Blood is a bright red in its oxygenated form (i.e., leaving the lungs). It's a dark red in its deoxygenated form (i.e., returning to the lungs). Veins appear blue because light, penetrating the skin, is absorbed and reflected back to the eye. Since only the higher energy wavelengths can do this (lower energy wavelengths just don't have the *oomph*), only higher energy wavelengths are seen. And higher energy wavelengths are what we call "blue."
When blood LEAVES the heart, it travels through arteries.
Right ventricles pumps to lungs
Left ventricle pumps blood through aorta
Organs get blood from arteries that branch off aorta
First vessels that branch off the aorta
Carry blood to the heart
Innermost: Epithelial Tissue
Middle: Muscle Tissue
Outer Wall: Flexible Connective Tissue
Tiny blood vessels that receive blood from the arteries
It is here that substances are exchanges between the blood and body cells
Diffusion: high concentration to low
Ex: glucose into cells
From capillaries, these vessels carry blood BACK to the heart
Thinner than arteries
Blood Flow in Veins
Less force than when in arteries
Help move blood
1. Muscles inside veins contract and move blood along
2. Skeletal muscles nearby contract and move blood along
3. Larger veins have valves to prevent backwards flow
Pressure = force exerted over an area
BP = blood exerting pressure against walls of blood vessels
Caused by = force with which ventricles contract
As blood moves away from the heart, the pressure lowers. Why?
Highest in arteries, lowest in veins.
Sphygmomanometer = instrument used
Expressed with 2 numbers in mm of Mercury
1st number: measure of BP while ventricles contract
2nd number: lower, MP while ventricles relax
Typical young BP: 120/80
Expansion and relaxation of the artery wall
When ventricle contracts, it squirts blood through arteries in the body & walls expand.