PDF Working Copy Outline Chapter 7

PDF Working Copy Outline Chapter 7 - Chapter 7 Regulation...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Chapter 7 Regulation of Potassium Balance Potassium Homeostasis Why is it essential to maintain K + balance in the body?- Recall the role of K + ions in the maintenance of the resting membrane potential and the role of voltage-gated Na + and K + channels for the events of the action potential. In a 70 Kg individual, total body K + is 50 mEq/Kg of body weight, or 3500 mEq - 98% of total K + content is in cells (150 mEq/L) - 2% in the ECF (4.5 mEq/L) - This large K + concentration gradient is maintained by which pump? ________________- High K + needed for many cell functions: cell growth, cell division, volume regulation. - Hyperkalemia:- Hypokalemia:- Cardiac arrhythmias are produced by both hypokalemia and hyperkalemia It is a challenge to maintain low extracellular K + concentration 1. Large amount of intracellular K + a shift can produce a change The distribution of K + across cell membranes is called the internal K + balance- What factors may alter this distribution and thus alter the extracellular K + concentration? - 2. Variation in dietary K + intake Varies _______________________ To maintain balance, urinary excretion of K + must be equal to dietary K + intake- In other words, K + excretion must be capable of varying from ______________________________ The renal mechanisms that allow for this variability are called the ______________________________ Internal K + Balance Ingested K + is absorbed by GI tract and enters ECF within minutes after a meal. K Ingested during a Normal Meal = 33 mEq 33 /14L (ECF) = 2.4 mEq/L K (Potentially Lethal K Conc.) All of the absorbed K + must be excreted by the kidneys. - Done slowly (6 hours) - In this time period, buffering K + by cells is important to prevent life-threatening hyperkalemia The amount of K + remains constant. What factors may affect the internal K + balance? _______________________________ Hormones Which hormones increase K + uptake into skeletal muscle, liver, bone and RBC?- How?- Insulin Stimulates K + uptake into cells after ingestion of K + in a meal Hyperkalemia: Acute therapy for hyperkalemia in diabetic patients: Epinephrine Catecholamines affect K + distribution across cell membranes- Done by activating -adrenergic receptors - What might happen if K + is released from liver cells?...
View Full Document

Page1 / 9

PDF Working Copy Outline Chapter 7 - Chapter 7 Regulation...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online