Capillaries I Flashcards
what does the H2O solution that leaves capillaries contain?
metabolic end-products
e.g. CO2, urea
what does the H2O solution that enters capillaries contain?
O2, glucose, amino acids,
hormones, immune response etc.
– energy, growth & repair
what does metabolism create?
a need to transport solutes and fluids
if you are a complex animal, what do you need in order to support metabolism?
a transport mechanism which can supply the body with oxygen and nutrients to maintain electrolyte balance
what fluid are the metabolites in?
mostly in intracellular fluid
how is extracellular fluid split
Extracellular fluid consists of 2 compartments
1. fluid that is bathing the tissues - interstitial fluid
- fluid that is in the circulatory system - plasma
do plasma and interstitial fluid have a similar composition?
yes
what is cell metabolism continually generating?
concentration gradients that facilitate the movement of nutrients in and waste products out of cells
The problem is that we need to get across membranes….membranes are a barrier to movement.
what are cell membranes a barrier to?
solute transport
-movement of any solute that isn’t lipid soluble (glucose, aa, ions etc.), meaning it acts as a selective barrier
cell membrane structure
- Lipid bilayer consists of two layers of amphipathic phospholipids
- Phosphate head is polar (hydrophilic) so it can interact with water
- Fatty acid tails are non-polar (hydrophobic)
- Form bilayers in solution
what do polar substances not mix with?
non-polar substances
role of the cell membrane
- Provide support and protection
- Cell-to-cell recognition – (recognising different kinds of cells) e.g. immune system, allowing hormones and neurotransmitters to work
- Controls what enters or leaves the cell – e.g. ion movement in nerves
- Regulates cell function – e.g. insulin-mediated glucose uptake
phospholipids have what?
both charged and non charged groups – hydrophilic and hydrophobic regions - that creates the bi-lipid membrane
its difficult to get solutes across which part of the membrane?
the hydrophobic centre of the membrane
other structures in the cell membrane and their role
- transmembrane proteins that span across the membrane and facilitate transport and signalling
- carbohydrates anchoring the proteins and orientating them
- these complicated structures are a barrier and also help things move across the membrane.
what are the diff types of transport and when are they used?
passive or active
- use passive transport = move molecules down a gradient
- active transport = against a gradient
define passive transport:
- Movement of molecules DOWN a gradient
- gradient can be concentration / pressure / osmotic / electrical
- Does not require energy
- Simple (O2/CO2) or facilitated (ions, glucose)
explain the differences between simple and facilitated diffusion:
Simple
-simple diffusion for oxygen and carbon dioxide
Facilitated
- for ions and glucose where specific channels or transmembrane molecules help with the transport
- no external energy needed because the movement is still due to a gradient
- GLUT transporters
define active transport:
- Movement of molecules AGAINST a gradient
- Therefore requires energy (uses ATP)
- e.g. ATP-dependent pumps, endocytosis, exocytosis
give an example of active transport
sodium potassium ATPase
- taking potassium into the cell and sodium out
- moving potassium into the cell against its concentration gradient
Name 4 passive transport processes:
Diffusion
• Concentration gradient
• e.g. O2 uptake from lungs into blood
Convection
• Pressure gradient
• e.g. blood flow from heart to blood vessels
Osmosis
• Osmotic pressure gradient
• e.g. water uptake by cells
Electrochemical flux
• Electrical and concentration gradient
• e.g. ion flow during an action potential in a nerve