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Chapter 21

Vessels

TermDefinition
Vessels heart and blood vessels form a closed-loop system blood constantly pumped to and from tissues vessels can pulsate and change shape according with bodys needs
Blood Vessels share names with body region systemic=body (extend to & from body tissues) pulmonary=lungs (blood to lungs for gas exchange)
3 types of blood vessels Arteries (carry blood away) Veins (carry blood to heart) Capillaries (connection between smallest arteries and veins) Nutrients, waste, and gases exchange
Artery thick, elastic wall, small lumen must withstand forceful cardiac contractions resilient & strong; largest closest to heart, smallest further away
Vein thin wall, large lumen, valves stretchable; not subjected to high pressure small at beginning and large towards the heart
Capillary single cell wall
Blood vessel layers are tunics Tunica Intima (innermost) simple squamous, produces vasoconstrictors and vasodilators( chem.) Tunica Media (middle ) smooth muscle; thickest layer; allows changes in diameter Tunica Externa (outer) Strong; flexible thickest in veins; thin in arteries
Aneurysm weakened arterial wall MC cause in atherosclerosis + high blood pressure MC sites are aorta, renal arteries, circle of Willis at base of brain Pain/ death due to pressure in surrounding nerves, tissues, & organs
Conducting & Disturbing Arteries Conducting(largest, closest to heart, Elastic) Aorta, Carotid, & Subclavian Disturbing(median size, Most Common) Brachial, femoral, & renal
Arterioles Smallest arteries, resistance vessels cuz of flow resistant using smooth muscle contractions help regulate blood pressure & control how much blood enters an organ connected to capillaries(metarterioles)
Venules & Medium-sized Veins smallest veins, collect blood from capillaries, thin walls, porous; can exchange fluid with surrounding tissues venules converge, have thicker and more elastic walls one-way flow to prevent backflow & help fight gravity in legs
large veins formed medium size veins converge on the heart thick tunica externa
Cappilaries for Exchange microscopic vessels connecting arterioles & venules site of gas, hormone, and waste exchange small diameter- one cell at a time (4-6 cell width)
Capillary Organization into beds network connectings microcirculation
precapillary Sphincter 'beaver dam' band of smooth muscle that adjusts blood flow during exercise(+ oxygen) OPEN during rest(-oxygen)CLOSE allows blood to bypass the network & head straight to venule on the throughfare channel
3 types of capillaries Continuous (uninterrupted lining; only allows small molecules) Fenestrated (tiny windows in the endothelial lining; small molecules & limited amounts of protein) Sinusoid (open-pore capillaries with increased permeability; allows RBCs, WBCs, serum
Capillary Exchange moving oxygen, glucose, hormones, and nutrients out taking up waste gases & substances needing transport to other parts of body Glucose=liver, Calcium=bones, antibodies=immune cells, hormones=endocrine glands
3 mechanisms of capillary exchange diffusion=gases only filtration=hydrostic pressure(heartbeat) osmosis=osmotic pressure(water to salt)
Edema fluid filters out of capillaries faster than it can be absorbed and builds up in tissues 3 causes: increased capillary filtration, reduced capillary reabsorption, & obstructed lymphatic drainage
Portal Systems when blood flows through two networks (capillaries) than one as usual 2 major circulation pathways: somatic & Pulmonary
Created by: Asuzenam