Ch 21 Blood vessel Anatomy Flashcards
What are vessels
tubes of muscle that blood flows through
Cardiovascular system vs Circulatory system
Cardio: Heart and blood vessels
Circle: Heart, blood vessels and blood
Arteries
carry blood away
Veins
Bring blood to the heart
3rd type of blood vessel
capillaries
Blood vessel walls layers are called
tunics
3 tunic layers
tunic interna
tunic media
tunic externa (adventita)
tunic interna
- Endothelium - simple squamous lining
- Sub endothelial layer - areola connective tissue
tunic media
- Smooth muscle (circular arrangement)
- Sympathetic activity causes contraction resulting in vasoconstriction
tunic externa
- Outer connective tissue - helps anchor blood vessel to surroundings
- Vasa vasorum
Aneurysm
- Weak region in artery or heart wall
common anuerysm locations
- Abdominal aorta
- Renal arteries
- Arterial circle at base of brain
Microscopic comparison of artery and vein
- Vein
- Open w blood dots
- Artery
- Tight and closed w blood dots in middle
Elastic artery
- Lots of fibers
- Largest diameter
- Walls contain elastic fibers throughout all tunicas
muscular arteries
- Medium cells w medium fiber
- Internal elastic lamina - between tunica intimate and media
- External elastic lamina - between tunica media and externa
Arterioles
- Very squamous looking
- Smallest arteries
- Have <6 cell layers of smooth muscle I tunica media
- Vasoconstriction is important prior to arriving to capillaries
muscular arteries examples
- Brachial
- Femoral
- Renal
- Splenic
Elastic artery examples
- Aorta
- Common carotid
- Brachiocephalic true
- Pulmonary trunk
- Common iliac
Capillaries
- The smallest blood vessels
- Diameter only slightly larger than erythrocyte
- Composed of tunica intima
Capillary beds
- Networks of 10-100 capillaries
- Supplied by a single arteriole that branch into a metarteriole
- At any given time 75% of body’s capillaries are shut down
- Pre capillary sphincters control flow in capillary beds supplied by metarterioles
3 types of capillaries
continuous
fenestrated
sinusoids
continuous capillaries
- Has thin arrow line and medium oval
- Most common type
- Endothelia cells have tight junctions
- Continuous tube
- Pericytes - contract and regulate blood flow
- Fenestrated capillaries
- Looks ribbed with small ovals
- Endothelia cells with small pores (fenestrations)
- Allow rapid fluid exchange, passage of only small molecules
Sinusoids capillaries
- Thick arrow line and thick oval
- Blood filled spaces with large fenestrations
- Allow passage of proteins (albumin), clotting factors, and new blood cells
fenestrated capillary location
- Located in kidneys and small intestine
sinusoid capillary location
- Example of location
- Liver, bone marrow, spleen
Veins
- Veins return blood to the heart
- At rest, veins hold 60% of the body’s blood
types of veins
venules
veins
large veins
venules
- Post capillary and muscular
- Smallest veins (10-30mm)
- Tunica intima with only a few fibroblasts around it
- Venues merge to form veins
- Small and medium veins
- Thin tunica media
- Thick tunica externa
- Tunica intima forms venous valves
- Skeletal muscle pump propels venous blood back to the heart
Large veins
- Thin tunica media wit moderate amount of smooth muscle
- Tunica externa is the thickest layer
large vein examples
- Vena cava (superior, inferior)
- Pulmonary veins
- Internal jugular veins
- Renal veins
Varicose veins
- Blood pools in the lower legs
- Cusps of the elves pull apart in enlarged veins
- Hereditary weakness, obesity, and pregnancy promote problems
- Hemorrhoids are varicose veins of the anal canal
