Karteikarten
Solute and Fluid exchange
Karten in diesem Stapel (40)
- 1Many substances are transported around the body in ______water
- 2What controls what enters and leaves cells?the membrane
- 3What are the features of passive transport?1. no energy required
2. down a gradient
3. can be simple or facilitated - 4name 4 different types of passive transport1. diffusion (concentration gradient)
2. osmosis
3. convection (pressure gradient)
4. electrochemical flux (electrochemical gradient) - 5What are the features of active transport?1. requires energy
2. against the gradient - 6Name the 3 types of capillaries1. continuous - no gaps (e.g. BBB)
2. fenestrated - small gaps between cells (v. water permeable, in kidneys)
3. discontinuous - large gaps (e.g. sinusoids in liver, spleen) - 7What controls rate of solute transport?1. Passive diffusion
2. Fick's Law
3. Lipid solubility of solute
4. Properties of the membrane
5. Presence of intercellular clefts
6. Glycocalyx - 8What is the equation for time taken for particles to diffuse a certain distance?t = x^2/2D
- 9what are x and D in that equation?x = distance for particle to move
D = diffusion coefficient for that solute in a specific medium - 10What determines D?1. size/shape of molecule
2. viscosity of the fluid
3. strength of interactions between solute and solvent - 11What is Fick's Law?Js (mass movement of solute in certain time) = -D x area x (change in concentration)/x
- 12What properties of the membrane affect solute transport?1. thickness/composition
2. presence of aqueous pores
3. carrier proteins
4. active transport mechanisms - 13What is the glycocalyx?A layer covering the endothelium acting like a sieve to block proteins passing through
- 14How can Fick's Law be modified for permeability?Js = -P x Am x change in concentration
- 15What is Am?The actual route taken by a solute through a membrane
- 16What are 4 routes of transport for solutes across a membrane?1. Transcellular
2. vesicles
3. intercellular
4. aquaporins - 17What is transcellular transport?Through the cell, via simple diffusion or using carrier proteins/channels
- 18What solutes use vesicles?Large, lipophobic proteins
- 19How can solutes travel intercellularly?1. through gap junctions (small lipophobic)
2. through fenestrations
3. through large gaps (e.g. in inflammation) - 20What is flow limiting diffusion?Diffusion is very efficient so only flow affects it
- 21How is diffusion limited by flow in alveoli?If flow is slow, O2 diffuses readily into blood at one end of alveoli, but by the time it reaches the other end, some may have diffused out again.
- 22How can rate of diffusion be increased?1. increase blood flow
2. recruit capillaries
3. change concentration gradient
4. dilate arterioles to increase no. of perfused capillaries - 23What does an abnormality in fluid exchange result in?Oedema
- 24What 2 pressures act on capillary walls in both directions?1. hydrostatic pressures
2. osmotic pressures - 25What is the hydrostatic pressure?the 'push' of a fluid to leave the area it is in (e.g. move out of the vessel)
- 26What is the overall hydrostatic pressure?(Pc - Pi) = Pressure in capillary pushing outwards minus pressure in interstitial fluid pushing in
- 27What is the osmotic pressure and how is it determined?The pull of water back into an area, due to the pull of large proteins
- 28What is the overall osmotic pressure?(πp - πi) = pull of the proteins in the capillary minus pull from interstitial fluid
- 29Jv = Lp x A x [(Pc-Pi) - σ(πp-πi)] This is Starling's principle of fluid exchange, what do Lp and A represent?Lp = 'hydraulic conductance of epithelium' (how leaky it is)
A = wall area - 30What is σ?It is the reflection coefficient. This is the fraction of the osmotic pressure actually exerted (taking into account proteins that travel through the membrane)
- 31In normal capillaries, what is favoured, filtration or absorption?Filtration
- 32What happens in hypovolaemia? (e.g. haemorrhage)Reabsorption is favoured, so that blood volume can be restored
- 33What is the net filtration pressure?= Pc - [ σ(πp - πi) + Pi]
= Pc - 13 (approx) - 34Where does the fluid which is filtered go?Drains into lymphatics - will be drained back into circulation via left subclavian vein)
- 35The lymphatic system contains _______ and _____ _______ to aid flow against ________.valves,
smooth muscle,
gravity - 36How is lymph flow helped by skeletal muscle?Lymph vessels surround skeletal muscle. As muscle contracts, it contracts lymph vessels too, to help its return to the great veins.
- 37What are 5 causes of oedema?1. Increased Pc
2. Decreased πp
3. Increased πi
4. inflammatory response
5. lymphatic problems - 38How could Pc be increased?DVT or heart failure causing build up of blood
- 39How could πp be decreased?malnutrition or liver disease which prevents the proteins being taken into blood
- 40What can cause lymphatic problems?1. obstruction of lymph drainage
2. removal of lymphatics after cancer surgery
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- Beschreibung
- Degree CVS1 Karteikarten am Solute and Fluid exchange, erstellt von Hannah Tribe am 27/04/2014.
- Erstellt von
- Hannah Tribe
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