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69 Cards in this Set
- Front
- Back
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Name the main structures of the respiratory system from superior to inferior. |
Nasal cavity - oral cavity - pharynx - larynx - trachea - primary bronchus - bronchial tree - lung. |
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Name the 2 groups the respiratory system structures can be divided into? |
Upper and lower respiratory tracts. |
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The upper consists of? |
Nasal cavity Pharynx Larynx |
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The lower consists of? |
Trachea Lungs and bronchi |
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Describe the general structure of the lungs? |
The lungs are large, spongy-like structures that fill the thoracic cavity, sitting on either side of the heart. While the right and left lungs consist of the same structures and facilitate the same function, they exhibit a few differences. |
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Difference between right and left lung? |
The left lung is smaller than the right lung and contains the cardiac notch which allows room for the heart (which sits more towards the left side of the thoracic cavity). The left lung is divided into two lobes, while the right lung has three obvious lobes. |
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The lungs are surrounded by the? |
Pleural membrane |
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Name the 2 layers of the pleural membrane |
Parietal and visceral layer |
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What sits between the layers? |
Pleural fluid. |
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What does this achieve? |
The pleura provide a smooth and friction-less space within which the lungs can expand and recoil during breathing. |
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Describe the structure of the bronchial tree starting at the primary bronchi. |
Primary bronchi - smaller bronchi - respiratory bronchioles - terminal alveoli and alveolar clusters (sacs). |
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What supports the alveolus which allows for the facilitation of gas exchange between the air and blood? |
An extensive capillary bed. |
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Name the 2 function zones of the respiratory system? |
Conducting and respiratory zones |
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Describe the main features of the conducting zone. |
From nasal cavity to terminal bronchioles and contains respiratory mucosa. Warms, moisturises and cleanses air. |
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Describe the main features of the respiratory zone |
Includes the respiratory bronchioles and alveoli |
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Describe the structure of the nasal cavity. |
The nasal cavity is divided into right and left sides by the nasal septum. Projecting from the lateral walls of the cavity are the nasal conchae (turbinates), which generate a turbulent air flow to ensure all air comes into contact with the respiratory mucosa. Air enters the nasal cavity via the anterior nares (nostrils) and exits into the pharynx via the posterior nares (nasal aperture). Behind the anterior nares, the nasal vestibule contains vibrissae which trap large particles while the olfactory epithelium lies at the superior surface of the cavity. |
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Describe the structure of the pharynx.
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The pharynx is divided into three parts:Nasopharynx: Posterior to the nasal cavities. Contains the pharyngeal tonsils and opening of the pharyngotympanic tube.Oropharynx: Posterior to the oral cavity, the oropharynx conducts both food and air. Contains the palantine and lingual tonsils. Soft palate and uvula at superior margin are pushed up during swallowing to close off the nasopharynx.Laryngopharynx: Inferior to the oropharynx and superior to the larynx. Also conducts both food and air. Posterior aspect diverges into the esophagus (conducts food) and larynx (conducts air through rest of respiratory tract). |
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Describe the structure of the larynx. |
The larynx sits inferior to the pharynx and conducts air to the trachea. It is composed of nine cartilages of different sizes and shapes and contains the vocal folds which produce sound. |
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Describe the structure of the trachea. |
The trachea is a connective tissue tube that extends from the larynx and terminates in a division into the two primary bronchi. 'C' shaped cartilages surround the trachea anteriorly to prevent collapse, while posteriorly a line of smooth muscle extends down the length of the trachea which can rapidly force air out upon contraction (e.g. coughing). |
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Describe the structure of the bronchial tree. |
The right and left primary bronchi begin to branch once inside the lungs, dividing into secondary bronchi, then tertiary bronchi, etc. until there are 23 successive branches. Branches smaller than 1mm in diameter are referred to as bronchioles. The very last branches are the terminal bronchioles- these give rise to the respiratory bronchioles of the respiratory zone. |
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Describe the structure of bronchi. |
