Functions of respiratory system and respiratory cycle Flashcards
What are the divisions of the respiratory tract?
Upper respiratory tract/Conducting passage
* Nasal cavity
* Pharynx
* Larynx
Lower respiratory tract
* Trachea
* Primary Bronchi
* Lungs
What are the divisions of the lower respiratory tract?
Trachea
Bronchi
Bronchioles
Terminal bronchiole
Respiratory bronchiole
Alveolar duct
Alveolar sac
Alveoli
How many generations does the lower respiratory track have?
23 divisions
The 0 generation level is …
Trachea
The 23rd generation level is …
Alveoli
What are the zones of the lower respiratory tract?
0-16 generation = Conducting Zone (Trachea → Terminal Bronchiole)
17-23 generation = Respiratory Zone (Respiratory Bronchiole → Alveoli)
What is the functional unit of the lung?
Respiratory acinus/respiratory lobule (formed from one respiratory bronchiole and its generations)
What are the functions of the respiratory system?
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
How are particles >10µ removed from the nasal passages?
Removed by nose hairs
How are particles 6-10µ removed?
Stick to nasal mucosa and trigger sneezing reflex
How are particles 2-5µ removed?
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
How are particles <2µ removed?
Reach the alveoli and are removed by pulmonary alveolar macrophages (PAMs)
How are particles <0.5µ removed?
Stay in alveoli during inspiration and removed during expiration
What are the divisions of respiration?
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
What is pulmonary ventilation?
Mechanical process that moves air in and out of the lungs
What is the normal physiological respiratory rate?
12-20/min
Tachypnea?
More than 20 breaths/min
Bradypnea?
Less than 12 breaths/min
Apnea?
Stoppage of breathing
What is tidal volume?
Volume of air that is inspired or expired in a quiet normal respiration
~ 500 ml
What is inspiration?
Pressure inside lungs < pressure outside lungs = air moves in
What is expiration?
Pressure inside lungs > pressure outside lungs = air moves out
What is the role of muscles in respiration?
Muscles change the volume of the thoracic cavity which alters the pressure inside the lungs
What are the muscles involved in inspiration?
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
What are the muscles involved in expiration?
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
