Functions of respiratory system and respiratory cycle

Question 1

What are the divisions of the respiratory tract?

Answer 1

Upper respiratory tract/Conducting passage
* Nasal cavity
* Pharynx
* Larynx

Lower respiratory tract
* Trachea
* Primary Bronchi
* Lungs

Question 2

What are the divisions of the lower respiratory tract?

Answer 2

Trachea
Bronchi
Bronchioles
Terminal bronchiole
Respiratory bronchiole
Alveolar duct
Alveolar sac
Alveoli

Question 3

How many generations does the lower respiratory track have?

Answer 3

23 divisions

Question 4

The 0 generation level is …

Answer 4

Trachea

Question 5

The 23rd generation level is …

Answer 5

Alveoli

Question 6

What are the zones of the lower respiratory tract?

Answer 6

0-16 generation = Conducting Zone (Trachea → Terminal Bronchiole)
17-23 generation = Respiratory Zone (Respiratory Bronchiole → Alveoli)

Question 7

What is the functional unit of the lung?

Answer 7

Respiratory acinus/respiratory lobule (formed from one respiratory bronchiole and its generations)

Question 8

What are the functions of the respiratory system?

Answer 8

GAP BOVOST MED
Gas exchange: Supplies the body with O2 and removes CO2
Regulation of pH of the blood: Excretes CO2
Regulation of body temperature: Responsible for 4% heat loss
Vocalization: Vibration of vocal cords against expired air
Smell and taste: Olfactory membrane on roof of nasal cavity + taste receptors in mouth and pharynx
Metabolic functions: Secretes: (1) Surfactant, (2) Fibronlytic agents such as plasmin, (3) Angiotensin Converting Enzyme (ACE) and Removes serotonin and norepinephrine
Defensive funtions: (1) Bronchial secretions contain IgA, (2) Mechanisms to prevent foreign matters entering alveoli

Question 9

How are particles >10µ removed from the nasal passages?

Answer 9

Removed by nose hairs

Question 10

How are particles 6-10µ removed?

Answer 10

Stick to nasal mucosa and trigger sneezing reflex

Question 11

How are particles 2-5µ removed?

Answer 11

Reach the trachea and bronchi removed by:
1. Reflex bronchial constriction: Stops particles reaching the tracheobronchial tree
2. Mucociliary escalator: Mucus secreted by goblet cells. Cilia from nose to respiratory bronchiole. Cilia beat at 1000-1500 cycles/min to remove particles from lungs at 16mm/min rate
3. Cough reflex: Particles stick to mucous membrane of the trachea. Deep inspiration followed by forced expiration against a closed glottis. This increases the intrapleural pressure to 100 mmHg or more. The glottis is then suddenly opened, producing an explosive outflow of air at high velocities (965 km/hr)

Smoking reduces the efficiency of the mucocilliary escalator

Question 12

How are particles <2µ removed?

Answer 12

Reach the alveoli and are removed by pulmonary alveolar macrophages (PAMs)

Question 13

How are particles <0.5µ removed?

Answer 13

Stay in alveoli during inspiration and removed during expiration

Question 14

What are the divisions of respiration?

Answer 14

External respiration
* Pulmonary ventilation: Exchange of gases between lungs and atmosphere
* Pulmonary perfusion: Blood flow through capillaries
* Pulmonary respiration: Diffusion of gases from alveoli to blood

Transport of O2 and CO2 in the blood

Internal respiration: Utilization of O2 and removal of CO2

Tissue O2 consumption ~200-250ml/min

Question 15

What is pulmonary ventilation?

Answer 15

Mechanical process that moves air in and out of the lungs

Question 16

What is the normal physiological respiratory rate?

Answer 16

12-20/min

Question 17

Tachypnea?

Answer 17

More than 20 breaths/min

Question 18

Bradypnea?

Answer 18

Less than 12 breaths/min

Question 19

Apnea?

Answer 19

Stoppage of breathing

Question 20

What is tidal volume?

Answer 20

Volume of air that is inspired or expired in a quiet normal respiration
~ 500 ml

Question 21

What is inspiration?

Answer 21

Pressure inside lungs < pressure outside lungs = air moves in

Question 22

What is expiration?

Answer 22

Pressure inside lungs > pressure outside lungs = air moves out

Question 23

What is the role of muscles in respiration?

Answer 23

Muscles change the volume of the thoracic cavity which alters the pressure inside the lungs

Question 24

What are the muscles involved in inspiration?

Answer 24

Normal inspiration, flexion of:
* External intercostals (moves ribs to increase transverse and anteroposterior diameter of chest)
* Diaphragm (increases vertical diameter of thoracic cavity)

Deep inspiration, flexion of:
* Sternocleidomastoids (lift sternum upwards)
* Anterior Serrati and Scalenes

Inspiration is an active process

Question 25

What are the muscles involved in expiration?

Answer 25

Normal expiration, relaxation of:
* External intercostals
* Diaphragm

Deep/forced expiration, flexion of:
* Internal incostals (pulls ribs downwards)
* Abdominal muscles (abdominal recti, internal and external oblique contract to increase abdominal pressure and push the diaphragm upwards)

Normal expiration is a passive process
Active expiration is an active process