Ch. 6: The Respiratory System Flashcards
Thoracic Cavity
Structure designed to perform breathing, location of lungs and heart
Air flow
Air is drawn into through the 1. Nares and through the 2. Nasal cavity (It is filtered by nasal hairs (vibrissae) and mucous membranes) and 3. Pharynx (common pathway for both food and air) where it is warmed and humidified 5. It then enters the larynx (only air, contains vocal cords which are maneuvered by skeletal muscle and cartilage, the glottis is the opening which is covered by the epiglottis to prevent food from entering the respiratory tract) 6. Followed by the trachea 7. Which divides into 2 mainstem bronchi, which divide into bronchioles 8. Which divide continually into smaller passages called bronchioles until reaching the alveoli
Surfactant
In the alveoli, reduces surface tension @ the liquid gas interface preventing collapse
Pleurae
Cover the lungs and line the chest wall, closed sac against which lung expands
- Visceral pleura: lies adjacent to the lung itself
- Parietal Pleura: lines the chest wall
- Intrapleural space: lies between these 2 layers and contains a thin layer of fluid which lubricates the 2 pleural surfaces
Diaphragm
A thin skeletal muscle that helps to create the pressure differential required for breathing bc lungs do not fill passively– divides the thoracic cavity from abdominal cavity, under somatic control even though breathing is autonomic control
Labored Breathing
Muscles of the chest wall, back and neck may also participate in breathing esp when breathing is labored due to pathogenic condition
Inhalation
Active process. Diaphragm and external intercostal muscles expand the thoracic cavity increasing the volume of the intrapleural space first then the intrathoracic volume. This decreases the intrapleural pressure
Negative-Pressure Breathing (part of inhalation)
The pressure differential ultimately expands the lungs, dropping their pressure and drawing in air from the environment. Boyles law– lower pressure in lungs causes atmospheric air to be drawn in to match atmospheric pressure
Exhalation
May be passive or active. In passive exhalation relaxation of the muscles of inspiration and elastic recoil of the lungs allow the chest cavity to decrease in volume, reversing the pressure differentials seen in inhalation. In active exhalation the internal intercostal muscles and abdominal muscles can be used to forcibly decrease the volume of the thoracic cavity, pushing out air.
Spirometer
Can be used to measure lung capacities and volumes
Total lung capacity (TLC)
Maximum volume of air in the lungs when one inhales completely
Residual Volume (RV)
Minimum volume of air in the lungs when one exhales completely
Vital capacity (VC)
Difference between the minimum and maximum volume of the air in the lungs (TLC - RV)
Tidal volume (TV)
The volume of air inhaled or exhaled in a normal breath
Expiratory reserve volume (ERV)
Volume of additional air that can be forcibly exhaled after a normal exhalation
Inspiratory Reserve Volume (IRV)
Volume of additional air that can be forcibly inhaled after a normal inhalation
Ventilation Center
A collection of neurons in the medulla oblongata that regulates ventilation
Chemoreceptors
Respond to CO2 concentrations, increasing the respiratory rate when there are high concentrations of CO2 in the blood (hypercarbia or hypercapnia) also respond to changes in O2 concentration in significant hypoxemia
Hypoxemia
Low oxygen concentrations in the blood; ventilation center responds by increasing the ventilation rate
Conscious Control of Ventilation
Ventilation can also be controlled consciously though the cerebrum, although the medulla oblongata will override the cerebrum during extended periods of hypo- or hyperventilation
Functions of the Respiratory System
- Gas exchange 2. Lungs lined w capillaries used in thermoregulation 3. Serve an immune function to prevent invaders from gaining access to bloodstream 4. Control blood pH by controlling concentrations
The lungs and gas exchange
The lungs perform gas exchange w the blood through simple diffusion across concentration gradients
Pulmonary Arteries
Brings deoxygenated with high CO2 concentration to the lungs, where the capillaries which surround alveolus bring deoxygenated blood, originate from left ventricle
Pulmonary Veins
Oxygenated blood w a low CO2 concentration leaves the lungs via pulmonary veins to right atrium of heart
Respiratory adjustment to higher altitudes
Less O2 available, breathe more rapidly to avoid hypoxia, binding dynamics of hemoglobin would be altered to facilitate O2 unloading at tissue, natural response of hemoglobin to decreased CO2 concentration in environment would actaully be to decrease unloading of O2 to tissues, other mechanisms can counteract and override phenomenon to allow adequate delivery of O2 (ie more red blood cells) in the long term form more blood vessels
Vasodilation and Vasoconstriction
The large surface area of interaction between the alveoli and capillaries allows the respiratory sys to assist in thermoregulation through vasodilation and vasoconstriction of capillary beds→ capillaries expand means more blood passes through vessels means more thermal energy can be dissipated. When capillaries contract less blood passes to conserve thermal energy
Thermoregulation
Regulation of body temp, highly vascular nature of respiratory sys makes it conducive for this function via vasodilation and vasoconstriction
Protection from Pathogens in the Respiratory System:
Multiple mechanisms that help filter the incoming air and trap particulate matter
Vibrissae,
In nasal cavity, small hairs which help trap particulate matter and potentially infectious particles
mucous membranes, Mucociliary Escalator
Internal airways are lined with mucus to trap particulate matter and larger invaders, underlying cilia propel mucus up respiratory tract to oral cavity where it can be expelled or swallowed
Lysozyme
In the nasal cavity and saliva attacks peptidoglycan cell walls of gram-positive bacteria
Macrophages
Can engulf and digest pathogens and signal to the rest of the immune system that there is an invader
Mucosal Surfaces
Covered w IgA antibodies help protect against pathoges which contact mucus membranes
Mast Cells
Have antibodies on their surface that, when triggered, can promote the release of inflammatory chemicals. Mast cells are often involved in allergic reactions as well
pH control through bicarbonate buffer system
When blood pH decreases (should be 7.35-7.45), respiration rate increases to compensate by blowing off CO2. This cause a left shift in the buffer equation, reducing hydrogen ion concentration. When blood pH increases, respiration rate decreases to compensate by trapping CO2. This causes a right shift in the buffer equation, increasing hydrogen ion concentration
Body pH equation
CO2 (g) + H2O (l) H2CO3 (aq) H+ (aq) + HCO3- (aq)
Acidemia
ower body pH than normal (higher H+ concentration)– acid sensing chemoreceptors just outside blood brain barrier send signals to breain to increase resp rate to shift rxn toward more CO2
Alkalemia
Blood is too basic respiratory rate is slowed to retain more CO2 which shifts rxn to produce more H+ ions and lower pH
