Blood Vessels and Circulation ➢ smooth muscle with elastin and collagen
fibers
Blood vessels outside the heart are divided into two 3. Tunica adventitia:
classes: ➢ outermost layer
➢ connective tissue
Pulmonary vessels - which transport blood from the
right ventricle of the heart through the lungs and Types of Arteries
back to the left atrium 1. Elastic arteries:
➢ largest in diameter
Systemic vessels - which transport blood from the ➢ thickest walls
left ventricle of the heart through all parts of the ➢ Example - aorta and pulmonary trunk
body and back to the right atrium 2. Muscular arteries:
➢ medium to small size
Blood Flow Through the Circulatory System ➢ thick in diameter
The circulatory system has pulmonary ➢ contain smooth muscle cells
circulation to lungs and systemic circulation to ➢ can control blood flow to body regions
body. Blood from the heart circulates to head
where oxygen is taken up and carbon dioxide is Capillaries
released to the tissue capillaries which then ➢ Blood flows from arterioles into capillaries
comes back to the right side of the heart. From ➢ Capillaries branch to form networks
the right-side blood enters the left lung where ➢ Blood flow is regulated by smooth muscle
oxygen is taken up and carbon dioxide is cells, precapillary sphincters
released out. Blood from the heart also
Capillary Structure
circulates to tissues of lower body along with
Walls consist of only a simple endothelium
liver, digestive tract, kidney where oxygen is
taken up and carbon dioxide is released into the surrounded by delicate loose connective
tissue capillaries. tissue.
Blood Vessel Functions Types of Veins
✓ Carry blood Blood flows from capillaries into venules
✓ Exchange nutrients, waste products, gases Blood flows from venules into small veins
within tissues All 3 tunics are present in small veins
✓ Transport substances
✓ Regulate blood pressure 1. Medium sized veins:
✓ Direct blood flow to tissues ➢ collect blood from small veins and deliver to
large veins
Vessel Structures 2. Large veins:
Arteries: ➢ contain valves
➢ carry blood away from heart
➢ thick with a lot of elastic tissue Valves
Veins: The valves keep blood moving through the
➢ carry blood toward heart heart in the right direction. The mitral valve
➢ thick with less elastic tissue and tricuspid valve are located between the
atria (upper heart chambers) and the ventricles
Capillaries: (lower heart chambers).
➢ exchange occurs between blood and tissue
fluids Pulmonary Circulation Vessels
1. Pulmonary circulation:
Blood Flow ➢ blood vessels that carry blood from right
Blood flows from arteries into arterioles ventricle to lungs and back from left atrium
Arterioles into capillaries of heart
Capillaries into venules 2. Pulmonary trunk:
Venules to small veins ➢ Carries blood from right ventricle towards
Veins return to heart lung
Blood Vessel Walls 3. Pulmonary veins:
1. Tunica intima: ➢ exit lungs and carry O2 rich blood to left
➢ innermost layer atrium
➢ simple squamous
2. Tunica media:
➢ middle layer
fibers
Blood vessels outside the heart are divided into two 3. Tunica adventitia:
classes: ➢ outermost layer
➢ connective tissue
Pulmonary vessels - which transport blood from the
right ventricle of the heart through the lungs and Types of Arteries
back to the left atrium 1. Elastic arteries:
➢ largest in diameter
Systemic vessels - which transport blood from the ➢ thickest walls
left ventricle of the heart through all parts of the ➢ Example - aorta and pulmonary trunk
body and back to the right atrium 2. Muscular arteries:
➢ medium to small size
Blood Flow Through the Circulatory System ➢ thick in diameter
The circulatory system has pulmonary ➢ contain smooth muscle cells
circulation to lungs and systemic circulation to ➢ can control blood flow to body regions
body. Blood from the heart circulates to head
where oxygen is taken up and carbon dioxide is Capillaries
released to the tissue capillaries which then ➢ Blood flows from arterioles into capillaries
comes back to the right side of the heart. From ➢ Capillaries branch to form networks
the right-side blood enters the left lung where ➢ Blood flow is regulated by smooth muscle
oxygen is taken up and carbon dioxide is cells, precapillary sphincters
released out. Blood from the heart also
Capillary Structure
circulates to tissues of lower body along with
Walls consist of only a simple endothelium
liver, digestive tract, kidney where oxygen is
taken up and carbon dioxide is released into the surrounded by delicate loose connective
tissue capillaries. tissue.
Blood Vessel Functions Types of Veins
✓ Carry blood Blood flows from capillaries into venules
✓ Exchange nutrients, waste products, gases Blood flows from venules into small veins
within tissues All 3 tunics are present in small veins
✓ Transport substances
✓ Regulate blood pressure 1. Medium sized veins:
✓ Direct blood flow to tissues ➢ collect blood from small veins and deliver to
large veins
Vessel Structures 2. Large veins:
Arteries: ➢ contain valves
➢ carry blood away from heart
➢ thick with a lot of elastic tissue Valves
Veins: The valves keep blood moving through the
➢ carry blood toward heart heart in the right direction. The mitral valve
➢ thick with less elastic tissue and tricuspid valve are located between the
atria (upper heart chambers) and the ventricles
Capillaries: (lower heart chambers).
➢ exchange occurs between blood and tissue
fluids Pulmonary Circulation Vessels
1. Pulmonary circulation:
Blood Flow ➢ blood vessels that carry blood from right
Blood flows from arteries into arterioles ventricle to lungs and back from left atrium
Arterioles into capillaries of heart
Capillaries into venules 2. Pulmonary trunk:
Venules to small veins ➢ Carries blood from right ventricle towards
Veins return to heart lung
Blood Vessel Walls 3. Pulmonary veins:
1. Tunica intima: ➢ exit lungs and carry O2 rich blood to left
➢ innermost layer atrium
➢ simple squamous
2. Tunica media:
➢ middle layer
