VASCULAR SYSTEM Flashcards
what is the vascular system made up of
Blood and blood vessels
what is blood made up of
45 % cells
- red blood cells (transports O2)
- white blood cells (immune system)
- platelets (blood clotting)
55% plasma
what is plasma made up of
92% water
7% proteins
electrolytes
nutrients
hormones
waste products
gases
what is the role of blood
transportation - oxygen, glucose, lipids, amino acids, vitamins, hormones
regulation - temperature, pH
protection - immune system
homeostasis - thermoregulation
name the blood vessels
arteries
arterioles
capillaries
venules
veins
what are the characteristics and their functions of the arteries
thick walls - to withstand high pressure
elastic walls - allows for stretching (maintaining blood pressure)
smooth muscle - can vaso constrict/dilate to control blood flow
narrow lumen - maintains high blood pressure
no valves - high pressure maintains blood flow in 1 direction
what is the mains roles of the arteries
transport oxygenated blood to tissues
maintain blood pressure
distribution of blood - e.g. to the working muscles during exercise
tissue oxygenation
what are the characteristics of the arterioles
smaller than arterioles
smooth muscle
less elastic
narrow lumen
no valves
what are the roles of arterioles
regulate blood flow
control blood pressure
direct blood to capillaries
redistribute blood during exercise
what are the characteristics of the capillaries
small and thin
large surface area
narrow lumen
permeable walls
no valves or muscle
what is the role of capillaries
exchange of substances
- O2 and CO2
- nutrients
- waste products
- support working muscles during exercise
- link arterioles to venules
- regulate temperature
what are the characteristics of venules
capillaries>venules>veins
thin walls
less smooth muscle
no valves
what is the role of venules
collect deoxygenated blood
transport waste products
regulate blood flow to veins
facilitate recovery post exercise
what is the characteristics of veins
thin walls
larger lumen
valves
less elastic
surrounded by skeletal muscle
what is the role of veins
return deoxygenated blood to the heart
contain blood reservoirs
air venous return
prevent backflow
facilitate recovery
why are veins the only blood vessels with valves
they have the lowest pressure so they need help getting the deoxygenated blood back to the heart.
the valves only allow blood to flow in 1 direction and prevent backflow
what is vascular shunt
the redistribution of blood during exercise.
at rest:
80% of blood goes to the ‘non essential organs’ (stomach, kidney, liver)
20% of the blood to the ‘‘working muscles’’
during exercise:
20% of blood goes to the non essential organs (stomach, kidney, liver)
80% of blood now goes to the working muscles
how does the redistribution of blood happen
by vasoconstriction, vasodilation and widening, narrowing of pre-capillary sphincters
EXAM Q:
how does the redistribution of blood during exercise happen
-vasodilation (widening of blood vessels) of the arteries/arterioles towards the working muscles occurs, in order to meet the higher oxygen demand.
-vasoconstriction (narrowing of the blood vessels) of the arteries/arterioles towards the non essential organs occurs at they don’t demand as much oxygen during exercise.
-the precapillary sphincters (small rings of smooth muscle located at the entrance of capillary beds, either constrict (towards non essential organs) or dilate (towards the working muscles), in order to allow more blood to where it needs to be.
How does vascular shunting change blood flow?
at rest, 80% of blood goes to the non essential organs (kidneys, liver, stomach), to carry out normal bodily functions e.g. digestion, and 20% goes to the ‘working’ muscles. once exercise starts, this changes to 80% to the working muscles and 20% to the non essential organs. this is due to the higher oxygen demand at the working muscles, this happens via vasodilation, vasoconstriction and the narrowing and widening of pre-capillary sphincters.
what is the importance of vascular shunting
- increases supply of o2 to working muscles
- removes waste products - co2
- gets more blood to skin - thermoregulation
- gest more blood back to the heart
