Respiratory System

Question 1

What are the components of the upper and lower respiratory tract?

Answer 1

Upper: Nose, nasal cavity, the sinuses and the nasopharynx

Lower: Larynx, trachea, main bronchi, 2’ bronchi, 3’ bronchi, bronchioles, terminal bronchioles, respiratory bronchioles, alverolar ducts, alveolar sacs, alveolus

Question 2

What do type II pneumocytes do?

Answer 2

Secrete surfactant into alveoli to reduce surface tension and prevent the fragile alveoli from collapsing

Question 3

What are the connective tissue layers around the lungs called?

Answer 3

The pleura

Question 4

What are the 6 steps of breathing?

Answer 4

Inspiration (active)

1. Nerve impulse from phrenic nerve causes diaphragm to contract downwards
2. Intercostal muscles (between ribs) and/neck muscles contract further, increasing thoracic cavity
3. Internal pressure of thoracic cavity drops and air is forced into the respiratory tract/lungs

Expiration (passive)

1. The diaphragm and accessory muscles relax
2. Elastic tissue of the lungs, thoracic cage and abdominal organs suddenly recoil
3. Recoil increases the pressure within the lungs (making the pressure relatively positive), thus forcing the air out of the lungs and passageways.

Question 5

What (most) increases the breathing rate?

Answer 5

High CO2 and acidity in the blood increases breathing rate

Low O2 does too, but to a lesser extent.

Question 6

How does high blood CO2 make the blood acidic?

Answer 6

It can be converted into carbonic acid by dissolving in blood plasma (5%) or by conversion in red blood cells by carbonic anhydrase (75%)

CO2 + H2O ↔ H2CO3 (cabonic acid) ↔ HCO3- (bircarbonate) + H+

Question 7

Contraction of the diaphragm results in a:

A. More negative IPP (intrapleural pressure) and inspiration
B. More negative IPP and expiration
C. More positive IPP and inspiration
D. More positive IPP and expiration

Answer 7

A. More negative IPP and inspiration

The diaphragm is a muscular partition between the abdominal and thoracic cavities. It is dome shaped at rest curving up towards the lungs and heart. It flattens when it contracts during inspiration. Because it is anchored around its edges to the ribs and spine, when the diaphragm contracts, the volume of the thoracic cavity increases.

This decreases the pressure (IPP) in the pleural cavity between the thoracic wall and the lungs. Fresh air flows in to equalize the pressure, inflating the lungs.