chapter 17 - blood Flashcards
What are the 2 components of blood?
plasma: 55% (fluid matrix)
formed elements: 45% (cells)
What are the three cells that make up the formed elements?
erythrocytes - RBC
Leukocytes - WBC
Thrombocytes - platelets
What is the colour of blood dependent on?
oxygen levels.
High O2 = bright red
Low O2 = dark red
What is the normal pH of blood?
7.35-7.45 slightly basic
What is the normal temp of blood?
37 degrees (periphery) 38 degrees (core)
What percent of body weight does blood amount to?
8%
What is the average volume of blood in a person
5L
What are the three functions of blood?
- transport of: oxygen, nutrients, waste products, hormones, and other molecules
- regulation of temperature and pH (important to enzyme activity) and blood volume (pressure maintenance)
- protection against blood loss (hemostasis) and infection
Give a percentage breakdown of the components of blood plasma.
90% water
8% proteins
2% dissolved materials
Give a percentage breakdown of the components that make up the protein component of blood plasma.
60% albumin - maintains osmotic balance, carrier proteins, and pH buffers
36% globulins - transport proteins and antibodies
4% clotting proteins like fibrinogen and prothrombin
What are the characteristics of erythrocytes (RBC)
- bioconcave discs (large surface area)
- no nucleus
- lose most of their organelle as they mature to max space avail for hemoglobin (97% hemoglobin)
- no mitochondria, use anaerobic respiration for ATP
- flexible protein skeleton to squeeze through small capillaries
5 million/microlitre
What is the most numerous formed element
erythrocytes (RBC)
What is the function of erythrocytes?
transport of oxygen and carbon dioxide
iron binds reversibly with hemoglobin: oxyhemoglobin
globin binds reversibly with CO2: carbaminohemoglobin
what is the structure of hemoglobin
Consists of two alpha and two beta chains (think like a four square)
Heme pigment is bonded to each of these chains (heme has one iron atom in each)
Iron atom can each bind with one 02 (4 O2/hemoglobin)
How many hemoglobin molecules are in each RBC?
125,000,000
What are the three types or names for hemoglobin as they travel throughout the body?
Oxyhemoglobin - result of O2 loading in the lungs
Deoxyhemoglobin (reduced hemoglobin) - result of O2 unloading in the tissues
Carbaminohemoglobin - result of CO2 loading in the tissues
What is the process of forming blood cells called?
hematopoiesis
Where does blood formation occur and what cells do they arise from?
in the red bone marrow
hemocytoblasts (hematopoietic stem cells)
-give rise to all types of blood cells
What is the process of forming RBCs called?
Erythropoiesis
Describe the process of erythropoiesis
starts with hemocytoblast cell
nucleus begins fairly large and has organelle
nucleus slowly shrinks and organelle number decreases as the cell fills with hemoglobin
eventually get to the reticulocyte stage where they have very a very small nucleus
last step is to eject/pinch off the nucleus to become a fully developed erythrocyte
What percent of RBCs are reticulocytes?
1-2%
Explain the control mechanism for the stimulation of erythropoiesis and what is the result of too many erythrocytes in the blood?
Hypoxia (decreased oxygen levels in blood) is detected by kidney (primary responder) and liver.
they then release erythropoietin (EPO hormone) which stimulates production.
Too many erythrocytes results in an increase in blood viscosity which increases heart strain
What are the dietary requirements for erythropoiesis?
iron
B12
folic acid (for globin synthesis)
what is the lifespan of erythrocytes? explain what limits their lifespan and what happens to the by-products when they die.
about 100 days
because they do not have nucleus/organelles, they cannot synthesize proteins for cell repair
macrophages engulf dying RBCs in the spleen
- iron of heme is recycled and rest of heme goes in feces
- globin is recycled: amino acids used to make new proteins