Lecture 4 - The respiratory system Flashcards
List four functions of the respiratory system
1- Exchange of gases
2- Warming/cooling and moistening of air
3- Removal of inhaled particles
4- Voice production and olfaction
Describe specifically the route air flows through the respiratory tract, identifying key structures
Air flows in through the nose (and mouth) and through the paranasal sinuses down into the nasopharynx, oropharynx and laryngopharynx. Then through the larynx (voice box) into the trachea which branches into the left and right bronchi. These then branch into smaller bronchioles and finally into millions of alveoli where gas exchange occurs.
Describe the difference between external and internal respiration
External respiration is the exchange of gases between the blood and lungs where the pulmonary capillaries carry blood around the alveoli.
Internal respiration is the exchange of gases between blood and cells.
What is cellular respiration?
The process whereby energy (ATP) is obtained by metabolising carbs, fats and proteins.
The mucous membrane of the respiratory tract is lined with a ________ epithelial membrane that contains mucous-secreting _______ cells. Mucus traps ______ particles and acts as a surfactant. It also has _______ properties. Cilia move the particles towards the _________ where they can be coughed up and/or swallowed. This protects the lungs from inhaled ________.
ciliary
goblet
inhaled
antimicrobial
oesophagus
pathogens
Describe the role of nasal concha
Nasal concha are shelves that increase surface area and trap water during exhalation. They also spin the air which filters it and encourages particles to become trapped in nasal mucous membranes.
List four functions of the nasal cavity
1- Filtering air - hairs and concha
2- Warming air - lots of capillaries near the surface
3- Humidification - air travelling over moist mucosa
4- Sneezing reflex - in case of mucosal irritation
5- Olfactory function - olfactory receptors
List two functions of the paranasal sinuses
1- Moistening/humidifying the air
2- Resonance in speech
3- Lightening the cranial mass
4- Nasolacrimal ducts drain tears from the eyes
Name two paranasal sinuses
Ethmoid
Frontal
Sphenoid
Maxillary
List four functions of the pharynx
1- Passageway for air and food
2- Warming and humidifying of air
3- Taste
4- Speech
5- Equalising of pressure in the middle ear
6- Immune protection (adenoids0
7- Hearing
Which hormone thickens and lengthens the vocal cords?
Testosterone
List four functions of the larynx
1- Production of sound and speech
2- Warming and humidifying air
3- Protection (epiglottis closes and protects the airway)
4- Air passageway
What are the two main components that the trachea is made up of?
C-shaped rings of hyaline cartilage with interconnecting smooth muscle (trachealis).
The larynx is also known as the ___________ and connects the _______________ with the trachea. It consists of _____ pieces of cartilage (including the thyroid cartilage and ___________ ) and _____ cords.
voice box
laryngopharynx
nine
epiglottis
vocal
The trachea divides into the left and right ______ at the vertebral level of T5. The ______ bronchi is more ________, shorter and wider. Where the trachea divides into two bronchi, an internal ridge called the _______ is formed. The latter is a sensitive structure and triggers the _____ _______.
bronchi
right
vertical
carina
cough reflex
List four functions of the trachea
1- Air flow
2- Mucociliary escalator
3- Cough reflex
4- Warming, humidifying and filtering air
Describe in specific detail the ‘cough reflex’
1- The coughing reflex starts when the highly sensitive epithelial receptors in the respiratory tract mucus membrane become irritated
2- Sensitive nerve endings get stimulated in the larynx, trachea and bronchi
3- Via the vagus nerve, an impulse travels to the respiratory centre in the brainstem.
4- This leads to deep inhalation and closure of the glottis (and vocal cords)
5- Contraction of abdominal and respiratory muscles occurs to increase pressure
6- Finally, there is a forced removal of irritation (at a speed of up to 600 miles/hr)
Why is an aspirated object more likely to enter the right lung?
Because the right bronchus is more vertical, wider and shorter.
Explain fully how alveoli are maximised for gaseous exchange.
The 250 million alveoli in each lung creates a large surface area (approx 80m2) and the alveolar walls are only a single cell layer thick. Each alveoli is surrounded by many blood capillaries and the alveolar surfaces are moist to enable gasses
What role does the nervous system play in air entry into the bronchi?
The sympathetic nervous system stimulates bronchodilation and thus more air can be taken in.
The parasympathetic nervous system encourages bronchoconstriction during a restful state.
Describe the difference between Type I and Type II alveolar cells
Type I alveolar cells are simple epithelial cells, that cover 90% of the alveolar surface and are very thin to support gas exchange.
Type II alveolar cells secrete alveolar fluid that contains pulmonary surfactant which reduces surface tension, preventing alveolar collapse and allowing gasses to diffuse through it.
How many lobes in the
a) right lung
b) left lung
a) 3
b) 2
Describe the main role of the pleura
The pleura are serous membranes that surround the lungs and have the characteristic visceral and parietal layers with a small quantity of serous fluid inbetween. Its main role is in preventing friction and as it adheres to the lungs, it helps the expansion of the lungs.
Name two a) primary and two b) secondary muscles of ventilation
a) Intercostal muscles; diaphragm
b) scalenes; sternocleidomastoid; trapezius
Name one pathology that could lead to over-recruitment of ventilation muscles
Pulmonary fibrosis
Define tidal volume
The normal volume of air that enters the lungs during inspiration when no extra effort is applied.
Name two factors (not gender) that contribute to a larger lung volume
Living at higher altitudes
Taller individuals
Athletes
Non-smokers
Why is there no difference between inspired and expired nitrogen gas levels?
Nitrogen doesn’t bind to haemoglobin and is not used or created in the body.
What percentage of the following is oxygen
a. inspired air
b. expired air
a. 21%
b. 16%
Which blood cells transport oxygen around the body?
Red blood cells
List three ways (% highest to lowest) in which carbon dioxide is transported in the body
70% is found in plasma as bicarbonate (HCO3-)
23% is carried in RBSs (bound to haemoglobin)
7% is dissolved in blood plasma