The Respiratory System Flashcards
(20 cards)
Function of the respiratory system
The major function of the respiratory system is to supply blood with oxygen and dispose of carbon dioxide. To accomplish this function at least four processes collectively called respiration must occur; Pulmonary ventilation External respiration Transport of respiratory gases Internal respiration
Explain the 4 respiration processes
Pulmonary ventilation: Air is moved into( inspiration) and out of the lungs( expiration) so the gases( oxygen and carbon dioxide) are continuously changed and refreshed
External respiration: oxygen diffuses from the lungs to the blood, and carbon dioxide diffuses from the blood to the lungs
Transport of respiratory gases: oxygen is transported from the lungs to the tissue cells of the body, and carbon dioxide is transported from the tissue cells to the lungs. The cardiovascular system accomplishes this transport using blood as the transporting fluid
Internal respiration: oxygen diffuses from blood to tissue cells, and carbon dioxide diffuses from tissue cells to blood
The respiratory system is responsible for only the 1st two processes but it cannot accomplish its primary goal of obtaining oxygen and eliminating carbon dioxide unless the 3rd and 4th processes also occur
Process of respiration
Respiration starts at the nose or mouth where oxygenated air is brought in before moving down the pharynx larynx and the trachea. The trachea branches into two bronchi each leading into a lung. Each bronchus divides into smaller bronchi, and again into even smaller tubes called bronchioles. At the end of the bronchioles are air sacs called alveoli and this is where gas exchange occurs
Organs of the respiratory tract
The upper respiratory system: Nasal cavity Mouth Pharynx Larynx The lower respiratory system: Trachea Bronchi Lungs
The lower respiratory system is enclosed in the thorax, encompassed by the ribs spine and diaphragm
Nasal cavity
The nasal cavity is divided into two by a septum.
Hairs inside- prevent foreign material from entering
The openings into the nasal cavity(nares): Anterior- outside Posterior- leading to pharynx
Sinuses :cavities in the bones of the face and cranium - hollow bones ; lighten the bones & give resonance to voice
Lined with ciliates mucous membrane
Contain nerve endings for smell
Functions: warm, moisten and filter( trap dust)
Mouth
The mouth also known as the oral cavity is the secondary external opening for the respiratory tract
Most normal breathing takes place through the nasal cavity but the oral cavity can also be used to supplement or replace the nasal cavity’s functions when needed
Pharynx
A tube that’s 12-14cm (about 5 inches)
Extend from base of the skull to the 6th cervical vertebrae
Inferiority continues with the oesophagus
Lies behind the nose mouth larynx and wider at upper part
Anterior wall is incomplete because of the opening into the nose mouth and larynx
Functions: Further warm and moisten the air
The larynx
It’s also known as the voice box
Extended for about 5cm( 2in) from 4th to the 6th cervical vertebrae
Composed of several irregular cartilage joined by ligaments and membranes
Thyroid gland on either side
Adam’s apple : laryngeal prominence
Larger in males than females ( influenced by sex hormone during puberty)
Epiglottis : leaf shaped cartilage inside thyroid cartilage
During swelling larynx moves upwards and forewords - opening occluded by epiglottis
Functions
Provide patient airway
Route air and food properly
Voice production
Trachea
Begins below larynx and run in front of neck and chest
Divides into R & L main bronchi at 5th thoracic vertebrae (at the carina)
About 12cm long
Oesophagus lies behind trachea
Lung lies on either side of trachea
Wall made of involuntary muscles
Lined with ciliates epithelium and goblet cells ( secrete mucus)
Cilia sweep mucus and foreign particles upwards
Trachea part2
Bronchi : two main bronchi, one in each lung . Right bronchus wider, shorter and more verticals than the left ( common site for foreign body to lodge)
Bronchioles: finest bronchi, no cartilage but muscular, fibrous and elastic tissue
Alveolar duct & alveoli: terminal bronchiole form alveolar duct from alveoli open
Alveoli surrounded by capillary network
Looks like a branch of grapes
Provide tremendous surface area ( 300 million)
Pleura
The function of the pleura is to allow optimal expansion and contraction of the lungs during breathing. The pleural fluid acts as a lubricant allowing the parietal and visceral pleura to glide over each other friction free. This fluid is produced by the pleural layers themselves.
