CHAPTER 22: THE RESPIRATORY SYSTEM Flashcards
WHAT IS THE ORDER FROM THE NARIS TO ALVEOLI THAT AIR PASSES
naris –> pharynx –> larynx –> trachea –> main (primary) bronchi –> lobar (secondary) bronchi –> segmental (tertiary bronchi) –> bronchioles –> terminal bronchioles –> respiratory bronchioles –> alveolar ducts –> alveolar sacs –> alveoli
WHAT IS THE FUNCTION AND FEATURES OF THE NARIS/NASAL CAVITY
FEATURES: it is the only external structure of the respiratory system. the nasal cavity is inferior and posterior to the nose and is lined by mucous membrane
respiratory mucosa: pseudostratified ciliated columnar epithelium that secretes mucous and watery enzyme containing fluid
olfactory mucosa: olfactory epithelia, lines superior region
overall function is to warm, moisten, air and produce mucous
WHAT ARE THE FUNCTIONS OF THE PHARYNX, LARYNX AND TRACHEA
pharynx: passageway for air and food, facilitates exposire to inhaled antigens
larynx: passageway for air, is responsible for vocalization and prevents food from entering
trachea: passageway for air
EXPLAIN THE SUBDIVISIONS OF THE BRONCHI AND THE CONDUCTING AND RESPIRATORY ZONES
the air passes through 23 orders of branching (bronchial tree). the conducting zones give rise to the respiratory zones.
conducting zone: left and right main (primary) bronchi enter each lobe through the hilum and branch into the lobar (secondary bronchi) which will then branch into the segmental (tertiary bronchi). the segmental branches will keep dividing to give ruse to the bronchioles and then the terminal bronchioles which are the smallest ones
respiratory zone: the respiratory bronchioles –> alveolar ducts –> alveolar sacs which are filled with alveoli which is the site for gas exchnage.
WHAT IS THE RESPIRATORY MEMBRANE? RELATE IT’S STRUCTURE TO IT’S FUNCTION
WHAT: it is a blood-air membrane that is very thin and consists of capillary and alveolar walls with fused basement membranes.
- single layer of simple squamous epithelium (type 1 alveolar cells)
- scattered cuboidal type 2 alveolar cells that produce surfacant and antimicrobial proteins.
function: the thin walls allow for very easy simple diffusion across the membrane
WHAT ARE SOME OTHER SIGNIFICANT FACTORS OF THE RESPIRATORY MEMBRANE?
hint: alveolar….?
1) it is surrounded by elastic fibers and pulmonary capillaries
2) alveolar pores: connect the adjacent alevoli together to allow for more routes incase of blockage and equalize air pressure in the lungs
3) alveolar macrophages: leep alveolar surfaces sterile, around 2 million of them and hour are carried by cilia to be swallowed
WHAT IS THE NAME OF THE LAW THAT DEMONSTRATED THE INVERSE RELATIONSHIP BETWEEN PRESSURE AND VOLUME IN GASSES?
boyle’s law
HOW DOES INSPIRATION WORK WHAT HAPPENS IN THE CASE THAT FORCED INHALATION OCCURS?
Inspiratory muscles contract (diaphram moves inferiorly and external intercostal muscles move ribcage out and up) –> causes thoracic cavity volume to increase –> causes Ppul<Patm –> air moves into the lungs untill Ppul=Patm
forced: accessory muscles would also contract to increase the pressure gradient
can connect to the ventral respiration group!
HOW DOES EXPIRATION WORK, WHAT HAPPENS IN THE CASE OF FORCED EXPIRATION
expiration is normally a quirt and passive process. inspiratory muscles relax causing thoracic volume to decrease and lungs to recoil –> Ppul>Patm –> air moves out of the lungs untill Ppul=Patm
in forcex expiration the obliques, transverse abdominal muscles, internal intercostal muscles, etc, work since expiration is now an active process
WHY IS THE VACUUM IN THE INTRAPLEURAL SPACE SO IMPORTANT?
pressure in pleural cavity (intrapleural space) is Pip, that of which needs to be negative
this is so transpulmonary pressure can stay positive to prevent the lungs from collapsing.
