Respiratory System Flashcards
What is the primary function of the respiratory system?
To uptake air from the surroundings and allow gaseous exchange between the lungs and the bloodstream
What are the 6 conducting passageways?
- Nose
- Pharynx
- Larynx
- Trachea
- Bronchus
- Bronchioles
What are the conducting passageways also responsible for?
Preventing food/ foreign bodies from being inhaled and structural support
Describe the interior of the nose
Nasal cavity which is divided midline by the nasal septum
What are responsible for sense of smell and where are they located?
Olfactions, located on the nasal mucosa which is found just beneath the nasal bone
Where is mucus made and what is it used for?
- Glands in the mucosa
- Protects from irritation and prevents drying
What is the nasal cavity lined with and what are they for?
- Ciliated columnar epithelium
- Move mucus towards the throat to be swallowed/ coughed up
What are nasal conchae and what are they for?
Thin, curled bones in the nasal cavity that increase the surface area to warm and humidify air as it passes through
What is the nasal cavity surrounded by and what are they for?
Paranasal sinuses which decrease the weight of the front skull, increase resonance of voice and provide a buffer against facial trauma
What is the common name for the pharynx?
Throat
Describe the pharynx and explain its function
- Muscular passageway
- 12-14cm long
- Passageway for air and food
What are the 3 parts of the pharynx called?
- Nasopharynx
- Oropharynx
- Laryngopharynx
What are tonsils and what is their function?
- Clusters of lymphatic tissue in the pharynx
- Protect the body against respiratory and gastrointestinal infections
What are the 3 types of tonsils and where are they found?
- Palastine - back of mouth and side of tongue
- Lingual - on hyoid bone (root of tongue)
- Pharyngeal - above palate of mouth
What is another name for the larynx?
Voice box
What is the main function of the larynx?
To route air and food via the appropriate channels and plays a role in speech
Where is the larynx and what is it made of?
- Located in front of the laryngopharynx
- Formed of hyaline cartilage and the epiglottis
What is the epiglottis and what is its function?
- A spoon-shaped flap of elastic cartilage
- Acts as a lid and closes off the larynx during swallowing to prevent accidental inhalation of food/ foreign objects
What is the function of the vocal cords?
- Located in the larynx
- Control speech and sound
- When surrounding muscles relax, vocal cords open (low pitch) and when surrounding muscles contract, vocal cords stretch across the larynx (high pitch)
What is another name for the trachea?
Windpipe
Describe the trachea
- Located on the level of the 5th thoracic vertebrae
- 10-11cm long
- Made up of rigid cartilage
What are the 3 main functions of the rigid cartilage walls of the trachea?
- To hold the trachea open
- To allow the trachea to expand and contract
- To allow the head and neck to move
What is the trachea lined with and why?
- Ciliated columnar epithelium
- Traps dust and dirt to prevent them being inhaled
At what level do the two main bronchi divide?
5th thoracic vertebrae
Describe the right main bronchus
- 2.5cm long
- Wider, shorter and more vertical
- Divides into 3 branches in the right lung
Describe the left main bronchus
- 5cm long
- Narrower and longer
- Divides into 2 branches in the left lung
What is the apex?
The narrow, superior portion of each lung located just below the clavicle
How many lobes does each lung have?
- Right = 3 lobes (superior, middle, inferior)
- Left = 2 lobes (superior, inferior)
What are the lungs and thoracic cavity lined with?
Visceral serosa called the pleural cavity which allows the lungs to move without damage or friction
What are bronchioles?
Small passageways that branch off from the bronchi and are no longer made of cartilage
What are alveoli?
- Small air sacs at the end of the bronchioles
- Site of gaseous exchange
- Walls that are one cell thick
- Moist surface
How are the alveoli connected?
Alveolar pores
What is the respiratory membrane made up of?
- Alveoli
- Capillaries (alveolar epithelial cells and pulmonary capillary endothelial cells)
What provides the final line of defence for the respiratory system and where are they located?
- Lymphocytes and plasma cells
- Produce antibodies
- Located in the alveoli along with phagocytes
What are the 2 types of alveolar cells?
- Type I = squamous epithelium
2. Type II = produce surfactant to decrease surface tension and allow membranes to separate
What is volume?
The amount of space that a substance occupies
What is pressure?
A continuous force extended on/against an object
What is capacity?
The maximum amount of a substance that something can contain/produce
Describe the relationship between volume and pressure
High volume = Low pressure
Low volume = High pressure
What are intercostal muscles and the diaphragm stimulated by?
Intercostal muscles = intercostal nerves
Diaphragm = phrenic nerves
Are inspiration and expiration passive or active?
Inspiration = active Expiration = passive
Describe the process of inspiration
- Diaphragm contracts and flattens
- Intercostal muscles pull ribs up and out
- Intrapulmonary volume increases (large thoracic cavity)
- Pressure decreases (below atmospheric pressure)
- Air is drawn in to the lungs
Describe the process of expiration
- Diaphragm relaxes and rises to a dome shape
- Intercostal muscles relax and ribs are pulled down and in
- Intrapulmonary volume decreases (smaller thoracic cavity, causing elastic recoil of lungs)
- Pressure increases (above atmospheric pressure)
- Air is forced out of the lungs
What is Tidal Volume and what is the usual value for men and women?
