Chapter 19 Blood Vessels Flashcards
The Cardiovascular system consists of
the heart and blood vessels
There are about ___ miles of blood vessels in the body and the blood vessels are made of ____
- 60,000 miles
2. Living Cells
Arteries
carry blood away from the heart
- narrow lumen compared to veins
- thicker walls than veins
Veins
carry blood toward the heart
- wider lumen than arteries
- have thinner walls compared to arteries
Capillaries
exchange sites
3 Main Parts of The Vascular System
- Arterial System
- Capillaries
- Venous System
Arterial System
High Pressure System, thickest layer is tunica media, all layers have more elastic fibers
- Elastic Arteries- (1-2.5 cm diameter) conducting arteries, has much elastic fibers for stretch + recoil
ex: aorta, pulmonary arteries - Muscular Arteries- (0.3mm- 1cm diameter (smaller)) distributing arteries (distribute blood to specific parts of the body/organs)
- tunica media cause changes in diameter (vasoconstriction + vasodilation)
ex: brachial and radial arteries - Arterioles (10 micrometers- 0.3 mm (smallest diameter blood vessel)
- resistance vessels
- affects blood pressure
- carry blood to specific capillary beds
- vasoconstriction + vasodilation to distribute blood to specific capillary beds
Arterial System: Elastic Arteries
Size: (1-2.5 cm diameter) widest diameter artery
- conducting arteries
- has much electric fibers for stretch + recoil
ex: aorta, pulmonary arteries
Arterial System: Muscular Arteries
Size: (0.3mm- 1 cm diameter) smaller
- distributing arteries (distributing blood to specific parts of the body/ organs)
- tunica media causes changes in diameter(vasoconstriction + vasodilation)
- ex: brachial + radial arteries
Arterial System: Arterioles
Size: (10 micrometers- 0.3mm) smallest diameter blood vessel
- resistance vessels; affects blood pressure
- vasoconstriction + vasodilation to distribute blood to specific capillary beds
The Walls of Arteries and Veins have 3 Layers
- Tunica Interna- endothelial cells
- Tunica Media- smooth muscle cells
- Tunica externa- collagen and elastic fibers
Blood Flows through the hollow part called the
Lumen
Layer of the wall from arteries and veins: Tunica Interna
lined with endothelial cells
-innermost layer
Layer of the wall from arteries and veins: Tunica Media
made of smooth muscle tissue
- middle layer
- has ability to change diameter of blood vessel
- causes Vasoconstriction- when the tunica media shorten–> causes lumen to narrow
- causes Vasodilation- lumen widens, increasing blood flow
Layer of the wall from arteries and veins: Tunica Externa
made of connective tissue fibers like collagen and elastic fibers
-outermost layer
Capillary walls have only 1 layer:
Tunica Interna
Capillaries
exchange sites
- medium pressure
- only has layer tunica interna- thin walls
- size: 5-10 micrometers in diameter
- tight junctions join cells together
- Clefts- gaps between neighboring cells; makes capillaries permeable (leaky)
3 Types of Capillaries
- Continuous Capillaries
- Fenestrated Capillaries
- Sinusoids
Type of Capillary: Continuous Capillaries
- least permeable (less leaky)
- has more tight junctions + clefts
- most common in skin + muscles
Type of Capillary: Fenestrated Capillaries
- very permeable
- has pores to allow materials to go through walls of capillaries
- have clefts
- fewer tight junctions
- found in: small intestine and kidney filtration membranes
Type of Capillary: Sinusoids
- extremely permeable
- large pores and clefts
- fewest tight junctions
- found in Red bone marrow (where hemopoiesis happens)
- allows whole cells to cross (RBC, WBC , platelets)
- found in spleen (macrophages in spleen that remove damaged RBCs
- found in liver (macrophages remove bacteria)
- big cells move through sinusoids
Venous System
- lowest pressure
- have wide lumens
- thin walled
- tunica externa is the thickest layer
- blood reservoirs of the vascular system; holds about 65% of total blood supply (all blood)
The Venous System Consists of
- Venules
- Veins
- Venous Sinuses
The Venous System: Venules
size: 8 micrometers- 0.1 mm in diameter
- carries blood away from capillary beds; join together to make larger diameter blood vessels to make veins
The Venous System: Veins
size: 0.1mm- 4cm in diameter
- valves present in veins prevent backflow from low pressure
The Venous System: Venous Sinus
specialized, broad veins supported by surrounding tissue, unique because it has only tunica interna
- has 1 layer- tunica interna
ex: dural sinus (in brain; drains cerebral spinal fluid CSF and blood from brain)
ex: coronary sinus (in heart) drains blood from myocardium
Anastomosis
(detour)
alternate pathways for blood to reach specific tissue or organ (incase their is a blockage because blood needs to keep flowing and moving to the heart)
