Formulas of Importance Diffusion – net movement of certain particles from a region of high concentration of those certain particles to region of low concentration of those certain particles D = A x Dc /t (Co – Ci) A is the area of the membrane being diffused through, Dc is the diffusion coefficient, t- is the thickness of the membrane being diffused through, Co – Ci is the concentration difference between the o (outside) and I (inside) of the container The diffusion coefficient = solubility coefficient divided by the square root of the molecular weight of the substance diffusing (this applies more to gases) Analysis- the greater the area and/or diffusion coefficient – the faster the rate of diffusion. The more the concentration difference the faster the rate of diffusion. However, the thicker the membrane to diffuse through the slower the rate of diffusion.
Explanation of Curve Shift (use p50 value) The red curve (more leftward) represents a higher O 2 /Hgb affinity. Notice that even if the partial pressure of O 2 around Hgb is down as low as a partial pressure of 8 mm Hg – only 50% of the oxygen molecules on Hgb will unload (2 out of 4). However the blue curve (more rightward) represents a lower O 2 /Hgb affinity. Notice that at a higher (30 mm hg) partial pressure of O 2 around Hgb – the Hgb is willing to unload 50% of its oxygen. Thus it is not holding onto O2 as tightly.
Questions 1. Where would you position the fetal hemoglobin curve – A. to the right of the adult curve B. to the left of the adult curve C. superimposed on top of the adult curve 2. Where would you position the myoglobin curve (red chemical in muscle that holds reserve oxygen) - A. to the right of the adult curve B. to the left of the adult curve C. superimposed on top of the adult curve
Internal Respiration (Unloading) O 2 to the tissues O2 is delivered to tissue cells – some from the dissolved form in the plasma and some from the Hgb. The partial pressure in the tissue cells is generally around 40 mm Hg (Krebs cycle use of O 2 ). The partial pressure of O 2 in the arteriole end of the capillary (PaO 2 ) is around 104 mm Hg. Thus O 2 diffuses from the blood into the interstitial fluids then into the tissue cells. Under normal conditions only 1 out of 4 O 2 molecules will diffuse from Hgb in the capillaries if the tissue (interstitial fluid) partial pressure is 40 mm Hg. However, if the tissue (interstitial fluid) partial pressure of O 2 is lower than 40 mm Hg more O 2 molecules will dissociate off the Hgb – and dissociate quicker (shown by the parabolic nature of the O2 curve.
Brain Centers that Control of Respiration Breathing is a somatic motor controlled action. There are nuclei in the brain that control the respiration – known as the respiratory centers. Medullary Centers 1.DRG (Dorsal Respiratory Group) 2.VRG (Ventral Respiratory Group) Pontine Centers 3. Pneumotaxic Center 4. Apneustic Center