A&P2 Chapter 18 BLOOD - Cardiovascular system

Hemocytoblasts produce two different lines for blood cell development:

(1) The myeloid line forms erythrocytes, all leukocytes except lymphocytes (this would include granulocytes and monocytes), and megakaryocytes (cells that produce platelets). (2) The lymphoid line forms only lymphocytes.

Erythropoiesis

Erythrocytes make up more than 99% of formed elements, with a concentration between 4.2 and 6.2 million per cubic millimeter. The process of erythrocyte production is called erythropoiesis

Blood vessels form a circuit away from the heart and back to the heart that includes...

arteries, veins, and capillaries

Blood is formed of what formed elements?

Erythrocytes (red blood cells), leukocytes (white blood cells), platelets..... and plasma (not a formed element).

Why is Blood is considered a colloid?

because it contains proteins in the plasma.

Collectively, erythrocytes, leukocytes, and platelets are called the

formed elements and make up approximately 45% of whole blood.

How many pulmonary veins are there?

four

Each hemoglobin molecule consists of four protein molecules called

globins.

Urobilinogen can either

1) continue through the large intestine and eventually be converted by the intestinal bacteria to stercobilin, a brown pigment that is expelled from the body as a component of feces; or (2) be absorbed back into the blood. In this latter case, it is converted to urobilin, a yellow pigment that is excreted by the kidneys.

What does the blood do during transportation?

1.) Blood transports formed elements and dissolved molecules and ions throughout the body. 2.) It is transported through blood vessels and transports oxygen and carbon dioxide to the lungs for gas exchange. 3.) nutrients absorbed from the GI tract 4.) hormones released by endocrine glands 5.) heat and waste products in the systemic cells. It is the DELIVERY system of the body.

Common Molecules Found in Blood Plasma VLDL/LDL

10-100 mg/dL Functions: Transport lipids from the liver

Common Molecules Found in Blood Plasma Cholesterol

100-200 mg/dL Function: Plasma membrane component; synthesis of steroid hormones; bile salts

Common Molecules Found in Blood Plasma Triglycerides

30-149 mg/dL Functions: 30-149 mg/dL

Common Molecules Found in Blood Plasma HDL

40-80 mg/dL Function: Transports lipids to the liver

Common Molecules Found in Blood Plasma Phospholipids

6-12 mg/dL Functions: Molecules that form plasma membrane bilayer.

Blood smear

A blood test performed on slides that gives information about the number and shape of blood cells. 1. Erythrocytes are the most numerous of the formed elements. 2. Leukocytes are larger and you can see the nucleus. 3. Platelets are the smallest.

The aortic arch gives off branches that supply all of the following areas of the body, except the...

Abdomen. The aortic arch supplies the head, neck and upper limbs.

Left ventricular contraction propels blood through which valve?

Aortic valve. Contraction of the left ventricle propels blood through the aortic semilunar valve.

The types of anemia include the following:

Aplastic anemia is characterized by significantly decreased formation of both erythrocytes and hemoglobin. This condition results from defective red bone marrow, perhaps as a result of poisons, toxins, or radiation exposure. Congenital hemolytic anemia occurs when destruction of erythrocytes is more rapid than normal. It is usually due to a genetic defect, which results in the production of abnormal membrane proteins that make the erythrocyte plasma membrane very fragile. Erythroblastic anemia is characterized by the presence of large numbers of immature, nucleated cells (called erythroblasts and normoblasts) in the circulating blood. An accelerated pace of cell maturation causes immature cells to be present in the blood. These cells cannot function normally and thus anemia results. Hemorrhagic anemia results from heavy blood loss. The hemorrhage may be caused, for example, by chronic ulcers or by heavy or prolonged menstrual flow. Pernicious anemia is a chronic, progressive anemia of adults caused by failure of the body to absorb vitamin B12. This vitamin is found in fish and meat, so most individuals receive enough B12 in their diets, unless they are vegans or strict vegetarians. (Thus, it is recommended that all vegetarians take a B12 vitamin supplement.) A defect in the production of intrinsic factor, a glycoprotein secreted by stomach lining cells to protect B12 in the stomach and enhance B12 absorption in the small intestine, leads to pernicious anemia. Individuals who have pernicious anemia due to defective intrinsic factor production must receive B12 intramuscular or subcutaneous injections, since they are unable to absorb oral B12 supplements. Sickle-cell disease is an autosomal recessive anemia that occurs when a person inherits two copies of the sickle-cell gene. Erythrocytes become sickle-shaped at lower blood oxygen concentrations, making them unable to flow efficiently through the blood vessels to body tissues and more prone to destruction (a process called hemolysis).