WHAT ARE THE NORMAL VALUES FOR TRANSPULMONARY PRESSURE, Ppul, and Pip
transpulmonary pressure: must remain positive so the lung can stay inflated and not collapse.
Ppul: aka intrapulmonary pressure. Is usually at 0mm/hg but equalizes with the atmospheric at some point during exhaltion and flunctuates since it’s connected by the airway to Patm.
Pip: aka intrapleural pressure, is the pressure inside the fluid in the lungs, must always be negative. it is usually 4mm/hg lower than the intrapulmonary pressure
WHAT ARE THE 3 PHYSICAL FACTORS THAT AFFECT PULMONARY VENTILATION
lung compliance, alveolar surface tension, and airway resistance
EXPLAIN AIRWAY RESISTANCE, WHERE IS IT MORE OR LESS SIGNIFICANT?
hint: think respiratory and conducting zones
WHAT: is non-elastic friction that is the source of resistance for gas
it is a relationship between flow, resistance, and the change in pressure (transpulmonary) and is calculated using F=ΔP/R
Airway resistance is more significant in the 1st part of conducting zones because they are larger, the bronchial frequently branch and is small, the branches greatly increase cross sectional area. the teminal bronchials rely on difusion for gas exchange, not resistance.
EXPLAIN ALVEOLAR SURFACE TENSION, WHAT HELPS GET RID OF IT?
In a liquid-gas interface, oftentimes liquid molecules are attracted to one another causing surface tension.
water forms a thin film on top of the surface of the alveoli causing it to immensly shrink and collapse. surface tension is also good at resisiting things that will try to spread the liquid since they like to cluster up.
SURFACANT: is a lipid-protein complex that helps reduce surface tension on the alveoli and is produced by type 2 alveolar cells. lack of surfacant can cause alveoli to collapse.
EXPLAIN LUNG COMPLIANCE, WHAT IS IT DIMINISHED BY?
it’s the change in volume that occurs with a given change in transpulmonary pressure. its basically measuring how much the lungs can strech.
- is normally a llittle high because of surfacant and ditensibility of lung tissue which increases strech
1) nonelastic scar tissue replacing lung tissue (fibrosis)
2) reduced surfacant
3) devreased flexibility of thoracic cage
EXPLAIN THE DIFFERENCE IN COMPOSITION BETWEEN ALVEOLAR AIR AND ATMOSPHERIC AIR
alveolar: is mainly composed of water vapour and Co2. this is because of gas exchangem humidification of air, and mixing of alveolar air with old air still left in the airway
atmospheric: is mostly nitrogen and oxygen
WHAT IS EXTERNAL RESPIRATION? WHAT IS IT INFLUENCED BY?
external respiration is the exchange of gas across the respiratory membrane. it is influenced by
1) partial pressure gradients and gas solubility
2) thickness of the respiratory membrane
3) ventilation and perfusion coupling
EXPLAIN PARTIAL PRESSURE GRADIENTS AND GAS SOLUBILITIES DURING EXTERNAL RESPIRATION
oxygen: the partial pressure gradients between the lungs and blood are steep. The Po2 in the alveoli is around 104 mm/Hg and in the venous blod it is 40 mm/hg. this pushes blood from the Lungs into the blood.
^^ equilibrium is reached in abt 0.25 seconds but it takes blood 0.75 seconds to reach from one end of the capillary to the other, so it ensures for efficent o2 loading.
carbon dioxide: the partial pressure gradient is not as steep. In the alveoli it is 40 mm/Hg and in the blood it is 45 mm/hg. this encourages Co2 to move into the lungs to be exhaled.
despite it not being as aggressive it will still difuse at a similar rate to O2 because CO2 is 20x more soluble to plasma and alveolar fluid than O2.
EXPLAIN THICKNESS OF THE RESPIRATORY MEMBRANE INFLUENCING EXTERNAL RESPIRATION
respiratory membranes are very thin (around 0.5 micrometers). tthis allows for efficent difusion. the SA of the respirtaory memvrane is 40x larger than thr SA of the skin.
