Chapter 29 Flashcards
What is angiogenesis?
-development of blood vessles
What are the functions of arteries, veins, and capillaries?
- arteries: conduct blood away from the heart
- veins: conduct blood toward the heart
- capillaries: small vessels that permit gas, nutrient, and waste exchange
What kinds of arteries are there?
- elastic
- muscular
- arterioles
What are the characteristics of all the different types of arteries?
- elastic: stretch and recoil without causing harm; accommodates blood that is forced out of the heart
- muscular: distributing arteries; carry blood to specific organs; smaller than elastic; thick muscular layer
- arterioles: resistance vessels; smallest arteries; divert blood to a specific area
What are examples of the different types of arteries?
- elastic: aorta and major branches; pulmonary arteries
- muscular: brachial artery, gastric artery, and superior mesenteric artery
- arterioles: not individually named
What are metarterioles?
-a vessel that connects an arteriole to a venule
What are precapillary sphincters? Function?
- smooth muscle cells that wrap around the entrance to a capillary
- increase or decrease blood flow to a capillary bed by dilation or constriction
What is a capillary?
- primary exchange vessels
- where the transfer of nutrients, gases, and waste occurs
- microscopic vessels
- carries blood from arterioles to venules
What kinds of capillaries are there?
- continuous capillaries
- fenestrated capillaries
- sinusoids
What are characteristics of continuous capillaries? Location?
- have a continuous lining of endothelial cells
- have small openings in the walls called intercellular clefts
- found in skeletal muscle, lungs, and connective tissue
What are characteristics of fenestrated capillaries? Location?
- have intercellular clefts
- also have small holes called fenestrations
- found in endocrine glands, kidneys, and small intestine
What are characteristics of sinusoids? Location? Function?
- incomplete basement membrane
- wider lumen
- large fenestrations
- found in bone marrow, liver, and lymph nodes
- allow blood cells to migrate
What are the characteristics of a vein?
- carries blood toward the heart
- receives blood from venules
- becomes larger towards the heart
- can stretch greatly
- maintains blood pressure
What is a venous sinus? Location?
- venous structure that contains no smooth muscle cells
- in dural venous sinuses of the brain and coronary sinus of the heart
What is a venule?
- small diameter
- receives blood from metarterioles
What types of tissues make up vessels? Function?
- endothelial tissue: smooth inside layer containing holes
- collagen fibers: protein strands that strengthen and provide support
- elastic fibers: allow for recoil after distention and maintains passive tension
- smooth muscle tissue: involuntary muscle that constricts or dilates blood vessels
What is unique about capillaries?
- they only have endothelium
- they only have tunica intima
What are the layers of a blood vessels?
- tunica externa
- tunica media
- tunica intima
What makes up each layer of a blood vessel?
- tunica externa: fibrous connective tissue; prevents tearing
- tunica media: smooth muscle and elastic fibers
- tunica intima: endothelium and basement membrane
How does the thickness of each layer compare in an artery and a vein?
- tunica externa: thickest layer of veins; thinner than arteries
- tunica media: very thick in arteries; much thinner in veins
- tunica intima: smooth in arteries; valves in veins
What are vasa vasorum?
- little vessels that supply the arteries
- they run in the tunica externa
What layer forms the valves in the veins?
-tunica intima
What is a portal system? Examples?
- blood passes through two consecutive capillary beds before returning to the heart
- hypophyseal portal system between hypothalamus and anterior pituitary
- hepatic portal system between the intestines and the liver
What is vascular anastomosis? Purpose?
- connection of blood vessels from one to another
- provides an alternate route for blood flow which may bypass a blocked vessel
