Physiology of Breathing
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- two: inhalation/ exhalation
- 1. breathing in (inspiration)
- a. Active; requires energy; muscle contractions in the intercostals muscles (between ribs) and diaphragm (Separates thoracic)
- i. Must contract to get water in, increasing size of thorax, and therefore, the lungs
- 1. breathing out (expiration)
- a. Passive; normal recoil of muscles
- i. They go back and air comes out
Transport of the Respiratory gases occurs by __.
How is oxygen transported?
- i. If you look at normal arterial blood, most of the oxygen (osver 98.5% percent) is transported by hemoglobin
- ii. 1.5% is dissolved oxygen in plasma; majority is in red blood cell being transported by hemoglobin
i. Oxygenated blood= __
1. Attached to __group, specifically, the __of the __group
i. If every hemoglobin molecule had four oxygen attached to it, your blood will be __
1. Factors that affect this percentage and how much oxygen attaches to hemoglobin
- the partial pressure of oxygen
- i. Increased amounts of Carbon dioxide
Explain partial pressure of oxygen
i. The greater the PO2, the greater the percent of oxyhemoglobin (with increase in PO2, % saturation increases until you reach one hundred percent)
Increased amounts of Carbon dioxide
- 1. When CO2 is in circulatory system, it combines with water and forms carbonic acid, which forms the hydrogen ion and the bicarbonate ion
- 2. High carbon dioxide or low PH (acid) is going to affect the amount of saturation
- a. High PCo2 (high acid; low pH) is going to cause less saturation and oxygen to be released from hemoglobin BECAUSE THE TISSUES WANT IT
What does high PCO2 result in?
- i. Results in decreased saturation of hemoglobin because the hemoglobin is releasing oxygen
- ii. Hemoglobin releases oxygen because of the Bohr effect, which is the hydrogen ions (that came from the carbon dioxide dissociating with water combining with hemoglobin) cause a conformational change in the hemoglobin molecule such that it releases oxygen; hydrogen ions attached to hemoglobin cause conformational change that causes release
- iii. Bohr effect is a RESULT of high CO2, low PH, and high acid
Where is High PO2 located?
i. High PO2 is going to be highest in lungs; the more the tissues are creating CO2, the more they want oxygen; so, the Bohr effect causes oxygen to be released
- 1. Within normal limits, an increase in temperature favors dissociation (oxygen release from hemoglobin)
- 2. Less saturation at higher temperatures
- a. If oxygen is coming off, then it is less saturated
- b. Examples of high temperature is when the metabolically active cells are releasing a lot of heatà wants more oxygen; favors dissociation
- i. Unlike Oxygen (98.5% carried by hemoglobin), carbon dioxide is carried in three ways
- 1. 10% dissolved blood
- 2. 30% attached to hemoglobin (Carb-amino hemoglobin; attaches to globin portion, not heme; it does not compete with oxygen)
- 3. 60% as bicarbonate ions (will combine with water and form carbonic acid, which dissociates into bicarbonate and hydrogen ion)
What don't want to do?
- i. We don’t want to dump a lot of ions in the plasma and have osmotic pressure
- 1. So, for every bicarbonate that leaves, a chloride ion enters the red blood cell to prevent ionic imbalance
- a. CHLORIDE SHIFT
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