physiology 12 - ccsf home pageeshanson/physiology 12/lec... · 2005. 8. 30. · physiology 12...
Post on 21-Aug-2020
4 Views
Preview:
TRANSCRIPT
1
Physiology 12Physiology 12
RespirationRespiration
Germann Ch: 15 &16
Respiratory systemRespiratory system
Functions of the Respiratory SystemFunctions of the Respiratory System
Gas ExchangeGas ExchangeO2 inO2 inCO2 outCO2 out
Other FunctionsOther FunctionspH regulationpH regulationBlood clot removalBlood clot removalSpeech etc.Speech etc.
2
External External RespirationRespiration
3
Internal Internal RespirationRespiration
4
5
6
The lungs are surrounded by a The lungs are surrounded by a Pleural sacPleural sac
Parietal Pleura Parietal Pleura Visceral PleuraVisceral PleuraIntrapleuralIntrapleural fluidfluid
7
VentilationVentilation
8
Ventilation of the lungs is achieved Ventilation of the lungs is achieved by bulk flowby bulk flow
RememberF = ∆P/R
Boyle’s LawBoyle’s LawPP11VV11=P=P22VV22
9
Mechanics of Abdominal Mechanics of Abdominal ContractionContraction
10
Pressure changes at maximal Pressure changes at maximal inspiration and Expirationinspiration and Expiration
IntrapleuralIntrapleural pressure always remains pressure always remains less than atmospheric to keep lungs less than atmospheric to keep lungs
from collapsingfrom collapsing
11
Why don’t the lungs collapse during Why don’t the lungs collapse during inspiration when the alveolar inspiration when the alveolar
pressure is much less than pressure is much less than atmospheric?atmospheric?
PneumothoraxPneumothorax
12
Lung Compliance is essential to a Lung Compliance is essential to a healthy respiratory systemhealthy respiratory system
Compliance = ∆volume ÷ ∆ Pressure
13
Surfactant: Surfactant: A detergent like substance secreted A detergent like substance secreted
by the Type II alveolar cells that by the Type II alveolar cells that helps maintain lung compliancehelps maintain lung compliance
Lung VolumesLung Volumes
14
Minute ventilationMinute ventilation
Tidal volume X respiratory rate
500ml X 10 breathes/minute
= 5000ml of air per minute
15
Not all inspired air makes it into Not all inspired air makes it into places where it can contact and places where it can contact and exchange gasses with the blood.exchange gasses with the blood.
16
AveolarAveolar ventilationventilation
tidal volume – dead spaceX
Respiratory rate
Control of RespirationControl of Respiration
17
Brainstem centers involved in Brainstem centers involved in Respiratory ControlRespiratory Control
18
An experimentAn experiment
What if you increased the amount of CO2 in the What if you increased the amount of CO2 in the inspired air?inspired air?
19
Carbon Dioxide ReceptorsCarbon Dioxide Receptors(Changes in PCO2 produce changes in pH)(Changes in PCO2 produce changes in pH)
Central Central ChemoreceptorsChemoreceptors (listen to [H+])(listen to [H+])Peripheral Peripheral ChemoreptorsChemoreptors (listen to [H+])(listen to [H+])
20
Effect of pH on RespirationEffect of pH on Respiration
Changes in Respiration Rate not due Changes in Respiration Rate not due to COto CO22
Metabolic AcidosisMetabolic AcidosisMetabolic AlkalosisMetabolic Alkalosis
21
Summary of ventilation controlSummary of ventilation control
Respiration is regulated byRespiration is regulated by
PO2PO2via via chemoreceptorschemoreceptors (carotid bodies in the arteries)(carotid bodies in the arteries)
PCO2PCO2via via chemorecptorschemorecptors for H+ in both the brain and for H+ in both the brain and
body.body.pH pH
via the same via the same chemorecptorschemorecptors in brain and bodyin brain and bodyDirect voluntary controlDirect voluntary control
22
Exchange of gassesExchange of gasses
23
Respiratory QuotientRespiratory Quotient
Ratio of: CORatio of: CO22 produced ÷ produced ÷ OO22 consumedconsumed
Some Respiratory Quotients for Some Respiratory Quotients for different foodsdifferent foods
Most combined diets = .8Most combined diets = .8Carbohydrate = 1Carbohydrate = 1
Fat = .7Fat = .7Protein = .8Protein = .8
Lets simplify this accounting of Gas Lets simplify this accounting of Gas exchangeexchange
24
Daltons LawDaltons Law
In a mixture of gasses each gas behaves In a mixture of gasses each gas behaves as if it is independent of the other as if it is independent of the other
gasses.gasses.
