The goals of this study were to describe the anatomy of the ferret SA node, and to characterize expression of ion channel transcripts within the node and surrounding regions. We choose ferrets for this study because the size of their SA node made them amenable to microscopic studies and future electrophysiological characterization. As we have shown, a second advantage of the ferret is that the anatomy of its SA node more closely resembles that of the human than the popular rabbit and mouse models. Finally, the availability of a sequence in the domestic ferret may ultimately lead to the development of transgenic ferrets, which will enable us to further investigate the role played by individual channels in the ferret SA node.
There are striking similarities in SA node architecture between the human and ferret {890, 1014, 1050, 1053, 1057, 1069, 1505, 2599, 5693, 10719}. Both show the presence of central nodal arteries surrounded by concentrically arranged small dark and large pale cells. In contrast, the rabbit SA node has no central nodal artery and no distribution of dark and lightly stained cells as seen in ferret and human {1043}. The physiological consequences of the ferret architecture are potentially important to understanding human physiology and pathophysiology. For example, changes in intravascular pressure in the SA nodal artery should affect heart rate in the ferret but not rabbit {1042}. The differences in morphology could be indicative of different cells types expressing a different array of ion channels. The combination of central nodal arteries and distribution of dark and light cells that are similar to that described for the human SA node led us to suggest that the location and expression levels of ion ch...
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...ies in patients with sinus bradycardia resulting from genetic mutations or in mice resulting from knock out of a gene encoding a specific ion channel {7369, 7748, 8033, 9136, 9382, 8733}. Alternatively, the negative chronotropic effects of K+, Na+ and Ca2+channel blockers can also slow the heart rate. In addition, the negative chronotropic effects of TTX on the spontaneous heart rate of the isolated mouse heart, led to the identification of TTX-sensitive Na channels (brain type) in the mouse SA node {8033} We have documented their presence in the ferret SA node. Finally, if our findings are substantiated in the human heart, we believe that the widespread distribution of Na channels is functionally important. In patients with diseased SA node, Class I antiarrhythmic drugs could further impair the propagation of impulses out of the SA node to the crista terminalis.
In the beginning phases of muscle contraction, a “cocked” motor neuron in the spinal cord is activated to form a neuromuscular junction with each muscle fiber when it begins branching out to each cell. An action potential is passed down the nerve, releasing calcium, which simultaneously stimulates the release of acetylcholine onto the sarcolemma. As long as calcium and ATP are present, the contraction will continue. Acetylcholine then initiates the resting potential’s change under the motor end plate, stimulates the action potential, and passes along both directions on the surface of the muscle fiber. Sodium ions rush into the cell through the open channels to depolarize the sarcolemma. The depolarization spreads. The potassium channels open while the sodium channels close off, which repolarizes the entire cell. The action potential is dispersed throughout the cell through the transverse tubule, causing the sarcoplasmic reticulum to release
Stone, J. (1972). Morphology and physiology of the geniculocortical synapse in the cat: The question of parallel input to the striate cortex. Investigative Ophthalmology & Visual Science, 11, 338-46.
In this lab, I took two recordings of my heart using an electrocardiogram. An electrocardiogram, EKG pg. 628 Y and pg. 688 D, is a recording of the heart's electrical impulses, action potentials, going through the heart. The different phases of the EKG are referred to as waves; the P wave, QRS Complex, and the T wave. These waves each signify the different things that are occurring in the heart. For example, the P wave occurs when the sinoatrial (SA) node, aka the pacemaker, fires an action potential. This causes the atria, which is currently full of blood, to depolarize and to contract, aka atrial systole. The signal travels from the SA node to the atrioventricular (AV) node during the P-Q segment of the EKG. The AV node purposefully delays
There are a series of nodes along the axon where there is a high concentration of sodium (Na+) and K+ channels. There is a high concentration of Na+ outside the cell and a high concentration of K+ inside the cell. As the nodes sen...
Introduction: The purpose of this lab is to have a better understanding of the internal and external anatomy. The reasons for performing this lab is that pigs are similar to humans because they have skin, omnivores and as fetus they receive nutrients from an umbilical cord connected to the mother. As well as the similarities to human organ systems. The hypothesis of this lab is if the fetal pig has a similar organ system of a human and assuming those organs will be in the same locations as in a human then the organ systems should operate in the same fashion. Based on what I’ve learned from this lab and what I’ve learned during lecture I predict that the fetal pigs nervous and circulatory system would operate and look the same way as in a human.
