Blood, tissue fluid and lymph Flashcards
What is the function of plasma in the blood?
yellow liquid that cazrries a variety of components including dissolved glucose, amino acids, ions and hormones
contains plasma proteins, erythrocytes and platelets
What are the functions of blood?
transport O2 to and CO2 from respiring cells
transport digested food
transport nitrogenous waste products
transport hormones and leucocytes
platelets to damaged areas
acts as a buffer to minimise pH changes
Why does water have a tendency to move into the blood?
plasma proteins, particulary albumin give the blood a high solute potential and a low water potential
terned oncotic pressure and is about -3.3kPa
What causes fluid to move out of the capillaries?
hydristatuc oressyre at the arterial end of the capillaries
higher than the oncotic pressure attracting water
fluid fills spaces between the cells and is called tissue fluid
What is tissue fluid composed of and what is its function?
same composition of plasma w/o erythrocytes and plasma proteins
diffusion takes place between the blood and the cells via the tissue fluid
How does water return to the vessels?
near the venous end the forces change
the hydrostatic pressure falls from 4.6kPa to around 2.3kPa
oncotic pressure becomes stronger than the hydrostatic pressure so water moves back into the capillaries as it approaches the venous end
90% of the tissue fluid returns to the vessels by the time the blood returns to the vein
How is lymph formed?
10% of tissue fluid does not return to the capillaries
it drains into a system of blind-ended tubes called lymph capillaries
What is lymph composed of?
similar to plasma but fewer oxygen and nutrients
also contains fatty acids that have been absorbed from the villi
How is lymph transport?
lymph capillaries join up to form larger vessels with valves
the fluid is transported through them by the squeezing of the body muscles
eventuall lymph returns to the blood flowing into the right and left subclavian veins
What is the function of lymph nodes?
along the lymph vessels are lymph nodes
lymphocytes build up in the lymph node when necessary and produce antibodies that are then passed into the blood
lymph nodes also intercept bacteria and other debris in the lymph which are ingested by phagocytes in the node
What does enlarged lymph nodes a sign of?
body is fighting off an invading pathogen
why doctors examine the neck, armpits and stomach or groin of their patients
these are some of the sites of the major lymph nodes
