Structure And Function Of Blood Pdf

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Blood , fluid that transports oxygen and nutrients to the cells and carries away carbon dioxide and other waste products. Technically, blood is a transport liquid pumped by the heart or an equivalent structure to all parts of the body, after which it is returned to the heart to repeat the process.

Blood is a combination of plasma and cells that circulate through the entire body. It is a specialized bodily fluid that supplies essential substances around the body, such as sugars, oxygen, and hormones. Hematologists work to identify and prevent blood and bone marrow diseases, as well as studying and treating the immune system, blood clotting, and the veins and arteries. In the United States U. This constitutes less than one percent of total deaths from disease.

How does blood work, and what problems occur?

Discuss the structure and function of erythrocytes red blood cells and hemoglobin. The erythrocyte , commonly known as a red blood cell or RBC , is by far the most common formed element: A single drop of blood contains millions of erythrocytes and only thousands of leukocytes Figure Specifically, males have about 5. In fact, erythrocytes are estimated to make up about 25 percent of the total cells in the body. Although leukocytes typically leave the blood vessels to perform their defensive functions, movement of erythrocytes from the blood vessels is abnormal.

As an erythrocyte matures in the red bone marrow, it extrudes its nucleus and most of its other organelles. During the first day or two that it is in the circulation, an immature erythrocyte, known as a reticulocyte , will still typically contain remnants of organelles. Reticulocytes should comprise approximately 1—2 percent of the erythrocyte count and provide a rough estimate of the rate of RBC production.

Abnormally low or high levels of reticulocytes indicates deviations in the production of these erythrocytes. These organelle remnants are quickly shed, so circulating erythrocytes have few internal cellular structural components.

Lacking mitochondria, erythrocytes rely on anaerobic respiration. This means that they do not utilize any of the oxygen they are transporting, so they can deliver it all to the tissues. They also lack endoplasmic reticula and do not synthesize proteins. Erythrocytes do, however, contain some structural proteins that help the blood cells maintain their unique structure and enable them to change their shape to squeeze through capillaries.

This includes the protein spectrin, a cytoskeletal protein element. Erythrocytes are biconcave disks; that is, they are plump at their periphery and very thin in the center Figure Since they lack most organelles, there is more interior space for the presence of the hemoglobin molecules that, as you will see shortly, transport gases.

The biconcave shape also provides a greater surface area across which gas exchange can occur, relative to its volume; a sphere of a similar diameter would have a lower surface area-to-volume ratio. In the capillaries, the oxygen carried by the erythrocytes can diffuse into the plasma and then through the capillary walls to reach the cells, whereas some of the carbon dioxide produced by the cells as a waste product diffuses into the capillaries to be picked up by the erythrocytes.

Capillary beds are extremely narrow, slowing the passage of the erythrocytes and providing an extended opportunity for gas exchange to occur. However, the space within capillaries can be so small that, despite their own small size, erythrocytes sometimes fold in on themselves to pass through. Fortunately, their structural proteins like spectrin are flexible, allowing them to fold and then spring back again when they enter a wider vessel.

Hemoglobin is a large molecule made up of proteins and iron. It consists of four folded chains of the protein globin , designated alpha 1 and 2, and beta 1 and 2 Figure Each iron ion in the heme can bind to one oxygen molecule, therefore, each hemoglobin molecule can transport four oxygen molecules.

An individual erythrocyte may contain about million hemoglobin molecules, and can bind to and transport up to 1. In the lungs, hemoglobin picks up oxygen, which binds to the iron ions, forming oxyhemoglobin. The bright red, oxygenated hemoglobin travels to the capillaries of the body tissues, where it releases some of the oxygen molecules, becoming darker red deoxyhemoglobin. Oxygen release depends on the need for oxygen in the surrounding tissues, so hemoglobin rarely leaves all of its oxygen behind.

At the time time, carbon dioxide CO 2 enters the bloodstream. About 76 percent of the CO 2 dissolves in the plasma, some of it remaining as dissolved CO 2 , and the remainder forming bicarbonate.

