2.5 Flashcards
what does the cardiovascular system consist of
the heart, blood vessels and the blood which they contain
what is the function of the cardiovascular system
to exchange substances between different structures in the body and it’s environment
what is the central cavity of a blood vessel called
the central lumen
what is the central lumen lined with
a layer of cells called the endothelium
what do arteries do
carry blood away from the heart at a high pressure
arteries have _____ walls and a ______ lumen
THICK walls and a NARROW lumen
what does the outer layer of connective tissue contain (artery)
elastic fibres
what does the muscle wall contain (artery)
smooth muscle and elastic fibres
what do the arteries do to accommodate the surge of blood after each contraction of the heart
stretch and recoil
why do arteries recoil between beats
to maintain the high pressure of blood
how does the smooth muscle surrounding the arteries control blood flow
they contract causing vasoconstriction or relax causing vasodilation
what is vasoconstriction
when the smooth muscle on the arteries contract
what is vasodilation
when the smooth muscle on the arteries relax
what do veins do
carry blood back to the heart at a low pressure
veins have _____ walls and a _____ lumen
THIN walls and a WIDE lumen
do veins have valves
yes
why do veins have valves
to prevent back flow of blood as blood is moving and a low pressure and against gravity
what do capillaries do
allow the exchange is substances to occur between the blood and tissues
do capillaries have thick or thin walls
thin (very thin)
how many cells thick are the capillaries endothelium
one cell thick
why are the walls of capillaries so thin
to allow for efficient exchange of substances
what is blood composed of
red blood cells, white blood cells and proteins bathed in plasma
what is plasma
a watery yellow fluid
what does plasma contain
dissolved substances - eg:
- glucose
- amino acids
- respiratory gasses
- plasma proteins
