EAC Respiratory System Flashcards
respiratory systems four specific functions
Extract oxygen from the atmosphere and transfer it to the blood stream
excrete water vapour and Co2
Maintain acid base status of the blood
Ventilate the lungs
components of inspired air
O2 = 20% Nitrogen = 79% Inert gasses = 1% Carbon dioxide = 0.04% Water vapour (variable)
components of expired air
O2 = 16% Nitrogen = 79% Inert gases = 1% Carbon dioxide = 4% Water vapour (to saturation)
structure and function of:
Nasal cavity
The nasal cavity is a hollow space within the nose and skull that is lined with hairs and mucus membrane. The function of the nasal cavity is to warm, moisturize, and filter air entering the body before it reaches the lungs.
structure of:
Pharynx
The area of the respiratory tract behind the nasal and oral cavity extending down as far as the cricoid cartilage of the larynx. Its lined with mucous membrane and is composed of skeletal muscle.
functions of:
Pharynx
act as a passageway for air, food and water.
Is a resonating chamber for speech sounds.
Houses the tonsils.
three parts of the pharynx are:
nasopharynx - behind nasal cavity superior to the soft palate
oropharynx - extends from level of soft palate to level of hyoid bone
laryngopharynx - starts at the level of the hyoid bone leading to the oesophagus and the larynx
structure of:
Larynx
connects laryngopharynx with the trachea
lies in mid line of neck anterior to 4th - 6th cervical vertebrae (C4,5,6)
consists of Hyoid bone, thyroid cartilage and cricoid cartilage
there are 3 single cartilages (thyroid, epiglottis and cricoid)
there are also 3 paired cartilages (arytenoid, cuneiform and corniculate)
functions of:
Larynx
Production of sound
Speech
Protection of the lower respiratory tract during swallowing
Provide passageway for air from the pharynx to the trachea
Continues the process of humidifying, filtering and warming inspired air
in swallowing as the larynx rises the free edge of the epiglottis descends shutting of the respiratory tract preventing food, drink, secretions etc. from entering. Directing them down the gastrointestinal tract. should they pass into the larynx this stimulates the cough reflex which expels them from the respiratory tract.
structure and function of:
Epiglottis
Large piece of elastic cartilage attached to anterior rim of thyroid
It is leaf shaped
The leaf like portion is unattached and moves up and down like a trap door
structure and function of :
Thyroid
Forms anterior wall of the larynx and gives it its prominence
Connected to the hyoid bone by the thyrohyoid membrane
Structure of:
Trachea
Composed of 16-20 incomplete C shaped rings of cartilage that lie on top of each other. Providing semi-rigid support to trachea wall so that with changes of air pressure it does not collapse.
Incomplete part of C faces oesophagus
Extends from Larynx to the level of 5th thoracic vertebrae (T5)
Approx. 12cm long and 2.5cm diameter
Inner layer lined with ciliated columnar epithelium containing goblet cells
terminates at the Carina, formed by the last C shaped ring at the level of T5, dividing into left and right primary bronchus.
Function of:
Trachea
Support and Patency
Mucociliary escalator
Cough reflex
Warming, humidifying and filtering air
structure of:
Bronchus/Bronchi and Bronchioles
The right primary bronchus is more vertical, shorter and wider then the left. An aspirated object is therefore more liable to enter the right primary bronchus.
Primary bronchi divide to form smaller secondary (lobar) bronchi
Secondary bronchi branch off forming smaller tertiary bronchi
tertiary bronchi divide into bronchioles
bronchioles branch repeatedly until they’re minute, termed ‘Terminal bronchioles’
this branching from the trachea is commonly referred to as ‘the bronchial tree’
structure changes as The Bronchial Tree extends
epithelium changes from pseudo-stratified ciliated columnar epithelium in bronchi to non ciliated simple cuboidal epithelium in terminal bronchioles
incomplete rings of cartilage in primary bronchi are gradually replaced by plates of cartilage that finally disappear
as the amount of cartilage decreases the amount of smooth muscle increases
smooth muscle encircles the bronchioles in spiral bands
dilation of this muscle will increase bronchiolar diameter
function and structure of: Alveolar ducts and Alveoli
Terminal bronchioles - respiratory bronchioles - alveolar ducts
alveolar ducts end in the air sacs/Alveoli
gas exchange can only take place in the Alveoli and walls of alveolar ducts
Structure of:
Lungs
the lungs are 2 coney shaped, spongy organs situated either side of the mediastinum within the thoracic cavity
the right has 3 lobes and the left 2 lobes
has an apex, base, costal surface and medial surface
All structures enter the lung at the hilum on the medial surface
the lungs and the interior of thoracic cavity are lined by serous membrane (the pleura/pleural membrane)
thoracic cage firmly attached to and lined by parietal pleura
lungs enclosed and protected by visceral pleura
the two layers are in close contact during normal health separated by a thin film of serous fluid
between the two layers is the pleural cavity, filled with serous fluid to reduce friction allowing them to slide easily over one and other during breathing
blood supply to the lungs
the blood supply to the lungs is a double circulation:
pulmonary circulation
Systemic circulation