About 23—24 percent of it binds to the amino acids in hemoglobin, forming a molecule known as carbaminohemoglobin. From the capillaries, the hemoglobin carries CO 2 back to the lungs. An overproduction of RBCs produces a condition called polycythemia. The primary drawback with polycythemia is not a failure to deliver enough oxygen to the tissues, but rather the increased viscosity of the blood, which makes it more difficult for the heart to circulate the blood.

Ineffective hematopoiesis results in insufficient numbers of RBCs and results in one of several forms of anemia. In patients with insufficient hemoglobin, the tissues may not receive sufficient oxygen, resulting in another form of anemia. The device works by sending two different wavelengths of light one red, the other infrared through the finger and measuring the light with a photodetector as it exits. Hemoglobin absorbs light differentially depending upon its saturation with oxygen. The machine calibrates the amount of light received by the photodetector against the amount absorbed by the partially oxygenated hemoglobin and presents the data as percent saturation.

Normal pulse oximeter readings range from 95— percent. Lower percentages reflect hypoxemia , or low blood oxygen. The term hypoxia is more generic and simply refers to low oxygen levels. Oxygen levels are also directly monitored from free oxygen in the plasma typically following an arterial stick. When this method is applied, the amount of oxygen present is expressed in terms of partial pressure of oxygen or simply pO 2 and is typically recorded in units of millimeters of mercury, mm Hg.

In response to hypoxemia, less oxygen is diffused into the kidney, resulting in hypoxia of the kidney cells where oxygen concentration is actually monitored. Interstitial fibroblasts within the kidney secrete EPO, leading to increased erythrocyte production and eventually restoring oxygen levels. In a negative-feedback loop, as oxygen saturation rises, EPO secretion falls, and vice versa, thereby maintaining homeostasis.

Populations dwelling at high elevations, with inherently lower levels of oxygen in the atmosphere, naturally maintain a hematocrit higher than people living at sea level. Consequently, people traveling to high elevations may experience symptoms of hypoxemia, such as fatigue, headache, and shortness of breath, for a few days after their arrival.

In response to the hypoxemia, the kidneys secrete EPO to step up the production of erythrocytes until homeostasis is achieved once again. To avoid the symptoms of hypoxemia, or altitude sickness, mountain climbers typically rest for several days to a week or more at a series of camps situated at increasing elevations to allow EPO levels and, consequently, erythrocyte counts to rise. When climbing the tallest peaks, such as Mt. Everest and K2 in the Himalayas, many mountain climbers rely upon bottled oxygen as they near the summit.

Production of erythrocytes in the marrow occurs at the staggering rate of more than 2 million cells per second. For this production to occur, a number of raw materials must be present in adequate amounts. These include the same nutrients that are essential to the production and maintenance of any cell, such as glucose, lipids, and amino acids.

However, erythrocyte production also requires several trace elements:. Erythrocytes live up to days in the circulation, after which the worn-out cells are removed by a type of myeloid phagocytic cell called a macrophage , located primarily within the bone marrow, liver, and spleen. The breakdown pigments formed from the destruction of hemoglobin can be seen in a variety of situations.

At the site of an injury, biliverdin from damaged RBCs produces some of the dramatic colors associated with bruising. With a failing liver, bilirubin cannot be removed effectively from circulation and causes the body to assume a yellowish tinge associated with jaundice. Stercobilins within the feces produce the typical brown color associated with this waste.

And the yellow of urine is associated with the urobilins. The erythrocyte lifecycle is summarized in Figure When the number of RBCs or hemoglobin is deficient, the general condition is called anemia. There are more than types of anemia and more than 3. Anemia can be broken down into three major groups: those caused by blood loss, those caused by faulty or decreased RBC production, and those caused by excessive destruction of RBCs.

Clinicians often use two groupings in diagnosis: The kinetic approach focuses on evaluating the production, destruction, and removal of RBCs, whereas the morphological approach examines the RBCs themselves, paying particular emphasis to their size.

