Pacemaker, by Chris Carr

From OpenWetWare

(Difference between revisions)
Jump to: navigation, search
(Background)
Line 2: Line 2:
[[Image:Nephron.jpg|right|thumb|275px|Figure 1. Diagram of a nephron and the processes [1] ]]
[[Image:Nephron.jpg|right|thumb|275px|Figure 1. Diagram of a nephron and the processes [1] ]]
-
The human kidney is an essential organ, playing vital roles in both the urinary and endocrine system. The kidney maintains the chemical and water balance of the body with the help of nephrons, which are the functioning units that remove waste from the blood. Nephrons accomplish this through filtration and both active and passive transport; each kidney has approximately 1 million nephrons. Figure 1 shows a nephron and the processes that occur [1][2][3].
+
The heart is one of the most vital organs in the body responsible for the circulation of blood throughout the whole body. The heart is made up of four chambers and separated into two sides, left and right. These chambers are the left atrium, left ventricle, right atrium and right ventricle. The separations between these chambers are made up of four different valves. These four valves consist of the tricuspid, pulmonary, mitral and aortic valves (1, pg 472).  
-
It is important to note that the blood enters the nephron at the glomerulus, which filtrates solutes up to 60,000 Da. The glomerular filtration rate (GFR) for an average person is roughly 125 mL/min, or 180 liters/day. The resulting fluid and solutes then enter the renal tubes, where different types of transport occurs [1][2].
+
The flow of blood goes in the order from right to left alternating between atrium and ventricle. The flow consists of two main steps; bringing the deoxygenated blood to the lungs and bringing the oxygenated blood to the rest of the body. Starting with the collection of the deoxygenated blood in the right atrium, it then passes by the tricuspid valve into the right ventricle. From here it can then pass through the pulmonary valve to the pulmonary artery into the lungs where CO2 can be released. Next the now oxygenated blood flows from the lungs into the left atrium and through the mitral valve to the left ventricle. Lastly, the blood can then flow through the aortic valve into the aorta to the rest of the body (1, pg 472).  
-
In the proximal tube (first part of the renal tube), water is reabsorbed back in the blood stream: around 178 liters/day. Other substances are also reabsorbed, such as sodium and glucose. Glucose is always fully recovered while sodium is regulated; depending on the salt concentration within the body, sodium is either reabsorbed or secreted [1].
+
This whole process is made possible by the initial electrical signal from the sinoatrial node (SAN) and the depolarization of cardiac myocytes. This is because the electrical impulse causes the depolarization of the cardiac myocytes which then causes the contraction of the heart’s chambers. After the SAN creates its initial impulse, it flows through both of the atria causing them to contract. It then reaches the second node, atrioventricular node (AVN). From here the electrical impulse can then spread through the ventricles creating the second contraction (1, pg 483).  
-
The substances that were not filtered out in the glomerulus, like hydrogen and potassium ions, ammonia, and certain drugs, enter the peritubular capillaries. These components are then secreted into the distal tubule (second part of the renal tube). The toxins are then sent to the bladder with the ~1% of water that wasn't reabsorbed [1].
+
A pacemaker is a small implanted device that sends electrical impulses to your heart in order to create an adequate heart rate. These devices replace the SAN’s signal and create a small 2-4 mA current in order to contract the heart. Currently there are more than half a million people in the United States with a pacemaker with an average of over 150,000 new ones implanted every year (1, pg 483).
-
 
+
-
The kidney also has other important functions by sensing the composition of the blood and secreting substances that aid in bone metabolism, red blood cell production, and blood pressure regulation. When kidneys are no longer able to function as intended, renal failure occurs and can be classified as acute or chronic. Both can be treated with dialysis if there is not a donor organ available [2].
+
== History ==
== History ==

Revision as of 17:04, 17 February 2013

Background

Figure 1. Diagram of a nephron and the processes [1]
Figure 1. Diagram of a nephron and the processes [1]

The heart is one of the most vital organs in the body responsible for the circulation of blood throughout the whole body. The heart is made up of four chambers and separated into two sides, left and right. These chambers are the left atrium, left ventricle, right atrium and right ventricle. The separations between these chambers are made up of four different valves. These four valves consist of the tricuspid, pulmonary, mitral and aortic valves (1, pg 472).

The flow of blood goes in the order from right to left alternating between atrium and ventricle. The flow consists of two main steps; bringing the deoxygenated blood to the lungs and bringing the oxygenated blood to the rest of the body. Starting with the collection of the deoxygenated blood in the right atrium, it then passes by the tricuspid valve into the right ventricle. From here it can then pass through the pulmonary valve to the pulmonary artery into the lungs where CO2 can be released. Next the now oxygenated blood flows from the lungs into the left atrium and through the mitral valve to the left ventricle. Lastly, the blood can then flow through the aortic valve into the aorta to the rest of the body (1, pg 472).

This whole process is made possible by the initial electrical signal from the sinoatrial node (SAN) and the depolarization of cardiac myocytes. This is because the electrical impulse causes the depolarization of the cardiac myocytes which then causes the contraction of the heart’s chambers. After the SAN creates its initial impulse, it flows through both of the atria causing them to contract. It then reaches the second node, atrioventricular node (AVN). From here the electrical impulse can then spread through the ventricles creating the second contraction (1, pg 483).

A pacemaker is a small implanted device that sends electrical impulses to your heart in order to create an adequate heart rate. These devices replace the SAN’s signal and create a small 2-4 mA current in order to contract the heart. Currently there are more than half a million people in the United States with a pacemaker with an average of over 150,000 new ones implanted every year (1, pg 483).

History

Figure 2. Willem Johan Kolff (1911-2009) [5]
Figure 2. Willem Johan Kolff (1911-2009) [5]
Figure 3. Kolff's first dialysis machine on a Dutch stamp [6]
Figure 3. Kolff's first dialysis machine on a Dutch stamp [6]


1854 - Thomas Graham developed an apparatus that held urine and water separated with a membrane. After several hours, sodium chloride and urea were found to have transported across the membrane. Set the basis for dialysis. [4]

1924 - Georg Haas performed first human hemodialysis on a uremic patient. [4]

1937 - First flat hemodialysis membrane made of cellophane produced. [4]

1940 - Willem Kolff takes interest in acute renal failure. [4]

1943 - Kolff created dialysis machine using sausage casings, washing machine, and orange juice cans. Treated 15 patients with little to no success. [4][5][6][7]

1945 - Kolff treated a 67 year old woman with longer dialysis time and she survived for another seven more years. [5]

1947 - Kolff donates his dialysis machines to other hospitals, allowing other doctors to learn the design of the machine and improve upon it. [5][7]

1948 - First hermodialysis machine constructed in the US to be used at Peter Bent Brigham Hospital. [5]

1954 - First kidney transplant. [7]

1960 - Belding Hibbard Scribner invented the Scribner shunt, preventing the numerous incisions required for dialysis. [7]

1962 - Scribner opened the first outpatient dialysis facility. [7]

Health Issues

Personal tools