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33 Cards in this Set
- Front
- Back
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Basic structure of heart |
- four chambers atrium + ventricle left + right - atrium thin walled + elastic - ventricle thicker muscular wall - two pumps needed for high pressure: loses pressure when it goes through lung capillaries - left ventricle thicker wall |
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What is connected to what chamber |
- Aorta: connected to L ventricle + carries oxygenated blood around body - Vena Cava: connected to R atrium + bring deoxygenated blood back from tissues of body - pulmonary artery: brings deoxygenated blood to the lungs from R ventricle - Pulmonary vein: brings oxygenated blood from lungs to L atria |
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Coronary arteries |
- branch off aorta + supply heat w blood, if blocked causes heart attack |
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Stages of heart beat |
- Diastole - atrial systole - ventricular systole |
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Diastole |
- blood returns to heart through Pulmonary vein + Vena Cava - as atria fills, pressure ^, when pressure > than that in ventricles -> av valves open - walls of ventricle relax causing them to recoil and decrease pressure - pressure lower than in aorta/p artery so semi lunar valves close |
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Ventricular systole |
- After short delay -> ventricular walls contract simultaneously - ^ blood pressure shuts av valves preventing backflow to atria - av valves closing ^ pressure in ventricles, once it exceeds that of aorta and pulmonary artery, blood forced into them |
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Valves |
- Atrioventricular valves: prevent backflow when contraction means ventricular pressure greater than than in atria - semilunar: prevent backflow when blood pressure in pulmonary artery + aorta greater than that in ventricles, happens when their elastic walls recoil whilst the ventricle walls relax - pocket valves: occur in veins, when veins are squeezed they ensure blood stays flowing towards heart |
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Why valves needed |
- needed for situations when pressure differences would result in blood flowing in opposite direction |
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Types of blood vessels |
- Arteries: carry blood away from heart + into arterioles - arterioles: are smaller arteries that control blood flow from arteries to capillaries - capillaries: are tiny vessels that link arterioles to veins - veins: carry blood from capillaries back to heart |
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Layered structure of blood vessels |
- muscle layer: can contract + so control flow of blood - tough fibrous outer layer: resists pressure changes from inside/outside- muscle layer: can contract + so control flow of blood- elastic layer: stretches and recoils to maintain high pressure- thin inner lining: smooth to reduce friction, thin for diffusion - lumen: central cavity of vessel which blood flows through high pressure outside- muscle layer: can contract + so control flow of blood- elastic layer: stretches and recoils to maintain high pressure- thin inner lining: smooth to reduce friction, thin for diffusion - lumen: central cavity of vessel which blood flows through - elastic layer: stretches and recoils to maintain high pressure- thin inner lining: smooth to reduce friction, thin for diffusion - lumen: central cavity of vessel which blood flows through - thin inner lining: smooth to reduce friction, thin for diffusion - lumen: central cavity of vessel which blood flows through |
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Artery structure |
Function is to transport blood rapidly under ^ pressure - muscle layer thick compared to veins: means smaller arteries can be constricted + dilated to control vol of blood passing through - elastic layer thick: bp kept ^ to reach all body, stretched during systole + recoil at diastole - overall thickness great: resist vessel bursting due to pressure - no valves: not needed due to constant high pressure |
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Arteriole structure |
Function is to carry blood under lower pressure than arteries from arteries to capillaries - muscle layer R thicker than arteries: contraction of this layer allows constriction of the lumen -> restricts flow of blood, controlling it's movement into capillaries - elastic layer relatively thinner than Arteries as bp lower |
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Vein structure |
Carry blood slowly under low pressure from capillaries in tissues to the heart - muscle layer R thin compared to arteries: veins carry blood away from tissue -> their constriction/dilation cannot control flow of blood to the tissues - elastic layer thin: low bp cant cause veins to burst - thickness small: pressure low, allows vein to flatten - valves throughout: stop backflow due to low bp |
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Capillary structure |
Function to exchange metabolic materials between blood+cells, slow blood flow - walls consist mostly of lining layer: very thin so short diffusion pathway - numerous + highly branched: provide large SA for exchange - lumen very narrow: short diffusion path - spaces within lining cells: allow WBC to escape to deal w infections in tissues |
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Tissue fluid |
- watery fluid that contains glucose, amino acid, fatty acids, oxygen - supplies this to tissue, receives co² and other waste - formed from blood plasma |
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Formation |
- pumping of heart creates hydrostatic pressure at arterial end of capillary -> cause tissue fluid to move out the blood plasma, this opposed by: * Hydrostatic pressure of tissue fluid outside capillaries * Lower WP of blood due to proteins causing water to move back into blood |
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Ultrafiltration |
- pressure that pushes tissue out at artenial end only enough to force small molecules out, big molecules can't go through membrane |
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Return of tissue fluid to circulatory system |
