Respiratory System - Notes
Respiratory System - Notes
Respiratory System - Notes
RESPIRATORY SYSTEM
- function:
o supply of oxygen - to the blood so it can be distributed around the body
o removal of carbon dioxide – waste product of metabolic processes
- composition:
o upper airways
nasal cavity
preferred entrance of air from external environment to body
function
o Filtration– sticky mucous membrane traps dust particles which are either
sneezed or blown out
o Lightening of skull– thanks to paranasal sinuses
o Sound formation – echoing of sound, creation of vocal resonance
Nasopharynx
Upper part of pharynx behind nose
Extends from the base of the skull to the upper surface of the soft palate
Contains adenoids – lymph nodes
Contains opening of Eustachian tube (functions to equalize the pressure in ear)
Larynx
Essential role in speech formation
Contains vocal cords – 2 ligaments
During speech ligaments open and close as vibrating air is exhaled from lungs
3
o lower airways
trachea
also called windpipe
the main airway to lungs
divides into 2 primary bronchi channelling air into right or left lung
supported by C-shape cartilage
bronchi
originate in trachea
branch progressively into bronchioles
bronchioles
tiny bronchioles are called terminal
circa 30 000 in each lung
divide into two or more bronchioles which end in alveolar sacs composed of alveoli
o lungs
2 sponge-like cone-shaped lungs filling the most of the thoracic cavity
Protected by flexible ribcage
Form one of the largest organs in the body
Left lungs – 2 lobes, right lung – 3 lobes
Thanks to compartmentation of lungs the surface is of lungs is 40x larger than the body
surface
o Alveoli
Sg. alveolus
Functional units of lungs
Estimated number – 300 000 000
Total surface - 70m2
Single-layered walls are surrounded by rich network of single-layered walls of capillaries
Moist environment
Macrophages– white blood cells present in alveoli – function to destroy bacteria, chemicals,
and dust
o respiratory muscles
Diaphragm & intercostals muscles
enable enlargement of thoracic cavity and ribcage for inhalation
enable lowering of thoracic cavity volume and push out the air for exhalation
o pleurae
membrane covering internal surface of thoracic cavity (ribs) and external surface of lungs
lower the friction between lungs and ribs by production of liquid
- respiration as exchange of gases is:
o internal
exchange of respiratory gases between blood and individual cells
o external
exchange of respiratory organs between outside environment and blood through organs of
respiratory system
- ventilation
o mechanics of breathing
o inhalation
expansion of thoracic cavity
intercostal muscles lift and pull ribs away from body
diaphragm moves down
lower pressure in lungs causes air to get in
3
o exhalation
lowering of thoracic cavity volume
intercostal muscles push ribs in and towards the body
diaphragm moves up
air is pushed out from lungs
- functionality of one’s respiratory system is described using these terms
o Minute volume – the volume of air inhaled and exhaled per minute in rest – 12-16 breaths/min – 6-
8l
o Residual volume – the air that remains in lungs after exhalation and cannot be exhaled (the first
breath air); app. 0.35l
o Tidal volume – the amount of air in one breath (one inhalation & one exhalation); app. 0.5l
o Vital capacity – the maximum exhalation after maximal inhalation; varies – depends on sex, training,
lifestyle (males 3.5-5l, females 2.5-4l)
- breathing is regulated by respiratory centre in medulla oblongata and pons (brain)
- breathing regulated by sensing the concentration of O 2 and CO2 in blood flowing into brain centre
- protective reflexes:
o sneezing - sudden involuntary expulsion of air from the nose and mouth due to irritation of one's
nostrils
o coughing – irritation of trachea/larynx (by mucus)
- other reflexes
o yawning
o hiccup
- HW: diseases of respiratory tract:
o Sinusitis - inflammation of a nasal sinus or swelling of the tissue lining the sinuses. Healthy sinuses are
filled with air. But when they become blocked and filled with fluid, germs can grow and cause an
infection.
o Tonsillitis - Tonsillitis is inflammation of the tonsils, two oval-shaped pads of tissue at the back of the
throat — one tonsil on each side.
o Laryngitis - Laryngitis is an inflammation of voice box (larynx) from overuse, irritation or infection.
o Bronchitis - Bronchitis is an inflammation of the lining of your bronchial tubes, which carry air to and
from your lungs.
o Pneumonia - Pneumonia is an infection that inflames the air sacs (alveoli) in one or both lungs.
o Asthma - Asthma is a condition in which your airways narrow and swell and may produce extra
mucus.
o Cancer - Lung cancer is a type of cancer that begins in the lungs. Lungs are two spongy organs in
chest that take in oxygen when you inhale and release carbon dioxide when you exhale.
3
3