The task of maintaining an adequate interstitial homeostasis (the proper nutritional environment surrounding all cells in your body) requires that blood flows almost continuously through each of the millions of capillaries in the body. The following is a brief description of the parameters that govern flow through a given vessel. All bloods vessels have certain lengths (L) and internal radii (r) through which blood flows when the pressure in the inlet and outlet are unequal (Pi and Po respectively); in other words there is a pressure difference (ΔP) between the vessel ends, which supplies the driving force for flow. Because friction develops between moving blood and the stationary vessels walls, this fluid movement has a given resistance (vascular), which is the measure of how difficult it is to move blood through a vessel. One can then describe a relative relationship between vascular flow, the pressure difference, and resistance (i.e., the basic flow equation):
about 6 years ago
Overview of Organ Systems and Homeostasis
over 6 years ago
Four Major Lober Diencephalon - Homeostasis Brain stem - Relay Station Limic System - Memory and Emotion Image: https://docs.google.com/open?id=0B8Ss3-wJfHrpejFtSkdLWHlNdWs Facebook: http://www.facebook.com/home.php#!/ArmandoHasudungan
over 6 years ago
Professor Saltzman continues his description of nephron anatomy, and the specific role of each part of the nephron in establishing concentration gradients to help in secretion and reabsorption of water, ions, nutrients and wastes. A number of molecular transport processes that produces urine from the initial ultra-filtrate, such as passive diffusion by concentration difference, osmosis, and active transport with sodium-potassium ATPase, are listed. Next, Professor Saltzman describes a method to measure glomerular filtration rate (GFR) using tracer molecule, inulin. He then talks about regulation of sodium, an important ion for cell signaling in the body, as an example to demonstrate the different ways in which nephrons maintain homeostasis.
over 6 years ago
This is an excerpt from "Fluids and Electrolytes Made Incredibly Easy! 1st UK Edition" by William N. Scott. For more information, or to purchase your copy, visit: http://tiny.cc/Fande. Save 15% (and get free P&P) on this, and a whole host of other LWW titles at lww.co.uk when you use the code MEDUCATION when you check out! Introduction The chemical reactions that sustain life depend on a delicate balance – or homeostasis – between acids and bases in the body. Even a slight imbalance can profoundly affect metabolism and essential body functions. Several conditions, such as infection or trauma, and certain medications can affect acid-base balance. However, to understand this balance, you need to understand some basic chemistry. Understanding pH Understanding acids and bases requires an understanding of pH, a calculation based on the concentration of hydrogen ions in a solution. It may also be defi ned as the amount of acid or base within a solution. Acids consist of molecules that can give up, or donate, hydrogen ions to other molecules. Carbonic acid is an acid that occurs naturally in the body. Bases consist of molecules that can accept hydrogen ions; bicarbonate is one example of a base. A solution that contains more base than acid has fewer hydrogen ions, so it has a higher pH. A solution with a pH above 7 is a base, or alkaline. A solution that contains more acid than base has more hydrogen ions, so it has a lower pH. A solution with a pH below 7 is an acid, or acidotic. Getting your PhD in pH A patient’s acid-base balance can be assessed if the pH of their blood is known. Because arterial blood is usually used to measure pH, this discussion focuses on arterial samples. Arterial blood is normally slightly alkaline, ranging from 7.35 to 7.45. A pH level within that range represents a balance between the concentration of hydrogen ions and bicarbonate ions. The pH of blood is generally maintained in a ratio of 20 parts bicarbonate to 1 part carbonic acid. A pH below 6.8 or above 7.8 is usually fatal. Too low Under certain conditions, the pH of arterial blood may deviate significantly from its normal narrow range. If the blood’s hydrogen ion concentration increases or bicarbonate level decreases, pH may decrease. In either case, a decrease in pH below 7.35 signals acidosis. Too high If the blood’s bicarbonate level increases or hydrogen ion concentration decreases, pH may rise. In either case, an increase in pH above 7.45 signals alkalosis. Regulating acids and bases A person’s well-being depends on their ability to maintain a normal pH. A deviation in pH can compromise essential body processes, including electrolyte balance, activity of critical enzymes, muscle contraction and basic cellular function. The body normally maintains pH within a narrow range by carefully balancing acidic and alkaline elements. When one aspect of that balancing act breaks down, the body can’t maintain a healthy pH as easily, and problems arise.
Lippincott Williams & Wilkins
about 7 years ago
Originally created in 2012 as a set of lecture notes for my own use, this document aims to complement the lectures given under the Homeostasis Panel at the Cardiff University School of Medicine. All material covered in lectures is explored in detail, helping students to understand and apply the teachings.
almost 8 years ago
First Year Faculty of Life Sciences notes from lectures and textbooks. There may be paragraphs copied from Martini et al. (2010) so if anyone has any issues with copyright or plagiarism please let me know and I will remove it immediately.
almost 9 years ago