Biology: Circulatory System Flashcards
Where is the blood in a closed circulatory system?
confined to vessels only
Where is blood in an open circulatory system?
blood pumped into cavity, not confined to blood vessels
What are the two types of circulatory system?
-open -closed
What are the two forms of a closed circulatory system?
-single -double
What does a single circulatory system consist of?
a heart with two chambers
How does blood flow in a single circulatory system?
blood flows through heart ONCE for every circuit of the body
What does a double circulatory system consist of?
a heart with four chambers
How does blood flow in a double circulatory system?
blood flows through heart TWICE for every circuit of the body
What vessels provide the heart with its own blood supply?
coronary arteries
Outline the structure of the blood vessel system
-arteries branch into arterioles -arterioles form network throughout body -arterioles branch into capillaries -capillary networks in tissue form capillary bed -capillaries pass blood into venules -venules join to veins
What is the function of the smooth muscle layer in blood vessels?
contracts to control blood flow
What is the function of the elastic layer in blood vessels?
allows vessels to stretch and recoil
What is the function of the endothelium in blood vessels?
smooth inner lining which reduces friction
Where do arteries carry blood?
away from the heart
How are arteries structured?
-narrow lumen, high pressure -thick muscular walls and elastic layer for stretch, recoil and high pressure -endothelium folded for stretching and maintaining high pressure
Where do veins carry blood?
towards the heart
How are veins structured?
-wide lumen, low pressure -thin muscular walls and elastic layers -valves to prevent back flow
-skeletal muscles contract, veins compress to increase pressure
What are capillaries the site of?
substance exchange within cells
How are capillaries adapted to their function?
-close to cells, short diffusion distance -one cell thick, short diffusion distance
-fenestrations between endothelial allows substances to diffuse out -many capillaries, increase surface area -small diameter, slow red blood cells and increase diffusion time