A common test is the mean corpuscle volume MCV , which measures size. Normal-sized cells are referred to as normocytic, smaller-than-normal cells are referred to as microcytic, and larger-than-normal cells are referred to as macrocytic. Reticulocyte counts are also important and may reveal inadequate production of RBCs.

The effects of the various anemias are widespread, because reduced numbers of RBCs or hemoglobin will result in lower levels of oxygen being delivered to body tissues. Since oxygen is required for tissue functioning, anemia produces fatigue, lethargy, and an increased risk for infection.

An oxygen deficit in the brain impairs the ability to think clearly, and may prompt headaches and irritability. Lack of oxygen leaves the patient short of breath, even as the heart and lungs work harder in response to the deficit. Blood loss anemias are fairly straightforward. In addition to bleeding from wounds or other lesions, these forms of anemia may be due to ulcers, hemorrhoids, inflammation of the stomach gastritis , and some cancers of the gastrointestinal tract.

The excessive use of aspirin or other nonsteroidal anti-inflammatory drugs such as ibuprofen can trigger ulceration and gastritis. Excessive menstruation and loss of blood during childbirth are also potential causes.

Anemias caused by faulty or decreased RBC production include sickle cell anemia, iron deficiency anemia, vitamin deficiency anemia, and diseases of the bone marrow and stem cells. It can occur transiently in a person who is dehydrated; when water intake is inadequate or water losses are excessive, the plasma volume falls.

As a result, the hematocrit rises. For reasons mentioned earlier, a mild form of polycythemia is chronic but normal in people living at high altitudes.

Some elite athletes train at high elevations specifically to induce this phenomenon. Polycythemia vera can dangerously elevate the viscosity of blood, raising blood pressure and making it more difficult for the heart to pump blood throughout the body. It is a relatively rare disease that occurs more often in men than women, and is more likely to be present in elderly patients those over 60 years of age.

The most abundant formed elements in blood, erythrocytes are red, biconcave disks packed with an oxygen-carrying compound called hemoglobin. The hemoglobin molecule contains four globin proteins bound to a pigment molecule called heme, which contains an ion of iron.

In the bloodstream, iron picks up oxygen in the lungs and drops it off in the tissues; the amino acids in hemoglobin then transport carbon dioxide from the tissues back to the lungs. Erythrocytes live only days on average, and thus must be continually replaced.

Worn-out erythrocytes are phagocytized by macrophages and their hemoglobin is broken down. The breakdown products are recycled or removed as wastes: Globin is broken down into amino acids for synthesis of new proteins; iron is stored in the liver or spleen or used by the bone marrow for production of new erythrocytes; and the remnants of heme are converted into bilirubin, or other waste products that are taken up by the liver and excreted in the bile or removed by the kidneys.

A young woman has been experiencing unusually heavy menstrual bleeding for several years. She follows a strict vegan diet no animal foods. She is at risk for what disorder, and why? A patient has thalassemia, a genetic disorder characterized by abnormal synthesis of globin proteins and excessive destruction of erythrocytes.

This patient is jaundiced and is found to have an excessive level of bilirubin in his blood. Explain the connection.

Red Blood Cells (Erythrocytes)

Find GPs in Australia. The formed elements are so named because they are enclosed in a plasma membrane and have a definite structure and shape. All formed elements are cells except for the platelets, which are tiny fragments of bone marrow cells. Leukocytes are further classified into two subcategories called granulocytes which consist of neutrophils, eosinophils and basophils; and agranulocytes which consist of lymphocytes and monocytes. The formed elements can be separated from plasma by centrifuge, where a blood sample is spun for a few minutes in a tube to separate its components according to their densities. This volume is known as the haematocrit.

