Chapter 42 (4)

Vertebrate blood is connective tissue consisting of cells suspended in a lique matrix called __. Dissolved in the ___ are ions and proteins that, togethe with the bllood cells, function in osmotic regulation, transport and defense. Separating the components of blood using a centriuge reveals that cell elements occupy about 45% of the volume of blood.

Among the many solutes in __ are inorganic salts int eh form of dissolved ions, sometimes referred to as __. Although plasma is about 90% water, the dissolved salts are an essential component of the blood. Some of these ions buffer hte blood, which in hhumans normally has a pH of __.Salts are also important in maintaining the osmotic balance of the blood. In addition, the concentration of ions in plasma directly affects the composition of the interstitial fluid, were many of tehse ions ahve a vital role in muscle and nerve activity. To serve all of these functions, __ must be kept within narrow concentration ranges.

__ proteins act as uffers agains pH changes, help maintain the osmotic balance between blood and interstitoal fluid and contribute to the blood's __ (thickness). Particular plasma proteins have additional functions. The __, or antibodies, help combat viruses and other foreign agents that invade the body. Others are escorts for lipis which are insoluble in water and can travel in blood only when bound to proeteins. A third group of plasma proteins are clotting factors that help plug leaks when blood vessels are injured. (The term __ refers to blood plasma from which these clotting factors have been removed.)

__ also contains a wide variety of other substances in transit from one part of hte body to another, including nurients, metabolic wasts, respiraory gases, and hormones. __ has a much higher protein concentration than interstitial fluid, although the two fluids are similar.

Suspended in blood plasma are two classes of cells: __, which transport O2 and __, which functinn in defense. Blood also contains __, fragments of cells that are involved int eh clotting process.

RBCs, or __, are the most numerous. Their main function is O2 transport, and their structure is closely related to this function. Human __ are small disks that are __- thinner int he center than at the endes. This shape increases surface area, enhancing the rate of diffusion f O2 across their plasma membranes. Mature mammalian __ lack nuclei. This unuausla characteristic leaves more space in tehse tiny cells for __, the iron-containing protein that transports O2. __ also lack mitochondria and generate their ATP exclusively by anaerobic metabolism. Oxygen transport would be less efficient if __ were aerobic and consimed some of the O2 they carry.

Despite its small size, an __ contains about 250 mil molecuels of hemoglobin. BEcause each molecule of hemoglobnin bnds up to four molecuels of O2, one __ can transport about a bil O2 molecules. as __ pass through the capillary beds of lungs, gills, or other respiratory organs O2 diffuses into teh __ and binds to hemoglobin. Int he systemic capillaries, O2 dissociates from hemoglobin adn diffuses into body cells.

The blood contains five major types of WBCs, or __. Their functin is t fight infections. SOme are __, engulifing and digesting microorganisms, as well as debris fromt eh bod's own dead cells. Other __, called __,d evelop into specialized B and T cells that mount immune responses against foreing substances. unlike __, __ are also found outside the circulatory ststem, patrolling both interstitial fluid and the lymphatic system.

__ are pinched off cytoplasmic fragments of specialized bone marrow cells. They are about 2-3 micrometer in diameter and have no nuclei. __ serve both structural and moleculear functions in blood clotting.

A break in a blood vessel wall exposes proteins that attract __ and initiate __, tehg conersion of liquid components of blood to a solid clot. THe __, or sealant, circulates in an inactive form called __. Clotting invloves the conversion of __ to its cctive form __, which aggregatyes into threads that form the framework of teh clot. The formation of __ is the las tep in a series of reactions triggered by the release of clotting factors from __. A genetic mutation that affects any step of the clotting process causes __.

Anticlotting factors in the blood normally prevent spontaneous clotting in the absence of injury. Sometimes, however, clots form within a blood vessel, blocking the flow of blood. Such a clot is called a __.

