Unit 5 Flashcards
Ventilation
Gas exchange between the atmosphere and the lungs.
Expiration
Air moves out of the lungs (exhalation). Somatic motor neurons stop firing to trigger it. Passive for quiet breathing and active during exercise or heavy breathing.
Lungs
The main organ of the respiratory system.
Thorax
Chest.
Pleural Fluid
Between the pleural sac layers which acts as a lubricant.
Larynx
Voice box.
Bronchioles
Branches off of the bronchi.
Compliance
The ability for the lung to stretch. The lower it is, the harder it is to expand the lungs (ie. inhalation).
Surfactant
Reduces surface tension to prevent collapsing of the alveoli.
Bronchoconstriction
Caused by histamine and parasympathetic neurons.
Spirometer
An instrument that measures movement of air during breathing.
Expiratory Reserve Volume (ERV)
The amount of air that can be exhaled after a normal expiration.
Vital Capacity (VC)
The maximum amount of air that can be voluntarily moved into or out of the respiratory system.
Inspiratory Capacity
The sum of the tidal volume and the inspiratory reverse volume.
Ventilation Rate
The amount of air inhaled or exhaled over a given amount of time.
Alveolar Ventilation
The amount of air that reaches the alveoli each minute. Is a more accurate indicator of efficiency of ventilation.
Perfusion
The flow of blood to the alveolar capillaries.
Hypoxia
Lack of oxygen. Results in tissue death.
Dissociation Curve
A graph that highlights the relationship between the partial pressure of oxygen and hemoglobin saturation.
Carbonic Anhydrase
Catalyzes the reaction of carbon dioxide into bicarbonate.
Central Chemoreceptors
Located in the medulla oblongata (most important chemical controller of ventilation). Activated when CO2 crosses the blood brain barrier into the cerebrospinal fluid (CSF) resulting in changes in pH. Senses changes in pH in the CSF not the arterial blood.
Aortic Body
Peripheral chemoreceptors found near the aorta.
Partial Pressure
The partial pressure of an atmospheric gas is equal to the atmospheric pressure times the percent gas in the atmosphere.
Inspiration
Air moves into the lungs (inhalation). Somatic motor neurons trigger it.
Airways
Pathways where air travels through to reach the alveoi or to leave the lungs.
Alveoli
Tiny hollow sacs found at the ends of the terminal bronchiole that are the sites of gas exchange. Wrapped with an extensive capillary network (the diameter is larger than in the heart so more red blood cells can flow through (not single file)) which covers 80-90% of the alveolar surface.
Pleural Sacs
A double membrane that surrounds each lung.
Pharynx
Throat.
Trachea
Windpipe.
Bronchi
Branch off of the trachea.
Intrapulmonary Pressure
The pressure inside the lungs. Is greater than the pressure in the pleural cavity.
Elastance
The degree and/or speed of return to resting volume after the lung is stretched. When it is low, the lung does not return to resting volume passively (expiration must be active not passive).
Resistance
Created by narrowing or increasing the diameter.
Bronchodilation
Caused by CO2 and circulating epinephrine.
Inspiratory Reserve Volume (IRV)
The maximum amount of air that can be inspired above tidal volume.
Total Lung Capacity (TLC)
The vital capacity plus the residual volume.
Tidal Volume (TV)
The amount of air moved in a single normal inspiration or expiration.
Dead Space
Air in the trachea, bronchi, and bronchioles that does not participate in gas exchange.
Hypoventilation
Too shallow breathing. Results in not enough oxygen and too much carbon dioxide.
Pulmonary Edema
A condition caused by to much fluid in the lungs.
Chloride Shift
Moves bicarbonate ions out of the red blood cell by a transporter protein which exchanges HCO3- for Cl- in order to help maintain pH.
Reverse Chloride Shift
Moves bicarbonate ions into the red blood cell and pushes Cl- out of the cell.
Peripheral Chemoreceptors
Located in carotid bodies which are found in carotid arteries (at the sides of the neck which supply the brain with blood). Are glomus cells. Sense changes in PO2 and pH of the plasma or increase in PCO2.
Carotid Bodies
Found in the carotid arteries and acts as a chemoreceptor.
Mechanoreceptor
Control ventilation to protect the lungs.
Gas Laws
Gases move from areas of high pressure to areas of low pressure. Volume and pressure of a gas are inversely related.
Respiratory Cycle
One sequence of inspiration and expiration.
The Respiratory System Allows For
1) Exchange of gases between atmosphere and blood.
2) Homeostatic regulation of body pH.
3) Protection from inhaled pathogens and irritating substances.
4) Vocalization.
4 Main Processes of the Respiratory System
1) Gas exchange between atmosphere and lungs.
2) Gas exchange between lungs and blood.
3) Transport of gases by blood.