________ transports blood away from the heart

arteries

Blood regulation of body pH.

Blood absorbs acid and base from body cells, helps maintain pH of cells. Blood contains chemical buffers (proteins, bicarbonate) that bind and release hydrogen ions (H+) to maintain blood pH until the excess is eliminated from the body.

Blood color

Blood color depends on if it is oxygen rich (bright red) or oxygen poor (dark bluish red).

Blood protection functions

Blood contains leukocytes, plasma protein and various molecules that help protect the body against potential harmful substances. These substances are apart of the immune system. Blood platelets and plasma proteins help protect against blood loss.

Blood regulation of body temperature

Blood helps regulate body temperature. Blood absorbs heat from body cells, especially skeletal muscle, as it passes through blood vessels of body tissues. Heat is then released from the blood at the body surface as the blood is transported through blood vessels of the skin.

Blood viscosity

Blood is more viscous than water (about 4-5x thicker) because of the substances in it mainly erythrocytes which can make it thicker or thinner.

What is blood regulation?

Blood participates in regulation of body temperature, body pH and fluid balance.

Blood pH

Blood plasma is slightly alkaline. pH between 7.35-7.45. Plasma protein has a 3D shape that depends on H+ concentration. If pH is altered from normal range, plasma proteins become denatured and unable to carry out their functions.

Common Molecules Found in Blood Plasma Lactate

By-product of glycolysis

Blood is a specliazed fluid that is transported through the...

Cardiovascular system

Name six characteristics that describe blood.

Color, volume, viscosity, plasma concentration, temperature and blood pH.

The Role of EPO in Erythropoiesis

Erythropoiesis is controlled by the hormone erythropoietin (EPO). The kidneys are the primary producers of EPO, although the liver also secretes a small amount of EPO. The initial stimulus for EPO release is a decrease in blood oxygen levels. This decrease may be caused by the continuous removal of aged erythrocytes, blood loss, or exposure to high altitudes (where atmospheric oxygen levels are lower). Chemoreceptors within the kidneys detect low blood oxygen levels as the blood is transported through blood vessels within the kidneys. As a result, certain cells in the kidneys release the hormone EPO into the blood. EPO is transported through the blood and reaches the red bone marrow. There, EPO stimulates myeloid cells in the red bone marrow to increase the rate of erythrocyte production. Additional erythrocytes are released into circulation (a process that takes a few days), so more oxygen can be transported from the lungs and delivered to the cells. Blood oxygen levels increase as a result. Increased blood oxygen levels inhibit release of EPO from kidney cells through negative feedback.

True or false The lower limbs receive blood from branches of the ascending aorta.

False. The lower limbs receive blood from the descending aorta.

True or False The only arteries in the body that carry oxygen-poor blood are the coronary arteries...

False. The pulmonary arteries are the only arteries that carry oxygen-poor blood.

Electrolytes in Arterial Plasma Chloride (Cl−)

Functions Anion bound to sodium; component of gastric acid (HCl); chloride shift Substances and Structures That Regulate Electrolyte Blood Level. Regulated indirectly through sodium.