A red blood cell has what is known as a biconcave shape. Both sides of the cell's surface curve inward like the interior of a sphere. Blood type is determined by the presence or absence of certain identifiers on the surface of red blood cells. Red blood cells have a unique structure. Their flexible disc shape helps to increase the surface area-to-volume ratio of these extremely small cells. This enables oxygen and carbon dioxide to diffuse across the red blood cell's plasma membrane more readily. Red blood cells contain enormous amounts of a protein called hemoglobin.

Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. In vertebrates , it is composed of blood cells suspended in blood plasma. Albumin is the main protein in plasma, and it functions to regulate the colloidal osmotic pressure of blood. The blood cells are mainly red blood cells also called RBCs or erythrocytes , white blood cells also called WBCs or leukocytes and platelets also called thrombocytes. The most abundant cells in vertebrate blood are red blood cells.


Describe the structure and function of blood in the body. Blood is important for regulation of the body's pH, temperature, osmotic pressure, the circulation of.


Blood Basics

Blood is a specialized body fluid. It has four main components: plasma, red blood cells, white blood cells, and platelets. Blood has many different functions, including:. The blood that runs through the veins, arteries, and capillaries is known as whole blood, a mixture of about 55 percent plasma and 45 percent blood cells.

Blood is made of of several components, including red blood cells, white blood cells, platelets, and the plasma, which contains coagulation factors and serum. Blood helps maintain homeostasis by stabilizing pH, temperature, osmotic pressure, and by eliminating excess heat. Blood supports growth by distributing nutrients and hormones, and by removing waste. These cells deliver oxygen to the cells and remove carbon dioxide. Blood plays a protective role by transporting clotting factors and platelets to prevent blood loss after injury.

The liquid component of the blood in which the following blood cells are suspended:. Red blood cells erythrocytes. These carry oxygen from the lungs to the rest of the body. White blood cells leukocytes. These help fight infections and aid in the immune process.

ГЛАВА 82 Когда мысль о последствиях звонка Стратмора в службу безопасности дошла до сознания Грега Хейла, его окатила парализующая волна паники. Агенты сейчас будут. Сьюзан попробовала выскользнуть из его рук, Хейл очнулся и притянул ее к себе за талию. - Отпусти меня! - крикнула она, и ее голос эхом разнесся под куполом шифровалки.

Все системы должны заработать через пять минут. Грег Хейл убил одного из младших сотрудников лаборатории систем безопасности и взял в заложники моего старшего криптографа. Если нужно, используйте против всех нас слезоточивый газ.

 Zumo de arandano, - с удивлением услышал он собственный голос.  - Клюквенный сок. Бармен смотрел на него озадаченно. - Solo? - Клюквенный сок популярен в Испании, но пить его в чистом виде - неслыханное .

Вся сцена напоминала некий извращенный вариант представления, посвященного празднику Хэллоуин. Хотя Стратмор и сожалел о смерти своего молодого сотрудника, он был уверен, что ее можно отнести к числу оправданных потерь. Фил Чатрукьян не оставил ему выбора. Когда запыхавшийся сотрудник лаборатории безопасности завопил о вирусе, Стратмор, столкнувшийся с ним на лестнице служебного помещения, попытался наставить его на путь истинный. Но Чатрукьян отказывался прислушаться к голосу разума.

В нескольких метрах от нее ярко светился экран Хейла. - Со мной… все в порядке, - выдавила. Сердце ее готово было выскочить из груди.

 Самое разрушительное последствие - полное уничтожение всего банка данных, - продолжал Джабба, - но этот червь посложнее. Он стирает только те файлы, которые отвечают определенным параметрам. - Вы хотите сказать, что он не нападет на весь банк данных? - с надеждой спросил Бринкерхофф.  - Это ведь хорошо, правда.

3 Response
  1. Genara M.

    (a) The structure of red blood cells, white blood cells, and platelets. (6) Blood cells and list the proteins of blood plasma and state their functions;. • name the​.

  2. Simone H.

    Blood cells. Structure and function of red and white blood cells. Barbara J Bain. Abstract. Red cells have a major function in transport of oxygen and minor func-.

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