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What is Henry's law?
- at a constant temperature, the solubility of a gas (partial P) that is in the air dictates the solubility (amount dissolved) of a the same gas in the liquid.
- So when the partial pressure is increased, the solubility of the gas is increased.
- the pressure exerted by a gas in a sealed container is created by the collison of gas molecules
- -smaller space, high pressure
- -bigger space, lower pressure
total pressure is the sum of the individual gases
what is Partial pressure of a gas
Partial pressure of a gas is the amount of pressure of a single gas that is in a mixture
What Gas contributes most to atmospheric pressure?
What is the partial pressure of O2 and CO2 in atmosphere?
What is the partial pressure of O2 and CO2 in Alveoli?
- O2 : 100mmHg
- CO2 : 40mmHg
What is the partial pressure of O2 and CO2 in Oxygenated blood (arteries)?
- O2 : 100mmHg
- PO2 : 40mmHg
What is the partial pressure of O2 and CO2 in veins
What is the partial pressure of O2 and CO2 in tissues cell
Explain how gases move down partial pressure gradients during gas exchange between the atmosphere and the lungs?
during inspiration a muscle pump creates a pressure gradient for airflow. During expiration: elastic recoil of the lung creates a pressure gradient for airflow
Explain how gases move down partial pressure gradients during gas exchange between the lung and blood
- -O2 from the lung is dissolved in plasma then binds to hemoglobin by red blood cells
- Remember: CO2 is more soluble than O2.
Explain how gases move down partial pressure gradients during gas exchange between the blood and tissues pg 573
since plasma has a low solubility for oxygen, most of the oxygen is transported to cell tissues by hemoglobin. Heme=oxygen, globin=CO2
when a cell is at rest, extra oxygen that isn't needed is preserved for exercise, when it needs more.
What is special about a fetus' gas affinity?
a fetus' hemoglobin has a higher affinity for O2 instead of Co2
In detail, how is O2 transported in blood?
- from the alveoli oxygen gets transported to the blood where it is partially dissolved in the plasma and the rest is picked up by heme in hemoglobin of red blood cells.
- (pay attention to Hb-O2 saturation curve)
- The amount of dissolved PO2 is the most important factor that determines the saturation of hemoglobin. It can also be influenced by 2,3 DPG (made in RBCs during hypoxia) to produce more oxyhemoglobin
Whats the biggest factor determining Hb Saturation?
In detail, how is CO2 transported in the blood?
- 1. ~7% is dissolved in plasma
- 2. ~23% binds to hemoglobin on RBCs (HbCo2)
- -Haldane effect: increases the release of O2 from Hb, so it increases affinity of CO2.
- -Bohr effect: increases H+ levels so that it decreases the affinity of O2 on Hb
- 3. ~70% is converted to bicarbonate ion HbCO3- (most important extracellular buffer)
- -stabilizes body's PH
- -additional way to transport CO2 from cells to lungs
What is the Haldane effect?
-Haldane effect: increases the release of O2 from Hb, so it increases affinity of CO2. -Bohr effect: increases H+ levels so that it decreases the affinity of O2 on Hb
How does an increase in CO2 change the PH of the blood? What happens to plasma during hyperventilation?
- It becomes more acidic (lower PH)
- Sensed by central and peripheral chemoreceptors in the plasma to regulate PO2 and PCO2 levels.
During hyperventilation, peripheral chemoreceptors would notice too many O2 in the plasma and cause hypoventilation.
What is hemoglobin saturation? Where is it happening?
Understand O2-Hb saturation curve graph
The amount of binding sites on hemoglobin that are filled with oxygen
- at normal alveolar and arterial PO2 levels in the lung capillaries, there is 98% saturation at 100mmHg PO2. Beyond this, even large increases of PO2 barely change the percent saturation.
- After 60-40mmHg range, the percent saturation drops drastically. Small decrease makes big % change.
- Venous blood is normally 40mmHg or 75% at rest. So they unload only about 1/4 of its O2 at the tissue cells. The rest is used when metabolism increases.
What factors influence O2-Hb affinity?
What way do they shift the curve?
- Increased temp, decreased PH (more acidic), or increased CO2 will shift the curve to the right, giving hemoglobin less affinity to O2
Also 2,3 DPG shifts to the right. Is triggered in RBCs by hypoxia (low O2 levels for long period of time)
Why would hyperventilation shift O2-Hb saturation curve to the left?
It is a respiratory compensation causing the intake of more oxygen via the removal of CO2.
How is it possible that arteriolar PO2 and CO2 doesn't change much during exercise?
How is the increased unloading of O2 at the tissues accomplished?
What 2 factors change locally?
previously closed capillary beds (at rest) open in response to higher blood pressure, during exercise to produce a larger cardiac output.
