Lecture 13: COMPOSITION AND GENERAL FUNCTIONS OF BLOOD Flashcards
What are the general functions of blood?
Transport, Immune and Coagulation
What does the blood transport?
Oxygen, water, nutrients, carbon dioxide, waste products, ions, heat, hormones, coagulation factors and immune cells
What does the blood transport which is needed by cells?
Oxygen, water and nutrients
What does the blood transport to be broken down and removed?
Carbon dioxide and waste products
What are ions in the blood associated with?
pH and homeostasis
How does heat get into the blood?
A product of oxidative reactions in cells
What are hormones in the blood needed for?
To coordinate the activity of organs of the body
What is the immune function of blood needed for?
Fighting infection and production of the immune response
What is the immune response largely via?
White blood cells
What is coagulation needed for?
To prevent bleeding
How does coagulation occur?
Via platelets and coagulation factors in the plasma
What does blood consist of?
Plasma and formed elements
What amount is plasma?
55%
What amount is formed elements?
45%
What is blood volume typically proportional to?
Lean body mass
How many ml of blood per kg?
60-80
What makes up the plasma?
Plasma proteins (7%), other solutes (1%) and water (92%)
What are the plasma proteins?
Albumins, globulins, fibrinogen, enzymes and hormones
What do albumins do?
Maintain osmotic pressure
What do globulins do?
Immune response
What does fibrinogen do?
Coagulation factor
What doe enzymes and hormones do?
Lots of functions, varies by person
What are the other solutes?
Electrolytes, organic nutrients and organic wastes
What do electrolytes do?
Maintain pH and ion balance
What are organic nutrients needed for?
Cells need these to function
What are organic wastes for?
Cells are getting rid of this
What is the main component of plasma?
Water
What can water in the plasma do?
Hold a lot of heat
What makes up the formed elements?
Platelets (<0.1%), White blood cells (<0.1%) and red blood cells (99.9%)
What are platelets?
Cell fragments that participate in clotting (coagulation) to stop bleeding
What are white blood cells?
Immune response and defence mechanisms which seek and destroy invading pathogens
What are red blood cells?
By far the most common cell found in blood. Highly specialised to transport oxygen
What is hematopoiesis?
The formation of blood cells
Where is hematopoiesis initiated?
In the red bone marrow which contains hemocytoblasts
What are hemocytoblasts?
The progenitors for all blood cells
What is erythropoietin (EPO)?
The stimulating chemical to produce more red blood cells
What is the shape of RBC’s/erythrocytes?
Biconcave disc
What does the shape of RBC’s mean?
Large surface area: volume ration which allows efficient diffusion of gases. Also flexibility for movement through narrow capillaries
What do RBC’s contain?
A large amount of haemoglobin (1/3 of weight)
What do RBC’s use to bind oxygen?
Iron as part of the heme structure
How many heme suits in a haemoglobin?
Four, so each haemoglobin van bind four oxygen molecules
What determines oxygen carrying capacity?
The amount of haemoglobin and red blood cells
What does centrifuged blood do?
Separate into its main components by weight
What is hematocrit or packed cell volume (PCV)?
The fraction of blood occupied by red blood cells
What is the hematocrits range for men?
0.4-0.54
What is the hematocrits range for women?
0.37-0.47
What is the Buffy coat?
The white blood cells and platelets (not always visible)
What is low hematocrits?
Anemic
What is high hematocrit?
Polycythemic
What is erythropoiesis?
Generation of red blood cells
What is required for erythropoiesis?
Iron so that haemoglobin can be made
What is RBC production controlled by?
Homeostatic mechanism involving erythropoietin (EPO)
What happens when oxygen levels are lower in the atmosphere?
There is less oxygen delivered to places throughout the body
What is decreased oxygen levels sensed by?
The kidneys and in response more EPO is produced to increase the amount of RBC and therefore oxygen carrying capacity
What improves the rate of erythropoiesis?
testosterone