Electrolytes in Arterial Plasma Phosphate (PO43−)

Functions Binds with calcium and deposited in bone Substances and Structures That Regulate Electrolyte Blood Level. Parathyroid hormone

Electrolytes in Arterial Plasma Hydrogen (H+)

Functions pH balance Substances and Structures That Regulate Electrolyte Blood Level. Buffering systems—chemicals in blood, kidney, respiratory system

Electrolytes in Arterial Plasma Bicarbonate (HCO3−)

Functions pH balance Substances and Structures That Regulate Electrolyte Blood Level. Dependent upon carbon dioxide and H+ blood levels.

Electrolytes in Arterial Plasma Calcium (Ca2+)

Functions Hardens bone; release of neurotransmitter; muscle contraction; blood clotting; second messenger. Substances and Structures That Regulate Electrolyte Blood Level. Parathyroid hormone, calcitriol, calcitonin.

Electrolytes in Arterial Plasma Potassium (K+)

Functions Neuron and muscle function. Substances and Structures That Regulate Electrolyte Blood Level. Aldosterone, ANP

Electrolytes in Arterial Plasma Sodium (Na+)

Functions Neuron and muscle function; fluid balance; cotransporter. Substances and Structures That Regulate Electrolyte Blood Level. Aldosterone, atrial natriuretic peptide (ANP), estrogen, progesterone, glucocorticoids.

Substances That Influence Hemopoiesis

Growth factors Multi-colony-stimulating factor (multi-CSF) Increases the formation of erythrocytes, granulocytes, monocytes, and platelets from myeloid stem cells. Granulocyte-macrophage colony-stimulating factor (GM-CSF) Accelerates the formation of all granulocytes and monocytes from their progenitor cells. Granulocyte colony-stimulating factor (G-CSF). Stimulates the formation of granulocytes from myeloblast cells Macrophage colony-stimulating factor (M-CSF) Stimulates the production of monocytes from monoblasts. Thrombopoietin Stimulates both the production of megakaryocytes in the bone marrow and the subsequent formation of platelets. Hormone (produced primarily by the kidneys) Erythropoietin (EPO) Increases the rate of production and maturation of erythrocyte progenitor and erythroblast cells

Leukocytes (e.g., neutrophils, eosinophils, basophils, monocytes, and lymphocytes) function?

Initiate immune response; defend against potentially harmful substances.

Pulmonary veins enter the...

Left atrium

Leukopoiesis

Leukocytes make up less than 0.01% of formed elements. The production of leukocytes is called leukopoiesis.

What is plasma?

Liquid portion of blood which contains dissolved proteins and dissolved solutes.

How Erythropoietin (EPO) Regulates Erythrocyte Production.

Low blood oxygen levels are detected by kidney chemoreceptors, which triggers the release of erythropoietin (EPO) into the blood. EPO stimulates the red bone marrow to produce more erythrocytes. EPO release is then inhibited when blood oxygen levels rise.

Common Molecules Found in Blood Plasma Lipids

Molecules that generally do not dissolve in water

Common Molecules Found in Blood Plasma Glucose

Normal range: Fasting: 70-100 mg/dL; 2 hours after a meal: <145 mg/dL Functions Fuel molecule for cellular respiration (primary energy source for nervous tissue); tightly regulated by a number of hormones, including insulin and glucagon

Common Molecules Found in Blood Plasma Amino acids

Normal range: Varies, based on specific amino acid being measured Functions Monomers for synthesizing protein; also regulated by some of the same hormones as glucose.

Which is not associated with the left atrioventricular valve?

Papillary muscles 2 cusps Chordae tendineae Pectinate muscles

Platelets function?

Participate in hemostasis

What is the name for the muscular ridges on the inner wall of the right atrium?

Pectinate muscles

Thrombopoiesis

Platelets (or thrombocytes) make up less than 1% of formed elements. The production of platelets is called thrombopoiesis. From the myeloid stem cell, a committed cell called a megakaryoblast is produced. It matures under the influence of thrombopoietin to form a megakaryocyte Megakaryocytes are easily distinguished both by their large size and by their dense, multilobed nucleus. Each megakaryocyte then produces thousands of platelets.

The inferior vena cava empties blood into the...

Right Atrium

Oxygen-poor blood enters which chamber of the heart?

