Respiratory system Flashcards
What are the main functions of the respiratory system?
- allow continuous supply of oxygen to cells so they can carry out normal function
- produce sound
- remove waste gas
- sense of smell
- protect airway from harmful substances and pathogens
What are the two ways the respiratory tract can be divided into components?
- the conducting portion (moving air from outside into the lungs) and the respiratory portion (where gas exchange happens)
- upper respiratory tract and lower respiratory tract
What are the main parts of the nasal cavity?
- nasal septum
- vestibule area
- rich blood supply
- turbinates
- paranasal sinuses
What are the parts of the upper respiratory tract?
- nasal cavity
- pharynx
- larynx
What are the features and functions of the vestibule area of the nasal cavity?
Made of skin-like squamous epithelium with coarse hairs to trap larger particles from entering
What cells are above the vestibule in the nasal cavity?
ciliated psuedostratified columnar epithelial cells and goblet cells (mucous)
What is the role of the rich blood supply in the nasal cavity?
Warms the air entering
What is the function of turbinates?
They increase surface area of cavity and cause turbulence. This makes the air twist as it passes through which traps more particles
What are the features and functions of the paranasal sinuses?
- They are air filled cavities in she skull and the bones around the nose which are lined with columnar ciliated epthelium and goblet cells
- They are a source of moisture if nasal cavity becomes dry and are imp for making speech sounds
What is the pharynx lined with?
Ciliated pseudostratified columnar epithelium with goblet cells and mucous glands
What are the three parts of the pharynx?
Nasopharynx, oropharynx, and laryngopharynx
What are the main parts of the larynx?
- lined by ciliated psuedostratified columnar epthelium
- cartilage reinforcement
- epiglottis
- vocal folds
What are the roles of the larynx?
- protect airway by preventing food and liquid from entering pharynx
- generate sounds for speech
What are the parts of the lower respiratory tract?
- trachea
- bronchi
- bronchioles
- terminal bronchioles
- respiratory bronchioles
- lungs
- alveoli
What are the features of the trachea?
- lined by ciliated psuedostratified columnar epithelium with some goblet cells
- stack of 16-20 c-shaped hyaline cartilages around its anterior
- cartilage connected by trachealis muscle which can constrict and dilate
Where does the trachea end?
At the carina bifurcation where it divides into right and left bronchi
What is the order of bronchi branching?
- right and left primary bronchi
- secondary (lobar) bronchi (3 right lung, 2 in left lung)
- bronchioles
What are the features of the primary bronchi?
- cartilage
- layer of smooth muscle
- ciliated psuedostratified epithelial cells and goblet cells in lining
What are the features of the bronchioles?
- smooth muscle
- less cartilage so rely on elastic tissue for support
- simple ciliated columnar epithelium
- clara cells instead of goblet cells
What are the lobes of the right lung?
Superior, middle and inferior
What are the lobes of the left lung?
Superior and inferior
What is the cardiac notch?
The space for the heart in the mediastinal cavity of the left lung
What is the hilum?
Where the pulmonary artery and the pulmonary vein enter and exit the lungs
What are the three pleural membranes in the lower respiratory tract?
- visceral pleura - encases lungs
- parietal pleura - lines the thoracic cavity
- diaphragmic pleura - contacts the diaphragm
Where is pleural fluid found?
In the pleural cavity between the pleural membranes
What are the functions of pleural fluid?
- allows frictionless movement of the lungs inside the thoracic wall
- creates a bond between the layers so that is the thorax expands and moves up, the lungs do the same
What do terminal bronchioles divide into?
respiratory bronchioles
What are the features of respiratory bronchioles?
- smooth muscle
- elastic fibres
- end in alveolar sacs which contain alveoli
What are the features of alveoli?
- thin walls - one squamous epithelial cell on a basement membrane
- extensive blood capillaries
How many alveoli are in each lung?
Approx. 150 million
Define external respiration
The exchange of oxygen and carbon dioxide between the alveoli of the lungs and the pulmonary capillary
Define internal respiration
The exchange of oxygen and carbon dioxide between blood and tissues
Define ventilation
The continuous movement of inspiration and expiration in a repeating cycle
Define inspiration
Breathing in
Define expiration
Breathing out
When does ventilation pattern change?
- Can override automatic system by changing breathing pattern or changing breath for short time
- during speech
How is volume and pressure changed during inspiration?
- ribs are pulled up and out and diaphragm pulled down which increases volume in lungs
- decreases pressure in lungs
- air flows into lungs down a pressure gradient
What is Boyle’s law?
At a constant temperature, an increase in the volume of a chamber will decrease the pressure in that chamber, and a decrease of volume will increase the pressure
What structures are needed for continuous ventilation to happen?
- ribs and sternum
- vertabrae
- intercostal muscles
- diaphragm
- abdominal muscles
- accessory muscles of head and neck
What is the sternum?
