may change
During submaximal exercise, no changes or very very slight changes are observed. Sometimes a decline in VE can be observed.
During maximal exercise, the training does result in increases in VE
These changes may be due to the increase in both strength and endurance of the respiratory muscles

Question 28

Define maximal rate of oxygen consumption. How is it proportional to workload?

Answer 28

Maximal rate of oxygen consumption (VO2 max): The maximum volume (V) of oxygen (O2) in millilitres that the human body can use in one minute per kilogram of body weight, while breathing air at sea level.
VO2 is proportional to workload, meaning that the greater the workload, the greater the VO2 or the greater the amount of O2 used in the body.

Question 29

What is the RER and what information does it give us?

Answer 29

Respiratory Exchange Ratio (RER):
The ratio between VCO2 and VO2 is used to calculate the respiratory exchange ratio (RER). The RER is indicative (suggestive) of which metabolic systems are being used within the working muscle.

Question 30

What do MOST exercise physiologists accept as the most influential limiting factor for VO2 max?

Answer 30

Most exercise physiologists support the notion that it is the cardiovascular system that limits the VO2max in healthy people.
More specifically, it appears that the cardiovascular system is unable to meet the demands of the working muscle and deliver adequate amounts of oxygen.
The limitation to VO2max within the cardiovascular system appears to be related to cardiac output (Q).

Question 31

What is oxygen deficit?

Answer 31

Oxygen deficit (O2 deficit): The amount of oxygen taken in during stressful exercise minus the amount of oxygen that would have otherwise been required for steady-state aerobic exercise.

Question 32

What metabolic systems does the body rely on for energy during the oxygen deficit phase?

Answer 32

During this period, the working muscle must partially rely on metabolic systems that do not require oxygen (anaerobic metabolic systems).
These anaerobic systems make up the difference and compensate for the “lag” in VO2, allowing the exercise to continue at the new workload.

Question 33

Do trained athletes have smaller or larger oxygen deficit?

Answer 33

Oxygen deficits represent the difference between the oxygen required to perform a task and the oxygen actually consumed prior to reaching a new steady state.
The trained individual will reach this steady-state plateau faster than an undertrained individual and therefore will have a smaller oxygen deficit for an exercise of a given duration.

Question 34

How does aerobic training affect the onset of blood lactate accumulation?

Answer 34

With proper aerobic training, the OBLA (onset of blood lactate accumulation) curve can be shifted to the right such that OBLA occurs later and during higher levels of intense exercise.

Question 35

What is asthma?

Answer 35

Asthma: A disease characterized by spasm of the smooth muscles that line the respiratory system, and over-secretion of mucous, and swelling of the cells lining the respiratory tract.

Question 36

Symptoms of asthma

Answer 36

shortness of breath (dyspnea)

wheezing sounds during breathing

Question 37

What is COPD?

Answer 37

Chronic Obstructive Pulmonary Disease (COP):
A general term that describes a family of diseases that lead to a dramatic reduction in airflow through the respiratory system.

Individuals with COPD cannot perform everyday activities without experiencing dyspnea

Question 38

What is the conductive zone?

Answer 38

The area composed of all of the structures that convey air from the outside of the body through to the lungs. This zone includes the mouth, nose, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles.

Question 39

What is the respiratory zone?

Answer 39

The area composed of the respiratory bronchioles, alveolar ducts, and the alveolar sacs. All of these structures are involved with the exchange of gases between inspired air and the blood.