Right atrium

Oxygen leaves the blood and carbon dioxide enters the blood in the...

Systemic capillary beds. Carbon dioxide is produced by cells of the body and is exchanged for oxygen in the systemic capillary beds. Whereas carbon dioxide leaves the blood in the pulmonary capillary beds of the lungs as oxygen enters.

Hematocrit

The percentage of the volume of all formed elements (erythrocytes, leukocytes, and platelets) in the blood. Depends on age and sex. Elevated hematocrit would suggest dehydration or BLOOD DOPING (see picture). Lowered hematocrit would suggest anemia.

Blood temperature

The temperature of blood is about 2 degrees C higher than measured body temperature. Body temp (38C)98.6 = bed temp 100.4 F Therefore, blood warms the area through which it travels.

What do leukocytes (white blood cells) do?

They contribute to defending the body against pathogens.

What do erythrocytes (red blood cells) do?

They function to transport respiratory gasses in the blood.

What do platelets do?

They help clot the blood and help prevent blood loss from damaged vessels.

Blood Doping

To enhance their performance in endurance events, some athletes may try to boost their bodies' ability to deliver oxygen to the muscles by increasing the number of erythrocytes in their blood. One way the number of erythrocytes can be increased naturally is by living and training at high altitude. The body compensates for the decreased oxygen concentration in the atmosphere by increasing the rate of erythrocyte production, thus increasing the number of erythrocytes per unit volume of blood. An illegal procedure used by some athletes is called blood doping. There are two different methods for blood doping. In the first (and older) method, the athlete essentially donates erythrocytes to himself or herself. Prior to competition, the athlete has a unit of blood removed and stored. As the kidneys detect the decreased blood oxygen, the hormone erythropoietin (EPO) is released and the bone marrow responds by increasing production of erythrocytes. This causes the body to increase erythrocyte production to make up for the ones just removed. A few days before the competition, the erythrocytes from the donated unit are transfused back into the athlete's body. The increased number of erythrocytes increases the amount of oxygen transported in the blood and is thought to favorably affect muscle performance, thereby improving athletic performance. The second method of blood doping has occurred with the development of pharmaceutical EPO, which is used to treat anemia. In this method of blood doping, an athlete is injected with pharmaceutical EPO to further increase erythrocyte levels. Potentially deadly dangers are inherent in blood doping. By increasing the number of erythrocytes per measured volume of blood, blood doping also increases the viscosity of the blood. Thus, the heart must work harder to pump this more viscous blood. Eventually, temporary athletic success may be overshadowed by permanent cardiovascular damage that can even lead to death, as has occurred with some athletes. Thus, blood doping has now been banned by athletic competition governing bodies.

What is the name for the muscular ridges on the inner walls of the right and left ventricles?

Trabeculae Carneae

Erythrocytes function?

Transport oxygen and carbon dioxide

The right atrioventricular valve is also called the...

Tricuspid valve

True or false The pulmonary veins contain oxygenated blood.

True

Plasma Component

Water (∼92% of plasma) Functions The solvent in which formed elements are suspended and proteins and solutes are dissolved. PLASMA PROTEINS (∼7% OF PLASMA): All proteins buffer against pH changes. Albumin (∼58% of plasma proteins) -Exerts osmotic force to retain fluid within the blood. -Contributes to blood's viscosity -Responsible for transport of some ions, lipids (e.g., fatty acids), and hormones Globulins (∼37% of plasma proteins) -Alpha-globulins transport lipids and some metal ions (e.g., copper) -Beta-globulins transport iron ions and lipids in blood -Gamma-globulins are antibodies that immobilize pathogens. Fibrinogen (∼4% of plasma proteins) -Participates in blood coagulation (clotting) Regulatory proteins (<1% of plasma proteins) -Consists of enzymes and hormones OTHER SOLUTES (∼1% OF BLOOD PLASMA) Electrolytes (e.g., sodium, potassium, calcium, chloride, iron, bicarbonate, hydrogen). -Help establish, maintain, and change membrane potentials, maintain pH balance, and regulate osmosis. Nutrients (e.g., amino acids, glucose, cholesterol, vitamins, fatty acids). -Energy source; precursor for synthesizing other molecules. Respiratory gases (oxygen: <2% dissolved in plasma, 98% bound to hemoglobin within erythrocytes, and carbon dioxide: ∼7% dissolved in plasma, ∼23% bound to hemoglobin within erythrocytes, ∼70% converted to HCO3−). -Oxygen is needed for aerobic cellular respiration; carbon dioxide is a waste product produced by cells during this process Wastes (breakdown products of metabolism, such as lactate, creatinine, urea, bilirubin, ammonia). -Waste products serve no function in the blood plasma; rather, they merely are being transported to the liver and kidneys, where they can be removed from the blood