EXPLAIN VENTILAITON AND PERFUSION COUPLING INFLUENCING EXTERNAL RESPIRATION
ventilation: amount of gas reaching the alveoli
perfusion:how much blood is reaching alveoli
they must be balanced or in sync for optimal and efficent gas exchange and are controlled by autoregulatory mechanisms.
Partial pressure of oxygen controls perfusion by changing arteriole diamter, partial pressure of Co2 controls ventilation by changing bronchiole diameter.
HOW DOES BALANCING PERFUSION AND VENTILATION WORK?
changing the diameter of local arterioles and bronchioles syncs ventilation and perfusion. however it is never balanced for ALL alveoli
HOW DO PARTIAL PRESSURE GRADIENTS INFLUENCE INTERNAL RESPIRATION
tissue Po2 is 40mm/hg and arterial blood Po2 is 100 mm/hg. this encourages O2 to enter the tissues
Tissie Pco2 is 45 mm/hg, and arterial blood Pco2 is 40 mm/hg. this encourages Co2 to leave tissues and into the blood
DESCRIBE HOW OXYGEN IS TRANSPORTED IN THE BLOOD
hint: 2 ways
1) 1.5% is dissolved in plasma OR
2) 98.5% is loosly bound to each iron in hemoglobinn
saturated hemoglobin: O2 attached to all 4 hemegroups
partially saturated: O2 bount to 1-3 heme groups
oxyhemoglobin: O2 bound hemoglobin
Deoxyhemoglobin: hemoglobin that has released O2.
HOW DOES SHAPE INFLUENCE AFFINITY IN HEMOGLOBIN, HOW IS RATE AFFECTED AND HEMOGLOBIN SATURATION?
oxygen release influences shape which decreases affinity to O2
Oxygen loading influences shape which increases affinity to O2.
RATE: is influenced by PH, temp, PCO2, and PO2 (determined by free O2 in the blood)
Binding and release of O2 influences hemoglobin oxygen saturation.
WHAT IS THE PO2 AND HEMOGLOBIN OXYGEN SATURATION IN ARTERIAL AND VENOUS BLOOD
arterial: Po2= 100mm/Hg and Hb O2 sat is 98. Increasing Po2 has a minimal affect in increasing O2 loading
venous: Po2= 40 mm/hg and Hb O2 sat is still 73%.
DRAW THE OXYGEN-HEMOGLOBIN DISSOCIATION CURVES. FOR LUNGS AND TISSUES, SEA LEVEL AND HIGH ATMOSPHERE, AND REST AND METABOLIC ACTIVITY
answer on ipad
WHAT ARE SOME OTHER FACTORS BESIDES PO2 THAT AFFECT OXYGEN SATURATION IN HEMOGLOBIN?
Increased PCO2, Temp, and H+ cause a decreased affinity to O2 in the blood. and causes more oxygen to be released thus lowered O2 sat. usually occurs in systemic
decreased PCO2, Temp, and H+ causes an increased affinity to O2 in the blood, encouraging O2 loading and increased O2 sat. usually occurs in pulmonary
WHAT ARE THE 3 WAYS THAT CARBON DIOXIDE CAN BE TRANSPORTED IN THE BLOOD? WHAT ENZYME IS INVOLVED.
1) dissolved in plasma: 7-10%
2) chemically bound to hemoglobin: just iver 20%. CO2 binds to globin making carbaminohemoglobin
3) as bicarbonate ions in plasma: 70%. Co2 binds with H2O to make H2CO3 (carbonic acid), and then dissociates into H+ and HCO3
CARBONIC ANHYDRASE
HOW IS TRANSPORT OF CO2 DIFFERENT IN SYSTEMIC AND PULMONARY CIRCULATIONS
use the diagram! of the RBC, make note of the dissolving in plasma, fast and slow bicarbonate-carbonic acid reaction, and chemically binding to hemoglobin!
