Final: 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
jawed vertebrates: circulatory system (2)
- all have closed systems
- structure varies depending on respiratory strategy (air vs water breathing)
water-breathing fish: circulatory system (3)
- closed system
- single circuit
- some fish have accessory hearts in the tail to help pump blood
air-breathing tetrapods: circulatory system (2)
- closed system
- two circuits
air-breathing tetrapods: two circuits (2)
- pulmonary circuit for perfusing lungs: right side of heart
- system circuit for perfusing other tissues: left side of heart
single-circuit, closed circulatory system: basics (2)
- blood leaving heart makes a single circuit before returning to the heart
- cardiac output passes through two, in-series capillary networks
single-circuit, closed circulatory system: in-series capillary networks (2)
- respiratory (gills; bronchial) capillaries for O2 uptake and CO2 excretion
- system (peripheral;tissue) capillaries for tissue O2 delivery and CO2 removal
single-circuit, closed circulatory system: vessel resistance (3)
- vessel resistant to blood flow in gills & tissue is additive
- Ohm’s Law
- a lot of pressure is needed to get through two capillary beds
fish hearts (3)
- two contractile chambers (cardiac muscle)
- two other cardiac chambers
- valves direct blood flow when chambers contract
fish hearts: two contractile chambers (3)
- atrium (thinner-walled) and ventricle (thicker-walled)
- wall thickness if indicative of the blood pressure it can generate
- chambers contract in sequence and generate sufficient blood pressure to propel blood around entire body
fish hearts: two cardiac chambers (2)
- sinus venosus and bulbus arteriosus
- located inside pericardial cavity
fish hearts: sinus venosus (2)
- elastic chamber that collects venous blood before it enters the atrium
- sinoatrial region is site of the cardiac pacemaker
fish hearts: bulbus arteriosus (2)
- elastic chamber connected to aorta
- takes deoxygenated blood to the gills
double-circuit, closed circulatory system: basics (2)
- blood returns twice to the heart to complete a circuit of the body
- contains two functional pumps in one heart, each having an atrium and ventricle
double-circuit, closed circulatory system: right side (2)
- right atrium and right ventricle pump deoxygenated blood to the pulmonary circuit
- low pressure system
double-circuit, closed circulatory system: left side (2)
- left atrium and left ventricle pump oxygenated blood into the systemic circuit
- high pressure system
double-circuit, closed circulatory system: benefits (2)
- two functional pumps can work at different blood pressures, but their flow outputs are identical
- don’t have to create sufficient pressure to go through two capillary beds
circulatory system: birds & mammals (3)
- heart chambers
- circuits & pressure
- blood mixing
- four-chambered heart: two atria and two ventricles
- system and pulmonary circuits are divided into two different pressure systems
- oxygenated and deoxygenated blood are completely separate
law of bulk flow
Q = △P/R
law of bulk flow: Q
- flow
law of bulk flow: △P
- pressure drop
law of bulk flow: R
- resistance
resistance formula
8Ln/πr^4
resistance formula: n
- viscosity of the fluid
Poiseuille’s equation
- more detailed version of law of bulk flow
- Q = △Pπr^4/8Ln
what does Poiseuille’s equation reveal (2)
- radius affects flow much more than length or other factors
- vasoconstriction and vasodilation will greatly affect flow
how can blood vessels be arranged (2)
- in series
- in parallel
resistance in series formula
Rt = R1 + R2 + R3…..
resistance in parallel formula
1/Rt = 1/R1 + 1/R2 + 1/R3 ….
flow (Q)
- volume of fluid transferred per unit time
blood velocity formula
blood velocity = Q/A
blood velocity: A
- cross-sectional area of the channels/vessels
how does the large cross-sectional area of the capillaries affect blood flow and diffusion (2)
- blood velocity through capillaries is very slow
- there is a longer time for diffusion to occur
