Circulation 2 Flashcards
what is the split between water and air breathers in craniates
- quite even split between both groups
how many circuits can a closed circulatory system have (2)
- single-circuit (most fishes)
- double-circuit (all birds & mammals)
what is the basic circulatory plan of vertebrates (8)
- muscular, chambered heart contracts to increase pressure of the blood
- blood flows away from heart into arteries
- arteries branch to form more numerous, but smaller diameter, arteries
- small arteries branch into arterioles within tissues
- blood flows from arterioles into capillaries
- capillaries coalesce to form venules
- venules coalesce to form veins
- veins carry blood to the heart
what occurs at the capillaries
- site of diffusion of molecules between blood and interstitial fluid
vertebrate blood vessels (2)
- complex wall surrounding a central lumen
- thickness of all varies among vessels
vertebrate blood vessel: layers (3)
- tunica intima
- tunica media
- tunica externa
vertebrate blood vessels: tunica intima (3)
- internal lining
- smooth, epithelial cells that make up a vascular endothelium
- in direct contact with the blood
vertebrate blood vessels: tunica media (3)
- middle layer
- smooth muscle
- elastic connective tissue to allow expansion and compression
vertebrate blood vessels: tunica externa (3)
- outermost layer
- collagen
- structural support against pressure
why are the arteries more muscular and elastic than veins (3)
- arteries must maintain and restrict blood pressure from the heart
- arteries must evenly distribute pressure to transport blood
- venous side has lower pressure system
large vein structure (6)
- largest diameter vessel of the venous system
- thin layers
- tunica externa
- tunica media
- tunica intima
- endothelium
vein structure (5)
- thin layers
- tunica externa
- tunica media
- tunica intima
- endothelium
venule structure (4)
- smallest vessel diameter of the venous system
- thin layers
- tunica externa
- endothelium
elastic artery structure (6)
- largest vessel diameter of the artery system
- thicker layers
- tunica externa
- tunica media
- tunica intima
- endothelium
muscular artery structure (4)
- thin tunica externa
- very thick tunica media
- thin tunica intima
- endothelium
arteriole structure (3)
- thin layers
- tunica media
- endothelium
capillaries structure and types (2)
- lack tunica media and tunica externa
- can be continuous, fenestrated, or sinusoidal
continuous capillaries (2)
- cells held together by tight junctions, blocking transport through cell junctions
- present in skin and muscle
fenestrated capillaries (3)
- cells contain pores, making them “leaky” for passive transport
- specialized for exchange
- present in kidneys, endocrine organs, and intestines
sinusoidal capillaries (2)
- few tight junction and most porous for exchange of large proteins
- present in liver and bone marrow
tank treading (2)
- when capillary diameter is less than RBC diameter
- forces RBC to squeeze through capillary to mix their contents