Chapter 19 - Cardiovascular System: The Blood Flashcards
What is interstitial fluid?
Fluid that bathes body cells
- constantly renewed by the blood
What are the three general functions of blood?
- Transportation - 02, C02, nutrients, wastes, hormones
- Regulation - pH, body temperature, maintain homeostasis of all body fluids
- Protection - clotting ability (protect against major blood loss), white blood cells protect against disease, antibodies, interferons
Describe the physical characteristics of blood.
- denser and thicker than water, feels sticky
- 38 degrees in temperature
- pH from 7.35 to 7.45
- 5 to 6 liters in an adult male
- 4 to 5 liters in an adult female
- 8% of total body mass
What are the components of blood?
- Blood plasma
2. Formed elements (cells and cell fragments)
What is blood?
Liquid connective tissue
- consists of cells surrounded by a liquid extracellular matrix
What are the components of blood plasma?
- 91.5% water
- 8.5% solutes
What are the blood plasma proteins?
- Albumin (regulating blood volume)
- Globulins (attack viruses & bacteria)
- Fibrinogen (help in blood clotting)
What is another name for blood plasma proteins?
Antibodies or immunoglobulins
What are antibodies and what is their function?
Plasma proteins
- Bind to the specific antigen that stimulated its production
- Disables invading antigen
What is the hematocrit?
The percentage of total blood volume occupied by RBCs
- a hematocrit of 40 would indicate 40% volume of blood is composed of RBCs
What is the normal range for the hematocrit?
38-46% in females
40-54% in males
What contributes to a higher hematocrit in males?
Testosterone
What is hemopoiesis? (hematopoiesis)
The process by which the formed elements of blood develop
Where does hemopoiesis occur before birth?
In the yolk sac of an embyro and later in the spleen, thymus and lymph nodes of the fetus
Where is the source of blood cells after birth?
Red bone marrow
What is red bone marrow?
Highly vascularized connective tissue located in the spaces between trabeculae of spongy bone tissue
Where are pluripotent stem cells derived from and what is their capacity?
Red bone marrow cells derived from mesenchyme
- have the capacity to develop into many different types of cells
What are the formed elements of blood?
- Red blood cells (whole cells)
- White blood cells (whole cells)
- Platelets (cell fragments)
In order to form blood cells, pluripotent stem cells must produce what two types of cells first?
- Myeloid stem cells
2. Lymphoid stem cells
What do myeloid stem cells give rise to?
- Red blood cells
- Platelets
- Monocytes
- Neurtophils
- Eosinophils
- Basophils
What do lymphoid stem cells give rise to?
Lymphocytes
What are progenitor cells?
Similar to a stem cell
- has a tendency to differentiate into a specific type of cell, but is already more specific than a stem cell and is pushed to differentiate into its “target” cell
- give rise to more specific elements of blood
- no longer capable of reproducing themselves
What are the CFU-designations and what does each produce?
- CFU-E: Erythrocytes (red blood cells)
- CFU-Meg: Meagkaryocytes (source of platelets)
- CFU-GM: Granulocytes (Neutrophil and monocytes)
What are precursor cells?
The next generation of blood cells (after progenitor)
- over several cell divisions they develop into the actual formed elements of blood
- monoblasts into monocytes
- eosinophilic myeloblasts intoeosinophils
- have recognizable microscopic appearances
What are hemopoietic growth factors and what do they regulate?
Hormones
- regulate the differentiation and proliferation of particular progenitor cells
What is the function of erythropoietin (EPO)?Where is it produced?
Increases the number of red blood cell precursors
Produced primarily by cells in the kidneys
What is the function of thrombopoietin (TPO)?Where is it produced?
Hormone that stimulates the formation of platelets (thrombocytes) from megakaryocytes
- produced by the liver
What is the function of cytokines?Where are they produced?
Generally act as local hormones
- stimulate proliferation of progenitor cells in red bone marrow and regulate activities of cells involved in nonspecific defenses and immune responses
- produced by red bone marrow cells, leukocytes, macrophages, fibroblasts and endothelial cells
What are the two important families of cytokines?
- Colony-stimulating factors (CSFs)
2. Interleukins
What are the colony-stimulating factors (CSFs)?
A substance secreted by bone marrow that promotes the growth and differentiation of stem cells into colonies of specific blood cells.
What are interleukins?
Any of a class of glycoproteins produced by leukocytes for regulating immune responses
What do red blood cells (erythrocytes) contain?