Daltons LawDaltons Law
At sea level air is 760 mmHgOxygen only makes up 21% of
airTherefore the partial pressure
of oxygen =
760 X .21 = 160 mmHg
In air PO2 = 160mmHg
Henry’ s LawHenry’ s Law
The amount of gas The amount of gas dissolved in a solution dissolved in a solution will be directly will be directly proportional to the proportional to the partial pressure of the partial pressure of the gas with which the liquid gas with which the liquid is in equilibrium.is in equilibrium.
25
Gas Exchange in partial PressuresGas Exchange in partial Pressures
In Pulmonary In Pulmonary venulesvenulesOxygen POOxygen PO22 = 100mmHg= 100mmHgCarbon dioxide COCarbon dioxide CO22 = 40mmHg= 40mmHg
In Pulmonary ArteriesIn Pulmonary ArteriesOxygen POOxygen PO22 = 40 mmHg= 40 mmHgCarbon dioxide COCarbon dioxide CO22 = 46mmHg= 46mmHg
26
Ventilation of lungs should match Ventilation of lungs should match metabolismmetabolism
Hypoventilation = Increase in ratio of COHypoventilation = Increase in ratio of CO22production to ventilationproduction to ventilationHyperventilation = decrease in ratio of COHyperventilation = decrease in ratio of CO22production to ventilationproduction to ventilation
27
Pulmonary saturation of OxygenPulmonary saturation of Oxygen
Ventilation PerfusionVentilation Perfusion
In the healthy lungs blood leaves fully saturated In the healthy lungs blood leaves fully saturated with oxygenwith oxygen
Ventilation PerfusionVentilation Perfusion
In the healthy lungs blood leaves fully saturated In the healthy lungs blood leaves fully saturated with oxygenwith oxygenLung capillaries Lung capillaries vasoconstrictvasoconstrict in response to low in response to low OO22
VentilationVentilation-- Perfusion inequalities can lead to reduced Perfusion inequalities can lead to reduced Oxygen levels in bloodOxygen levels in blood
28
Transport of Oxygen in bloodTransport of Oxygen in blood
Less than 2% of Oxygen in blood is found freely Less than 2% of Oxygen in blood is found freely dissolved in plasma.dissolved in plasma.
29
30
31
Carbon Dioxide in BloodCarbon Dioxide in Blood(normal person generates ~ 200ml/min)(normal person generates ~ 200ml/min)
32
Carbon Dioxide in BloodCarbon Dioxide in Blood(normal person generates ~ 200ml/min)(normal person generates ~ 200ml/min)
10% dissolved in plasma10% dissolved in plasma30% bound to Hemoglobin30% bound to Hemoglobin60% converted to Bicarbonate60% converted to Bicarbonate
Hydrogen Ion RegulationHydrogen Ion Regulation
CO2 + H2O ↔ H2CO3 ↔ HCO3- + H+
Carbonic Anhydrase
Hydrogen Ion buffer system
33
Effect of pH on Hemoglobin Effect of pH on Hemoglobin bindingbinding
34
Control of Ventilation during Control of Ventilation during ExerciseExercise
35
36
endend
top related