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Relational A+P Week 16

Terms in this set (54)

external respiration occurs by diffusion controlled by
1. partial pressure gradients of gases
2. solubilities of gases
external respiration is
exchange O2 and CO2 btw alveolar air and pulmonary capillary bed
Dalton's law of partial pressure
-total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of each individual gas
nitrogen partial pressure
78.6%
oxygen partial pressure
20.9%
argon partial pressure
.093%
CO2 partial pressure
.04%
other gases partial pressure
.06%
increased difference in partial pressures leads to,_______ rate of diffusion
faster
Henry's Law
the quantity of gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility in the liquid
Solubilities in blood
CO2 very soluble
O2 less soluble
N2 very low solubility
when gas pressure decreases, the gas becomes ______ soluble
less
what happens is a diver ascends too quickly
-N2 is forced into blood when diver goes down
-if ascends to quickly it rapidly comes out of the solution forming gas bubbles in body fluids and tissues
-results in joint pain (bends), brain issues, itchy skin
compared to atmospheric air, alveolar air contains
less O2
less CO2
more H2O
Pulmonary gas exchange (external resp)
-partial pressure gradients cause O2 to enter the blood and CO2 to exit
-
systemic gas exchange is aka
internal respiration
oxygen transport in blood
-1.5% is dissolved in plasma
-98.5% carried by hemoglobin (binds to heme group)
each Hb can bind ____ oxygen
4
At rest Hb arterial blood percentage
94-100%
At rest Hb venous blood percentage
75%
As pressure of PO2 increases
binding of an O2 molecule to Hb causes change in Hb shape enhancing the binding of another O2
As pressure of PO2 decreases:
Hb subunit releases O2 causing a change in binding affinity causing more O2 release
Factors affecting Hb saturation
-PO2 of blood
-temp
-blood pH
-PCO2 of blood
-metabolic activity of RBCs
Plateau region of O2 saturation
between 60 and 100mmHg
Hb more than 90% saturated
at rest, tissue PO2=
40mmHg
Hb releases only____% of O2 into tissues
25%
during exersize, PO2 in tissues=
20mmHg
normal blood
37 degrees C, pH of 7.4
Effect of temperature on binding affinity
-increasing temp causing Hb to release more O2 (shifts ox-Hb curve to the right)
-tissues with high metabolic rate need more O2
Effect of pH on binding affinity
increased pH causes Hb to have higher binding affinity and release less O2
-ox-Hb curve shifts to left
what happens when CO2 released by tissue cells?
-enters RBCs and
1. binds to Hb decreasing its affinity of O2
2. CO2 converted to H+ and HCO3-

-release of CO2 (pressure of CO@ increases) causes O2 to unload from Hb
carbonic anhydrase
catalyze CO2's reaction with H2O
CO2 + H2O-->
H2CO2 (carbonic acid) + H+ + CO3-
modes of CO2 transport
1. 7% dissolved in plasma
2. 23% bound to global group of Hb
3. 70% converted to bicarbonate (HCO3-) which diffuses into blood
chloride shift
Cl moving into red blood cells when bicarbonate diffuses out to balance electrical charge
Haldene Effect
-describes property of Hb
-deox Hb= increased ability to carry CO2
-ox Hb=decreased ability to carry CO2
2 controls of respiration
1. local regulation (auto regulation)
2. neural regulation
Local regulation of respiration
-smooth muscle cells of bronchioles sensitive to PCO2
-PCO2 increases= bronchioles dilate to direct airflow to alveoli
Hypoxic pulmonary vasoconstriction
-low PO2 and high PCO2 in pulmonary arterioles= vasoconstriction
-permits blood flow to better ventilated areas (alveoli)
-this is opposite to tissues
where is the respiratory control centre
pons and medulla ob.
respiratory control centres receive input from where
-chemoreceptors
-baroreceptors (BP)
-irritant receptors
-cerebral cortex
-limbic system (hypothalamus)
resp control centres affect the
1. frequency of contraction aka res rate
2. which muscles activated (quiet or forced breathing)
neural regulation of respiration
-control changes in resp rate and breathing depth
-respond to change in metabolic activity and O2 demand
the medullary rest centre contains the ____ and _____
DRG and VRG
DRG (dorsal respiratory group)
-rythmic innervation of diaphragm and external intercostals in quiet breathing
VRG (ventral resp group)
- pacemaker cells that regulate DRG firing of neurons
-innervation of accessory muscles during forced breathing
Pontine Respiratory group (pneumotaxic centre)
-active in inhalation/exhalation-- assist VRG modification
**regulate the regulator
peripheral chemoreceptors
-located in aortic arch and carotid sinuses
-detect PO2 and pH decreasing
-send input to medulla ob via vagus nerve and glossopharyngeal nerves
where are the central chemoreceptors?
in medulla oblongata
what do the central chemoreceptors do?
detect increase in H+ in CSF which indicates low pH ad high PCO2
Hering-Breur Reflex (inflation Reflex)
-prevents over inflation during forced breathing
-overexpansion of lungs stems stretch receptors in wall of bronchi sending sensory info to DRG inhibiting innervation of diaphragm and external intercostals
protective reflexes
-involve irritant receptors located in epithelium of respiratory tract
cortical influences of breathing
allow voluntary control of breathing
-over ride respiratory control centres and innervate lower motor neurons directly
-alter activity of resp control centre
chemoreceptors cannot be consciously suppressed which is why....
you can't kill yourself from holding your breath
-blood CO2 increases and chemoreceptors stimulated to cause inhalation
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