Lecture 13 Flashcards
Functions of the respiratory system
Pulmonary ventilation (Gas exchange)
* Supply of O2, Removal of CO2
Vocalisation (speaking)
Olfaction (smelling)
Biotransformation (metabolism)
* Bronchiolar secretoglobin cells (BSCs) > alveolar type II cells > macrophages, endothelial cells
ACE
*Angiotensin-converting enzyme (ACE) is a central component of the renin–angiotensin system (RAS), which controls blood pressure by regulating the volume of fluids in the body. It converts the hormone angiotensin I to the active vasoconstrictor angiotensin II. Therefore, ACE indirectly increases blood pressure by causing blood vessels to constrict. ACE inhibitors are widely used as pharmaceutical drugs for treatment of cardiovascular diseases.
Removal of inhaled particulate matter
Regions of the respiratory system
- Nasal cavities
- Pharynx (throat)
- Larynx (voice box)
- Trachea (wind-pipe)
- Lungs
Respiratory meaning
refers to the overall process of breathing (all parts of the breathing system, including lungs)
Pulmonary meaning
specifically refers to the lungs (function, disease, etc)
The nasal cavities
*Nasal cartilages
*Anterior nares (nostrils)
*Choanae (posterior nares)
*Olfactory receptors
* Cribriform plate of the ethmoid bone
* Nasolacrimal aperture
* Nasal septum
* Nasal conchae (shelves)
* Paranasal air sinuses
Nasal cartilages
- Structures within the nose that provide form and support to the nasal cavity. The nasal cartilages are made up of a flexible
material
Anterior nares (nostrils)
- Allow air to enter the nose and pass into the nasal cavity. Individually, each opening is referred to as an anterior naris
- Olfactory receptors
- Cribriform plate of the ethmoid bone
- Nasolacrimal aperture
- Nasal septum
- Nasal conchae (shelves)
- Paranasal air sinuses
Choanae (posterior nares)
- Openings found at the back of the nasal passage between the nasal cavity and the throat
What are olfactory receptors
- Olfactory receptors (ORs) belong to the G-protein-coupled receptor family and play a critical role in recognizing thousands of odorant molecules in the olfactory sensory system
- Any odor stimulus is initially represented as activation of one to many different olfactory receptors
- Some receptors, in particular, those for pheromones, show very high specificity
Cribriform plate of the ethmoid bone
- Lies within the ethmoidal notch of the frontal bone and forms the roof of the nasal cavity
Nasolacrimal aperture
- The purpose of the nasolacrimal system is to drain tears from the ocular surface to the lacrimal sac and, ultimately, the nasal cavity
Nasal septum
It is the bone in the nose that divides the nasal cavity (inside your nose) into a right and left side
Nasal conchae (shelves)
- Nasal concha, also called Turbinate, or Turbinal
- Three bony shelves called the inferior, middle and superior nasal conchae are
attached to the lateral walls and by projecting into the cavities, they divide both nasal
cavities into four air channels - They increase the surface area of these cavities, thus providing for rapid warming and
humidification of air as it passes to the lungs.
Paranasal air sinuses
- Small hollow spaces in the bones around the nose. The prime function of the paranasal
sinuses is to protect the organism, mostly by humidifying the inhaled air and facilitating the immune response of the respiratory system
Parts of the pharynx
- Nasopharynx (auditory tubes)
- Oropharynx
- Laryngopharynx
Nasopharynx (auditory tubes)
- The main function of your nasopharynx is to connect your nasal passages to the rest of your respiratory system. This allows air to get from your nose to your lungs.
- Also controls pressure between nasopharynx and middle ear.
Oropharynx
- The middle part of the throat connects to the oral cavity (mouth) and allows air, food and fluid to pass through
Laryngopharynx
- The bottom part of the throat is near the larynx (or voice box). It regulates the passage of air to the lungs and food and fluid to the esophagus (the hollow, muscular tube that
connects the throat to the stomach)
The larynx (“voice box”)
- Larynx has several functions including:
- Creating vocal sounds and preventing food and other particles from getting into trachea, lungs and the rest of your respiratory system.
The trachea (“wind-pipe”)
- The trachea is a key part of respiratory system.
- The trachea is composed of about 20 rings of tough cartilage. The back part of each ring is made of muscle and connective tissue. Moist, smooth tissue called mucosa lines the inside of the trachea. The trachea widens and lengthens slightly with each breath in, returning to its resting size with each breath out.
- It is lined with cells that produce mucus. This
mucus keeps allergens, dust particles or other
debris out of lungs. - Tracheobronchomalacia (TBM) is a condition
caused by a weak airway that collapses when
the patient breathes. - TBM in adults can be caused by exposure to
toxic gases such as mustard gas, exposure to
secondhand smoke (inhaled accidentally).
