Respiratory System II Flashcards
Secretion of EPO is stimulated by
Testosterone
In an O2 poor envionment EPO begins to be produced and reahed peak levels in
24 hours
takes days for mature RBCs to appear in circulation as a result of low O2 levels
Large amount of EPO in the blod increases RBC production rate 10x over the normal level
Hemoglobin
Produced in immature RBC containing a nucleus
once mature the nucleus is lost (no more hemoglobin is produced)
24 pg of hemoglobin in each RBC
Hemoglobin Structure
Each hemoglobin contains 4 subunits
Each subunit contains a single heme molecule attached to a polypeptide
4 polypeptides are called a globin
each heme carries one oxygen atom attached to the central iron atom
each hemoglobin can carry four oxygen molecules
iron atom makes blood red in colour
When Blood Leaves the Lungs after picking up oxygen
Hemoglobin is almost completely saturated with oxygen
O2 and Hemoglobin
O2 easily binds w/ Hb in a reversible reaction to produce oxyhemoglobin (HbO2)
Reaction is driven in each direction either by the amount of O2 or HbO2 at either end of the reaction
______ determines if we are loading or unloading oxygen
Amount of PO2 dissolved in the blood
PO2 is high
In the lungs
O2 loads onto hemoglobin
PO2 is low
In the tissues
O2 unload into the tissues
Temperature and Acidity
When the body warms up and is working muscles produce lactic acid this increases the acidity of the blood
Increase the unloading of oxygen from hemoglobin
Three Ways to Transport Carbon Dioxide
Dissolved in the Plasma
Carried as a Bicarbonate ion
Bound to Globin forming a carbamino compound
Dissolved in Plasma (CO2)
20% more soluble in plasma and will dissolve much easier
7%-10% of all the CO2 is carried dissolved in plasma
PCO2 levels (Veneous v Arterial)
40 mmHg on the arterial side
46 mmHg on the venous side
the significant amount of CO2 in the arterial blood passes through the lungs without all beng removed it helpsmaintain blood flow by keeping arterioles dilated
Bicarbonate Ion
70% of the total CO2 is carried in the blood as bicarbonate ions (HCO3-)
CO2 reacting w/ water produced carbonic acid
Carbonic anhydrous acts as an enzyme
Carbonic acid dissociated into bicarbonate ions and hydrogen ions
CO2 released from the cells diffuses into the blood and then into RBCs
Carbonic anhydrase found in RBCs catalyzes the first step of the reaction inside the cell
H+
After CO2 has been converted to bicorbonate ions most of the H+ will bind w/ hemoglobin (Hb) found inside the red blood cell
important since h+ is able to diffuse out of the cell making the blood acidic
Bicarbonate ions diffuse out of the RBC into the plasma to act as a buffer to help stabilize the pH of the blood
Chloride Shift
HCO3- leaving the RBC makes inside of the RBC more (+)ve
To balance the (+)ve charge Cl- must diffuse into the cell
Chloride shift can occur very quickly because the membrane is permeable to (-ve) charge
Carbocamino compounds
20% to 30% of all carbon dioxide is transported in the blood attached to proteins forming carbamino compounds
Hemoglobin which has unloaded some of its O2 to the tissue is one of the most abundant proteins that can carry CO2
CO2 attaches to the globin portion of hemoglobin
HbCO2 will return to the lungs on the RBC
Once in the lungs CO2 detaches from Hb and will diffuse into the alveolar space
Oxygen then diffuses into the RBC and will attach to the heme portion of hemoglobin
In the tissues high PCO2
Moves the reaction to the reight to form HbCO2 and HCO3-
In the lungs the low PCO2
Moves the reaction to the left to form CO2 and Hb/H20
Control of Breathing
We can increase, decrease or stop respiration at will
Most breathing done spontaneously
Spontaneous Respiration
Originates in the medullary respiratory center of the medulla oblongata of the brainstem
Produced by rythmic activity from neurons
Voluntary Center
Located in the cerebral cortex
Capable of overriding the center in the brainstem (when holding your breath)
Inhalation
Inspiratory center in the MRC activates inspiratory muscles during inhalation
Inspiration is an active process
requiring the contraction of the diaphragm and external intercostal space
Inspiratory center stimulates the contraction of these inspiratory muscles at the same time it also inhibts the expiratory center
Exhalation
Quiet exhalation is a passive process involuntary only the relaxation of the inpiratory muscles
the lungs own elastic properties and recoiling of muscle causes exhalation at rest
Forceful exhalation requires contraction of the abdominal muscle + internal intercostal muscles of the ribs
signals to these muscles originate in the expiratory center of the medulla
while this center is active the inspiration center is inhibted
