Respiration

Question 1

What are the two forms of respiration?

Answer 1

Tissue - aerobic metabolism in cells

Ventilation - Gas exchange and all associated processes

Question 2

At rest what is the PO2 and PCO2?

Answer 2

PO2 = 100 mmHg
PCO2 = 40 mmHg

Question 3

What is the pathway for air to enter the lungs?

Answer 3

Air enters into nasal/oral cavities
Pharynx
Larynx
Trachea/Bronchi
Lungs 
Alveoli

Question 4

What is the role of the upper airways?

Answer 4

Filter and humidify air, keeps surface of the system from being damaged and removes particles in air

Question 5

Describe the process of quiet breathing.

Answer 5

During inspiration, diaphragm contracts and external intercostal muscles contract causing the thoracic cavity to expand, this means the intrapleural pressure drops below the atmospheric pressure making a pressure gradient so air flows into the lungs.

The process of normal expiration is passive, elasticity of the lung tissue causes the lung to recoil, as the diaphragm and intercostal muscles relax following inspiration. In turn, the thoracic cavity and lungs decrease in volume, causing an increase in interpulmonary pressure. The interpulmonary pressure rises above atmospheric pressure, creating a pressure gradient that causes air to leave the lungs.

Question 6

What accessory muscles contract in forced breathing to aid the diaphragm and external intercostal muscles?

Answer 6

Muscles of the neck
Accessory muscles of the abdomen - obliques (force organs against diaphragm)
Internal intercostals - compress rib cage

Question 7

What are conducting zones?

Answer 7

Areas of the respiratory tract where gas exchange does not occur

Nose, pharynx, larynx, trachea, bronchi, bronchioles

Question 8

What are the two types of alveolar cells?

Answer 8

Type 1 epithelial cell - occupy 97% of SA and site of gas exchange

Type 2 epithelial cell - occupy 3% and produce a surfactant to act as a lubricant to reduce surface tension

Question 9

What are the two circulation systems of the lung?

Answer 9

Pulmonary circulation - bring deoxygenated blood to the lungs to become oxygenated before returning to heart for circulation

Bronchial circulation - brings oxygenated blood to the lung parenchyma

Question 10

What is the normal V/Q ratio?

Answer 10

0.8

Question 11

Where is ventilation the greatest in the lung and why?

Answer 11

Ventilation not evenly distributed throughout lung due to gravity. Greater Ventilation at base of alveoli than at apex, therefore greater perfusion at the base than apex.

Question 12

How is the respiratory and CVS systems specialised?

Answer 12

Large SAs for gas exchange
Large partial pressure gradients
Specialised mechanisms for transporting O2 and CO2

Question 13

How can oxygen be transported around the body?

Answer 13

Dissolved - proportionate to partial pressure, for every 1mmHg O2 there is 0.003ml/100m2 of O2

Bound to haemoglobin - major transport system molecule

Question 14

What can be used to determine oxygen saturation in the body?

Answer 14

Pulse oximeter

Question 15

What does a V/Q ratio of 0.8 indicate?

Answer 15

The body produces 80 molecules of CO2 for every 100 molecules of oxygen inhaled

Question 16

How is CO2 transported?

Answer 16

Dissolved - 7%
Bound to haemoglobin - 23%
Bicarbonate - 70%

Question 17

How is bicarbonate produced?

Answer 17

Catalyzed by carbonic anhydrase, carbon dioxide (CO2) reacts with water (H2O) to form carbonic acid (H2CO3), which in turn rapidly dissociates to form a bicarbonate ion (HCO−
3 ) and a hydrogen ion (H+)

Question 18

Where can carbonic anyhdrase be found?

Answer 18

In the blood

Duodenum

Question 19

What is needed to maintain a 7.4 pH of the blood?

Answer 19

20:1 bicarbonate to carbonic acid ratio

Mainly mediated by pH sensors in medulla oblongata and probably in kidney

Question 20

Where in the brain controls breathing and through which signal receptors?

Answer 20

In the brainstem through:

• Sensory Chemoreceptors and Baroreceptors - Feedback on PO2, PCO2 and pH in blood.
• Mechanoreceptors - found in walls of lungs

These signals will be sent via vagus nerve to the NTS in the brainstem.

Question 21

Where are baroreceptors found in relation to the aorta?

Answer 21

In the aortic arch

In the carotid sinuses of the common carotid arteries

Question 22

Where are chemoreceptors found in relation to the aorta?

Answer 22

In the aortic and carotid bodies

Question 23

What is the Total Lung Capacity?

Answer 23

The volume in the lungs at maximum inflation, the sum of vital capacity and residual volume.

Question 24

What is the Tidal Volume?

Answer 24

Vol of air moved into or out of the lungs during quiet breathing, approx 500mL per inspiration

Question 25

What is Residual volume?

Answer 25

Vol of air remaining in the lungs after a maximal exhalation

Question 26

What is the Vital capacity?

Answer 26

The volume of air breathed out after the deepest inhalation

Question 27

What is the Inspiratory vital capacity?

Answer 27

The maximum volume of air inhaled from the point of maximum inhalation

Question 28

What is the functional residual capacity?

Answer 28

The volume in the lungs at the end-expiratory position

Question 29

What is the forced vital capacity?

Answer 29

Vital capacity from a maximally forced expiratory effort instead of passive exhale like normal vital capacity

Question 30

What is the FEV1?

Answer 30

Forced expiratory volume after 1 second

Measured using spirometer

Question 31

What are two important pulmonary function tests?

Answer 31

FEV1
FVC
Use ratio, divide FEV1 into FVC, for diagnosis

Decreased FVC associated with COPD, emphysema, chronic bronchitis, pulmonary fibrosis, inflammatory lung disease