Breathing rate is increased to keep up with the increased metabolic rate
- Factors that change locally are:
- Increases of CO2 being exhaled cause bronchioles to dilate. and opposite
- Increase in O2 causes dilation of arteries. and opposite.
Why is inspiration referred to as an active process while expiration is considered a passive process?
inspiration- the muscle contract, ribcage moves up and out, diaphragm contracts and pulls down to open lungs and create large volume/low pressure for air to move in
expiration- caused by the relaxation of muscles (except for blowing out candles)
What are the muscles involved in quiet breathing?
What kind of muscle?
How is contraction initiated?
quiet: diaphragm, external intercostals, and scalene muscles
exercise: diaphragm, external intercostals, scalene muscles, and sternocleidomastoid, abdominal muscles
contraction is initiated by pressure gradients. Inspiration happens when alveolar pressure decreases, expiration is when alveolar pressure increases
What is the respiratory control center?
What parts of the control center are used during quiet breathing? exercise?
Medulla and Pons are the control center
Medulla- DRG is quiet, VRG is active
Pons- both. Apneustic has excitability on DRG, Pneumotaxic has inhibitory effect on DRG+apneustic to switch between inspiration and expiration
What are ways that the pattern set by the respiratory control center can be altered?
Input from chemoreceptors: central and peripheral chemoreceptors
Cerebral cortex "central command"- increase in breathing at the thought of exercise
Drugs and alcohol and increase or depress breathing
What is the Hering-Breur reflex?
Its activated to prevent the over inflation of the lungs
What are the 2 chemoreceptors? Where are they? What do they do?
Which is more day to day?
Central-in the medulla-small changes in CO2 in arteries (CSF specifically)
Peripheral-in the carotid bodies-large changes in CO2 in arteries
central is more day to day because of regulation of small changes
True or False
Contraction of the diaphragm pushes air out during expiration
- Contraction of the diaphragm (flattening) pulls the lungs down and happens during inspiration
How would PO2 and CO2 levels change during a breath hold?
upon breathing, there would be more PO2. But upon holding, there would end up being more PCO2 after the PO2 has dissolved through the alveolus and into the plasma
define hypoxia, hypercapnia
hypoxia- having a low oxygen supply for a long period of time
hypercapnia- elevated concentrations of carbon dioxide
How can the following lead to hypoxia?
high altitude, damage to respiratory control center, pulmonary edema, anemia, carbon monoxide poisoning, pulmonary embolism
- high altitude- there is a low oxygen supply at high altitudes because there is a lower pressure
- damage to respiratory control center- the chemoreceptors aren't sensing the influx of CO2 and aren't regulating or creating compensation
- pulmonary edema- build up of fluid in the lungs leads to not enough O2 intake
- anemia- not enough healthy red blood cells means that hemoglobins % oxygen saturation is low
- carbon monoxide poisoning- higher affinity in the blood for CO than O2, this means oxygen cannot bind to hemoglobin
- pulmonary embolism- blockage in the artery of the lung. Oxygen is not passing through.
what is pulmonary fibrosis? how does lung compliance change?
is inspiratory or expiratory reserve volume effected more?
there is scare tissue in lung, elastin is replaced by stiff collagen, so it can't stretch as much. the inspiratory reserve volume is effected more
how does lung elastance change in emphysema? is inspiratory or expiratory reserve volume more effected?
elastance increases because the innerwalls of the air sacs become weak. The expiratory volume is effected more because it can't get rid of old air to make room for new fresh air.
what is surfactant and how is it useful?
surfactant is a detergent-like substance made in alveolar type 2 cells. Its a mix of lipids and fats that decrease surface tension on the cells so that the lung can have a higher compliance and increase easier
prematurely born babies often develop respiratory distress syndrome, why?
- surfactant is made during development. If the baby is born premature it hasn't made enough surfactant to keep the alveoli from collapsing.
- low surfactant=low compliance, so the lung can't inflate
why do athletes train at high altitudes
do force their bodies to produce more red blood cells via 2,3 DPG in order to increase more oxygen saturation
during asphyxia, why do we turn blue?
when hemoglobin looses oxygen it actually turns blue
whats the difference between albuterol (beta 2 receptor agonist) and atrovent (anti-cholergenic), even though they both treat asthma?
albuterol- increases sympathetic activity to act like bronchodiltor, causing the airways to relax
atrovent- inhibits bronchodilation, forcing the airways to relax for more oxygen intake. It stops acetylcholine so that the muscles can't contract
In anemia, how are these affected?
total arterial O2 contect
- arterial PO2- normal because less hemoglobin, not less affinity
- total arterial content- less