Composition and General Functions of Blood

Question 1

What are the three general functions of blood?

Answer 1

Transport, Immune response, Coagulation

Question 2

Describe the function of blood, transport

Answer 2

Transports oxygen, water and nutrients and ions associated with pH and homeostasis as well as removing CO2 and waste products.
Heat - a product of oxidative reactions in cells (puts heat into the blood so it can be transported to the skin surface for conduction.
Hormones - co-ordinate the activities of organs of the body
Immune cells and coagulation factors

Question 3

Describe the function of blood, Immune

Answer 3

• For fighting infection and production of the immune response
• Largely via white blood cells

Question 4

Describe the function of blood, coagulation

Answer 4

• for preventing bleeding
• via platelets and ‘coagulation factors’ in plasma

Question 5

Describe the composition of blood

Answer 5

Made of two groups of things:
Plasma - over 90% water! liquid and the solutes dissolved in it
Formed elements - platelets, white blood cells, red blood cells

Question 6

Describe the functions of the formed elements in the blood

Answer 6

Platelets: cell fragments that participate in clotting to stop bleeding
White blood cells: immune response and defence mechanisms; these seek and destroy invading pathogens
Red blood cells: by far the most common cell found in blood; highly specialised to transport oxygen

Question 7

What is hematopoiesis? and describe its role

Answer 7

Hematopoiesis is the formation of blood cells. It is initiated in the red bone marrow, which contains blood stem cells (hemocytoblasts). These are the progenitors for all blood cells.

Question 8

Describe how the biconcave disc shape of red blood cells helps them do their function

Answer 8

• large surface area:volume ratio
• allows for efficient diffusion of gases
• flexibility for movement through narrow capillaries
  (These things allow for the maximisation of diffusion)

Question 9

Describe the functions and charactaristics of red blood cells

Answer 9

• Contain large amounts of haemoglobin
• One third weigh of RBC
• Uses iron as part of the haem structures to bind oxygen
• Four haem units, so each can bind four oxygen molecules

Question 10

What is hematocrit and what does too little or too much make happen?

Answer 10

The fraction of blood occupied by the red cells is called hematocrit or packed cell volume (PCV).
Centrifuged blood separates it into its main components (plasma and hematocrit)
- Men on average have more than woman
Anemic: low iron so can’t make more red blood cells as there is no point without to haem
Polycythemic: too many red blood cells so thick blood, which makes heart work too hard and puts strain on capillaries.

Question 11

Describe erythropoiesis

Answer 11

This is the generation of red blood cells
- All blood cells derived from a common progenitor cell.
- RBC production stimulated by erythropoietin (EPO)
- Requires iron to make hemoglobin
- The process is augmented by testosterone

Question 12

Describe the physiological effects of training at a high altitude and why it is bad to just inject EPO

Answer 12

Air at high alittude has less available oxygen, so short term you breath deeper/faster and HR increases. Long term the kidneys sense that oxygen levels in blood are depressed so they release EPO to stimulate the production of more RBC’s and you get increased hematocrit. Whole body system adapts together.
If you just inject it, then you are pushing yourself towards polycythemia because making more RBC’s without your body adapting as well.