types of circulatory systems - open/closed
- open circulatory system - found in mollusks, arthropods
- no difference between circulating/extracellular fluid
- hemolymph - collective name for the fluid
- closed circulatory system - circulating fluid (blood) always in vessels
- found in all vertebrates
circulatory system functions - transportation, regulation, protection
- interstitial fluid - plasma fluid that leaks out of capillaries
- some return to capillaries, some enter lymph vessels
- transportation - substances needed for cellular metabolism carried by circulatory system
- erythrocytes carry the hemoglobin which carry oxygen for respiration
- absorbed nutrients sent to cells throughout body
- metabolic wastes carried out of body
- regulation - hormones carried in blood to distant organs
- endotherms - warm-blooded vertebrates
- cold temperature >> vessels constrict >> warm blood goes to deeper vessels
- warm temperature >> vessels dilate >> warmth of blood lost through radiation
- countercurrent heat exchange - vessel w/ warm blood passes by vessel w/ cold blood
- protection - prevents injury from foreign microbes/toxins
- blood clotting >> prevents blood loss when vessels get damaged
- leukocytes (white blood cells) provide immunity against certain microbes
blood - made up of fluid plasma, different types of blood cells
- plasma - extracellular matrix w/ solutes
- contains metabolites (used by cells), ions (mainly Na, Cl), proteins (mostly albumin)
- globulins - carry lipids, steroid hormones
- fibrinogen - needed for blood clotting
- serum - plasma w/o fibrinogen
- erythrocytes (red blood cells) - carry oxygen through hemoglobin
- hematocrit - fraction of blood volume occupied by red blood cells (45% in humans)
- develops from stem cells (unspecialized cells)
- in mammals only, nuclei disappear
- leukocytes (white blood cells) - 1% of blood cells
- able to go outside of capillaries into interstitial fluid
- defends body against microbes
- platelets - help blood clot
- formed from cytoplasm of megakaryocytes
- reinforced w/ fibrin when blood vessel breaks
blood vessels - high pressure in arteries >> low pressure in veins
- arteries - carry blood away from the heart
- arterioles - smallest branches of arteries
- aorta - largest artery coming from heart
- veins - returns blood to the heart
- venules - smallest branches of veins
- venous pump - skeletal muscles around veins contract >> squeezes veins
- venous valves - makes sure blood only moves in 1 direction
- capillaries - thinnest/most numerous blood vessels, connects arterioles w/ venules
- lack elastin fibers, smooth muscle layers, and connective tissue layers found in arteries/veins
- blood can filter in/out
- every cell within 100 micrometers of capillary
- vasoconstriction >> increases resistance, decreases flow
- vasodilation >> decreases resistance, increases flow
- precapillary sphincters - rings of smooth muscle around arterioles, regulates blood flow through capillaries
- lymphatic system - interstitial fluid brings oxygen/nutrients to tissue cells
- blood pressure >> filter out of capillaries near arterioles
- oncotic pressure (osmosis due to plasma proteins) >> filter in to capillaries near venules
- lymph - fluid in the system
- returns excess blood in open circulatory system to closed
- drains into veins on sides of neck
- germinal centers - found in lymph nodes/organs, lymphocytes (type of white blood cell) created/activated
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