LAB EXAM 1 Flashcards
Describe the general functions of blood
As blood is transported through the blood vessels it transports oxygen from and carbon dioxide to the lungs for gas exchange, nutrients absorbed from the gastrointestinal (GI) tract, hormones released by endocrine glands, and heat and waste products from the systemic cells
Regulation
Blood participates in the regulation of body temperature, body pH, and fluid balance:
∙ Body temperature. This is possible because blood absorbs heat from body cells, especially skeletal muscle, as it passes through blood vessels of body tissues. Heat is then released from blood at the body surface as blood is transported through blood vessels of the skin.
∙ Body pH. Blood, because it absorbs acid and base from body cells, helps maintain the pH of cells. Blood contains chemical buffers (e.g., proteins, bicarbonate) that bind and release hydrogen ions (H+) to maintain blood pH until the excess is eliminated from the body.
∙ Fluid balance. Water is added to the blood from the GI tract and lost in numerous ways (including in urine, sweat, and respired air). In addition, there is a constant exchange of fluid between the blood plasma in the capillaries and the interstitial fluid surrounding the cells of the body’s tissues. Blood contains proteins and ions that exert osmotic pressure to pull fluid back into the capillaries to help maintain normal fluid balance.
Protection
Blood contains leukocytes, plasma proteins, and various molecules that help protect the body against potentially harmful substances.
List six characteristics that describe blood
Scarlet (oxygen-rich) to dark red (oxygen-poor)
4–5 L (females) 5–6 L (males)
Viscosity (relative to water) - 4.5–5.5× (whole blood)
Plasma concentration - 0.09%: relative concentration of solutes (proteins, ions) in plasma
38°C (100.4°F)
7.35–7.45
List the three components of a centrifuged blood sample
Erythrocytes form the lower layer of the centrifuged blood. They typically make up about 44% of a blood sample.
∙ A thin buffy coat makes up the middle layer. This slightly gray-white layer is composed of both leukocytes and platelets. The buffy coat forms less than 1% of a blood sample.
∙ Plasma is a pale yellowish liquid that rises to the top in the test tube; it generally makes up about 55% of blood
Define hematocrit
The percentage of the volume of all formed elements (erythrocytes, leukocytes, and platelets) in the blood is called the hematocrit
Name the three formed elements of the blood and compare their relative abundance
erythrocytes, leukocytes, and platelets
Leukocytes: 4.5–11 thousand per cubic mm
Neutrophils 50–70%
Lymphocytes 20–40%
Eosinophils 1–4%
Monocytes 2–8%
Basophils 0.5–1%
Platelets: 150–400 thousand per cubic mm
Erythrocytes (44% of whole blood)
Erythrocytes
4.2–6.2 million per cubic mm
List the major types of plasma proteins and explain the general function of each
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
List the major solutes found in plasma
Electrolytes (e.g., sodium, potassium, calcium, chloride, iron, bicarbonate, hydrogen)
Nutrients (e.g., amino acids, glucose, cholesterol, vitamins, fatty acids)
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−)
Wastes (breakdown products of metabolism, such as lactate, creatinine, urea, bilirubin, ammonia)
Explain the general process of hematopoiesis, including the name of the hematopoietic stem cell
and the substances (CSFs) involved in hematopoiesis.
New ones are continually produced by the process of hemopoiesis, also called hematopoiesis. The red bone marrow (myeloid tissue) is responsible for hemopoiesis.
Hemocytoblasts are considered multipotent cells, meaning that they can differentiate and develop into many different kinds of cells
Hemocytoblasts produce two different lines for blood cell development:
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 like B/T/NK cells.
The maturation and division of hemopoietic stem cells are influenced by colony - stimulating factors (CSFs).
Thrombopoietin: Growth Factor
Stimulates both the production of megakaryocytes in the bone marrow and the subsequent formation of platelets
Multi-colony-stimulating factor (multi-CSF): Growth factor
Increases the formation of erythrocytes, granulocytes, monocytes, and platelets from myeloid stem cells
Erythropoietin (EPO) : Hormone (produced primarily by the kidneys)
Increases the rate of production and maturation of erythrocyte progenitor and erythroblast cells
Colloid osmotic pressure
Osmotic pressure exerted by plasma proteins is called colloid osmotic pressure. This osmotic force is responsible for drawing fluids into the blood and preventing excess fluid loss from blood capillaries into the interstitial fluid
Describe the process of erythropoiesis
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 eventually is formed. The transformation from myeloid
stem cell to reticulocyte takes about 5 days.
Compare the production of granulocytes, monocytes, and lymphocytes in leukopoiesis
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 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. 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. Some lymphoid stem cells differentiate directly into NK
Summarize the process by which platelets are formed in 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 produce platelets by forming long extensions from themselves called proplatelets. While still attached to the megakaryo-yte, 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.
Describe the structure of erythrocytes
An erythrocyte has a unique biconcave disc structure. It is composed of a plasma membrane within which are housed about 280 million hemoglobin molecules. This single file of erythrocytes is termed a rouleau, as they pass through capillaries.
List the events by which erythrocyte production is simulated
Stimulus: Decreased blood oxygen levels
RECEPTOR: Kidney detects decreased blood O2
Control center: Kidney cells release EPO into the blood.
EFFECTOR: EPO stimulates red bone marrow to increase the rate of production of erythrocytes.
NET EFFECT: Increased numbers of erythrocytes enter the circulation, during which time the erythrocytes are oxygenated and blood O2 levels increase.
Increased blood O2 levels are detected by the kidney, which inhibits EPO release by negative feedback.
Explain the process by which erythrocyte components are recycled
Erythrocytes circulate in the blood for about 120 days, after which they are phagocytized in the liver and spleen.
Aged erythrocytes are phagocytized by macrophages in the liver and spleen. The three components of hemoglobin are separated.
Each of the separated components of heme (globin, iron ion, and heme) has a different fate.
Globin proteins are broken down into amino acids and enter the blood. Some of these amino acids may be used to make new erythrocytes.
Small amounts of iron are lost in sweat, urine, and feces daily; iron is also lost via injury and menstruation.
Heme (minus the iron) is converted to Biliverdin –> Bilirubin
