ch 18 O2 transport

• successful respiration requires all 4 processes that include:

  1. O2 enters the blood at alveolar capillary interface
  2. pulmonary circulation
  3. systemic circulation
  4. Cellular respiration determines metabolic CO2 production
• process 4 is where blood diffusion occurs. In patients with diabetes there are blood issues with the capillaries
• Lunge disease is affected at process 2. At this process O2 diffuses from alveolar into the blood (increased distance & surface area = BAD)
• A good heart will transfer O2 to the lungs then the tissues and blood in process 3
• Process 1 brings O2 outside to the lung
• the concentration of dry air entering the alveoli is 760 mmHg. While the oxygenated blood in the alveoli's concentration is 100 mm
• The concentration of PO2 in the arterial blood is 100 mm
• The CO2 starts from the tissues
• Gas exchange between alveoli and capillary goes from low to high concentration (simple diffusion) *step 2*
• (surface area) distance permeability depends on oxygen and concentration gradient
• When cells form a diffusion barrier between the lung and blood having a shorter distance = good diffusion
• Pathologies causing hypoxia:

  emphysema, fibrotic lung disease, pulmonary edema, and asthma
• Emphysema is characterized by destruction of alveoli making less surface for gas exchange (alveoli puffs up). low / normal PO2 in alveoli and low PO2 in the blood.
• Fibrosis is when scar tissue forms around the airways which makes it harder for air to get through. Low/normal PO2 in alveoli and low PO2 in the blood.
• Pulmonary Edema is fluid buildup in the lungs that blocks off the airway. There is also an increased diffusion distance between alveoli and blood. Normal PO2 in alveoli and low PO2 in the blood.
• Asthma is inflammation of the bronchioles which causes them to narrow down(increased airway resistance). Low PO2 in alveoli and low PO2 in the blood.
• Atmospheric O2 is affected by altitude and humility
• Alveolar O2 is affected by lung compliance & airway resistance
• Plasma O2 is affected by factors that affect diffusion
• When HbO2 levels are low it is a sign of anemia. (not enough oxygen for the blood)
• The sequence for oxygen movement goes from Atmospheric O2 that determines alveolar O2 that determines Plasma O2 that determines HbO2. These 4 steps are connected. In step 4 O2 is used to make ATP
• When someone has anemia, there is not enough RBC to carry oxygen to the tissues
• Hematocrit is the complete blood count.

  total blood O2 = O2 dissolved in plasma (PO2) + O2 bound to hemoglobin (HbO2)
• 98% of oxygen in blood bound to hemoglobin in RBCs and 2% is dissolved in plasma
• In CO2 transport in the blood bicarbonate is used (HCO3-). There is 70% more bicarbonate in the plasma
• The main way to carry O2 is by RBCs
• The amount of oxygen bound to Hb depends on plasma O2 and the amount of Hemoglobin. not enough hemoglobin = anemia
• Total number of Hb binding sites = Hb content per RBC x Number of RBC
• Blood doping is when athletes take blood from a donor (or the Hormone EPO) and inject it into their body to increase their oxygen carrying capacity as there are more RBCs
• Hemoglobin has 4 polypeptides surrounded by a heme group. there are 2 alpha chains and 2 beta chains (in most adults)
• the heme group in hemoglobin has porphyrin rings that has a iron atom in the center
• factors that decrease affinity of hemoglobin for O2: increased CO2, increased temperature, and 2,3-BPG. These cause a right shift
• a left shift means more bound but less release
• Carbon monoxide poisoning is destructive because it prevents the oxygen-carrying hemoglobin from binding to oxygen