8.3 Blood, Tissue Fluid, Lymph Flashcards
What is blood? (general)
The main transport medium of the human circulatory system
What does blood primarily consist of?
Plasma
What is plasma?
A yellow liquid, the main component of blood
What are the key examples of large plasma proteins?
Albumin, fibrinogen, globulins
What does plasma carry?
A wide variety of non-cellular components (dissolved glucose, amino acids, mineral ions, hormones, large plasma proteins), red blood cells, platelets, white blood cells.
What are the only parts of the blood that are involved in its transport functions
Red blood cells and plasma
What is the function of the red blood cells?
Carry oxygen to the cells
What are the key functions of the blood?
TRANSPORT OF:
-Oxygen to, and carbon dioxide from, respiring cells
-Digested food from the small intestine
-Nitrogenous waste products from the cells to the excretory organs
-Chemical messages
-Food molecules from storage compounds to the cells that need them
-Platelets to damaged areas
-Cells and antibodies involved in the immune response
What is tissue fluid?
The fluid that exits capillaries and fills the spaces between cells
Compare the composition of tissue fluid to blood.
-Has the same composition as blood plasma, but without the cellular components and large proteins.
What percentage of tissue fluid is returned back to the blood vessels?
90%
How do substances enter the tissue fluid?
Substances pass through the fenestrations in the capillary walls
What is oncotic pressure?
Also called osmotic pressure, it is the pressure exerted by large proteins in the blood that makes water move into the blood by osmosis.
What is the name of the effect that large plasma proteins have?
Oncotic effect /osmotic effect.
What is the pressure that counteracts oncotic pressure?
Hydrostatic pressure.
What is the pressure that counteracts hydrostatic pressure?
Oncotic pressure.
What is the name of the end of the capillary that is closest to the artery?
The arterial end
What is the name of the end of the capillary that is closest to the vein?
The venous end
Describe the balance of the pressures at the arterial end of the capillary.
-Hydrostatic pressure is greater than oncotic pressure
-So more fluid is squeezed out of the capillaries than flows in
-So the net flow of liquid is out of the capillaries
Describe the balance of the pressures at the venous end of the capillary.
-Hydrostatic pressure is lower than oncotic pressure
-So more fluid moves back into the capillaries by osmosis than is squeezed out
-So the net flow of liquid is into the capillaries
What happens to the tissue fluid that does not return to the capillaries?
It drains into a system of blind-ended tubes called lymph-capillaries.
Compare the composition of lymph to tissue fluid
-More carbon dioxide
-Less oxygen
-More fatty acids
-Fewer nutrients
Why does lymph contain fatty acids?
Because it has been absorbed into the lymph from the villi of the small intestine
What lies along the lymph vessels?
Lymph nodes
What builds up in the lymph nodes?
Lymphocytes
What do lymphocytes do?
Produce antibodies, which are then passed into the blood
What does lymph nodes do?
-Allow the build-up of lymphocytes
-Intercept bacteria and other debris from the lymph, which are then ingested by phagocytes
What is the key role of the lymphatic system?
Defence mechanisms
What are enlarged lymphnodes a sign of?
That the body is fighting off an invading pathogen.
