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Chapter 22 Respiratory System

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Carbon Dioxide
waste product the body must get rid of
Respiratory System
action of supplying the body with oxygen and disposing of carbon dioxide is the major function
4 Processes of the Respiratory System
1.pulmonary ventilation
2. external respiration
3. respiratory gas transport
4. internal respiration
Pulmonary Ventilation
movement of air into and out of the lungs
-allows the gases in the lungs to be continuously refreshed
-commonly called breathing
External Respiration
movement of oxygen from the lungs to the blood and of carbon dioxide from the blood to the lungs
Respiratory Gas Transport
transport of oxygen from the lungs to the tissue cells and of carbon dioxide from the tissue cells
Internal Respiration
movement of oxygen from blood to the cells and of carbon dioxide from cells to blood
Path of Air Flow
nostrils/mouth, pharynx (upper respiratory), larynx, trachea, primary bronchis, bronchioles, alveolar ducts, alveolar sac, alveoli
Function of Nose
-moistens and warms entering air
-filters and cleans inspired air
-serves as resonating chamber for speech
-houses the olfactory receptors
Function of Larynx
provide patent airway and contains vocal cords
hyaline cartilage
u-shaped rings prevent trachea from collapsing
cilia
create tracheal walls
mucus
catches any inhaled particles and cilia move it out toward the esophagus where it is swallowed or spit out
Heimlich Manuever
rapidly squeezing out the air in the victim's lungs to pop out the obstruction
Primary Bronchi
goes to each lung, subdivides into secondary bronchi which supply one lung lobe
Secondary Bronchi
supply one lung lobe, divide into tertiary bronchi
respiratory tree
divisions of the bronchials
difference of bronchioles and bronchi
-bronchioles have no supportive cartilage
-epithelium pseudostratified columnar to simple columnar to simple cubodial
-no cilia or mucus producing cells(removed by macrophages)
-more smooth muscle
smooth muscle in bronchioles
muscle and lack of supportive cartilage allow bronchioles to dilate and constrict
respiratory bronchioles
feed into alveolar ducts and sac
alveolar sacs
contain alveoli where gas exchange occurs
Type II cells
produce surfactant, reduces surface tension
Infant Respiratory Distress Syndrome (IRDS)
treated with positive-pressure respirators that force air into the alveoli
alveolar pores
connect adjacent alveoli, allows equalized air pressure
alveolar macrophages
crawl freely along the internal alveolar surfaces
respiratory membrane
composed of alveolar wall, capillary wall, and basement membrane
gas exchange
oxygen dissolves into moist film coating the alveolar walls, O2 passes from alveolus into the blood, and CO2 leaves the blood to enter the gas-filled alveolus
lungs
composed of air space and elastic tissue
left lung
2 lobes superior and inferior
right lung
3 lobes superior, middle, and inferior
bronchopulmonary segments
each lung lobe contains a number of pyramid shaped segments, separated by septa, and each has its own artery and vein
pulmonary circulation
delivers systemic venous blood to be oxygenated in the lungs
pulmonary arteries
deliver deoxygenated blood to the lungs, feed into the capillary networks
pulmonary veins
return freshly oxygenated blood from the respiratory zones of the lungs to the heart
bronchial circulation
provide systemic blood that nourishes the lung tissue
bronchial arteries
arise from the aorta and run along the branching bronchi, ultimately supply all lung tissues except the alveoli
parasympathetic fibers
constrict the air tubes
sympathetic fibers
dilate the air tubes
atmospheric pressure (Patm)
pressure exerted by the air surrounding the body
-Patm 760 mm Hg at sea level=1atm
intrapulmonary pressure (Ppul)
pressure in the alveoli, rises and falls with the phases of breathing
intrapleural pressure (Pip)
pressure in the pleural cavity, fluctuates with breathing
*always negative relative to Ppul- prevents collapse
lung elasticity
natural tendency to recoil causes the lungs to always assume the smallest size possible
surface tension of alveolar fluid
constantly acts to draw the alveoli to their smallest size possible
lung collapse
due to equalizing of intrapleural pressure and intrapulmonary pressure
transpulmonary pressure
Ppul-Pip keeps lungs from collapsing
-determines the size of the lungs