in the pulmonary just reverse the reactions
EXPLAIN THE CARBONIC ACID-BICARBONATE BUFFER SYSTEM
it helps regulate the Ph of the blood. If Ph is high the H+ ions will combine with HCO3- to form H2CO3 which will then dissociate into H2O and CO2
If H+ is low then H2CO3 will dissociate into H+ and HCO3
WHAT ARE THE 3 NEURAL CONTROLS THAT AFFECT RESPIRATIONS
1) higher brain centers, chemoreceptors, and other reflexes. it involves reticular formation in the pons
WHAT ARE THE MEDULLARY RESPONSE CENTERS? WHAT ARE IT’S COMPONENTS?
medullary response centers: has a ventral and dorsal component
ventral respiratory group (VRG): is the rythmn generating group, a network of neurons (insp, and exp) extends in the ventral brain stem to the spinal cord and pons medulla junction.
- Inspiratory neurons send AP’s along phrenic and inrercostal nerves to contract inspiratory muscles.
- expiratory neurons will inhibit inspiratory neurons from generating AP’s so inspiratory muscles can relax
-cyclic activity of these 2 brian centers is what sets the resp rate at 12-16 per min.
Dorsal respiratory group: network of neurons located near cranial nerve IX. integrates input from peripheral strech and chemoreceptors and sends into th VRG neurons.
WHAT ARE POSITIVE RESPIRATORY CENTERS
they can modify and influence the activity of thr VRG, they mainly work to smooth the transition between breathing in and out. it communicated to VRG when sleeping, vocalizing, excerising and relies on input from peripheral receptors and higher brain centers.
WHAT ARE SOME CHEMICAL FACTORS THAT INFLUENCE RESPIRATORY RATE AND DEPTH. WHAT IS THE MOST IMPORTANT?
PCO2, PO2, and Ph. PCO2 IS THE MOST INFLUENTIAL IN DETERMINING RESP RATE AND DEPTH
WHERE ARE CENTRAL AND PERIPHERAL CHEMORECEPTORS LOCATED?
central chemoreceptors: located throughout brainstem and medulla
peripheral chemoreceptors: located in aortic arch and carotid arteries
HOW DOES THE BODY CONTROL RESP RATE AND DEPTH IF THERE IS HIGH PCO2?
HINT: draw a feedback loop looking thing
- high PCO2
- CO2 accumulates: CO2+H2O= H2CO3 (carbonic acid)
- H2CO3 –> HCO3 and H+= ph lowered (more acid)
- The increased H+ triggers chemoreceptors which synapse w/ respiratory regulatory centers
- respiratory centers increase depth and rate of breathing which lowers PCO2 and increased Ph to normal level
HOW DOES LOW PCO2 IMPACT RESPIRATORY RATE AND DEPTH
Low PCO2 causes shallow breathing.
WHAT IS THE INFLUENCE OF PO2 ON RESPIRATORY RATE AND DEPTH? WHAT DETECTS PO2?
peripheral chemoreceptors in thr aortic arch and carotid bodies sense arterial PO2. a drop in PO2 doesn’t really change Resp rate and depth because of O2 resovoir in Hb. A substantial drop is needed to increase rate and depth of respirations
WHAT IS THE INFLUENCE OF PH ON RESPIRATORY RATE AND DEPTH
PH is able to change resp rate and depth if O2 and Co2 levels are normal!
low ph causes increased respiration so Ph can go up
WHAT IS THE INFLUENCE OF HIGHER BRAIN CENTERS ON RESPIRATORY RATE AND DEPTH
HINT: theres 4 of them
hypothalmic controls: acts through the limbic (emotional) system to modify rate and depth. ex. holding breath when angry
cortical controls: direct signals from the cerebral motor conrtex that bypass the medullar controls (basically forces you to breath)
pulmonary irritant reflex: bronchioles respond to irritants and begin to constrict air passages
inflation reflex: hering-bever reflex: strech receptors in ther airways and pleura are stimulated by lung inflation. This sends inhibiting signals to the resp centers to end inhalation and behin exhalation. acts more as a protective measure
WHAT IS DALTONS- LAW OF PARTIAL PRESSURE
Total pressure exerted by mixture of gases is equal to sum of pressures exerted by each gas
WHAT IS THE EXACT COMPOSITION OF ATMOSPHERIC AIR
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