- loss of tissue fluid in capillaries reduces it hydrostatic pressure - as a result by time blood reaches venous end of capillary network it's hydrostatic pressure is lower than tissue fluid outside - so tissue fluid forced back into capillaries by higher hydrostatic pressure outside - in addition plasma has lost water + still has proteins -> lower WP than tissue outside - water leaves tissue by osmosis down gradient |
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Lymphatic system |
- not all tissue fluid can return to capillaries - system of vessels starting at tissues, start small, merge larger vessels that form network throughout body - the larger vessels drain contents back into bloodstream at two ducts that join veins near heart |
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How lymph is moved |
- hydrostatic pressure of tissue fluid that left the capillaries - contraction of body muscles -> squeeze lymph vessels, valves ensure fluid only moves towards the heart |
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Translocation |
- process by which organic molecules + mineral ions transported - tissue that transports biological molecules called phloem - phloem made of sieve tube elements, end walls perforated to form sieve plates - plant transports sugars from sources (site of production) to sinks (place where it's used/stored) - Inc organic molecules like sucrose, amino acid and inorganic like potassium, chloride, phosphate ions |
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Mechanisms of translocation |
- precise mechanism uncertain, mass flow theory most supported. Three phases |
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Transfer of sucrose into sieve elements from photosynthesising tissues |
- sucrose diffuses down concentration gradient by Faccilitated diffusion from photosynthesising tissue to companion cells - H ions activelytransported companion cells -> spaces within cell walls - H ions diffuse down concentration gradient through carrier proteins into sieve tube elements - is co-transport |
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Mass flow of sucrose through sieve tube elements |
- transport of sucrose to sieve tubes lowers their wp - xylem much higher wp, water moves from xylem to sieve tubes osmosis causing high hydrostatic pressure - at respiring cells (sinks) sucrose used/stored as starch - sucrose actively transported into these cells lowering their wp - lowered wp means water osmosis into cells lowering hydrostatic pressure of sieve tubes in that region - high hydrostatic pressure at source + low at the sink - mass flow of sucrose solution down hydrostatic gradient |
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Movement of water out stomata |
- humidity of atmosphere usually < that of air spaces next to stomata -> wp gradient from air spaces through stomata to air - when stomata open wv molecules diffuse out air spaces into surrounding air - water lost replaced by evaporation of water on cell walls of mesophyll cells - changing size of stomatal pores -> control rate of transpiration |
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Movement of water across cells of leaf |
- water lost from mesophyll cells = vaporation to air spaces due to heat - these cells have lowered wp so osmosis from neighboring cells occurs, lowers wp of those cells - they in turn take water from neighboring cell- wp gradient est pulling water from xylem to leaf mesophyll to atmosphere - wp gradient est pulling water from xylem to leaf mesophyll to atmosphere |
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Movement of water up stem in the xylem |
- cohesion tension responsible from movement of water from roots to leaf - water evaporates from mesophyll cells due to heat - water molecules form hydrogen bonds between one another, cohesion - water forms continuous colomn across mesophyll cells + down xylem - as water evaporates from mesophyll molecules of water pulled up by transpiration (transpiration pull) - this puts xylem under tension, neg pressure in xylem -> cohesion-tension theory |
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Evidence supporting cohesion-tension theory |
- change in tree diameter due to rate of transpiration, smallest diameter during day whilst greatest rate of transpiration + more tension in xylem, largest at night least pressure and transpiration - if xylem vessel broken water doesn't leak out as would under pressure but air drawn in as would under tension - when xylem vessel broken air enters, column of water broken |
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Transpiration pull passive process |
- xylem vessels dead, have dead end walls, continuous tubes from root -> leaves - energy drives process: sun heat evaporates H²O in leaves |
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Ringing experiment |
- woody stems: have outer protective layer of bark, on inside of which is layer of phloem - start of experiment protective layer and phloem removed - after period of time region of stem above missing ring sweeps up -> sample of liquad accumulated in swollen region rich in sugars + other dissolved substances - some non-photosynthetic tissue below region die whilst those above grow |
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Ringing experiment conclusion |
- sugars of phloem accumulating above ring - interruption of sugars to region below - conclusion that it's phloem not xylem responsible for translocating sugars in plant - ring of tissue didn't extend into xylem -> if xylem were responsible then wouldn't be swelling above + dying and withering below |
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Tracer experiments |
- radioactive isotopes useful for tracing movement of substances in plant e.g isotope 14C, plant grown in 14CO² atmosphere incorporates 14C into sugars - these radioactive sugars can be traced - e.g making thin cross sections of plant stem, placing them on x-ray film, film blackened where exposed to 14C radiation - blackened regions corresponded to where phloem tissue is in stem - Shows that phloem alone responsible for translocation, no other tissue blackened film |
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evidence that translocation of organic molecules occurs in phloem summarised |
- when phloem cut, solution of organic molecules flow out - plants provided w radioactive CO² can be shown to have radioactively labelled carbon in phloem after short time - removal of ring of phloem around whole circumference of stem leads to accumulation of sugars above the ring and disappearance from below it |
