BLOOD VESSEL PATHWAYS


vessels

BLOOD VESSELS

BLOOD VESSELS

BLOOD VESSELS
There are so many blood vessels in your body (60,000 miles if they were all lined up) that few cells are more than .13 mm away from one. Below are blood vessels in a cat.

blood vesselsblood vessels

The following arteries service abdominal organs in the cat.

blood vessels

There are three major types of blood vessels in the body. Arteries carry blood away from the heart and, (with the exception of those which travel to the lungs), carry oxygenated blood. Their walls are thicker and the smooth muscle which many contain allow them to direct blood flow where it is needed and control blood pressure. The tissues of the body possess microscopic vessels known as capillaries. Oxygen and nutrients leave the blood for the tissues and carbon dioxide and wastes leave the tissues for the blood here.The veins have thinner walls, carry blood towards the heart and, (with the exception of those which travel to the lungs), carry deoxygenated blood.

vessels

vessels

Veins often lie next to arteries and are joined to them by connective tissue. By the time the blood arrives here, its pressure has dropped greatly and thus the walls of veins do not need to be as strong. Some veins have valves to prevent gravity from pulling blood in the direction opposite the heart. These valves in veins can be pumped by the contraction of skeletal muscle in the legs and the movement of inspiration (blood in the abdomen is compressed and forced into thorax).

RISK FACTORS FOR HEART DISEASE
a) Nicotine constricts small blood vessels which raises blood pressure.
b) Weight gain causes the development of more capillaries through which your heart must pump blood. There are 180 miles of blood vessels in every pound of adipose. The greater the number of blood vessels, the higher the necessary blood pressure to pump blood through them.

Below is an image of blood vessels developing atherosclerotic plaques..

blood vessels

c) Cholesterol & Fats
Cholesterol and triglycerides are nonpolar molecules that will not dissolve in blood on their own; they must be transported by water-soluble lipoproteins (made in the liver and the intestines). These lipoproteins are divided into groups depending on their density (the more protein, the higher the density).
--Low density lipoproteins (LDLs) deliver cholesterol to all body parts, bind to receptors (located on most body cells). If there aren't enough receptors, cholesterol can't be removed from the blood.
--High density lipoproteins (HDLs) take excess cholesterol to the liver to be metabolized. The higher the concentration of HDLs, the lower the likelihood of heart disease.
--Very low density lipoproteins (VLDLs) carry triglycerides synthesized in the liver to be deposited in adipose. A high fat diet increases VLDL production; VLDLs may later be converted to LDLs.
Most of the cholesterol in the body is synthesized by the liver and cholesterol may be synthesized from saturated fats.
Atherosclerosis is a complex chain of events leading to the development of lipid plaques on blood vessel walls which raise blood pressure, increase the formation of blood clots, and may block blood flow to an organ.
1) It initiated by damage to the endothelial lining (many phenomena may cause this including high lipid content, cytomegalovirus, prolonged high blood pressure, CO from cigarettes, homocysteine, hereditary factors).
2) This damage causes proliferation of smooth muscle and leukocytes called monocytes invade the area. Both the smooth muscle and monocytes (and even endothelial cells lining the blood vessel) begin to absorb lipids, primarily cholesterol. This step occurs to some degree in everyone in childhood, often before one year of age.
3) As a lipid plaque grows, it becomes a fibrous plaque: the lesion becomes full of calcium, fibrous connective tissue, and debris. The smooth muscle cells and monocytes full of lipids may die and release toxic compounds which damage other cells; it obstructs the vessel. As the endothelial cells are stretched, some may break off and be swept away by circulation; with collagen exposed, blood clots form. Middle aged men who smoke, have high blood pressure, and high cholesterol levels are 4x as likely to have a heart attack.

SHOCK is an acute circulatory crisis marked by low blood pressure and inadequate peripheral blood flow. As blood pressure decreases, skin becomes clammy (pale & cool due to decreased flow). Disorientation occurs due to inadequate brain flow and acidosis due to lactic acid generation. After about 35% blood is lost, heart is damaged and causes of shock become worse; it can result in death.