4) Exchange of gases between blood and tissues.
Respiratory System Structures
1) Conducting System (airways)
2) Exchange Surface (alveoli)
3) Pumping System (bones and muscles of thorax)
Upper Respiratory Tract/System
Consists of the mouth, oral cavity, nostrils, nasal cavity, pharynx, and larynx.
Lower Respiratory Tract/System
Consists of the trachea, bronchi, bronchioles, lungs, and the diaphragm.
Type I Alveolar Cells
Large but thin allowing for rapid gas diffusion.
Type II Alveolar Cells
Small but thick. Synthesize and secrete surfactant.
Alveolar Pores
Holes in alveoli that help with the diffusion of O2 between alveoli. They become larger with age. Need to be the right size, not too small, not too large.
Amount of Gas That Will Dissolve in a Liquid is Determined By
1) Partial pressure of the gas.
2) Solubility of the gas in the liquid.
Boyle’s Law
P1V1 = P2V2
Volume Depends On
1) The transpulmonary pressure (difference between alveolar pressure and intrapleural pressure).
2) The degree of elasticity of the lungs.
Alveolar Pressure
Pressure inside the lungs.
Intrapleural Fluid Pressure
Pressure outside the lungs. Is lower than the inside of the lungs which helps keep the lungs expanded and open.
Airways Need To
1) Warm air to 37 °C to maintain core body temperature and protect alveoli. Is done by swirling the air in the naval cavity.
2) Add water vapour to air to prevent drying of epithelia.
3) Filter out foreign material.
NKCC
An apical anion channel that transports Cl- to the lumen of the airways.
Goblet Cells
Secrete mucus that covers cilia.
Lamina Propria
Where blood vessels, nerves, and white blood cells are located.
Passive Expiration
Depends on the elastic recoil of the thoracic muscles and the lungs.
Active Expiration
Depends on contraction of internal intercostals and abdominal muscles.
Pneumothorax
Collapsed lungs. Occurs when air enters the pleural cavity resulting in the pressure difference equilibrating.
Factors Required For Breathing
1) Compliance (stretchability) of the lungs.
2) The resistance to air flow in the airways.
Bronchiole Diameter
Can be affected by the nervous system, hormones, paracrines, and mucus buildup.
Pulmonary Function
Assessed to determine the amount of air a person moves during quiet breathing and maximal breathing effort. Allow for the diagnosis of many diseases.
Residual Volume (RV)
The amount of air left in the lungs after maximal expiration.
Capacity
The sum of two or more lung volumes.
VC (Formula)
IRV + ERV + VT
Minute Volume (MV)
The tidal volume times the respiratory rate.
Effectiveness of Ventilation
Determined by the rate and depth of breathing. Due to dead space, increase in depth of breathing is the most important.
Alveolar Ventilation (Formula)
Ventilation Rate x Alveolar Volume
Rate of Diffusion Across the Lungs Is
1) Proportional to partial pressure gradient.
2) Proportional to the available surface area.
3) Inversely proportional to the thickness of the membranes.
4) Greatest over short distances.
Partial Pressure Gradient Is Influenced By
1) Composition of inspired air (affected by altitude).
2) Alveolar ventilation (can be affected by changes in airway resistance ex. asthma and changes in lung compliance ex. fibrosis).
Oxygen
Has a low solubility in the plasma so most O2 is transported by red blood cells by binding to hemoglobin.
Oxyhaemoglobin (HbO2)
Haemoglobin bound to oxygen.
Deoxyhaemoglobin (Hb)
Unbound haemoglobin.
Percent Saturation of Haemoglobin
The percent of available binding sites that are bound to oxygen.
Transport of Carbon Dioxide
1) Dissolved in the plasma.
2) Interact with proteins (haemoglobin).
3) Converted to bicarbonate.
Medulla Oblongata
Initiates the contraction of the respiratory skeletal muscles. Contains a network of neurons called the central pattern generator.
Dorsal Respiratory Group (DRG)
Inspiratory neurons (I neurons) in the medulla oblongata. Controls external intercostal muscles and diaphragm (muscles of inspiration).
Ventral Respiratory Group (VRG)
Expiration neurons (E neurons) in the medulla oblongata. Controls internal intercostal and abdominal muscles (active expiration).
Chemoreceptors
Modify or adjust the rhythmicity of the central pattern generator neurons.
Glomus Cells
Modified neuron (excitable tissue).
Irritant Receptors
Located in airway mucosa. Stimulation triggers parasympathetic neurons that innervate bronchiolar smooth muscle resulting in bronchoconstriction.
Stretch Receptors
Located in airway smooth muscle. Triggered if lungs are over-inflated which terminates ventilation. This does not happen during quiet breathing or mild exertion.
Hering-Breuer Inflation Reflex
Terminates ventilation when lungs are over-inflated.
