Outline the mechanisms and molecules used for transport of blood-borne substances
Many water-soluble molecules can travel while dissolved in the blood. Other molecules, such as steroid hormones, often need to be bound to a carrier molecule to be transported through the blood. The most common carrier protein is albumin, but there are other carriers that transport particular hormones: for example, sex-hormone binding globulin transports sex hormones around the blood.
Describe the different classes of lipoproteins
Outline lipoprotein metabolism and the functions of apoproteins
Describe the structure & function of haemoglobin
Understand the Hb-O2 dissociation curve
Outline CO2 transport
Understand the importance of acid-base homeostasis in the body
Describe acid-base homeostatic regulatory systems
Describe pulmonary (respiratory) regulation of blood pH
Describe renal regulation of blood pH
Understand the Henderson-Hasselbalch equation
I don't think we need to know the Henderson-Hasselbalch equation in much detail. The main take-aways are that buffers work best when the pH is similar to the pKa and when there are roughly equal amounts of the two main components of the buffer (the weak acid/base and the salt of the weak acid/base).
Outline the principal buffers and know their strengths & weaknesses
The main buffers are as follows:
- Bicarbonate- pKa of roughly 6.37. Most common buffer in the extracellular fluid.
- Ammonia- pKa of roughly 9.25. Also found in the extracellular fluid, particularly in the renal tubules.
- Phosphate- pKa of roughly 7.21. A common buffer within cells.
- Proteins- pKa varies depending on the protein, but many have a pKa close to 7.4 (optimum pH for arterial blood. Haemoglobin has a pKa of 6.8. Perhaps the most important buffering system within cells.
Describe acid-base disorders and homeostatic compensation
The optimum pH for arterial blood is 7.4. If the pH falls below 7.35, that is called acidosis. If the pH rises above 7.45, that is called alkalosis.
Since pH is so important to the normal functioning of the body, there are many systems that can help to maintain pH (see here for more information). The most important systems are the respiratory system and the renal system. If we enter acidosis, our body may compensate by blowing off more carbon dioxide or reabsorbing more bicarbonate ions. If we enter alkalosis, our body may compensate by blowing off less carbon dioxide or secreting more bicarbonate ions. This is important to be aware of, because you don't want to mistake someone's hyperventilation for respiratory alkalosis when it might actually be a compensatory response for metabolic acidosis.
Interpret blood chemistry of acid-base disorders
When the kidneys and/or lungs fail to maintain blood pH, we can go into acidosis or alkalosis. If the acidosis or alkalosis is due to a problem with the kidneys, this is called metabolic acidosis or metabolic alkalosis. If the acidosis or alkalosis is due to a problem with the lungs, this is called respiratory acidosis or respiratory alkalosis.
In cases of acidosis or alkalosis, it is important to determine which organ is affected and if there are any compensatory effects. Firstly, look at the pH: is it acidic or alkaline? Next, look at the CO2 and HCO3- values, and determine which one of those is reflective of the pH seen in the patient. For instance, if you have measured acidosis, and you have high CO2 and high HCO3-, you are dealing with respiratory acidosis (since high CO2 results in acidosis whereas high HCO3- would normally be associated with alkalosis). Finally, determine if there are any compensatory responses. For example, in the example I just mentioned, there would be metabolic compensation as can be determined by the high HCO3- levels which would not otherwise be associated with acidosis.
No comments:
Post a Comment