The bronchi are tubular structures whose walls consist of the inner respiratory mucosa, underlying connective tissue layer, smooth muscle layer and outer cartilagenous rings. |
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How so these structures change coming up to the respiratory zone? |
- Cartilagenous rings transform into irregular shaped plates that become more sparse and dispersed until eventually disappearing - Smooth muscle layer progressively thickens - Respiratory mucosa transitions from pseudostratified columnar epithelium to simple cuboidal epithelium with progressively less cilia that eventually disappear |
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What does the increased smooth muscle and lack of supportive cartilage in the smaller bronchioles allow for? |
A greater ability for bronchiole dilation or constriction to control air flow into the respiratory zone. |
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The respiratory zone is defined by the presence of _________ which have the capability of gas exchange. |
alveoli |
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Where does the respiratory zone begin? |
Respiratory bronchioles |
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What are alveoli? |
Alveoli are thin-walled sacs that contain air (gases). |
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What are alveoli mostly made up of? |
Type I pneumocytes (alveolar cells) which form a simple squamous epithelial layer. |
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What are Type 1 pneumocytes? |
Squamous epithelial cells |
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Scattered amongst the type 1 pneumocytes are _______ and a few _________ |
type II pneumocytes and macrophages |
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What are type II pneumocytes? |
Epithelial cells which produce surfactant. |
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Where alveoli cluster, _____ exist between neighboring alveoli to permit the spread of air throughout the cluster for optimum aeration and gas exchange. |
pores |
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The type I pneumocytes of alveoli and the walls of the capillaries form the ______________________ which permits the diffusion of gases between air in the alveoli and blood in the capillaries. |
respiratory membrane |
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What is the respiratory membrane? |
The respiratory membrane is a thin membrane consisting of the alveolar cells, endothelial cells of the capillary and the basement membrane between these epithelial layers. |
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What is pulmonary ventilation? |
Breathing |
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Name the 2 steps of pulmonary ventilation. |
Inspiration and expiration |
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This movement occurs due to changes in the volume of the lungs which either decrease or increase ____________________ with respect to atmospheric pressure, driving air into or out of the lungs, respectively. |
intrapulmonary pressure |
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Name the 6 steps of inspiration in order |
1. Inspiratory muscles contract 2. Thoracic cavity expands 3. Lungs expand 4. Lung volume increases 5. Intrapulmonary pressure falls 6. Air moves into lungs |
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Name the 6 steps of expiration in order |
1. Inspiratory muscles relax 2. Thoracic cavity narrows 3. Lungs recoil 4. Lung volume decreases 5. Intrapulmonary pressure rises 6. Air moves out of lungs |
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A difference in pressure of only ____mmHg (+/-) is enough to drive about 500mL of air into or out of the lungs, such as occurs during normal, resting ventilation. |
1 |
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If, however, more air needs to be moved into and out of the lungs (e.g. during exercise), then recruitment of ___________ results in larger changes in thoracic cavity and lung volumes, with consequent larger changes in intrapulmonary pressure (e.g. +/- 2-4mmHg) driving a larger volume of air between the lungs and atmosphere. |
more respiratory muscles |
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What is inter pleural pressure? |
Pressure wishing the pleural cavity. |
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What does it achieve? |
As described in the video, intrapleural pressure also plays a role in pulmonary ventilation, by maintaining a pressure slightly below intrapulmonary pressure. The serous fluid within the pleural cavity acts as an adhesive force between the lungs and thoracic wall and balances inward and outward 'pulling' forces on the lungs. This is essential to ensuring the lungs remain inflated after expiration (i.e. don't collapse). |
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Name the three factors that have the greatest influence on the effectiveness on pulmonary ventilation. |
Airway resistance Alveolar surface tension Lung compliance |
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What is airway resistance? |
Airway resistance is the friction, or drag, that air encounters as it flows through the respiratory tract and is related to airflow in exactly the same way vascular resistance is related to blood flow. |
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What equation represents airway resistance? |
F = ΔP / R |
