Term | Definition |
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 |
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