8.3 Blood, tissue fluid & lymph Flashcards
What makes up blood
plasma/ erythrocytes ( red blood cells) , platelets and leucocytes (white blood cells)
Functions of blood
To transport:
- oxygen to and CO2 from respiring cells
- digested food from small intestine
- nitrogenous waste products from cells to excretory organs
- hormones
-food molecules to storage compounds
- platelets to damaged area
- cells and antibodies in immune response
What is oncotic pressure?
form of osmotic pressure, caused by plasma proteins, especially albumin that causes a pull on fluid e.g. water back into capillaries
–> this is because plasma protein conc makes blood in capillaries have a low water potential (high solute conc)
Substances disdolved in plasma can pass through ..?
through fenestrations in capillary walls (small holes)
Hydrostatic pressure
Pressure from the surge of blood due to the heart contracting
In the arterial end, describe the various pressures
At the arterial end of the capillary,
- HYDROSTATIC pressure forcing fluid out of capillaries is high
- HIGHER than ONCOTIC pressure that attracts water in via osmosis
–> fluid is squeezed out of capillaries
What is tissue fluid
fluid that fills spaces between cells
–> same composition as plasma without the red blood cells and plasma proteins
In the venous end, describe the various pressures
At the venous end of the capillaries,
- HYDROSTATIC pressure is low
- LOWER than ONCOTIC pressure (oncotic stronger)
–> water moves back into the capillaries via osmosis
By the time blood returns to the veins, how much tissue fluid is back in blood vessels?
What happens to the remaining %?
by the time blood returns to veins, 90% of tissue fluid returns to blood vessels
the remaining 10% drains into a system of blind-ended tubes called lymph capillaries (tissue fluid is now called lymph)
What is lypmh?
similar composition to plasma and tissue fluid but has less oxygen and fewer nutrients
–> contains fatty acids (have been absorbed into lymph from villi of small intestine)
How is lymph transported throughout the body?
fluid is transported through lymph capillaries by the squeezing of the body muscles
–> they have one way valves to prevent backflow of lymph
Where in the body does the lymph return to?
to the blood, flowing into right and left subclavian veins under clavicle
What are lymph nodes?
sac-like organs that trap pathogens and contain a large number of white blood cells
Function of lymph nodes
lymphocytes build up in lymph node when necessary & produce antibodies which are passed into blood
–> can also intercept bacteria and other debris from lymph (these get ingested by phagocytes)
What can an enlarged lymph node represent?
sign that body is fighting off an invading pathogen
