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Chapter 14: The respiratory system
Terms in this set (86)
-major function: gas exchange
-works with cardiovascular system to accomplish: pulmonary ventilation, external respiration, internal respiration, and transport of gases.
Breathing (inspiration and expiration).
oxygen & carbon dioxide exchange between the air (from internal environment) and blood (in lungs)
gas exchange between blood & tissue fluid.
Transport of gases
blood transports gases between the lungs & tissues.
-purpose is to provide oxygen for cellular respiration ad remove carbon dioxide waste from cellular respiration.
-cellular respiration produces ATP; cells need a continuous supply.
-Nasal hairs, cilia, and mucus cleanse inhaled air as it passes through passageways.
-Lysozyme: in mucus help kill bacteria.
-Mucociliary escalator: cilia push mucus, dust, pathogens toward the throat to be swallowed; substances dissolved in mucus are destroyed by stomach acid.
-inhaled air is warmed by suerficial blood vessels lining the airways, moistened by the mucous membrane.
Respiartory Tract cont'd
-the only external portion of the respiratory system
-air enters through the nostrils.
-contains 2 nasal cavities:
-lined by a mucous membrane.
-nasal conchae (bony ridges) increase the
surface area for moistening and warming
-odor receptors located in the olfactory
-tears empty into the nasal cavities by way of nasolacrimal canals.
-paranasal sinuses connect to the nasal cavities and act as resonating chambers for speech.
-palate separates the oral cavity from nasal cavity (has hard & soft palate).
The path of air
-connects nasal and oral cavities to the larynx.
-3 parts: nasopharynx, oropharynx, laryngopharynx.
-tonsils provide the primary lymphatic tissue defense for breathing.
-passageway for both food & air.
(posterior to thyroid cartilage)
-cartilagenous passageway for air between the pharynx & trachea. normally open-lets air to pass.
-houses vocal cords- mucosal folds that vibrate as air is expelled.
-Pitch: regulated by the tenson on the vocal
cords. high pitch- greater tension- glottis
narrow. low pitch-vocal cords relaxed - glottis
-Loudness: depends on the amplitude of
-Glottis: opening between vocal cords.
-Thyroid Cartilage: Adam's apple
-Epiglottis: flap of elastic cartilage; prevents food from entering the larynx
Anatomy of the Larynx
True vocal cords
Upper Respiratory Tract
nasal cavity, pharynx, larynx
-connects larynx to primary bonchi.
-ventral to esophagus
-C-Shaped cartilaginous rings: create a patent airway; allows expansion of esophagus.
-Mucosal lining has psuedostratified ciliated columnar epithelium that forms mucociliary escalator.
Pseudostratified Ciliated columnar epithelium
-trachea divides into right and left primary bronchi to enter the lungs.
-the primary bonchi branch into secondary bronchi, one for each lobe of the lungs.
-3 for right lung
-2 for left lung
Secondary (lobar) bronchi
Tertiary (segmental) bronchi
lower respiratory tract
Bronchial tree cont'd
-secondary bronchi divide into tertiary bronchi (segmental)
-moving along the pathway of air conduction, the bronchi get smaller & smaller.
-as they get smaller, they lose cartilage in the
walls and gain smooth muscle.
-bronchioles: smallest conducting airways; no cartilage.
-each bronchiole leads to air sacs called alveoli.
-paired, cone shaped organs.
-apex is at superioir end, the base is on the diaphragm.
-each lobe is divided into lobules
-each lobule has a bronchiole that serves many
-every alveolus is covered in pulmonary capillaries.
-elastic connective tissue helps with lung recoil when a person exhales.
-double-layered serous membrane
-Visceral pleurae: adheres to the surface of lung.
-Parietal pleurae: lines inside of thoracic cavity.
-produces a lubricating serous fluid that also creates surface tension between the layers to hold them together.
-alveolar sacs are made up of simple squamous epithelium surrounded by blood capillaries.
-site of gas exchange
-alveoli must stay open to receive inhaled air
-surfactant: lowers the surface tension of water
lining the alveoli preventing them from
-Respiratory distress syndrome: occurs in prema-
ture infants who lack surfactant.
-also contain dust cells- macrophages to defend against inhaled debris & pathogens.
water sticks very well to water (i.e. high surface tension), so if alveoli sacs collapsed, the wet surfaces would cling together, and would require a lot of force to come apart. the surfactants excreted in the lungs counter this and allow the alveoli to pop open much more easily (reduced surface tension) relative to what it would be with just water.
Gas exchange in the lungs
-facilitates rapid gas exchange.
-composed of the alveolar epithelium & the capillary epithelium and their fused basement membrane - very little tissue fluid separates hte two-one membrane.
-large surface area (50-70m2)
Structure of the alveolus & respiratory membrane
-manner in which air enters/exits lungs.
-lungs lie within the sealed off thoracic cavity.
-lungs adhere to the thoracic cavity wall by way of the pleurae; creates intrapleural pressure - the pressure between pleurae (less than atmospheric pressure)
-a continuous column of air extends from the pharynx to the alveoli of the lungs.
-active phase of venilation
-diaphragm contracts and moves down (flat)
-external intercostal muscles contract, and pull the rib cage outward.
-Thoracic cavity volume increases (lung adheres to the wall of the thoracic cavity), causing the lungs to increase in volume.
-alveolar volume increases
-air pressure within the alveoli (intrapulmonary pressure) decreases - partial vacuum.
-air flows form an area of high pressure (atmospheric pressure) to area of low pressure (within the lungs) until pressures are equal.