Blood regulation of fluid balance.

Water is added to the blood from the GI tract and lost in numerous ways (including urine, sweat and respired air). There is a constant exchange of fluid between blood plasma in the capillaries and interstitial fluid surrouding the cells of the body tissue. Blood contains proteins and ions that exert osmotic pressure to pull fluid back into the capillaries to maintain normal fluid balance.

Centrifuged Blood

Whole blood which is both plasma and formed elements, can be separated into its liquid and cellular components using a centrifuge device that spins the components in a test tube which separates them. Heavier components go to the bottom. Three layers are form from the bottom to the top. -Erythrocytes (red blood cells) at the bottom make up 44% of the test tube. -Buffy coat in the middle of platelets and leukocytes (white blood cells) 1% of sample -Plasma is yellow liquid at the top, makes up 55% of blood.

Bilirubin is then released into the blood and is transported by

albumin to the liver.

Plasma proteins include...

albumin, globulins, fibrinogen and other clotting proteins, as well as regulatory proteins such as enzymes and some hormones.

Fibrinogen makes up about 4% of...

all plasma proteins.

Two of these globins are called

alpha (α) chains, and the other two, which are slightly different, are called beta (β) chains.

Bilirubin is a component of a digestive system secretion called

bile, which is produced by the liver and released into the small intestine

Biliverdin is eventually converted into a yellowish pigment called

bilirubin within the macrophages.

The heme group (minus the Fe2+) released from hemoglobin is converted within macrophages first into a green pigment called

biliverdin.

The smaller alpha-globulins and the larger beta-globulins primarily...

bind and transport certain water-insoluble molecules and hormones, some metals, and ions.

Nonpolar molecules (e.g., cholesterol, triglycerides, and fatty acids) do not readily dissolve in...

blood and require a carrier protein.

Fibrinogen as well as other clotting proteins are responsible for....

blood clot formation.

Carbon dioxide and the globin molecule (not the Fe2+) have a similar weak attachment relationship for the transport of carbon dioxide molecules. Carbon dioxide binds to the globin protein molecule as

blood moves through systemic capillaries and is released as blood moves through the capillaries of the lungs.

_______ (name relating to hair) are microscopic vessels between arteries and veins

capillaries

_______ is where oxygen and nutrients exit the blood and carbon dioxide and cellular wastes enter the blood.

capillaries

The fact that erythrocytes lack a nucleus and organelles enables them to...

carry respiratory gases more efficiently.

Hemoglobin A red-pigmented protein that transports oxygen and carbon dioxide; responsible for

characteristic red color of blood. hemoglobins a red-pigmented protein that transports oxygen and carbon dioxide.

Because albumin is the most abundant type of plasma protein, it exerts the greatest...

colloid osmotic pressure to maintain blood volume and blood pressure. Secondarily, albumins act as transport proteins that carry ions, hormones, and some lipids in the blood.

Osmotic pressure exerted by plasma proteins is called

colloid osmotic pressure.

The maturation and division of hemopoietic stem cells are influenced by...

colony-stimulating factors (CSFs), or colony-forming units (CFUs). These molecules are all growth factors, except for erythropoietin, which is a hormone.

