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Anatomy & Physiology

Arterial Interstitial Cells of Cajal - Comment

Saturday 18th February 2006 In the 1890s, Santiago Ramon y Cajal described distinctive cells in the small intestine. These cells are special cells with processes interposed between nerve endings and smooth muscle cells in the gastrointestinal tract. It has been established that some ICC in the gastrointestinal tract are pacemaker cells. It has become clear that ICC are distributed more widely throughout the body than was previously thought (Huizinga and Faussone-Pellegrini, 2005). Recently, ICC-like cells were identified in the urogenital tract (Sergeant et al., 2000; Metzger et al., 2004; Duquette et al., 2005). A very recent publication reports the presence of ICC in the pancreas (Popescu et al ., 2005). The findings of ICC-like cells outside the gastrointestinal tract supports the opinion of Takayama et al . (2002) and Takaki (2003) and others who have suggested that some ICC are not pacemakers but rather are interposed between nerve endings and smooth muscle cells and have different and yet unkn…
 

Arterial Interstitial Cells of Cajal - Minireview

Friday 24th June 2005: Interstitial cells of Cajal, frequently abbreviated to Interstitial cells of Cajal. were first identified in the intestinal tract, and similar cells were later subsequently found in other organs namely; the colon, oesophagus and stomach (the gastrointestinal tract); the urethra and urinary bladder (the urinary tract); and in the portal vein (Povstyan et al 2003). Although Povstyan and his colleagues' observation of the Interstitial cells of Cajal like cells in the portal vein was the first of its kind involving the vasculature, Pucovsky et al, in 2003, examined cells resembling Interstitial cells of Cajal in the resistance arteries. They aptly called them arterial Interstitial cells of Cajal-like cells (AIL).
 
AIL have been found to be multipolar and elongated with numerous occasional thin branches. Located in the vessel wall, AIL are specifically found in the layer of media immediately under the basal lamina and scattered among the myocytes in the deeper layers of media. This loca…
 

Functions of the Circulatory System

Thursday 9th June 2005: The circulatory system has as main function the rapid transport of substances to cells throughout the body, but is also involved in other processes that are essential to the normal functioning of organisms. The basic functions of the cardiovascular system are, as follows:
 
Rapid substance transport to and from the tissues and organs of the body. This is done by convection over the long distances and by diffusion at the cellular level. The most important advantage convective transport has to offer is speed of transport. Oxygen, glucose, amino-acids, fatty acids, water, vitamins, drugs are carried along blood vessels, in a stream of fluid that is pumped through them by the heart. Oxygen is carried by the red cells of the blood, in the form of oxyhemoglobin, a stable compound formed of oxygen and hemoglobin, the characteristic pigment that gives red cells their colour.
 
Rapid removal of metabolic waste (carbon dioxide, urea, creatinine). The circulatory system collects th…
 

Anatomy of the Heart

Friday 3rd June 2005 : The heart is the muscular pump that is located between your lungs, slightly to the left of your breastbone. It is slightly larger than a human fist, with a weight of between 200 to 425 grams. Everyone's heart has to beat approximately 100,000 times each and every day.
 
Your heart comprises of four chambers, the upper chambers are referred to as the left and right atria, collectively called the atrium, whilst the lower chambers are called the right and left ventricle. A wall of muscle known as the septum separates the four chambers.
 
The largest of the chambers is the left ventricle, as they have to force the blood through the aortic valve into the body. The right side of the heart is small because it only has to transmit blood a short distance to the lungs.
 
The heart itself is merely a pump which contracts and relaxes, in the cardiac cycle . The coronary arteries feed the oxygen, and the nutrients to the heart muscles, which need it to function effectively. The two …
 

Veins Arteries and Capillaries

Tuesday 31st May 2005: Except for capillaries (comprising a single layer of endothelia
 
The cardiovascular system is composed of the heart and of blood vessels. The heart consists of two ventricles – right and left – that pump the blood out of the heart through arteries, and two atria, functioning as reservoirs for the ventricles, where the blood is brought back to the heart, by veins, from the body (deoxygenated) or lungs (oxygenated). Blood passes from the atria to the ventricles through a one-way valve.
 