atelectasis
lung collapse
1.plugged bronchiole
2. pneumothorax
plugged bronchiole
causes associated alveoli to absorb all of their air and collapse, could be result of pneumonia
pneumothorax
condition in which air enters the pleural cavity either through a chest wound or rupture of the visceral pleura
chest wound
allows atmospheric air to enter the pleural cavity directly
rupture of visceral pleura
allows air to enter the pleural cavity from the respiratory tract
pulmonary ventilation
1. inspiration
2. expiration
inspiration
period when air flows into the lungs. Pulmonary pressure decreases to 1 mm Hg below atmospheric
expiration
period when air flows out of the lungs, volume of thoracic cavity decrease as inspiratory muscles relax. Pulmonary pressure rises to about 1 mm Hg above atmospheric
diaphragm
contraction causes it to push down--> expands thoracic cavity and pushes lungs downward
external intercostals
expand the ribcage by pulling the ribs upward and the sternum downward
tidal volume
usually 500 ml of air that enters the lungs during normal inspiration--> pulmonary pressure decreases
thoracic volume decreases
1. intra-abdominal pressure increases
2. depressing the rib cage
airway resistance
friction, causes gas flow to decrease due to inhalation of irritants
parasympathetic
constriction of bronchioles--> increases resistance
epinephrine
dilates bronchioles and reduces airway resistance--> sympathetic stimulation
lung compliance
1. distensibility of the lung tissue
2. alveolar surface tension- low due to surfactant
diminished lung compliance
decrease elasticity, inflammation/infection--> scar tissue, decreased surfactant
Dalton's Law of Partial Pressures
total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gas in the mixture
partial pressure
pressure exerted by each constituent gas in a mixture, directly proportional to the percentage of that gas in the gas mixture
nitrogen
makes up 78.6% of air
Pn2= 78.6% x 760 mm Hg=597 mm Hg
oxygen
makes up 20.9% of the atmosphere
Po2= 20.9% x 760 mm Hg=159 mm Hg
Henry's Law
mixture of gases is in contact with a liquid, each gas will dissolve in the liquid in proportion to the partial pressure
atmospheric air
mostly all O2 and N2
alveoli
contain more CO2 and O2
Po2 of blood entering the lungs in pulmonary arteries
40 mm Hg
Po2 in the alveoli
104 mm Hg
Pco2 of blood entering the lungs in the pulmonary arteries
45 mm Hg
Pco2 of air in the alveoli
40 mm Hg
ventilation-perfusion coupling
for efficient gas exchange, there must be a close match between ventilation and perfusion
ventilation
amount of gas reaching the alveoli
perfusion
the blood flow in pulmonary capillaries
inadequate ventilation
Po2 is low and pulmonary arterioles constrict
ventilation maximum
Po2 is high and arterioles dilate
bronchioles dilate when
Pco2 is high
bronchioles constrict when
Pco2 is low
Respiratory membrane
0.5-1 mm thick in healthy lungs, efficiency of gas exchange is dependent on the thinnest of the membrane and shortness of diffusion
alveolar surface area
90m2
emphysema
walls of adjacent alveoli break through and the alveolar chambers become larger, decreases surface area available for gas exchange
oxygen carried in blood
1. bound to hemoglobin and RBC(98.5%)
2. dissolved in plasma(1.5%)
hemoglobin
composed of 4 polypeptide chains- each chain is bound to an iron-containing heme group. Iron binds to oxygen. Each combines to 4 molecules of O2
oxyhemoglobin
hemoglobin bound to oxygen, fully saturated when all 4 heme groups are bound
deoxyhemoglobin
hemoglobin that has released oxygen
Rate the Hb binds to O2
1. partial pressure
2. Temperature
3. blood pH
4. PCO2
Partial Pressure of PO2 and Hb Saturation
increases as PO2 increases, plateau around a PO2 OF 100 mm Hg, fully saturated when leaves lungs. Not linear relationship with PO2
Temperature, blood pH, PCO2 and Hb Saturation
increases in temp, PCO2, and H+(decrease pH) decrease Hb's affinity for oxygen
hypoxia
inadequate oxygen delivery to body tissues- bluish cast when Hb saturation falls below 75%
anemic hypoxia
reflects poor O2 delivery resulting from too few RBCs or from RBCs that contain abnormal or too little Hb
ichemic hypoxia
results when blood circulation is impaired or blocked
-congestive heart failure
-emboli/thrombi
histotoxic hypoxia
occurs when the body cells are unable to use O2 even though adequate amounts are delivered. Results from poisons(cyanide)
hypoxemic hypoxia