-usually the passive phase of ventilaiton.
-diaphragm relaxes and resumes its dome shape
-external intercostal muscles relax and the rib cage moves down and in.
-the volume of the thoracic cavity decreases and the lungs recoil (elastic tissue) - lung volume decreases.
-lung volume decreases and the intrapulmonary pressure increases (above atmospheric pressure)
-since intrapulmonary pressure is now greater than atmospheric pressure, air will flow out of the lungs until pressures are equal.
Maximum inspratory effort
-involves the accessory muscles of respiration : muscles of back, pectorali minor (chest), scalene & sternocleoidomastoid muscles.
-help increase the size of thoracic cavity (larger than normal)
-allows more air to be inspired.
-during heavy exercise.
-involves contraction of abdominal wall muscles and the internal intercostal muscles
-increased pressure in the thoracic cavity will expel more air.
instrument that records the volume of air exchanged during breathing.
shows the measurements recorded by a spiometer
-amount of air moving in and out of the lungs during normal, relaxed breathing.
-about 500mL per breath
-maximum volume of air that can be inhaled plus the maximum volume of air that can be exhaled in one breath
-inspiratory reserve volume: forced inspiration;
the volume of air inspired beyond the tidal
-expiratory reserve volume: forced expiration;
the volume of air expired beyond the tidal
volume - about 1,400 mL.
-amount of air remaining in lungs after foced expiration.
-about 1,000 mL.
Dead air space
-30% of the inspired air that does not reach the alveoli for exchange but remains in the passageways.
Control of ventilation
-ventilation is controlled by a primary respiratory center in the medulla oblongata; signals coming from here cause contaction of respiratory muscles.
-phrenic nerve carries impulses to the
-intercostal nerves: stimulate the external
-normal breathing rhythm (eupnea) also
requires input from the pons.
Nervous control of breathing
- can influence depth and rate of breathing
- cerebral cortex, limbic system, hypothalamus, and other brain centers
-The respiratory center is sensitive to the levels of CO2 and H+ in the blood.
-when they rise, as in exercise, breathing rate and depth is increased.
-Chemoreceptors in the carotid and aortic bodies are sensitive to the level of oxygen in the blood.
-respiration includes both exchange of gases in lungs & in tissues.
-concentrations of oxygen and carbon dioxide dictate the direction of movement (in or out of the blood)
-Exchange of gases in lungs e between air in alveoli and the blood in the pulmonary capillaries.
-Oxygen: higher concentration in the alveoli; diffuses from the alveoli into the blood.
-Carbon Dioxide: higher concentration in the blood; diffuses from the blood in the pulmonary capillaries to the alveoli.
-amount of pressure exerted by each gas
-symbolized as PO2 & PCO2
-alveolar PO2 is higher than in the blood.
-blood PCO2 is higher than in the alveoli
-exchange of gases in tissues between the blood in the systemic capillaries and tissue fluids.
-Oxygen: higher concentration in the blood; diffuses form the blood into the tissue fluid.
-PO2 of the blood is higher than in tissue fluid.
-Carbon dioxide: higher concentration in tissue fluid; diffuses from tissue fluid into the blood.
-PCO2 is higher in tissue fluid than in blood.
External & Internal Respiration
-97-98% transported by hemoglobin in the RBC's.
-Oxyhemoglobin: hemoglobin combined with oxygen.
-Deoxyhemoglobin: hemoglobin without oxygen.
-small amount (2-3%) transported in plasma.
Carbon dioxide transport
-as a dissolved gas in blood plasma and in the cytoplasm of RBC's- 10%
-combined with globin portion of hemoblogin- carbaminohemoglobin - 30%.
-most carried as bicarbonate ions HCO3- 60%
-carbon dioxide combines with water to form
carbonic acid in RBC.
-carobonic acid dissociates into H+ and
-the enzyme carbonic anhydrase catalyzes
-Excess H+ combines with the globin portion of hemoglobin (reduced hemoglobin)
-Bicarbonate ions diffuse out of red blood cells into the plasma in exchange for chloride shift.
Carbon dioxide transport
carbon dioxide transport
Gas transport, cont'd
-respiratory system helps regulate pH.
-Bicarbonate/Carbonic acid buffer system is altered by breathing.
-Hypoventilation= increased CO2= more
carbonic acid formed > decreased pH (more
H+ formed)= acidosis (pH less than 7.35)
-Hyperventilation = decreased CO2= less
carbonic acid formed > increased pH (less H+
formed)=alkalosis (pH greater than 7.45)
effects of aging
-respiratory fitness decreases with age
-maximum breathing capacities decline
-gas exchange in lungs become less efficient.
effects of aging cont'd
-respiratory membrane thickens
-ciliated cells of trachea decline in number
-respiratory diseases are more common.
-oxygen is needed by cells for cellular respiration.
-carbon dioxide is a waste product of cellular respiration.
Regulation of blood pH
-altering blood CO2 levels.
-increased CO2, increases H+, and decreases pH (acidosis)
-Decreased CO2, decreased H+, and increases pH (alkalosis)
-Hypoventilation - build up of CO2
-Hyperventilation - too much CO2 leaving
Control of Blood pressure
-assists in the renin-angiotensin-aldosterone pathway.
-lungs contain ACE (angiotensin converting enzyme) that converts angiotensin I into angiotensin II
-angiotensin II is a vasoconstrictor that raises blood pressure.
-part of the 1st line of defense
-mucus and cilia capture and remove pathogens
-assists immunity through the tonsils & alveolar dust cells.
This set is often in folders with...
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