Erythrocytes, leukkocytes, and platelets all develop from a common source: multipotent __ that are dedicated to replenishing the body's blood cell populations. __ that bproduce blood cells are located in the __ of bones, particularly the ribs, vertebraee, sternum and pelvis. Multipotent __ are so named because they have the ability to form multiple types of cells-in this case, the __ and __ cell lineages. When any __ divides, one daughter cell remains a stem cell while the other takes on a specialized function.

Throughout a person's life, __, __ and __ formed from stem cell divisions replace the worn-out cellular elements of blood. __ usually circulate for onyl three to four months before being replaced; the old cells are consumeed by phagocytic cells in the liver and spleen. The production of new erythrocytes involves recycling of materials, like iron scavenged from onld erythrocytes in new hemoglobin molecules.

A negative- feedback mechanism, sensitive to the amt of O2 reaching the body's tissues via the blood, controls erythrocyte production. If the tissues do not receive enough O2, the kidneys synthesize and secrete a hormone called __ that stimulates erythrocyte production.

If the blood is delivering more O2 than the tissues can use, the level of __ falls and erythrocyte production slows.

The tendency tyo develop particular __ is inherited but is also strongly influenced by lifestile.

__, the hardening of teh arteries by accumulation of fatty deposits; healthy arteries have a smooth inner lining that reduces resistance to blood flow. Damage or infection can roughen the lining and lead to inflammation. __ are attracted to the damaged lining and begin to take up lipids, including cholesterol. As the plaque grows, the walls of the artery become thick and stiff, and the obstruction of the artery increases.

__ someitmes produces warning sighs. Partial blockage of the cornoary arteries, which supply oxygen-rich bloood to the heart muscle, may cause occasional chest pain, a condition called _. The pain is most likely to be felt when the heart is laboring hard during physical or emotional stress, and it signals that part of the heart is not receiving enough O2. However, many people with __ are completely unawar of their condition until catastrophe strikes.

If unrecognized and untreated, the result of atherosclerosis is often a __ or a __.
- A __, also called __, is teh damage or death of cardiac muslce tissue resulting from blocakge of one or more coronary arteries. Because the coronary arteries are small in diameter, they are especially vulnerable to obstruction. Such blockage can destroy cardiac muscle quickly because the constanly beating heart muscle cannot survive long without O2. If the heart stops beating, the victim may nevertheless survive is the heartbeat is resotred by __ or some other emergency procedure within a few minutes of the attack.

A __ is the death of nervous tissue in the brain due to a lack of O2. Strokes usually result from rupture or blockage of arteries in the head. The effects of a stroke and the individual's chance of survival depend on the extent and location of the damaged brain tissue.

Heart attacks and strokes frequently result from a__ that clogs an artery. A key step in __ formation is the rupture of plaques by an inflammatory response. The __ may arise in a coronary artery or an artery in the brain, or it may develop elsewhere in the circulatory system and reach the ehart or brain via the bloodstream.

One major contributor to atherosclerosis is __, which travels in the plasma int he form of particles consisting of thousands of cholesterol molecuels and other lipids bound to a protein.

One type of particle- __, often called "bad cholesterol"- is associated with teh deposition of cholesterol in arterial plaques. Another type- __, or "good cholesterol", appears to reduce the deposition of cholesterol. Exercise decreases the __ ratio. Smoking and consumption of certain processed veggie oils called __ have the opposite effect. Many individuals at high risk for cardiovascular disease are treated with drugs called __, which lower __ levels and thereby reduce the frequency of heart attacks.

The recent recognition that inflammation has a central role in aterosclerosis and __ formation is changing the diagnosis and treatment of cardiovascular disease.
- __, which blocks the inflammatory response, has been found to help prevent the recurrence of heart attacks and stroke. Researachers have also focused attention on __, which is produced by the liver and found in the blood during episodes of acute inflammation.

_- contributes to heart attack and stroke as well as other health problems. According to one hypothesis, chronic high blood pressure danages the __ that lines the arteries, promting plaque formation. The usual definition of __ in adults is a systolic pressure above 140 mm Hg or a __ pressure above 90 mm Hg. Fortunately, __ is simple to diagnose and can usually be controlled by dietary changes, exercise, meds, or a combo of these.