4. Respiratory System Flashcards
List FOUR functions of the respiratory system.
- Gas Exchange - Oxygen for cell respiration and Carbon Dioxide as a waste product of cell respiration
- Warming, cooling, moistening of the air
- Immunity – removal of inhaled particles using nose, mucociliary escalator and alveolar macrophages
- Voice production and olfaction (smell)
What is the carina and why is it important
Where the trachea divides into two bronchi, an internal ridge called the carina is formed. The carina is a sensitive structure and triggers the cough reflex.
Describe specifically the route air flows through the respiratory tract, identifying key structures.
Air flows through the nasal cavity which is directly connected to the paranasal sinuses
which leads on to the pharynx (aka throat), a muscular tube connecting the nasal cavity and oral cavity to the larynx (aka voice box).
From the larynx air moves into the** trachea** (aka windpipe) and then below the trachea we have the division into the** left and right bronchi** and this further divides into smaller and smaller tubes called bronchioles. The bronchioles end in small air sacs called alveoli.
Describe the difference between external and internal respiration
External respiration: the exchange of gases between **air (lungs) ** that is inhaled and exhaled and blood. It is called ventilation.
Internal respiration is the exchange of gases between blood and **cells **
What is the function and structure of the mucociliary escalator?
A ciliated epithelial membrane lining the respiratory tract. It contains **mucous secreting goblet cells. **
Mucus
- traps inhaled particles and acts as a surfactant. (Lowers the surface tension of a liquid, allowing easier spreading)
- has antimicrobial properties.
Cilia move the particle laden mucus towards the oesophagus where they can be coughed up and/or swallowed. This protects the lungs from inhaled pathogens.
Describe the role of ‘nasal concha’.
There are three nasal concha in the nasal cavity.
They have foldings that create shelves that increase the surface area and trap water during exhalation.
They have a centrifuge effect pushing inhaled particles to the outer part of the nasal cavity where mucus is present and traps the particles.
List FOUR functions of the nasal cavity.
- Filtering Air
* Hairs filter large particles and cilia/mucus trap smaller particles.
* Nasal concha spin air to trap particles in mucus - Warms air
Warms and moistens incoming air so it doesn’t dry out the lung cells which are sensitive and must remain wet. - Humidification
A moist lining allows gases to dissolve and then diffuse. - Sneezing reflex in case of mucosal irritation
- Olfactory function
List FOUR functions of the paranasal sinuses.
Paranasal sinuses are connected to the nasal cavity and are air filled cavities within facial and cranial bones.
- Moistening/humidifying of the air
- Lighten the weight of the skull
- Resonance in speech
- Drain tears from the eyes – nasolacrimal duct connects the inside of the eye with the nasal cavity. It is why we get a runny nose when we cry.
Name TWO of the four paranasal sinuses.
Frontal
Ethmoid
Sphenoid
Maxillary
Describe the structure and function of the pharynx
The pharynx (throat) is a straight muscular 13cm tube which connects the nose and the throat terminating at the larynx.
It carries air, food and fluid down from the nose and mouth.
It consists of the nasopharynx, oropharynx and the laryngopharynx.
It contains eustachian tubes which Connects the nasal pharynx to the middle ear and allows**equalisation of pressure **in the middle ear.
Think being on a plane and opening mouth to equalise pressure
It contains adenoids, also called the nasopharyngeal tonsils.
List FOUR functions of the pharynx.
aka - the throat
1) Warming and humidifying
2) Passageway for air and food - 13 cm tube connecting nose and throat
3) Taste
4) Hearing
5) Equalisation of pressure through eustachian tubes that connect the nasopharynx to the middle ear
6) Immune protection – adenoids
7) Speech - resonating chamber
Describe how laryngeal muscles alter ‘tone’ when relaxed o contracted.
The larynx is the voice box (la la la). Laryngeal muscles attach to the vocal cords.
a. Relaxed – laryngeal muscles are relaxed which means the cords are loose and a low tone is produced
b. Contracted - laryngeal muscles are contracted which means the cords are tight and a high tone is produced
Which hormone thickens and lengthens the vocal cords?
Testosterone
Where is the epiglotis located and what does it do?
It is located in the larynx
It closes off the trachea during swallowing preventing food entering the lungs.
List FOUR functions of the larynx
It is the voice box. It is where adams apple sits
- Warming and humidifying (bit of a theme here!)