Blood circulation has two “branches” that have a simultaneous and continuous blood flow. The right ventricle pumps blood (deoxygenated, previously gathered from the body into the right atrium) to the lungs through the pulmonary artery, where it is oxygenated; the oxygenated blood is then carried back to the heart by the pulmonary veins, into the left atrium (this is the pulmonary circulation ). At the same time, the left ventricle, …
 

The Purpose of Circulation

Tuesday 31st May 2005: Substance exchange with the environment and transportation of substances within the living body are necessary conditions for the existence of life.
 
The basic method of substance transport in living organisms is diffusion; diffusion is the intermingling of the molecules of one body/fluid with the molecules of another body/fluid they come into contact with.
 
With primitive and smaller organisms, diffusion is sufficient to distribute oxygen, water, nutrients, throughout the entire body and to maintain a constant substance exchange with the environment. With the evolution of living matter, however, the necessity of superior means of transportation arose. So, the heart and the blood vessels, forming a convective system, have developed, in order to provide fast transport of substances and heat around the body.
 
For all protozoans, that are unicellular organisms, the only method of substance transport is diffusion; the processes of di…
 

Valve positions in the cardiac cycle

Saturday 28th May 2005 : Describe the sequence of valve positions in the four phases of the cardiac cycle and the corresponding changes in volume and pressure in each chamber Introduction [quote]The heart provides the vital function of facilitating convective transport of nutrients and metabolites through the body.:V F Murphy[/quote]The heart provides the vital function of facilitating convective transport of nutrients and metabolites through the body. An understanding of the heart is essential for the structure function relationships of both closely associated vessels and those more distal. The understanding of the nature of pulsatile flow, for example, may be an important consideration in the understanding of trigger mechanisms for atherosclerosis. Anatomical Aspects The heart consists essentially of two conjoined pumps, each with two chambers. The two pumps provide for two separate circulatory systems: the pulmonary circulation, and the systemic circulation.
 
Referring to figure 2, bel…
 

The Circulatory System

Friday 20th May 2005: The circulatory system, or the cardiovascular system is comprised of the heart, lungs and the blood vessels. The arteries are the blood vessels that carry the blood away from the heart, and the veins return the blood to the heart. The circulatory system is composed of three distinct types of classification. The pulmonary circulatory system transports the blood between the heart and the lungs. Coronary circulation controls the movement of blood within the heart chambers, to the heart tissues. Systemic circulation is the movement of blood between the heart and the body.
 
The function of the systemic circulatory system is to transport nutrients, oxygen and water to all parts of the body. In reverse it transports away the carbon dioxide that the body produces. The blood cells are comprised of red blood cells, platelets, lymphocytes, and phagocyte cells; the white cells are collectively comprised of the lymphocytes, and phagocyte cells.
 
Each type of blood cell has a separate a…
 

Cardiac enlargement (Cardiomyopathy)

Tuesday 17th May 2005 : Cardiac enlargement is one of the heart diseases caused due to an increase in the size of the heart. Increase can be in terms of thickness of the heart muscle, which is known as Hypertrophy, or it can be in terms of the size of the inside cavity of a chamber of the heart, which in medical terminology known as Dilation . Hypertrophy occurs in only one1 chamber of heart whereas Dilation occurs in 1, 2 and 3one, two, or three chambers. Both the diseases are matter of serious concern.
 
Cardiac hypertrophy:
 
Hypertrophy occurs due to increased stress on the heart. It generally takes place in ventricles. The most common causes of heart thickening is increased blood pressure in either the lungs or the body. The extra work of pumping blood against the increased pressure causes the ventricle to thicken.
 
Hypertrophy are can be divided intoof two types:
 
1) Left ventricular hypertrophy (LVH)
 
2) Right ventricular hypertrophy (RVH)
 
…
 

Science Spotlight

Stress Mechanism in Coronary Heart Disease

Stem Cells can Repair Damaged Heart

Hypertension

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