3.1.2 d blood, tissue fluid and lymph Flashcards
what is the main transport medium of the human circulatory system?
blood
what does blood consist of?
plasma
what does plasma carry?
dissolved glucose
amino acids
mineral ions
hormones
large plasma proteins- albumin, fibrinogen, globulins
red blood cells
white blood cells
platelets
what are platelets?
fragments of large cells called megakaryocytes found in the red bone marrow and they clot
how much of the blood does plasma make up?
55% of the blood by volume
what are some functions of the blood?
transport oxygen, carbon dioxide, digested food, nitrogenous waste, chemical messages, food molecules from storage compounds, platelets, cells and antibodies involved in immune response
maintenance of steady body temperature and acts as a buffer
what is oncotic pressure?
tendency of water to move into the blood by osmosis
what do the plasma proteins do to the blood?
give blood in capillaries a high solute potential and a low water potential so water moves into the blood in the capillaries
what is hydrostatic pressure?
blood flowing through the arterioles into the capillaries is still under pressure from the surge of blood due to heart contraction
what happens when blood from arterioles is still under pressure?
hydrostatic pressure forces fluid out of the capillaries at 4.6 kPa which is higher than oncotic pressure that is attracting water in so fluid is squeezed out of the capillaries
tissue fluid fills the spaces between the cells
what is tissue fluid?
fills spaces between the cells after the water is squeezed out by the hydrostatic pressure
what is tissue fluid made of?
same composition as plasma but no red blood cells or plasma proteins so diffusion still takes place between blood and the cells through tissue fluid
what happens as the blood moves through the capillaries towards the venous system?
hydrostatic pressure falls and pulse is lost
oncotic pressure becomes stronger than hydrostatic pressure
water moves back into the capillaries by osmosis as it approaches the venous end
blood returns to the veins, 90% of the tissue fluid is back in the blood vessels
what is lymph?
10% of the liquid that leaves the blood vessels and drains into the system of blind-ended tubes called lymph capillaries
what is the composition of lymph?
similar to plasma but has less oxygen and fewer nutrients
contains fatty acids absorbed from the villi
how is fluid transported through the lymph?
lymph capillaries join up to form larger vessels
fluid transported by squeezing of body muscles
one-way valves stop back flow
eventually lymph returns back to the blood flowing into the right and left subclavian veins
what are beside the lymph vessels?
lymph nodes
what build up in the lymph nodes?
lymphocytes
what do lymphocytes do?
produce antibodies when necessary and intercept bacteria and other debris from the lymph which are ingested by phagocytes found in the nodes
what are enlarged lymph nodes a sign of?
body fighting off an infection