indicated by reduced arterial PO2, abnormal ventilation-perfusion coupling, pulmonary diseases that impair ventilation, and breathing poorly oxygenated air
carbonic monoxide
hypoxemic hypoxia- gas competes with O2 for heme binding sites. Confused, throbbing H/A, rare cases cherry red skin. Hyperbaric therapy or 100% O2 until CO cleared from body
Transportation of Carbon Dioxide
1. dissolved in plasma(7-10%)
2. bound to hemoglobin(20%) carried in the RBCs as carbaminohemoglobin
3. as bicarbonate ion in plasma(70%)
Neural control of breathing
medulla oblongata and pons
medulla oblongata
1. ventral respiratory group VRG
2. Dorsal respiratory Group DRG
ventral respiratory group
primary rhythm generating and integrative center. Inspiratory neurons fire along the phrenic and intercostals to excite the diaphragm and intercostals. Expiratory neurons stop the muscles
eupnea
normal respiratory rate and rhythm 12-15 breaths per minute
morphine and alcohol
can suppress the VRG
Dorsal Respiratory group
integrates input from peripheral stretch and chemoreceptors
Pontine Respiratory Centers
transmit impulses to the VRG of the medulla. Fine tunes breathing rhythms
apneustic breathing
prolonged inspiration with a pause at the end followed by expiration
Factors influencing Breathing
1. inspiratory depth
-greater stimulation=greater # of motor units=greater force
2. respiratory rate
central chemoreceptors
located in the ventolateral medulla, regulate arterial PCO2(40+/- mm Hg)
carbonic acid
formed when CO2 combines with water in CSF
hypercapnia
PCO2 levels rise, CSF pH drops
hyperventilation
increase in the rate and depth of breathing that exceeds the body's need to remove CO2, dizziness low CO2 level
cerebral ischemia
reduced brain perfusion
apnea
breathing cessation
peripheral chemoreceptor
in the aortic arch and common carotid arteries are sensitive to arterial O2 levels (has to drop at least 60 mm Hg before major stimulus)
arterial pH
changes can modify respiratory rate and rhythm even when CO2 and O2 levels are normal
drop in arterial pH
1. CO2 retention
2. accumulation of lactic acid during exercise
3. accumulation fatty acid metabolites (ketone bodies)
hypothalmic controls
strong emotions and pain can modify respiratory rate and depth via interactions between the hypothalamus and respiratory centers
cortical controls
during voluntary control sends signals to the motor neurons that stimulate respiratory muscles
pulmonary irritant reflexes
the lungs contain receptors that respond to an enormous variety of irritants. Communicate via the vagus nerve. Stimulate a bronchiole constriction, cough, or sneeze.
Chronic Obstructive Pulmonary Disease (COPD)
4th leading cause of death in US. Chronic bronchitis and emphysema
hypoventilation
insufficient ventilation in relation to metabolic needs causing CO2 retention
asthma
episodes of coughing, labored breathing, wheezing, and chest tightness. Exacerbations and remissions. Obstruction is reversible. Inflammation due to T cells
T cells
secrete interleukins, stimulate the productions of antibodies and recruit inflammatory cells to the site
Tuberculosis (TB)
infectious disease caused by mycobacterium. Spread by coughing and primarily enters the body in inhaled air.
latent TB
immune system usually contains the primary infection in fibrous or calcified nodules of the lungs
active TB
fever, night sweats, weight loss, racking cough, and spitting up blood
pneumonia
inflammation of the lungs caused by an infection from bacteria, virus, or fungi. Air sacs in the lungs fill with pus and other fluids which makes it difficult for oxygen to reach the blood
bacterial pneumonia
tend to be the most serious- streptococcus pneumoniae
mycoplasma pneumoniae
school aged pneumonia
lung cancer
leading cause of cancer death
squamous cell carcinoma
25-30% rises in the epithelium of the bronchi or their larger subdivisions. Tends to form masses that may hollow out and bleed
adenocarcinoma
40% originates in the peripheral lung areas as solitary nodules that develop from bronchial glands and alveolar cells
small cell carcinoma
20% cancer that contains small round cells that originate in the main bronchi and grow aggressively in small grape-like clusters within the mediastinum
cystic fibrosis
most common lethal genetic disease in North America. Causes secretion of abnormally viscous/sticky mucuos. Impairs digestion by clogging the pancreatic ducts that deliver enzymes and bile to the small intestine