- Production of sound and speech (aided by the tongue, lips and cheeks)
- Protection – the epiglottis closes off the trachea during swallowing preventing food entering the lungs
- Air passageway
List FOUR functions of the trachea.
The trachea is the windpipe
1) Warming, humidifying and filtering (again!)
2) Air Flow - C Shaped rings of cartilage connected by smooth muscle keeps trachea open and unobstructed for air flow
3) Cough reflex – in response to irritation
4) Mucociliary escalator – traps inhaled particles and removes them from the respiratory tract
How does the trachea respond to?
a. The sympathetic (fight or flight) nervous system
b. The parasympathetic (rest and digest) nervous system
a. The sympathetic (fight or flight) nervous system
Tracheal dilation as we need more oxygen to deal with a danger. Airways dilate, more blood and therefore oxygen flows, pupils dilate to improve peripheral vision
b. The parasympathetic (rest and digest) nervous system
Tracheal constriction as we don’t need a huge amount of oxygen to chill
Describe in specific detail the ‘cough reflex’.
As we are often inhaling particles that may be dangerous, we are able to create a forceful expulsion from the respiratory system with a cough.
How does it work?
1. Irritation
The coughing reflex starts with iritation of the mucous membrane. Epithelial receptors in the respiratory tract are highly sensitive to this
This stimulates nerve endings in the larynx, trachea and bronchi
- Inspiration
A nerve impulse is sent via the vegus nerve to the respiratory center in the brain stem
This causes deep inhalation and closure of the glottis (vocal chords)
- Compression
Contraction of the abdominal respiratory muscles increases pressure. - Expulsion
Forced removal of irritation
Describe the structure of the trachea
The trachea is roughly 12cm long and is made of incomplete C shaped rings of hylaine cartridge adhering to the oesophagus.
These incomplete rings of cartilage are connected by smooth muscle which is called trachealis. This smooth muscle allows for some constriction and dilation but the c chaped rungs make sure we keep our respiratory system open
The trachea divides into the left and right bronchi at the vertebral level T5.
Where the trachea divides into two bronchi, an internal ridge called the carina is formed. The carina is a sensitive structure and triggers the cough reflex.
Describe the structure and function of the Bronchi
The bronchi deliver air into the lungs.
The trachea divides into the left and right bronchi at the vertebral level T5.
Where the trachea divides into two bronchi, an internal ridge called the carina is formed. The carina is a sensitive structure and triggers the cough reflex.
Bronchi are similar in structre to the trachea containing cartilage rings that maintain an open airway.
Bronchi are lined with ciliated epithelium.
Where do we find the bronchioles and what is their structure
The bronchioles are a continuation of the bronchi and lead directly into the alveoli where gas excahnge takes place.
They have no cartilage in their structure and instead contain smooth muscle.
Explain fully how alveoli are maximised for gaseous exchange.
(know this!!!)
Alveoil are small hollow cavities that mae up most of the lung volume and act as the sight of gas exchange in the lungs
They do this:
1. With a large surface area of approx 80m2 from over 250 million alveoli in each lung!
2. Walls of the alveoli are very thin – one layer only – which makes gas exchange easier
3. Surrounded by many blood capillaries that are also only one layer thick making gas exchange easier.
4. Alveoli surfaces are moist and gas exchange is easier when in water
Describe the difference between Type I and Type II alveolar cells.
Type 1: Simple epithelial cells that cover 90% of the alveolar surface. They are very thin to support gas exchange
Type 2: Secrete alveolar fluid that contains **pulmonary surfactant. **
Also: There is a third alveolar cell called alveolar macrophages which acts as another layer of immune defence. They are strategically located leukocytes that engulf and destroy microbes entering the alveoli
Describe the role of pulmonary surfactant and why this is so important.
Secreted by type 2 alveolar cells.
It reduces surface tension preventing alveoli from collapsing and reducing the pressure required to reinflate them.
Without it, when we exhale the alveoli would collapse and our lungs would not reinflate. The alveolar fluid keeps the alveoli moist to facilitate gas diffusion.
It is a mixture of lipids and proteins
The protein part is hydrophilic and resides in the alveolar fluid. The lipid part is hydrophobic and faces the air. So the fats are repelling away from the water and that is what keeps the alveoli open. They are opening up the space in order to distance themselves from the water.
