resp system 2 Flashcards
pontine respiratory group
In Pons
sending input to DRG
Helps to accomodate : exercising, speakings
mechanoreceptors
- found in joints and muscles (proprioceptors); respond to changes in body movement (rest-exercise/ quiet breathing - more forceful)
- send input signal to DRG; help recruit VRG
slowly adapting receptors -Hering Breuer reflex
- found in smooth muscle surrounding airways; respond to changes in lung volume
- terminates inspiratory neurons in DRG if large volume breathes
- protective function : preventing over expansion of lungs
rapidly adapting receptors
found in larger airway epithelium; respond to noxious gases, cold air, inhaled particles
- “irritant receptors” triggering airway narrowing, mucus production and coughing
- protective function : limit irritants getting to lungs
Peripheral chemoreceptors
carotid sinus and aortic arch
-respond to changes in arterial blood
stimulated by :
- decreased arterial PO2
- increased metabolic acidosis generating arterial H+
- increased arterial PCO2 generating arterial H+
central chemoreceptors
medulla oblongata (IN CNS)
-respond to changes in brain extracellular or Cerebrospinal fluid
stimulated by:
-increased brain PCO2 generating brain H+
temporarily stop breathing under voluntary control
= Apnea
- increase CO2 to critical level = involuntary breathing starts
- decrease oxygen to critical level = unconsciousness, breathing should resume
voluntary actions
come from cerebral or motor cortex of brain
tidal volume
amount of air inhaled or exhaled in one breath
inspiratory reserve volume (IRV)
amount of air in excess of tidal inspiration that can be inhaled with maximum effort
expiratory reserve volume (ERV)
amount of air in excess of tidal expiration that can be exhaled with maximum effort
residual volume (RV)
amount of air remaining in lungs after maximum expiration
-keeps alveoli inflated between breaths and mixes with fresh air on next inspiration
vital capacity
amount of air that can be exhaled with maximum effort after maximum inspiration
inspiratory capacity
maximum amount of air that can be inhaled after a normal tidal expiration
functional residual capacity (FRC)
amount of air remaining in lungs after a normal tidal expiration
total lung capacity
maximum amount of air lungs can contain
forced vital capacity (FVC)
volume of air expired forcefully after maximum inspiration
forced expiratory volume in 1 sec (FEV1)
volume of air expired forcefully in the 1st scond of FVC
FEV1/ FVC
percentage of total FVC expired in 1st second
obstructive lung disease
hard to exhale all the air in lungs
-low FEV percentage
restrictive lung disease
difficulty fully inspiring air into lungs
-higher FEV percentage or same as in normal
ventilation
combine tidal volume (depth of breathing) and breathing frequency (rate of breathing)
during increased breathing (exercise)
tidal volume increases (depth)
inspiratory reserve volume and expiratory reserve volume get smaller
residual volume remains the same
vital capacity remains the same
hyperpnea
increased ventilation in response to metabolic needs of exercise
changes : pre-exercising (resting)/ anticipatory increase/ exercise rapid increase/ exercise gradual increase/ exercise steady state/ recovery rapid decrease/ recovery slow decrease/ post-exercising (resting)
changes of hyperpnea driven by different factors at different stages
-neural changes
-physical changes
-chemical changes
minute ventilation (V e)
total amount of air flowing into or out of lungs per unit time (ml/min or L/min)
V e = V t x f
f: respiratory rate or breathing frequency (BPM)
Vt : tidal volume (mL/breath)
Vd: dead space (mL/breath)
Dot over equation : its a rate, volume unit per time
Vd Dead Space (ml/breath)
Where Gas exchange does not take place
anatomical : respiratory vs conducting
alvolar : dead alveoli
first tidal volume (ml) x frequency (BPM)
physiological dead space : alveolar + anatomical
effective ventilation alveolar/minute (%)
minute ventilation/ alveolar ventilation
daltons law
total pressure exerted by a mixture of gases is sum of pressure exerted independently by each gas in a mixture
-overall pressure is the sum total of all the partial pressures
partial pressure of a gas
Pg= Patm X Fg
partial pressure of gas = atmospheric pressure X fraction of the gas in mixture
hypobaric
decreased pressure environment
-decresed ambient PO2
Hypoxemia
low oxygen in blood
-(blood is emminent)
hypoxia
low oxygen in tissues
adjustments for decreased pressure environment (hypobaric)
hyperventilation -→ trying to bring in more oxygen
plasma volume decreased, increased HCT (hematocrit) = where there is erythrocytes; carry large amounts of oxygen
long term acclimatization
erythropoetin from kidneys stimulates eryhrocyte production
- increased HCT, HB in blood
- induced polycythemia
external respiration
total alveolar-capillary surface area very large and very thin walled (tissue paper)
- rapid exchange of large quantities of oxygen and carbon dioxide by diffusion
- pressure gradient between alveoli and lung capillaries
-02 moving from alveoli to lung capillaries because of pressure gradient
-C02 moving from lung capillaries to alveoli because of pressure gradient
-must look at individual gases in air for movement
factors affecting diffusion
- partial pressure gradient of gas
2. Fick’s law of diffusion → rate of diffusion of gas depends on :