If plasma protein levels decrease, as might occur due to liver disease (resulting in decreased production of plasma proteins) or kidney damage (resulting in increased elimination of plasma proteins), colloid osmotic pressure also....

decreases. This decrease results in fluid loss from the blood and fluid retention in the interstitial space

Conversely, when some oxygen is lost and carbon dioxide is gained during systemic cellular gas exchange, blood is called

deoxygenated (and appears dark red).

Regulatory proteins form a very minor class of plasma proteins (less than 1% of total plasma proteins). This group of proteins includes both...

enzymes to accelerate chemical reactions in the blood and hormones being transported throughout the body to target cells.

The adrenal gland secretes small amounts of gonadocorticoids (including testosterone) in both sexes and the testes secrete large amounts of testosterone in males. In addition to its many other functions, testosterone stimulates the kidney to produce more EPO. Because males have higher levels of testosterone, they also usually have a higher?

erythrocyte count and a higher hematocrit.

Capillaries serve as the sites of....

exchange between the blood and body tissue

Plasma is classified as an ___________ because it is fluid found outside of cells.

extracellular fluid (ECF). However, plasma is similar in composition to interstitial fluid, in that both have similar concentrations of electrolytes, nutrients, and waste products. Yet one of the most significant differences is that protein concentration is higher in plasma than in the interstitial fluid.

Leukopoiesis involves three different types of maturation processes:

granulocyte maturation, monocyte maturation, and lymphocyte maturation. All three types of granulocytes (neutrophils, basophils, and eosinophils) are derived from a myeloid stem cell. This stem cell is stimulated by multi-CSF and GM-CSF to form a progenitor cell. The granulocyte line develops when the progenitor cell forms a myeloblast (mī′ě-lō-blast) under the influence of G-CSF. The myeloblast ultimately differentiates into one of the three types of granulocytes. Like granulocytes, monocytes are also derived from a myeloid stem cell. The myeloid stem cell differentiates into a progenitor cell, and under the influence of M-CSF this cell forms a monoblast. This is the monocyte line. Eventually, the monoblast forms a promonocyte that differentiates and matures into a monocyte. Lymphocytes are derived from a lymphoid stem cell through the lymphoid line. The lymphoid stem cell differentiates into B-lymphoblasts and T-lymphoblasts. B-lymphoblasts mature into B-lymphocytes, whereas T-lymphoblasts mature into T-lymphocytes. Some lymphoid stem cells differentiate directly into NK (natural killer) cells.

The coronary sinuses contain blood from the...

heart musculature.

All globin chains contain a

heme group, which is composed of a porphyrin (organic compound) ring, with an iron ion (Fe2+) in its center. Oxygen binds to the Fe2+ in heme groups for transport in the blood.

The process of hemopoiesis starts with hemopoietic stem cells called...

hemocytoblasts.

The skeletal system is essential for...

hemopoeisis. Red bone marrow (the site for hemopoeisis) is found in the spongy bone of most children. However, as we age, much of that red bone marrow degenerates and is converted to fat (in the form of yellow bone marrow). As a result, adult red bone marrow (and thus, adult sites for hemopoiesis) are restricted to the flat bones of the skull, sternum, ribs, vertebrae, hip bones, and proximal epiphyses of the humerus and femur.

Formed elements have a relatively short life span; new ones are continually produced by the process of

hemopoiesis also called hematopoiesis.

The red bone marrow (myeloid tissue) is responsible for..

hemopoiesis. Hemopoiesis occurs in most bones in young children, but as an individual reaches adulthood, hemopoiesis is restricted to bones primarily in the axial skeleton.

Blood is also considered a solution because it contains dissolved...

ions as well as organic and inorganic molecules. These substances include electrolytes, nutrients, respiratory gases, some hormones, and waste products.

Normally, erythrocytes are produced at the rate of about 3 million per second. The hormone erythropoietin (EPO) controls this rate by increasing the rate of erythrocyte formation. Dietary requirements for normal erythropoiesis include

iron, B vitamins (e.g., folic acid, riboflavin), and amino acids (to build proteins).