- Volume of air passing through the lungs during normal breathing
- Men = 500ml
- Women = 500ml
What is Inspiratory Reserve Volume and what is the usual value for men and women?
- Extra volume of air that can be inhaled over and above the tidal volume
- Men = 3100ml
- Women = 1900ml
What is Inspiratory Capacity and what is the usual value for men and women?
- Maximum respiratory effort
- Tidal Volume + Inspiratory Reserve Volume
- Men = 3600ml
- Women = 2400ml
What is Expiratory Reserve Volume and what is the usual value for men and women?
- Largest volume of air that can be expelled during maximum expiration
- Men = 1200ml
- Women = 700ml
What is Residual Volume and what is the usual value for men and women?
- Volume of air remaining in the lungs after forced expiration
- Men = 1200ml
- Women = 1100ml
What is Functional Residual Capacity and what is the usual value for men and women?
- Volume of air remaining in the airways and alveoli at the end of quiet expiration
- Expiratory Reserve Volume + Residual Volume
- Men = 2400ml
- Women = 1800ml
What is Vital Capacity and what is the usual value for men and women?
- Maximum amount of air that can be expired after maximum inspiratory effort
- Men = 4800ml
- Women = 3100ml
What is Total Lung Capacity and what is the usual value for men and women?
- Total volume of air that the lungs can hold
- Tidal Volume + Inspiratory Reserve Volume + Expiratory Reserve Volume + Residual Volume
- Men = 6000ml
- Women = 4200ml
What factors affect the volume and capacity of the lungs?
- Elasticity - ability of lungs to return to their normal shape after a breath
- Compliance - measure of stretch ability of lungs and effort required to inflate alveoli
What is the difference between internal and external gaseous exchange?
Internal = cellular gas exchange External = alveolar gas exchange
What are the 4 main gases in air?
- Oxygen
- Carbon Dioxide
- Nitrogen
- Gaseous water
Describe the pressures exerted by the gases in the air
- Each gas exerts a partial pressure (PP) (mmHg) depending on its concentration
- Oxygen = 21% of the pressure in the air
- Gas exchange occurs when there is a difference in PP across a semi-permeable membrane (high PP - low PP)
- High PP = high concentration of gas
- Low PP = low concentration of gas
How are alveoli adapted for gas exchange?
- 1 cell thick (short diffusion pathway)
- Large SA
- Located close to the capillary network
External Respiration: How does oxygen travel in the blood?
- Diffuses from alveoli into the bloodstream
- Attaches to haemoglobin to form oxyhaemoglobin which travels in RBC
- A small amount dissolves into the blood plasma
External Respiration: How does carbon dioxide travel in the blood?
- Transported in plasma by bicarbonate ions (HCO3-)
- Some is carried in RBC attached to Hb in a different place to the oxygen
- Has to be released from the bicarbonate ion before it diffuses into alveoli; HCO3- enters the RBC and combines with H+ to form carbonic acid (H2CO3) which then splits into water and carbon dioxide
Internal Respiration: How does oxygen travel in the blood?
- Attaches to haemoglobin to form oxyhaemoglobin which travels in RBC
- Oxygen then leaves the capillaries and diffuses into body cells
Internal Respiration: How does carbon dioxide travel in the blood?
- Transported by combining with water in plasma to form carbonic acid which then releases HCO3- and H+ ions
- This reaction occurs in the RBC and is catalysed by carbonic anhydrase
- HCO3- is then released into the blood plasma and transported back to the lungs
What are the 2 types of control for breathing?
- Neural control
2. Non-neural control
What does neural control involve?
- Higher brain centres
- Respiratory centre (e.g. medulla and pons)
- Stretch receptors
- Irritant receptors
How is rate and depth of breathing affected by neural control?
- Neural centres in the medulla control rhythm and depth of breathing
- Phrenic and intercostal nerves send impulses to the medulla and pons to regulate activity of respiratory muscles, the diaphragm and external intercostals
How are stretch receptors affected by neural control?
- Respond to extreme over-inflation by initiating protective reflexes
- Example = vagus nerve sends impulses from stretch receptors to the medulla
How are irritant receptors affected by neural control?
- Found in lungs
- Respond to inhalation of foreign substances by initiating protective reflexes
- Example = coughing
What does non-neural control involve?
- Other receptors (e.g. pain)
- Emotional stimuli
- Central chemoreceptors
- Receptors in muscles and joints
What physical factors affect breathing in non-neural control?
- Coughing
- Talking
- Exercising
- Increasing body temperature
How does volition affect non-neural control?
- Volition = conscious control
- Examples = swallowing, singing
- Respiratory centre ignores messages from the cortex when oxygen in the blood is too low/ pH is falling
What emotional factors affect breathing in non-neural control?
- Reflexes initiated by emotional stimuli acting through the hypothalamus
- Example: watching a horror movie and holding your breath
What chemical factors affect breathing in non-neural control?
- Levels of carbon dioxide and oxygen in the blood
- pH levels
- Peripheral chemoreceptors in the aorta and carotid bodies
- Central chemoreceptors on the surface of the medulla