-surface area
-thickness of membrane gas is diffusing through
-diffusion coefficient of particular gas
diffusion coefficient : gas in particular fluid; bigger coefficient means more/quicker diffusion
ventilation-perfusing matching
ventilation : air flow into alveoli
perfusion : blood flow into pulmonary capillaries
ventilation-perfusion inequality will lead to trying to compensate
-never completely balanced
if bad air flow into area : vasoconstriction to lead blood flow away from area
If bad blood flow to area: bronchonostriction (constriction of bronchioles) diverting air flow from that area
internal respiration
same as external respiration but pressure gradients are reversed
-Between tissue capillaries and tissue cells
factors effecting diffusion in internal respiration
same as external respiration
-part pressure gradient of the gas
-ficks law of diffusion →rate of diffusion of a gas depends on
-surface area
-thickness of membrane gas is diffusing through
-diffusion coefficient of particular gas
arteriovenous oxygen difference (A-V O2 difference)
- difference between oxygen going into capillary bed and oxygen coming out of capillary bed
- difference is the amount delivered to working tissue
- more oxygen taken out in capillary bed with exercise to supply working muscles so bigger a-v 02 difference
henrys law
- at constant temperature amount of gas that is dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid
- cannot dissolve enough oxygen ad carbon dioxide to meet gas transport needs
- amount dissolved also dependant on solubility (CO2 20x more soluble than O2)
gas transport vs gas exchange
need loading for gas transport (LGT)
need unloading for gas exchange
- only dissolved gas can participate in gas exchange
- do this by manipulating affinity
affinity
tightness of binding
- low affinity= unloading
- high affinity = loading
oxygen hemoglobin binding
- each Hb can maximally bind four O2 molecules
- saturation : how much oxygen is binded
- lets go of oxygen :dissolved oxygen
hemoglobin : 4 heme proteins and iron in middle (hemes bind to oxygens)
oxygen transport
- 5% dissolves in plasma
- 5% oxygen binds to hb and makes oxyhemoglobin (HbO2) INSIDE ERYTHROCYTE
oxygen - hemoglobin dissociation curve
- increased partial pressure of oxygen causes more to bind to Hb (loading)
- decreasing partial pressure of oxygen causes less to bind to HB (unloading)
- not a linear relationship
plateau : loading portion (safety margin) little decrease in saturation if P02 decreases
steep portion : unloading portion. small change in oxygen can give large decrease in saturation
we want high Hb saturation for gas transport (loading)
we want low Hb saturation for gas exchange (unloading)
systemic venous value
can change with exercise. trained person will have lower value. can release more oxygen for hemoglobin
in exercise what happens in regards to arteriovenous oxygen difference
bigger arteriovenous oxygen difference which means more oxygen gets taken by capillaries to get brought to working muscles and tissues (unloading)
effects on oxygen saturation
Right shift : caused by high acidity, high CO2, or high temperature
-decreased affinity (unloading)
Left Shift : caused by low acidity, low CO2 or low temperature
-increased affinity (loading)
exercise increased acidity (lactic acid) creates what
that means an increased in acid which causes a right shift of oxygen saturation. this means that more oxygen is available for muscles because there is more unloading; oxygen made available for muscles
carbon dioxide transport
7% CO2 dissolved in plasma
23% carbon dioxide binds to Hb and forms carbaminoHemoglobin (HbCO2) inside erythrocyte
70%** carbon dioxide converted to **bicarbonate (HCO3) inside erythrocyte
- Bicarbonate then moves out of cell and dissolved in plasma
- chloride moves into erythrocyte when bicarbonate moves out into plasma to keep negative charge balanced (chloride shift)
Carbon monoxide affinity, and relationship with Oxygen in terms of binding to Hb
Carbon monoxide reduces the amount of O2 that combines with hemoglobin in pulmonary capillaries by competing for these binding sites
-CO changes shape of Hb an results in tighter binding of O2 (left shift)
When CO binds it forms carboxyhemoglobin
Bohr effect
How Co2 and H+ affect the affinity of hemoglobin for oxygen
-high Co2 and H+ concentrations cause decrease in HB affinity for oxygen (unloading)
-vice versa
in active muscles, carbon dioxide and H+ levels are high
oxygentated blood that flows past is affected by these conditions and the affinity of hemoglobin for oxygen is decreased, allowing oxygen to be unloaded and transferred to the working tissues
Hb is now available to bind carbon dioxide and H+ for gas transport
Haldare effect
describes how oxygen affects the affinity of hemoglobin for carbon dioxide
- high oxygen concentrations cause decreases in HB affinity for carbon dioxide (unloading)
- low oxygen concentration causes increases in HB affinity for carbon dioxide (loading)
- in pulmonary capilaries, when hemoglobin loaded with carbon dioxide is exposed to high oxygen levels coming from alveoli, hemoglobins affinity for carbon dioxide decreases.
CO2 lets go of hemoglobin and can move into alveoli by external respiration
Hb is now available to bind oxygen for gas transport
both
processes work together
cause shape change in hemoglobin to exert their full effect
