Blood Flashcards
What 2 things is blood composed of? State the percentages
Plasma 55%
Formed elements 45%
What is plasma?
A water based substance in which there are many solutes
State and describe the 5 solutes found in the blood plasma, providing examples for each.
1) NUTRIENTS: E.g Glucose=transported from small intestine and liver and muscles. E.g Amino acids= obtained from dietary protein
2) WASTE PRODUCTS: E.g Carbon dioxide= dissolved in plasma in form of hydrogen carbonate ions. E.g Urea= nitrogenous waste made in metabolism of excess amino acids
3) PROTEINS: E.g Albumin= maintains osmotic pressure of blood. E.g Fibrinogen= important in blood clotting as converted to fibrin helping to form a clot. E.g Globulins= immunoglobulins, knows as antibodies
4) ELECTROLYTES: mineral ions, including calcium, chloride, magnesium, phosphate, potassium, and sodium
5) HORMONES: protein or lipid in nature, travel to target cells and bind to complementary-shaped receptor
What is meant by formed elements?
The cells and cell fragments
State and describe the 3 formed elements found in the blood, giving the 5 examples for 1.
1) ERYTHROCYTES (red blood cells): anucleate (no nucleus) shaped like biconcave discs which are full of haemoglobin, which have an affinity for oxygen and oxyhemoglobin is made.
2) LEUCOCYTES (white blood cells): E.g Neutophil= a phagocyte. E.g Monocytes= phagocytic and become Macrophages when they leave blood stream through fenestrations of capillary wall. E.g Lymphocytes= produce antibodies. (Also Eosinophils=combating multicellular parasites and Basophils= inflammatory response)
3) PLATELETS= cell fragments which are produced in the red bone marrow from megakaryocyte cells. Play an important roll in clotting blood when blood vessel walls are damaged, reducing blood loss when injured
How can we separate the blood plasma and formed elements in a sample of blood?
Spinning whole blood in a centrifuge. The denser blood cells sink to the bottom, and the less dense plasma floats to the top.
List the main functions of blood in the body?
- transport of: oxygen to respiring cells, carbon dioxide from respiring cells, digested food from small intestine to cells, nitrogenous waste from tissues to excretory organs, hormones, platelets for clotting, antibodies as part of immune response
- maintaining: constant body temperature and pH
Explain how tissue fluid is formed in the blood capillaries.
- water and dissolved substances (oxygen, glucose) and forced out through the permeable capillary wall (at the arteriole end) due to high blood pressure. The forced out substances form the tissue fluid. Larger blood components (rbc, plasma proteins) remain inside the capillary
- some but not all (90%) of the water diffuses back into the capillary (at the venue end) by osmosis. The loss of the water molecules and large plasma proteins in the blood causes a reduction in the water potential of the capillary.
What are the purposes of tissue fluid being formed?
- Allows for more efficient exchange of substances between the blood supply and the cells
- it delivers oxygen, glucose and other nutrients to cells surrounding the capillary
What is meant by hydrostatic pressure?
The pressure from the heart beat forcing liquid out through the junctions of the capillary. This is high at the arteriole end of the capillary and lower at the venule end because pressure is lost in the capillary network.
What is meant by oncotic pressure?
The result of the water potential in the capillary due to the plasma proteins. The proteins attract free water molecules, lowering the water potential of the plasma
Explain where in the capillaries is hydrostatic pressure high and low, and where oncotic pressure is high and low.
Arterial end:
- Hydrostatic blood pressure is higher then oncotic pressure= water and solutes are forced out of capillary to form tissue fluid
- net pressure is out
Venous end:
- Oncotic pressure is higher then hydrostatic pressure= 90% of tissue fluid returns by osmosis to the capillary. It has given up much of its oxygen and nutrients but has picked up carbon dioxide and other waste
- net pressure is in
What is the equation for calculating filtration pressure?
Hydrostatic pressure - oncotic pressure = filtration pressure
mm Hg
Explain where the remaining 10% of the tissue fluid that does not return to the blood capillary goes
- it enters the lymphatic system and becomes lymph.
- The lymph capillaries are blind-ended vessels with bigger fenestrations then blood capillaries, and the excess tissue fluid drains into the lymph vessels, becoming lymph
Explain the difference in composition of the lymph compared to tissue fluid.
- lower concentration of oxygen and nutrients
- higher concentration of carbon dioxide and other waste products
- contains fatty acids which have been absorbed from the villi in the small intestine
