Topic 2.1: Ventilatory System

Question 1

2.1.1
List the principal structures of the ventilatory system.

Answer 1

Question 2

The Nose

Answer 2

• Nostrils hairs - block dust, insects from entering nose.
• Ensure air makes contact with mucous layer of the nasal cavity
• Allows the nose to warm, humidify (moisten) and cleanse the air

Question 3

Pharynx

Answer 3

• Located at the back of the nasal cavity involved in both respiration and digestion
• Made up of 3 parts
• Continues to warm and filter air

Question 4

Larynx

Answer 4

• The voice box situated at the top of the trachea.
• Continues to warm and filter air.
• The epiglottis blocks the trachea during swallowing, preventing food entry and halting breathing momentarily

Question 5

Trachea

Answer 5

• Delivers air into the lungs
• The cartilaginous trachea, branches into the two main bronchi

Question 6

Bronchi

Answer 6

Branches delivering air into each of the lungs (one bronchus into each lung)

Question 7

Bronchioles

Answer 7

• Bronchioles further divide delivering air to alveolar ducts
• Cilia carry mucus with trapped dust to back of the throat where it is swallowed.

Question 8

Alveoli

Answer 8

• Millions of thin walled air sacs which receive air from bronchioles through alveolar ducts.
• Responsible for gaseous exchange
• Takes place between alveoli and pulmonary capillaries.

Question 9

Diaphragm

Answer 9

• Primary muscle used in respiration
• Dome-shaped muscle is located just below the lungs and heart

Question 10

Outline the functions of the conducting airways (important)

Answer 10

• Low resistance pathway for airflow
• Defence against chemicals, foreign and harmful substances
• Warming and moistening the air

Question 11

Pulmonary ventilation

Answer 11

Inflow and outflow of air between the atmosphere and the lungs (also called breathing)

Question 12

Total lung capacity

Answer 12

Total amount of air that the lungs can
hold

TV + IRV + ERV + RV

Question 13

Tidal volume

Answer 13

volume of air breathed in and out in any one breath

Question 14

Expiratory reserve volume

Answer 14

The reserve amount that can be exhaled beyond what is normal

Question 15

Inspiratory reserve volume

Answer 15

additional amount of air that can be inhaled after a normal inhalation

Question 16

Residual volume

Answer 16

volume of air still contained in the lungs after a maximal exhalation

Question 17

Vital Capacity

Answer 17

max. amount of air that can be exhale after a max. inhale

TV + IRV + ERV

Question 18

2.1.5. Describe nervous and chemical control of ventilation during exercise. (important)

Answer 18

• Ventilation increase as a result of increase on blood activity level (low pH) due to increase CO2 content of blood detected by the respiratory center.
• Respiratory center send signals to muscles involves in ventilation
• Neural control of ventilation include lung stretch receptors, muscle proprioreceptors and chemoreceptors.

Question 19

2.1.6. Outline the role of hemoglobin in oxygen transportation.

Answer 19

• Most (98.5%) of oxygen in the blood is transported by hemoglobin as oxyhemoglobin within red blood cells
• Transports oxygen from the lungs to the rest of the body

Question 20

2.1.7. Explain the process of gaseous exchange at the alveoli.

Answer 20

1. We inhale oxygen and exhale CO2
2. Oxygen enters into our lungs and into alveoli
3. Alveoli wall is very thin so gas can enter and exit
4. Oxygen diffuses from the site of higher pressure (alveolar air) to the site of lower pressure (capillary blood)
5. CO2 from blood diffuses from site of higher pressure to lower pressure
6. Oxygen binds with red blood cell by hemoglobin = oxyhemoglobin

Question 21

Outline the mechanics of the diaphragm when breathing

Answer 21

1. Prime mover of pulmonary ventilation
2. In a relaxed state, bulges upward pressing against the base of the lungs, making the thoracic cavity smaller
3. When contracts, enlarges the thoracic cavity and lungs creating an inflow of air
4. When relaxes, bulges upward again, compresses the lungs and expels the air
5. Responsible for 2/3 of airflow

Question 22

Describe the role of the Intercostal Muscles during respiration.

Answer 22

There are two intercostal muscles:

• External and Internal

External Intercostal Muscles:

• Contract during inhalation - increases the width of the chest cavity. More volume = less pressure. Result in airflow into the lungs.

Internal Intercostal Muscles:

• Don’t contract during normal expiration.
• Only contract during forced exhilation or exercise to push air out faster

Question 23

Name the accessory muscles during exercise (inspiration)

Answer 23

Small muscles attached to ribs and sternum that aid in increasing thoracic volume.

During max. efforts:

• trapezius, back, neck extensors contract to increase thoracic cavity

Question 24

Name the accessory muscles during exercise (expiration)

Answer 24

• Internal Intercostal muscles and abdominals muscles contract to force air out of the lungs.
• Abdominal muscles pull the ribs down and force the diaphragm upward pushing air out.

Question 25

What is the relationship between volume and pressure in the thoracic cavity?

Answer 25

Inverse relationship: * Volume increase, pressure decrease * Volume decrease, pressure increase

Question 26

**Inspiration** Mechanism at **Rest**

Answer 26

1. External Intercostal Muscles contract → **increases the width of the chest cavity** 2. **Diaphragm** **contracts** at the same time pulling the muscle downwards 3. Both actions **increase** the **volume** **capacity** of the lungs, decreasing the air pressure inside the lungs. 4. Atmospheric air is forced into the lungs equalizing air pressure

Question 27

**Expiration** Mechanism at **Rest**

Answer 27

1. Diaphragm and external intercostal muscles relax to their original position. 2. Volume is decreased, air pressure inside the lungs is increased and air is forced out to equalize pressure

Question 28

Explain the difference between **hyperventilation** and **hypoventilation** in relation to PO2 and PCO2

Answer 28

Question 29

What causes ventilation to increase during exercise? A. High pH B. Decreased blood acidity level C. Increased carbon dioxide level D. Lower carbon dioxide level

Answer 29

c. Increased carbon dioxide level

Question 30

How does the Respiratory Centre know when to increase the breathing depth and rate?

Answer 30

Low blood pH level --> brain's respiratory center signals the respiratory muscles to increase breathing rate to expel excess co2

Question 31

Muscle proprioreceptors

Answer 31

Sensors that tell CNS about joint angles, muscle stretch, and body balance

Question 32

Chemoreceptors

Answer 32

Detect changes in blood acidity levels (pH), carbon dioxide (pCO2) and oxygen (O2) content of the blood

Question 33

Lung stretch receptors

Answer 33

Prevents overexpansion by signaling the respiratory center to stop inspiration and start expiration.