Lecture 8 Flashcards
Major types of blood vessels (3)
- Arteries
- Capillaries
- Veins
Arteries
Carry blood away from heart
Capillaries
The smallest blood vessels
RBC pass through single file
Site specific functions
Veins
Recieve blood from venules and bring it back to heart
Three layers of blood vessels
Called tunics
- Tunica intima
- Tunica media
- Tunica externa
Tunica intima
Innermost and comprises of simple squamous epithelium
Tunica media
Sheets of smooth muscle and elastic fibers
Vasocontraction/dilation
Tunica externa
Composed of connective tissue and vasa vasorum
Vase vasorum
Blood vessels to supply blood vessels
Types of arteries (3)
- Elastic
- Muscular
- Arterioles
Elastic arteries
Largest arteries
Includes aorta and major branches
Sometimes called conducting arteries
High elastin content (dampens surge of blood pressure)
Allows for continuous blood supply to tissue (instead of intermittenly due to pumping)
Muscular arteries
Distributing arteries
Lie distal to elastic arteries
Includes most named arteries
Tunica media is thick
Types of capillaries (3)
- Continuous
- Fenestrated
- Sinusoid
Continuous capillary
Least permeable, most common
Intercellular clefts: tight
Fenestrated capillary
Large fenestrations, increased permeability
Occurs in areas of active absorption or filtration
Sinusoid capillary
Most permeable
Occurs in specialized locations (liver, bone marrow, spleen)
Wide open intercellular cleft
Venules
Smallest veins, join to form veins
Veins
Larger lumen then arteries
Thicker tunica externa
Less elastin in walls
Walls thinner than comparable arteries
Valves
Prevent backflow of blood