Mucous membrane
- The airway surface liquid (ASL), often referred to as mucus, is a thin layer of fluid covering the luminal surface of the airway. The major function of mucus is
to protect the lung through mucociliary clearance against foreign particles and chemicals entering the lung. - Hairlike structures called cilia line the mucous membrane and move the particles trapped in the mucus out of the nose.
- Airway mucus traps inhaled toxins and transports them out of the lungs by means of ciliary beating and cough. Paradoxically, although a deficient mucous
barrier leaves the lungs vulnerable to injury, excessive mucus or impaired clearance contributes to the pathogenesis of all the common airway diseases. - Infections such as the flu, acute bronchitis
(inflammation of the airways), and pneumonia (inflammation of the lungs) can cause the airways to make extra mucus.
Specialised cells
- Ciliated cells
- Mucous cells
- Basal cells
Ciliated cells
- Ciliated cell provides the propelling force for the transport of mucus along the airways
Mucous cells
- Scattered throughout the cilia are goblet cells that secrete mucus which helps protect the lining of the bronchus and trap microorganisms and particles
Basal cells
- Basal cells provide an attachment site for ciliated and goblet cells to the basal lamina. They are also candidate stem cells in the conducting airways, responsible for normal cell replacement
Structure and location of the lungs
The right lung consists of three lobes: the right upper lobe, the right middle lobe, and the right lower lobe.
The left lung consists of two lobes: the left upper lobe and the left lower lobe.
Parts of the lungs
Apex of lung
Base of lung
* Each lung has a base resting on the diaphragm
Root (hilum) of lung
* Location where primary Bronchus, Bronchial
Artery, Pulmonary Artery, Pulmonary vein, Nerve and Lymphatic vessels enter and leave the lung
What is the respiratory zone and conducting zone
Respiratory zone is found deep inside the lungs. This zone corresponds to the lung parenchyma and includes the respiratory bronchioles, alveolar ducts, and alveoli.
All of the airway sections, before respiratory zone, are called conducting zone. The major functions of the conducting zone are to provide a route for incoming and outgoing air, remove debris and pathogens from the incoming air, and warm and humidify the incoming air.
Alveoli
- Alveoli represent the most distal portion of the respiratory tract.
- There are approximately 500 million alveoli in the human body.
- Each alveolus is separated from the other by an alveolar septum, which contains the pulmonary capillaries participating in gas exchange and connective tissue.
- Each alveolus consists mostly of three types of cell populations:
1. Type I pneumocytes
2. Type II pneumocytes
3. Alveolar macrophages
Type I pneumocytes
- Facilitate gas exchange
- Maintain ion and fluid balance within the alveoli
- Communicate with type II pneumocytes to secrete surfactant in response to stretch
Type II pneumocytes
- Produce and secrete pulmonary surfactant - surfactant is a vital substance that reduces surface tension, preventing alveoli from collapsing.
- Expression of immunomodulatory proteins that are necessary for host defense
- Regulates the movement of water across epithelium
- Regeneration of alveolar epithelium after injury
Alveolar macrophages
- Play an essential role in our immune system. They collect inhaled particles from the
environment, such as coal, silica, and asbestos, and microbes, including viruses,
bacteria, and fungi.
Gas exchange
- Upon inhalation, the diaphragm contracts and flattens and the chest cavity enlarges. This contraction creates a vacuum, which
pulls air into the lungs. Upon exhalation, the diaphragm relaxes and returns to its domelike shape, and air is forced out of the
lungs. - A nerve (phrenic nerve) automatically and involuntarily control the contractions and relaxation of the diaphragm to maintain a
steady blood-oxygen level. It can adjust the contraction frequency as needed when indicated by the brain. - The skeletal muscle of diaphragm can also be controlled voluntarily by an individual, for example, when performing meditative breathing
Three processes are essential for the transfer of gas (oxygen) from the outside air to the blood flowing through the lungs…
- Ventilation is the process by which air moves in and out of the lungs.
- Diffusion is the spontaneous movement of gases, without the use of
any energy or effort by the body, between the alveoli and the capillaries in the lungs. - Perfusion is the process by which the cardiovascular system pumps blood throughout the lungs
The pulmonary artery carries…
deoxygenated blood from the heart to the lungs, where it travels through pulmonary capillaries, picking up oxygen and releasing
carbon dioxide. The oxygenated blood then leaves the lungs through pulmonary veins. Gas exchange occurs by diffusion across cell membranes. Diffusion allows the spontaneous movement of gases, without the use of any energy.