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Airway resistance in the respiratory tract is mainly determined by the ________ |
Diameter of the airway |
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What is surface tension? |
Surface tension occurs anytime there is a liquid- gas interface and is due to the attraction of liquid molecules to each other in the presence of a gas. Surface tension is a force that resists an increase in the surface area of the liquid. |
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What does surface tension occur in the alveoli? |
Due to the interaction between the inhaled air (gases) and body fluids (which are found throughout all body cells/tissues). Within the alveoli, water molecules in our body fluids want to pull together where they are next to the air, but in doing so would collapse the alveoli. To prevent alveolar collapse, a substance must be introduced thatreduces the surface tension. |
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What substance reduces alveolar surface tension? |
Surfactant |
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The greater the _____________ of the lungs, the less energy it takes to fill them with air. |
compliance |
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Lung compliance is determined by two main factors: |
-Distensibility of lung tissue: this refers to how elastic lung tissue is; the greater the elasticity, the more compliant the lungs will be (and visa versa). -Alveolar surface tension: the greater the alveolar surface tension, the harder it is for the lungs to expand and inflate (and visa versa). |
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During quiet, resting breathing the average adult inhales and exhales around ______ of air, this is known as the ___________. |
500mL tidal volume |
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Total lung capacity? |
4200mL |
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To maintain a steady rhythm of pulmonary ventilation- and to make adjustments as necessary- the respiratory centers of the brainstem (pons & medulla) control the ____ and ______ of pulmonary ventilation. |
rate and depth |
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Name various stimuli that have an effect on the respiratory centres. either increasing (+) or decreasing (-) the rate and depth of pulmonary ventilation. |
Chemoreceptors Muscle and joint receptors pain and emotion stimuli stretch receptors in lungs irritant receptors |
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Off the previous stimuli, which is the most potent stimulator? |
blood level of carbon dioxide (PCO2) |
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What is respiration? |
Respiration is the movement of respiratory gases (O2 and CO2) into and out of blood |
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How does the gas movement occur? |
This gas movement occurs via diffusion and is driven by the difference in partial pressure of each gas in the blood and outside of the blood. Gases always move down their pressure gradient, from areas of high partial pressure to areas of low partial pressure. |
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Name the 2 types of respiration. |
External and internal; |
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Describe external respiration. |
Pulmonary gas exchange Gas exchange between air and blood O2 moves into blood CO2 moves out of blood |
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Describe internal respiration. |
Capillary gas exchange Gas exchange between blood and body tissues CO2 moves into blood O2 moves out of blood |
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What is the ventilation to perfusion ratio? |
What this means is that there must be a 'match' between the amount of oxygenated air in the alveoli (ventilation) and the amount of blood in the pulmonary capillaries (perfusion). If the volume of air in the alveoli and the volume of blood in the pulmonary capillaries are significantly different then the exchange of gases will not be maximal. |
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How do we ensure adequate V-Q match? |
Local autoregulatory mechanisms result in changes in pulmonary arteriole diameter (vasoconstriction or vasodilation) to regulate the volume of blood passing through pulmonary capillary beds. Vasoactive substances are released in response to local PO2 levels to regulation perfusion. |
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How is O2 transported through the blood? |
bound to hemoglobin, dissolved in plasma |
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How is CO2 transported through the blood? |
dissolved in plasma, bound to hemoglobin, within bicarbonate molecules |
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How is the majority of CO2 transported? |
Within a bicarbonate molecule. |
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What is bicarbonate? |
Bicarbonate is formed when CO2 dissolved in plasma interacts with water molecules (H2O) in the plasma. CO2 and H2O combine to form carbonic acid (H2CO3). Carbonic acid is a relatively unstable compound and quickly dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+) |
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What happens at the lungs? |
At the lungs the equation is reversed and CO2 and H2O are re-formed and expired (H2O is expired as water vapour). |
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Due to this transportation method, the levels of CO2 in the blood are intricately related to __________ |
blood pH |