Baroreceptors are sensors in the vascular system that respond to changes in pressure within blood vessels. Baroreceptors are found in the carotid sinus, aorta; the largest artery and the heart’s muscular pumping chamber, and wall of the left ventricle. They monitor the level of arterial pressure and act against in the order to lessen the force in the dilation of blood vessels, which decreases the blood pressure. Chemoreceptors, located in the brain, the two main arteries that carry blood to the head and neck, and aortic body of baroreceptors, are sensitive to changes in concentrations of oxygen, carbon dioxide, and hydrogen ions (Ph) in the blood. A decrease in arterial oxygen concentration or Ph causes a reflexive rise in pressure where an increase in carbon dioxide concentration causes a decrease in blood pressure. Ph is the numeric scale used to identify the basicity and acidity of a solution. Basic is on the top of the scale while acid is on the
Different cellular signaling pathways respond to calcium levels. The inflow of calcium resulting from glutamate receptor stimulation leads to their activation.
The second part of this lab was a computer simulation program to illustrate a frog’s electrocardiogram using various drugs in an isolated setting. The computer program entitled “Effects of Drugs on the Frog Heart” allowed experimental conditions to be set for specific drugs. The different drugs used were calcium, digitalis, pilocarpine, atropine, potassium, epinephrine, caffeine, and nicotine. Each of these drugs caused a different electrocardiogram and beats per minute reading. The calcium-magnesium ration affects “the permeability of the cell membrane”(Fox). When calcium is placed directly on the heart it results in three physiological functions. The force of the heart increases while the cardiac rate decreases. It also causes the appearance of “ectopic pacemakers in the ventricles, producing abnormal rhythms” (Fox). Digitalis’ affect on the heart is very similar to that of calcium. It inhibits the sodium-potassium pump activated by ATP that promotes the uptake of extracellular calcium by the heart. This in return strengthens myocardial contraction (Springhouse). Pilocarpine on the other hand
The occurrence of action potential is a very short process. When action potential occurs in the neuron the sodium channels open along the axon and sodium comes in. Because the sodium is positive it make the inside of the axon positive. When both the inside and outside are comparative in charge the sodium storms rushing in and starts the depolarization of the action potential. After this happens the sodium channels begin to close and the potassium channels begin to ...
All references and resources are taken from the Public Library of Science, Biology March 2004 issue and from Science March 16, 2004
The heart serves as a powerful function in the human body through two main jobs. It pumps oxygen-rich blood throughout the body and “blood vessels called coronary arteries that carry oxygenated blood straight into the heart muscle” (Katzenstein and Pinã, 2). There are four chambers and valves inside the heart that “help regulate the flow of blood as it travels through the heart’s chambers and out to the lungs and body” (Katzenstein Pinã, 2). Within the heart there is the upper chamber known as the atrium (atria) and the lower chamber known as the ventricles. “The atrium receive blood from the lu...
A mink is a good specimen to study the human anatomy because it is so closely related in internal features to that of a human being. Since these features are so closely related it provides a sort of “model” that can be used in order to better understand the anatomy of humans.
A normal heart rhythm begins at the sinoatrial node and follows the hearts conduction pathway without any problems. Typically the sinoatrial node fires between 60-100 times per minute (Ignatavicius & Workman, 2013). When a person has Atrial Fibrillation, the sinoatrial node releases multiple quick impulses at a rate of 350 -600 times per minute. When this happens, the ventricles respond by beating around 120- 200 beats per minute, making it tough to identify an accurate heart rate. This arrhythmia can be the result of various things. During a normal heart beat, the electrical impulse begins at the sinoatrial node and travels down the conduction pathway until the ventricles contract. Once that happe...
Nerve cells generate electrical signals to transmit information. Neurons are not necessarily intrinsically great electrical conductors, however, they have evolved specialized mechanisms for propagating signals based on the flow of ions across their membranes.
There were a few observations proven to be different between the rat’s anatomy in comparison to the human anatomy. First of all, the rat has no gallbladder present in it’s anatomy which a human does. Secondly, the rat’s lungs appeared dark red in color where as a human’s lungs are pink in color. Also the rat’s liver has more lobes as does their lungs compared to a human’s liver and lungs. Besides these said differences, the rat’s anatomy is basically very similar to that of the human body.