Ferritin is a large, water-soluble protein that serves as the primary storage mechanism for

iron.

Decreased oxygen delivery to body tissues-and consequently, the heart must work harder to supply oxygen to the body. Symptoms of anemia include

lethargy, shortness of breath, pallor of the skin and mucous membranes, fatigue, and heart palpitations.

Most plasma proteins are produced in the...

liver, including albumin, alpha- and beta-globulins, and both fibrinogen and other proteins involved with clotting. Some plasma proteins, such as gamma-globulins and regulatory proteins, are produced by leukocytes and other organs, respectively.

Following trauma to the walls of blood vessels, fibrinogen is converted into...

long, insoluble strands of fibrin, which help form a blood clot.

Anemia is any condition in which either the percentage of erythrocytes is

lower than normal or the oxygen-carrying capacity of the blood is reduced (as may occur if the amount of hemoglobin within erythrocytes is abnormal).

Origin, Differentiation, and Maturation of Formed Elements. All formed elements are derived from common hemopoietic stem cells, called hemocytoblasts. Both myeloid stem cells and lymphoid stem cells are derived from hemocytoblasts. Myeloid stem cells give rise to erythrocytes, platelets, and all leukocytes except...

lymphocytes. Lymphoid stem cells give rise to lymphocytes including NK (natural killer) cells.

This osmotic force is responsible for drawing fluids into the blood and preventing excess fluid loss from blood capillaries into the interstitial fluid, thus helping to...

maintain blood volume and consequently blood pressure.

In females, additional iron is lost in those who have a monthly

menstrual flow.

Aging and the wear-and-tear of circulation through blood vessels cause erythrocytes to become...

more fragile and less flexible. Therefore, the erythrocyte has a finite maximum life span of about 120 days.

The process of erythropoiesis begins with a...

myeloid stem cell, which under the influence of multi-CSF forms a progenitor cell. The progenitor cell forms a proerythroblast, which is a large, nucleated cell. It then becomes an erythroblast, which is a slightly smaller cell that is producing hemoglobin in its cytosol. The next stage, called a normoblast, is a still smaller cell with more hemoglobin in the cytosol; its nucleus has been ejected. A cell called a reticulocyte (re-tik′ū-lō-sīt) eventually is formed. The reticulocyte has lost all organelles except some ribosomes, so it can continue to produce hemoglobin (through protein synthesis). The transformation from myeloid stem cell to reticulocyte takes about 5 days. Some reticulocytes finish maturation while circulating in blood vessels (and in normal circumstances, make up 0.5-2.0% of the circulating blood). One to two days after entering the circulation, the ribosomes in the reticulocyte degenerate, and the reticulocyte becomes a mature erythrocyte. Without a nucleus and cellular organelles, the mature erythrocyte is essentially a plasma membrane "bag" containing hemoglobin.

The term formed elements is a more appropriate description than cells because mature erythrocytes contain neither..

nuclei nor organelles, and platelets are merely fragments broken off from a larger cell.

Erythrocytes are very small, flexible cells. Although erythrocytes are commonly referred to as red blood cells, or RBCs, the term red blood cell is a misnomer because a mature erythrocyte lacks a...

nucleus and cellular organelles. As a result, it is more appropriate to refer to an erythrocyte as a formed element. An erythrocyte has a unique biconcave disc structure. It is composed of a plasma membrane within which are housed about 280 million hemoglobin molecules.

When blood is maximally loaded with oxygen, it is termed

oxygenated (and appears bright red).

Globulins are the second largest group of...

plasma proteins, forming about 37% of all plasma proteins.

Albumins are the smallest and most abundant of the...

plasma proteins, making up approximately 58% of all plasma proteins.

