Respiration

Question 1

Describe how the nasal cavity is adapted for respiration

Answer 1

Contains TURBINATES that…
* Have a large surface area to heat and humidify air
* Increase airflow resistance ∴ increase the likeliness of harmful inhaled particles are trapped by hair and mucous.

Also contains CAPILLARIES under the mucosa that…
* Allow water transport to the surface and prevent dehydration

Question 2

Describe how the Nasopharynx is effective for respiration

Answer 2

Provides a change in airflow that increases the time in-which more harmful particles can become trapped.

Additionally, it contains lymphatic tissues that provides immunological defence.

Question 3

Describe how the trachea is effective in respiration

Answer 3

Comprised of a series of incomplete rings of hyaline cartilage.
* Provides structural support

Contains smooth muscle under the epithelial layer.
* Controls the diameter of the trachea

Question 4

What are the 5 stages of respiration

Answer 4

1. Pulmonary ventilation (movement of air in/out of the lungs)
2. External Respiration (exchange of O2&CO2 between the lungs and the pulmonary capillaries)
3. Transport of gases through blood circulation
4. Internal respiration (Exhange of O2&CO2 between tissue and systemic capillaries)
5. Cellular respiration (Utilisation of O2 followed by production of CO2)

Question 5

What is the cyclical respiratory muscle contraction sequence

Answer 5

A sequence of events that total up inspiration.
* Diaphragm is innervated by the phrenic nerve to contract
* Intercostal muscles are innervated by the intercostal nerves to contract (pushing on the ribcage)

• Resulting in the thoracic cavity expanding

Question 6

What causes and controls inspiration

Answer 6

Nerve impulses sent from the pre-Botzinger complex, medulla oblongata cause the contraction of the diaphragm and intercostal muscles.

Question 7

Explain what the Hering-Breuer reflex is and what it does

Answer 7

A negative feedback loop consisting of pulmonary stretch receptors in the airway smooth muscle. Once stimulated by the inflation of the lungs, they send out an action potential to the brain (signals to stop nerve impulse).

Expiration naturally follows once diaphragm and intercostal muscles relax

Question 8

How is the flow of air calculated

Answer 8

P_alv- P_alv / Resistance

Question 9

What is the transpulmonary pressure and how is it measured

Answer 9

Ptp is the difference in pressure between the inside and outside of the lungs.

Ptp = Palv - Ppip

Question 10

What happens to the Intrapleural pressure [Ppip] during inspiration

Answer 10

It decreases

Question 11

What mechanism allows air to flow into alveoli and how

Answer 11

The alveolar pressure decreases (becomes subatmospheric) to a value lower than the atmospheric pressure. Air diffuses down this gradient and into the alveoli.

Question 12

Define atelectasis

Answer 12

The complete or partial collapse of the lung or a specific area in the lung.

Question 13

What is lung compliance and its formula

Answer 13

Lung compliance is a measure of the lungs ability to stretch during inspiration.

LP = Δ Lung volume / Δ Transpulmonary pressure

Question 14

What impacts Lung compliance

Answer 14

• Pulmonary surfactant
• Stretchability

Question 15

What does having an increased lung compliance lead to

Answer 15

Lungs are susceptible to collapsing.
A high LP is usually see in Emphysema.

Question 16

What does it mean to have a LOW lung compliance

Answer 16

The elastic recoil is HIGH resulting in stiffer lungs which require more energy during respiration.

Chracterised by a difficutly to breath. It is commonly seen in cases of pulmonary fibrosis (COPD)

Question 17

What is primary surfactant and what does it do

Answer 17

A complex that line the alveoli that lowers the surface tension and thereby maintaining inflatability in the alveoli.

Question 18

What is the chain of events for oxygen upon entering the body

Answer 18

1. O2 enters pulmonary capillaries via the alveoli
2. High affinity to haemoglobin in the blood -> Oxyhaemoglobin
3. Dissociates once it reaches its target tissue into
4. Haemoglobin binds to a proton forming HHb in the systemic capillaries.

Question 19

What is the chain of events undertaken when CO2 enters the body

Answer 19

1. Enters the blood via systemic capillaries.
2. 25-30% binds to haemoglobin|60-65% converted to bicarbonate ions [HCO3]|Rest dissolves in the plasma
3. HCO3 is converted to water and CO2 in the pulmonary capillaries.
4. CO2 leaves

Question 20

What controls the rate of ventilation

Answer 20

Peripheral chemoreceptors
* Located in cartoid & aortic (Oxygen-rich)
* Sensetive to blood pH changes (primarily on O2 changes)

Central chemoreceptors
* Located in the brain
* Stimulated by an increase in H+
* Stimulate an increase in ventilation