The Respiratory System

Question 0

Distinguish between the upper and lower respiratory tracts

Answer 0

• UPPER -
  Nasal cavity, nose, pharynx, paranasal sinuses and larynx
• LOWER -
  Trachea, bronchi, bronchioles, alveoli, lungs and diaphragm

Question 1

What are the functions of the respiratory system?

Answer 1

• Supplies the body with O2 and ATP
• Excretes CO2, ketones, water vapour, alcohol and heat
• Maintains pH of body fluids

Question 2

Distinguish between the conductive and respiratory zones of the respiratory system

Answer 2

• CONDUCTING ZONE -
  Filters, warns and moistens air. Transmits air from/to lungs.
  Made of: nose, pharynx, larynx, trachea, bronchi, bronchioles and terminal bronchioles
• RESPIRATORY ZONE -
  Site of gas exchange. Transmits O2 into the blood from the air and CO2 from blood into the air.
  Made of: respiratory bronchioles, alveolar ducts, alveolar sacs and alveoli

Question 3

Explain quiet/normal ventilation

Answer 3

How we breath subconsciously 
- INSPIRATION -
Uses the diaphragm (80%) and external intercostals (20%)
- EXPIRATION -
Based on the elasticity of lungs.

Question 4

Explain forced/loud ventilation

Answer 4

Forced breathing such as when exercising.
- INSPIRATION -
Uses the scalenes, sternocleidomastoid, pectoralis major & minor.
- EXPIRATION -
Uses the intercostals, oblique/rectus abdominis and quadratus lumbarum.

Question 5

Discuss how alterations in lung compliance and elasticity can affect ventilation

Answer 5

• Healthy lungs are stretchy and have high compliance.
• Compliance can be reduced by scar tissue (inflammation, disease), muscle weakness and blockages from fluid and mucous. Also from a low level of surfactant (common in premature babies).

Question 6

Describe how blood transports O2 and CO2

Answer 6

• OXYGEN -
  98.5% carried bound to Haemoglobin (Hb). Each haem portion can carry 4 O2 molecules. 1.5% carried dissolved in plasma.
• CARBON DIOXIDE -
  ~7% dissolved in plasma. ~23% bound to globin peptide chains in Hb. Also present as bicarbonate (HCO3-) ion in plasma (~70%)

Question 7

Discuss the role of the respiratory system centres on the control of breathing

Answer 7

The respiratory centre is formed by groups of nerves in the medulla which controls respiratory pattern (rate/depth).
Activity is adjusted by nerves in the pons in response to input from other parts of the brain.
Motor impulses leaving pass the phrenic and intercostals nerves to the diaphragm and intercostal muscles.

Question 8

Describe the anatomical arrangement of the chest wall and pleura

Answer 8

• the pleura consists of a sac of serous membrane which contains a small amount of serous fluid.
• VISCERAL PLEURA - adherent to the lungs, covering each lobe and fluid
• PARIETAL PLEURA - adherent to the inside of the chest wall and the thoracic surface of the diaphragm, detached from adjacent structures

Question 9

Describe the pleural cavity

Answer 9

Separates the layers of pleura - a thin film of serous fluid allows them to glide over each other to prevent friction

Question 10

What is intrapleural pressure? (Pip)

Answer 10

• as chest wall expands - partietal membrane is pulled away from visceral which creates a ‘vacuum’ (suction)
• this forms a negative pressure as it is impossible to separate membranes - lungs recoil back

Question 11

What is Boyle’s law?

Answer 11

As the volume of the container increases; the pressure goes down and vice versa
EG - as lungs expand, the pressure decreases and particles have more space to move!

Question 12

Describe what happens during inspiration

Answer 12

1) diaphragm and external intercostals contract
2) rib cage rises
3) thoracic cavity volume increases
4) intrapulmonary volume increases
5) intrapulmonary pressure decreases
6) air enters lungs down the pressure gradient until intrapulmonary pressure is equal to atmospheric pressure

Question 13

Describe what happens during expiration?

Answer 13

1) Diaphragm and external intercostals relax
2) rib cage falls
3) thoracic cavity volume decreases
4) intrapulmonary volume decreases
5) intrapulmonary pressure increases
6) intrapulmonary pressure = atmospheric pressure. Air leaves lungs down pressure gradient until pressure balances out.

Question 14

What is partial pressure?

Answer 14

The pressure exerted by each gas (O2 and CO2). It is directly proportional to its percentage in the total gas mixture.

Question 15

Define the term respiratory acidosis

Answer 15

There are more hydrogen ions causing the pH to drop leading to a more acidic environment inside the lungs. CO2 increases causing limited gas exchange (emphysema)

Question 16

Define the term respiratory alkalosis

Answer 16

There are less hydrogen ions causing the pH to increase and become more alkaline. This causes hyperventilating.

Question 17

What are chemoreceptors?

Answer 17

Receptors that respond to changes in the partial pressures of O2 and CO2 in the blood and CSF.

Question 18

What are central chemoreceptors?

Answer 18

• located on the surface of the medulla and bathed in CSF.
  When the arterial partial pressure of CO2 rises they respond by stimulating the respiratory centre to increase ventilation and decrease the CO2 levels.
  Note: don’t want to reduce it too my as it depresses breathing.

Question 19

What are peripheral chemoreceptors?

Answer 19

• located in the aorta and carotid bodies
• sensitive to small rises is partial pressure of CO2 and cause nerve impulses coveted by the glossipharyngeal and vagus nerves to the medulla to stimulate the respiratory centres.
• rate and depth of breathing increase.
• an increase in blood acidity also stimulates these resulting in increased ventilation, CO2 excretion and blood pH

Question 20

The walls of the trachea possess:

Answer 20

C-shaped rings of hyaline cartilage

Question 21

During inspiration:

Answer 21

Pressure in the alveoli is less than atmospheric pressure