There are two pleura one for each lung
The space between the membranes( called the pleural cavity) is filled with a thin lubricating liquid( called pleural fluid)
The pleura is comprised of two distinct layers:
The visceral pleura is the thin slippery membrane that covers the surface of the lungs and dips into the areas separating the different lobes of the lungs( called hilum)
The parietal pleura is the outer membrane that lines the inner chest wall and diaphragm ( the muscle separating the chest and abdominal cavities)
Muscles used for ventilation
The muscles of inspiration include the diaphragm external intercostals sternocleidomastoids and scalenes. The muscles of expiration include the internal intercostals and the abdominals
Mechanism of respiration
Inspiration and expiration
Gas exchange
Lung capacity
Control of respiration
Mechanism
Inspiration: active as a result of muscle contraction.
Diaphragm and intercostal muscles contracts - thoracic cavity enlarged- increased pressure in the abdominal and pelvic cavities
When a patient has difficulty in breathing ( observed as increased WOB : work of breathing) the use of accessory muscles ie abdomen and shoulder may be involved.
Partly voluntary and partly involuntary
Expiration: passive, diaphragm & intercostal relaxed- rib glide back to the original position
Pause : shoulrt pause and the cycle continues
Lung capacity
Compliance means the effort that is needed for lung and chest expansion. Normal lungs have a high compliance and expand easily because the elastic fibres stretch readily and surfactant in the lungs reduces surface tension( in pulmonary diseases, for eg emphysema, there is decreased compliance due to loss of elastic fibres of the alveolar walls)
Volumes: a healthy adult at rest normally has a respiration rate of 12-18bpm and with each respiration 500mls of air is moved in or out of the lungs. The volume of air in one breath is called tidal volume. By taking a deep breath you can increase the tidal volume above 500mls ( inspiratory reserve volume)
Gas exchange
The pulmonary gas exchange is the diffusion of oxygen is the diffusion of oxygen from the alveolar sac to the lung capillaries and the diffusion of carbon dioxide from the lung capillaries to the alveolar sac to be exhaled
Before oxygen can enter the internal environment and before carbon dioxide can leave environment they must cross the capillary and alveolar membranes
Gas exchange p2
As blood flows through the capillaries oxygen and carbon dioxide follow their pressure gradients and continually diffuse between blood and tissue. The concentration of oxygen in blood flowing away from the tissues back towards the heart is described as being deoxygenated
Alveolar PO2 has got to be greater than the blood PO2 for oxygen to diffuse out from the alveolar sac into the lung capillaries
Control of respiration
Voluntary controls conscious effort - cerebral cortex
Involuntary controls : main respiratory centre- medulla oblong at a and pons ( pneumotaxic centre, apneustic centre, rhythm generator)
Humoral control: afferent stimuli received into medulla from chemoreceptors via glossopharyngeal and vagus nerve
Accumulation of CO2 ➡️ stimulates the central chemoreceptors in the medulla ➡️ impulse carried to the dorsal (inspiratory) respiratory centre➡️ from respiratory centre by phrenic nerve to diaphragm & intercostal nerve to intercostal muscle
Nursing assessment
Respiration rate (counting respiration rate) : 12-18bpm
Oxygen saturation (pulse oximetry): >96%-100%
Skin colour (pink, cyanotic)
Inspect, palpate, percuss and ausculte
Arterial blood gases( ABG)
Respiratory rates
Less than 1yr old : 30-40bpm
1-2yr old: 25-35bpm
Above 12yrs old: 15-20bpm
Adult: 12-18bpm
Rates varies with age and can be affected by some factors
Oxygen saturation> 96%-100%
