M3 - BLOOD VESSELS AND TISSUE FLUID Flashcards
(10 cards)
What do arteries do
Carry blood away from the heart to various organs of the body
Artery structure and why
Thick muscular wall w lots of elastic tissue - high oeessure from heart
Endothelium (inner lining of heart) is folded, allowing artery to expand and withstand pressure
Small lumen - ensures high pressure maintained
What do veins do
Carry blood from the organs of the body towards the heart
Vein structure and why
Blood flows at low pressure - large lumen and thinner
Valves prevent slow moving blood flowing back
Contraction of nearby muscles help blood to flow through veins
What do capillaries do
Connects arteries and veins
Substances will move out of blood into body tissues
waste produces will move out of body tissues into capillaries
Capillary structure and why
Pores enable exchange of substances
Walls are one cell thick - reduce diffusion distance
What is tissue fluid
Fluid that bathes cells in tissues
Made up of substances small enough to move out of capillary
Contains waste products released from cells
Doesn’t contain things that are too big to be forced out capillary - no red blood cells or large proteins
What happens at the arteriole end of the capillary (start of tissue fluid)
Hydrostatic pressure in capillary exceeds that of tissue fluid
Fluid and dissolved substances force out of capillary (down pressure gradient) and into spaces around the cells
THIS IS FORMATION OF TISSUE FLUID
What happens at the venue end of the capillary
Bc water moved out at artierioe end, water potential lower inside capillary compared to tissue fluid
Water moves into capillary by osmosis down water potential gradient
What happens to excess tissue fluid
Excess tissue fluid drains into lymphatics system which ebentualkt returns fluid back into the bloodstream