Why should attention be paid to lung development in premature babies?
Surfactant is not produced until **20-24 weeks gestation **so if a baby is less than 24 weeks it will need treatment to mature the lungs. Mums can be given steroids prior to birth to facilitate maturing of lungs.
Why is an aspirated object more likely to enter the right lung?
Because it is more vertical, wider and shorter
How does gas exchange work in alveoli?
It is in the alveoli that oxygen and carbon dioxide are exchanged between air and blood.
The process of gas exchange is between the alveoli and the capillaries.
After breathing in, oxygen moves from the alveoli into the blood and becomes oxygenated.
Carbon dioxide moves from the deoxygentaed blood into the alveoli to be exhaled.
The movement of both gases is through **diffusion. **
What role does the nervous system play in control of air entry into bronchi
The bronchi is a muscular tube. Control of entry into bronchi is via:
Sympathetic Nervous System (SNS) – bronchodilation. In a fight or flight situation we need to dilate the tracheal and bronchial muscles and the bronchial wall.
Parasympathetic nervous system (PNS) – Bronchoconstriction.
Which body organ separates the lungs?
The heart
How many lobes are in the lung?
The heart sits fairly centrally but points to the left side
a. Left lung -2 (due to heart)
b. Right lung -3
What role does the nervous system play in control of air entry into bronchi
The bronchi is a muscular tube. Control of entry into bronchi is via:
Sympathetic Nervous System (SNS) – bronchodilation. In a fight or flight situation we need to dilate the tracheal and bronchial muscles and the bronchial wall.
Parasympathetic nervous system (PNS) – Bronchoconstriction.
Why is an aspirated object more likely to enter the right lung?
Because it is more vertical, wider and shorter
Describe the main role of the pleura
Serous membranes (a single layer of epithelium) that surround the lungs.
The visceral and parietal pleura form a double layer separated by 5 to 10 ml of serous fluid that** prevents friction**
Pleura adhere to the lungs so that the lungs are sucked to the pleura which when breathing in helps expansion of the lungs and helps everything is move together.
List TWO phases of ventilation.
Ventilation is the process of breathing.
The two phases in a cycle of ventilation are
Inhalation - breathing in - 2 seconds
Exhalation - breathing out - 3 seconds
Name TWO areas where breathing comes form.
Abdominal (diaghramatic) breathing
Upper rib (intercostal) breathing
Name TWO primary muscles of ventilation.
I. The intercostal muscles which are attached between ribs at right angles. Their contraction pulls ribs upwards on inhalation, expanding outwards and increasing the size of the rib cage.
II. Diaphragm attached to the lower ribs, sternum and lumbar spine. A domed muscle that separates the thoracic and abdominal cavity.
Contraction moves the diaphragm into the abdomen and draws air into the lungs.
Name TWO secondary muscles of ventilation.(also known as accessory muscles)
They are often** over recruited** in patients suffering with breathlessness disorders and they can become fatigued and shortened.
Most accessory muscles are located around the neck and chest.
Secondary muscles include
I. Trapezius
II. Sternocleidomastoid
III. Scalines.
Name ONE pathology that could lead to over recruitment of ventilation muscles.
Asthma
Indicate if the following processes are active or passive:
a. Inhalation
b. Exhalation
a. Inhalation – active - requires muscles. Needs energy for muscles to contract and open up the thoraic cavity
b. Exhalation – passive – muscles relax, elastic recoil of the lungs aided by elasticity of the lungs and pluera. Does not need energy
Define tidal volume.
The normal volume of air that enters the lungs during inspiration when no extra effort is required. Normally around 10% of lung capacity.
A normal tidal volume is 500 ml but this differs by gender, size, altitude, smoking, exercise/fitness
Name TWO factors (not gender) that contribute to a larger lung volume.
Tall, non smokers, live at high altitude, athlete
Why is there no difference between inspired and expired nitrogen gas levels?
The air around us is around 80% concentrated nitrogen but we don’t have much use for it so when we inhale it into the blood it does not dissolve, it doesn’t bind to Hb, it is not used so the concentration does not change.
So whilst we do circulate a very small quantity of nitrogen it is tiny and doesn’t change. We breathe in 78% Nitrogen and we breathe out 78% nitrogen.
Alveolar gas exchange - fill in the diagram