The oxygen-carrying protein hemoglobin
- gives it it’s red color
What is hemoglobin?
The oxygen-carrying protein in red blood cells
Describe the anatomy of red blood cells.
- biconcave discs
- plasma membrane is both strong and flexible (allows them to deform without rupturing)
- lack a nucleus and other organelles
- cannot reproduce
- do not undergo extensive metabolic activities
How do red blood cells generate ATP?
Anaerobically
- they do not use up the oxygen that they transport
Describe the physiology of red blood cells.
- RBC shape provides great surface area for diffusion
- contains hemoglobin molecules
- all the internal space inside a RBC is used for oxygen transport
What are the two parts of a hemoglobin molecule?
- Globin - protein composed of 4 polypeptide chains
2. Heme - ring-like nonprotein pigment, is bound to each chain
How many oxygen molecules attach to the iron ion that is in the center of each heme ring?
4
How many hemoglobin molecules are contained in a single red blood cell?
About 280 million hemoglobin molecules
What is the significance of red blood cells containing the enzyme carbonic anhydrase (CA)?
It catalyzes the conversion of carbon dioxide and water to carbonic acid, which dissociates into hydrogen ions and HCO3
- (an important buffer in extracellular fluid)
- allows carbon dioxide to be transported in blood plasma
How long do red blood cells live for?
120 days
- ruptured cells are removed from circulation and destroyed by fixed phagocytic marcrophages in the spleen and liver
Describe the recycling process of red blood cells.
- Marcrophages phagocytize ruptured and worn-out RBCs
- Globin and heme portions of hemoglobin are split apart
- Globin is broken down into amino acids
- Iron is removed from heme
- Iron is stored in ferritin (protein)
- Iron reattaches to transferrin
- Iron is transferred to red bone marrow
- Erythropoiesis in red bone marrows results in production of RBCs
- When iron is removed from heme, non-iron portion is converted to biliverdin then into bilirubin
- Bilirubin enter blood, transported to liver
- Bilirubin is released into bile
- Bilirubin is converted into urobilinogen in large intestine
- Some is absorbed back into blood, converted into urobilin, excreted in urine
- Most urobilinogen is eliminated in feces
What is feritin?
A protein that serves to store iron in the tissues
What is erythropoiesis?
Production of red blood cells
- starts in the red bone marrow
What is a reticulocyte?
An immature RBC without a nucleus
- develops into a mature RBC within 1-2 days after release from red bone marrow
What is hypoxia?
Cellular oxygen deficiency
- occurs if too little oxygen enters the blood
What does hypoxia stimulate?
The kidneys to step up the release of erythropoietin, which speeds up the development of proerythroblasts into reticulocytes in the red bone marrow
- as the # of circulating RBCs increases, more oxygen can be delivered to body tissues
How are leukocytes (white blood cells) different from red blood cells?
Contain a nucleus and a full complement of other organelles
- do not contain hemoglobin
How are white blood cells classified?
- Granular
- Agranular- depending on whether or not they contain cytoplasmic granules (vesicles) that are made visible during staining
What are the granular leukocytes?
- Neutrophils
- Eosinophils
- Basophils
What are the agranular leukocytes?
- Lymphocytes
2. Monocytes
What distinguishes a neutrophil?
- granules are smaller, evenly distributed and pale lilac- nucleus has 2-5 lobes, connected by thin strands of nuclear material
- as the cells age, the number of nuclear lobes increase
What distinguishes an eosinophil?
- large, uniform-sized granules
- stain red-orange with acidic dyes
- nucleus has two lobes, connected by a thin or thick strand of nuclear material
What distinguishes a basophil?
- round, variable-sized granules- stain blue-purple with basic dyes
- granules commonly obscure the nucleus which has two lobes
What distinguishes a lymphocyte?
- nucleus stains dark, is round or slightly indented- cytoplasm stains sky blue, forms a ring around nucleus
- classified as small or large based on diameter
What distinguishes a monocyte?
- nucleus is kidney-shaped
- cytoplasm stains blue-gray and has a foamy appearance
- blood is a conduit for monocytes
What do monocytes become?
Fixed (tissue) or wandering macrophages
What is the difference between fixed & wandering macrophages?
Fixed: Reside in a particular tissue
Wandering: Roam the tissues and gather at sites of infection
What are major histocompatibility (MHC) antigens?
Proteins that protrude from their plasma membranes into the extracellular fluid
- “cell identity markers” are unique to each person (except identical twins)
How many times do RBCs outnumber WBCs?
700:1