Survey
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Download File
Document related concepts
Transcript
Biology 12 10.1 The Blood Vessels The circulatory system has ____ types of blood vessels. • ____________: carry blood _________ from the heart to the capillaries • ____________: permit exchange of material with the tissues • ____________: return blood from the capillaries ____ the heart All three blood vessel types have an inner endothelium, a simple squamous epithelium attached to a connective tissue basement membrane that has elastic fibres. The Arteries The _________ artery in the body is the ________, which carries O2-rich blood _________ the heart to other parts of the body. The arterial wall has three layers. • Inner layer: ________________ • Middle layer: ___________ muscle that contracts and relaxes to regulate blood flow and pressure • Outer layer: ____________ connective tissue ________________ are small arteries that branch off from an artery. Arterioles have three layers. • Inner layer: endothelium • Middle layer: some elastic tissue but mostly smooth muscle o Smooth muscle contracts: blood vessel constricts, resulting in higher blood pressure o Smooth muscle relaxes: blood vessel relaxes, resulting in lower blood pressure • Outer layer: fibrous connective tissue The Capillaries Capillaries are ____________ blood vessels that join _____________ to ____________. • Composed of a _____________ layer of epithelium with a basement membrane • Form vast _______________ (capillary beds) throughout the body • Only certain capillary beds are ________ at any given time. • After ____________, capillary beds that serve the digestive system are ________, and those that serve the muscles are mostly ____________ Biology 12 • • • ______________ muscles relax to _________ the bed and allow blood flow Sphincter muscles contract to _________ the bed and prevent blood flow • When the bed is closed, blood flows through ________________ (arteriovenous shunts) ______________ from arterioles to venules, bypassing the bed ______________ of substances takes place across the ________ walls of the capillaries. • Oxygen and nutrients _____________ out of the capillary and into the tissue fluid that surrounds cells • ____________ (carbon dioxide) diffuse into the capillary • Some water _____________ the capillaries, and excess is picked up by _______________vessels The Veins Veins and _____________ (small veins) take blood _________ the capillary beds to the __________. • Veins and venules have the same ________ layers as arteries, but there is ________ smooth muscle and connective tissue • Veins have _________, which allow blood to flow toward the heart when open and ___________ blood from flowing backward when closed • Veins act as a blood ______________ • Since their walls are ____________, they can _____________ to a greater extent • About ___% of blood is in the veins • The largest veins in the body are the ____________ __________ (superior vena cava, inferior vena cava), which deliver O2-poor blood to the heart
