Lecture 13: Composition and General Functions of Blood Mon 3 August Flashcards
What are the three general functions of blood?
Transport
Immune response
Coagulation
What 10 things does the body have to transport?
- O2
- CO2
- water
- nutrients
- Ions associated with pH and homeostasis
- heat
- hormones
- waste products
- immune cells
- coagulation
What is involved in the immune function of blood?
WBC (mostly) move in the blood to identify and destroy pathogens
What is involved in the coagulation function of blood?
Platelets and coagulation factors in the plasma are responsible for blood clotting to prevent bleeding
Describe the composition of blood
- 55% plasma
- 45% formed elements
Describe the composition of plasma
- water
- plasma proteins
- other solutes
What is the largest component of plasma?
water (92%)
What three things make up the formed elements of blood?
- Platelets
- WBC
- RBC
What is the largest component of formed elements?
RBC (99.9%)
What are platelets?
Cell fragments that participate in clotting to stop bleeding
What is hematopoiesis?
The formation of blood cells
Where is hematopoiesis initiated?
In the bone marrow
Describe the process of hematopoiesis
hemocytoblasts is the progenitor that differentiates into all the different blood cells in the bone marrow
What is the signal that makes hemocytoblasts differentiate into RBC?
the release of erythropoietin (EPO) which signals hemocytoblasts to go down the path to make RBC
Describe the shape of RBC
biconcave disc shape with a large surface area:volume ratio
What is the benefit of RBC having a large surface area:volume ratio?
Allows for efficient diffusion of gases and allows flexible movement through narrow capilaries
Do RBC have nuclei? Why?
No because they differentiate from the hemocytoblasts and because it needs to fit as much haemoglobin as possible
Describe the characteristics of RBC
- contains large amounts of haemoglobin
- haemoglobin takes up one third of the weight of RBC
- haemoglobin uses iron as part of the haem to bind O2
- four heam units per haemoglobin so each haemoglobin can bind to four O2 molecules
What is hematocrit?
The fraction of blood occupied by the red blood cells
What is low hematocrit called?
anemic
What is high hematocrit called?
polycythemic
What is the effect of testosterone on the production of RBC?
More testosterone = more EPO released = more RBC formed from hemocytoblasts so higher hematocrit
Why do athletes train at high altitudes?
high altitudes = less O2 in the air = increased secretion of EPO from the kidneys = more RBC formation = more O2 can bind
What is erythropoiesis?
the formation of red blood cells stimulated by erythropoietin