Megakaryocytes produce platelets by forming long extensions from themselves called...

proplatelets. While still attached to the megakaryocyte, these proplatelets extend through the blood vessel wall (between the endothelial cells) in the red bone marrow. The force from the blood flow "slices" these proplatelets into the fragments we know as platelets. Researchers previously thought that most, if not all, megakaryocytes were located within red bone marrow. However, research on mice published in 2017 demonstrated that megakaryocytes circulate through the lung vasculature and that while in the lung, these cells release platelets. This mouse model indicates that the lungs may be the site of up to 50% of platelet production. Research is ongoing to determine if this finding exists in humans.

Globin proteins are broken down into free amino acids, most of which are used by the body for

protein synthesis to make new erythrocytes or other body proteins.

Because each molecule of hemoglobin has four heme groups, it has four Fe2+ and is capable of binding four molecules of oxygen. The oxygen binding is fairly weak; this allows?

rapid attachment of oxygen with hemoglobin when erythrocytes pass through the blood capillaries of the lungs, and rapid detachment when erythrocytes pass through the systemic capillaries of body tissues.

Blood plasma concentration

relative concentration of solutes (proteins and ions) normally 0.09% concentration. Fluid moves in and out of cells depending on hydration/dehydration. (Plasma becomes hypertonic during dehydration). IV fluid is isotonic.

When the clotting proteins are removed from plasma, the remaining fluid is termed....

serum.

Every day, about 1% of the oldest circulating erythrocytes are removed from circulation. These old erythrocytes are phagocytized in both the...

spleen and liver by cells called macrophages.

The biconcave shape and flexibility of erythrocytes allow them to...

stack and line up in single file. This single file of erythrocytes is termed a rouleau as they pass through capillaries. A latticework of spectrin protein supports the plasma membrane of the erythrocyte on its internal surface and provides flexibility to the erythrocyte as it moves through the capillaries.

Iron is stored mainly in the liver and spleen, and it is transported by transferrin to the red bone marrow as needed for erythrocyte production. However, small amounts of iron, approximately 0.9 mg, are lost daily in

sweat, urine, and feces.

Erythrocyte Destruction The absence of both a nucleus and cellular organelles comes at a cost to the erythrocyte and affects its longevity. A mature erythrocyte cannot...

synthesize proteins either to repair itself or to replace damaged membrane regions.

Blood volume

the amount of fluid in blood in a human is 5L (liters). Depending on size 4-5L women, 5-6L for men.

Polar or charged substances (e.g., glucose, salts) dissolve readily in..

the blood.

Gamma-globulins are also called immunoglobulins, or antibodies, play a part in...

the body's defenses.

Three molecular components must be accounted for in the destruction of hemoglobin:

the globin protein, the iron ion, and the heme group. Two of the components are processed for recycling; the other component is metabolically altered and then excreted from the body.

Hemocytoblasts are considered multipotent cells, meaning that..

they can differentiate and develop into many different kinds of cells.

Erythrocytes transport oxygen and carbon dioxide between the

tissues and the lungs.

The iron ion (Fe2+) component in hemoglobin is removed and transported by a globulin protein called

transferrin to the liver or spleen, where the Fe2+ then is bound to storage proteins called ferritin and hemosiderin.

What are the functions of blood?

transportation, regulation, protection

Bilirubin is converted to

urobilinogen within the small intestine.

________ transports blood toward the heart

veins

Environmental factors, such as altitude, can affect EPO release and ultimately affect the hematocrit. Let us say a woman moves to a cabin high in the Rocky Mountains, where the atmospheric pressure is lower than it is at sea level a lower atmospheric pressure means less oxygen availability. Each time she takes a breath at this altitude, she takes in relatively less oxygen than she would on a beach by the ocean. Her body compensates by releasing more EPO and making more erythrocytes over time; more erythrocytes in the blood can carry more oxygen to the tissues. However, having more erythrocytes increases the blood's?

viscosity, which can increase the chance of cardiovascular complications, such as major blood clots that lead to heart attacks or strokes.

Plasma is composed primarily of...

water (about 92% of its volume), plasma proteins, and other solutes, including electrolytes (e.g., Na+), nutrients (e.g., glucose), respiratory gases (e.g., CO2), and wastes (e.g., urea)