A flat bone in the midline of the anterior thorax which acts as an attachment point for the ribs
How are the pairs of ribs divided?
1-7 = true ribs (attached to sternum)
8-10 = false ribs (attach to sternum by 6 and 7)
11 and 12 = floating ribs (not attached to sternum)
What are the main features of the ribs?
- slants downwards
- attached to sternum by costal cartilage which allows flexibility
- mobile - hinge joints with spinal vertebrae and cartilage joints to sternum
What are the divisions of the vertebrae of the spinal column?
- cervical (neck region) - C1-C7
- Thoracic - T1-T12 (where ribs attach)
- lumbar (L1-L5)
- Sacral - S1-S5 (fused)
- coccygeal (coccyx region) - 4 fused together
What separates vertebrae?
fibrocartilage discs
What is the diaphragm?
the primary muscle of inspiration which separates the thoracic and abdominal cavities
What are the features of the diaphragm?
- attach anteriorly to ribcage
- attach posteriorly to vertebral column
- has openings for descending aorta, ascending inferior vena cava and oesophagus
What does stimulation from the phrenic nerve to the diaphragm?
Makes it contract and flatten
What does contraction of the external intercostal muscles do?
Elevates the ribs and spreads them apart
What does contraction of the internal intercostal muscles do?
Depresses the ribs and pulls them together - used in forced expiration, not quiet breathing
What happens during inspiration?
- external intercostal muscles contract
- ribs are pulled up and out
- diaphragm contracts and flattens
- pressure in lungs decreases so air moves in
What happens during expiration?
- External intercostal muscles relax
- Ribs move down and in
- Diaphragm relaxes and returns to dome shape
- Increases pressure in lungs, so air moves out
What are the accessory muscles of expiration?
The abdominal muscles
What are the accessory muscles of inspiration?
sternocleidomastoid and scalenes (in head and neck)
What are the measures of lung capacity?
- tidal volume
- inspiratory reserve volume
- expiratory reserve volume
- residual volume
- vital capacity
- total lung capacity
Define tidal volume
the amount of air passing in and out of the lungs during each cycle of quiet breathing (approx. 500ml)
Define inspiratory reserve volume
the largest volume of air that can be inspired into the lungs during forced inspiration after the tidal volume (around 3l)
Define expiratory reserve volume
the largest volume of air that can be expelled from the lungs during forced expiration after tidal volume
Define residual volume
volume of air in the lungs after forced expiration (approx 1l)
Define vital capacity
maximum volume of air that can be expired after minimum inspiration
Define total lung capacity
maximum amount of air in the whole respiratory tract
What systems control breathing?
somatic nervous system and the respiratory centre in the brain stem
What regions in the medulla oblongata control respiration?
- dorsal respiratory group (DRG)
- ventral respiratory group (VRG)
What does the dorsal respiratory group do?
stimulates inspiration by activating the external intercostals and the diaphragm
What does the ventral respiratory group do?
stimulates expiration by stimulating internal intercostal muscles and abdominal muscles
What does the pons control in relation to respiration?
rate and depth of breathing
What are the regions of the pons used in respiration?
- the apneustic area
- the pneumotaxic area
What does the apneustic area do?
stimulates the inspiratory centre, prolonging the contraction of inspiratory muscles
What does the pneumotaxic area do?
inhibits the inspiratory centre, limiting the contraction of the inspiratory muscles and preventing the lungs from overinflating
What are the main factors affecting breathing rate?
- pulmonary stretch receptors
- peripheral chemoreceptors
- central chemoreceptors
Where are pulmonary stretch receptors found?
in the smooth muscle of the lungs - 40% in trachea/brochi, 60% in brochial trees
What do pulmonary stretch receptors do?
- detects pressure of lungs
- communicates pressure to respiratory centres via vagus nerve
- inhibits apneustic area of pons
- this inhibits inspiratory neurons allowing expiration
What peripheral chemoreceptors are there and where are they found?
- aortic bodies - in aortic arch
- carotid bodies - in carotid arteries
What nerve do aortic bodies use?
vagus nerve
What nerve do carotid bodies use?
Glossopharyngeal nerve
What do peripheral chemoreceptors do?
- detect changes in O2 and CO2 levels, and changes in pH
- activate dorsal respiratory group to increase inspiration which removes CO2 more quickly
Where are central chemoreceptors found?
medulla (and other brain areas)
What do central chemoreceptors do?
- detect pH changes in cerebrospinal fluid
- info carried to medulla which activates ventral and dorsal respiratory centres to increase inspiration and expiration rate
- gets rid of CO2 more quickly
What other factors affect breathing rate?
- emotional stress/anxiety
- pain
- emotion
- air resistance
- fever
- COPD (chronic obstructive pulmonary disease)
