The Respiratory System

Question 1

List the functions of the respiratory system.

Answer 1

Supply oxygen
Excrete carbon dioxide, water, heat, alcohol and ketones
Maintain pH levels

Question 2

Distinguish between the upper and lower respiratory tracts.

Answer 2

UPPER
Nose, nasal cavity, paraneal sinuses, pharynx and larynx

LOWER
Trachea, Bronchi (primary, secondary and tertiary), bronchioles and alveoli

Question 3

Describe the gross and microscopic anatomy of the respiratory tract and relate it to function.

Answer 3

Nasal cavity - warms, cleanses and humidifies air, detects odours, resinating chamber that modifies the voice. Has columnar ciliated pseudostatified epithelium cells. 3 conchae (folds in mucosa) on each side.
Paranasal air sinuses - Hollow areas in the skull
Pharynx - extends from nose to larynx. Passageway for air and food.
Epiglottis - prevents food from going down trachea
Larynx - made of cartilage which maintains an open airway
Trachea - Contains c-shaped rings of cartilage which maintain an open airway. Mucous glands and smooth muscle.

Question 4

Distinguish between the conductive and respiratory portions of the respiratory tract.

Answer 4

CONDUCTIVE
Nose, Pharynx, Larynx, Trachea, Bronchi, Bronchioles, Terminal bronchioles

RESPIRATORY
Respiratory bronchioles alveolar ducts, alveolar sacks, alvioli

Question 5

Describe the anatomical arrangement of the chest wall and pleura.

Answer 5

Hilum - Entrance into the lung
Visceral pleura - Coveres the lung
Parietal pleura - Lines the chest wall
Pleural cavity - Reduces friction, creates pressure gradient, isolates lungs.

Question 6

Describe the gross anatomy of the lung.

Answer 6

R lung = wider and shorter, 3 lobes (superior, middle and inferior) with oblique and horizontal fissures
L lung = longer and thinner, 2 lobes (superior and inferior) with oblique fissure.

Question 7

Identify the muscles of normal and forced ventilation.

Answer 7

QUIET INSPIRATION - External intercostals, diaphragm
QUIET EXPIRATION - Passive
FORCED INSPIRATION - Sternocleidomastoid, scalenes, pectorallis major and minor.
FORCED EXPIRATION - Internal intercostals, oblique and rectus abdominus, quadrates lumborum

Question 8

Explain the mechanisms of ventilation.

Answer 8

External intercostals push the ribcage up and out. Diaphragm flatters. This causes a decrease in intrapulmonary pressure. Gas then enters down a pressure gradient.

Question 9

Describe the principles that underlie the movement of gasses during ventilation - both in and out of the alveoli and across the respiratory epithelium.

Answer 9

Diffusion. The movement of substances from a high concentration to a low concentration

Question 10

Name and define each of the respiratory air volumes and capacities.

Answer 10

Tidal volume - Normal breath intake (5L)
Expiratory reserve volume - Extra volume when forced (M=2.2, F=2)
Inspiratory reserve volume - Extra volume when forced (M=3.2, F=2)
Residual volume - Left over air in lungs (M=1.1, F=1.2)
Vital capacity - Amount in/out when forced in total (4-5L)

Question 11

Discuss how alterations in lung compliance and elasticity can effect ventilation.

Answer 11

Pulmonary compliance - the ease at which the lungs can be expanded. Reduced by: Scar tissue, difficulty in expanding lungs and blockage e.g fluid and mucous in small respiratory passages and low levels of surfactant.

Question 12

List the components and describe the characteristics of the respiratory membrane.

Answer 12

Respiratory membrane = Alveoli and capillaries

Three very thin layers, squamous epithelium.

Question 13

Discuss how the partial pressure and solubility of a gas aid its diffusion.

Answer 13

Henry’s law - The amount of gas that dissolves in water is determined by its solubility in water and its partial pressure in air.
The more soluble a gas is the more it will diffuse as it has to be dissolved in surfactant. The higher the partial pressure the more diffusion will occur because there is a higher pressure gradient.

Question 14

Compare the exchange of oxygen and carbon dioxide during external and internal respiration.

Answer 14

External respiration = air into lungs

Internal respiration = particles moving into the cell from the blood

Question 15

Describe how blood transports oxygen and carbon dioxide.

Answer 15

CO2
7% in plasma, 23% Hb, 70% in blood plasma as HCO3-

O2
98.5% Hb, 1.5% in plasma

Question 16

Explain how the oxygen-haemoglobin dissociation curve is affected by PaCO2, pH, temperature and other factors.

Answer 16

When carbon dioxide increases, temperature increases and pH decreases saturation decreases.
Foetal haemoglobin has a higher affinity for oxygen than adult

Question 17

Discuss the role of the respiratory system in the maintenance of acid-base balance.

Answer 17

CO2 is acidic when dissolved in the blood. By expelling CO2 pH is reduced.

Question 18

RESPIRATORY ACIDOCIS

Answer 18

When the lungs cannot remove all the CO2 that the body produces. This causes bodily fluids particularly the blood to become acidic.

Question 19

RESPIRATORY ALKALOSIS

Answer 19

Where increased respiration elevates the blood pH beyond the normal range.

Question 20

Discuss the role of the respiratory centres in the control of breathing.

Answer 20

The respiratory centre is located in the medulla oblongata and the pons. It receives information from the chemoreceptors etc and sends signals to increase or decrease breathing rate

Question 21

Distinguish between peripheral and central chemoreceptors.

Answer 21

PERIPERAL
Located in the aortic bodies and carotid bodies (main O2 sensors). Mediate 30% of the response to CO2 changes.

CENTRAL
Located on the surface of the medulla. Monitor pH of CSF, mediate 70% of the response to CO2 changes.