8.3- Blood, Tissue Fluid, And Lymph Flashcards
What is the blood?
The main transport medium of the human circulatory system. Also considered a type of connective tissue.
- consists of plasma (a yellow liquid) which carries dissolved glucose, amino acids, mineral ions, hormones and plasma proteins.
- plasma =93% water. (Therefore Polar solvent)
- Has rbc(most) and wbc( least) and platelets.
- plasma makes up 55% of the blood by volume. (Rest is made up by stuff it carries^)
What are the main plasma proteins and their roles?
- Albumin- important for maintaining osmotic potential of blood.
- Fibrinogen- important in blood clotting.
- Globulins- involved in transport and the immune system.
What are platelets?
Aka thrombocytes
Fragments of large cells called megakaryocytes found in the red bone marrow.
- involved in clotting mechanism of blood.
- carried by the plasma in the blood.
Functions of the blood
- contributes to the maintenance of body temp. (Thermoregulation)
-Acts as a buffer, minimising pH changes.
Transport of: - oxygen to and carbon dioxide from respiring cells.
- digested food from small intestine.
- nitrogenous waste products from cells to excretory organs.
- hormones.
- food molecules from storage components to cells that need.
- platelets to damaged areas.
- cells/antibodies involved in immune system.
What is oncotic pressure?
The tendency of water to move into the blood by osmosis.
What is hydrostatic pressure?
The pressure from the surge of blood that occurs every time the heart contracts.
Explain the osmotic effect of the plasma proteins.
- The plasma proteins (especially albumin) give the blood in the capillaries high solute potential so therefore low water potential as compared to surrounding fluid.
- due to oncotic pressure, water has a tendency to move into the blood in the capillaries via osmosis from the surrounding fluid.
Explain the movement into and out of the capillaries. (Formation of tissue fluid)
At the arterial end of capillaries:
- blood entering from arterioles has high hydrostatic pressure. It is higher than the oncotic pressure attracting water in by osmosis so fluid is squeezed out. This fluid fills spaces between cells and is called tissue fluid.
At venous end:
- As blood moves through capillary, hydrostatic pressure decreases as fluid has moved out. Oncotic pressure= greater than hydrostatic so water moves back in via osmosis.
(By the time blood returns to veins, 90% of tissue fluid back in blood vessels)
What is tissue fluid? made up of?
The fluid that fills spaces between cells, after being forced out of arterial end of capillaries
Same composition as plasma but without RBCs and plasma protein.
Diffusion takes place between the blood and the cells through the tissue fluid.
What is lymph?
Not all the tissue fluid returns to the capillaries.
10% drains into a system of blind-ended tubes called lymph capillaries. Here it is known as Lymph.
- the lymph capillaries join up to form larger lymphatic vessels.
What is the composition of lymph?
- similar composition to plasma/tissue fluid but has less O2 and nutrients.
- also contains fatty acids, which have been absorbed into lymph from villi of small intestines.
How is lymph fluid transported and to where?
Transported through the lymphatic vessels by the squeezing of body muscles.
- one way valves prevent backflow.
- eventually it returns into the blood, flowing into the right and left subclavian veins (under the clavicle).
What are lymph nodes and lymphocytes? Function?
Along the lymph vessels are the lymph nodes.
Lymphocytes build up in the lymph nodes when necessary and produce antibodies which are then passed into the blood.
- lymph nodes also intercept bacteria from the lymph, which are ingested by phagocytes in the nodes.
Lymphatic system plays a major role in the defence mechanisms of the body.
What do enlarged lymph nodes show?
A sign that the body is fighting of an invading pathogen.
This is why doctors examine the neck, armpits, stomach or groin as these are the sites if major lymph nodes/glands.
