Body Systems L2 Flashcards
Body Fluids & their compartments?
- Total body water (TBW) -> 42 Litres
1. Intracellular fluid (ICF) -> 25 litres
2. Extracellular fluid (ECF) -> 17 litres
i) Interstitial Fluid (ISF) -> 13 litres
ii) Plasma -> 3 litres
iii) Transcellular fluid -> 1 litre
What is osmolality?
• Osmolality:
Conc of solute in solvent.
Same osmolality across all cellular fluid -> no movement of water.
Name the types of membrane?
- Plasma
- Capillary endothelium
- Epithelia
Describe the plasma membrane.
- Permeability -> Highly selective
- High number of transport protein -> acceptance & removal of specific solutes
- Maintains optimal of intracellular environment.
Describe the Capillary endothelium.
- Permeability -> Highly permeable in specific organs
- Thin lining of endothelial cells in blood vessels
- Maintains controlled regular flow of interstitial fluid
- > endothelial cells -> membrane
Describe the Epithelia.
- Used for protection
- Layers of cells internally & externally cover organ & tissue.
- Used in absorption & secretion.
List the types of transport in the plasma membrane.
Impermeable phospholipid bilayer -> ions & polar molecules -> simple diffusion.
Protein channels, carriers & pumps -> non-polar molecules.
Describe the types of transporter channels in plasma membranes.
- Channels – Passive transport -> down conc. gradient.
- Carriers – Passive transport -> down conc. gradient.
Binds to protein – changes shape – enables diffusion. - Pumps – Active transport -> against conc. gradient.
Requires hydrolysis of ATP.
Describe the types of carriers in plasma membranes.
- Uniport – Facilitator
- > Transports one ion species - Symporter – Co-transporter
- > Moves 2 ion species together — (one +ve & one -ve.) - Antiporter – Exchanger
- > One ion released and another replaces it (must be same charge eg. both +ve)
Describe the role of the uniport in plasma membranes.
- Uniport – Facilitator
- > Transports one ion species
Describe the role of the symporter in plasma membranes.
- Symporter – Co-transporter
- > Moves 2 ion species together — (one +ve & one -ve.)
Describe the role of the antiporter in plasma membranes.
- Antiporter – Exchanger
- > One ion released and another replaces it (must be same charge eg. both +ve)
What are the functions of transport proteins?
- > Uptake of nutrients, substances & cofactors
- > Export of waste products.
- > Regulation of intracellular ions, pH & cell volume.
What is the sodium-potassium pump responsible for?
• Na+/K+ pump -> gradient maintenance -> actively transports ions so everything else can diffuse passively (down conc. gradient)
Distribution of water & solutes across the plasma membrane
See notes for following pics:
Describe how Assymmetric distribution of K+ generates membrane potential in plasma membrane.
(Nerve) Cells have electrical gradients -> membrane potentials -> enabling contraction of muscles/impulses.
Resting membrane potential/electrical diff required.
Achieved by diff. conc of K+ in ICF & ECF.
If K+ channel opened, K+ -> down conc. gradient
However also attracted to -ve charged proteins.
Conc. gradient vs. attraction of ions at rest cause such resting
potential charges seen (mV) to be present.
Therefore at equilibrium, high conc. of +ve ion in cell but cell
Itself negative relative to charge outside cell.
Describe distribution of water in plasma membrane.
• Water moves down its osmotic conc from high to low conc by osmosis.
Water isn’t actively transported -> too energetically expensive -> ions move & water follows.
Cell volume regulated by ion channels, which then cause water to move osmotically.
Describe distribution of solutes in the capillary endothelium.
- Capillary Endothelium:
- Solutes: -> conc. gradients. - Ions & organic solutes easily transported -> approx. equal distribution.
- Proteins too large -> trapped in plasma. -> high conc. in plasma.
Describe the water distribution in the capillary endothelium.
- Water distribution: -> determined by hydrostatic and osmotic forces
1. Forced out of start of capillary network by pressure of heart rate.
> Ions carried out of capillaries also.
2. Pressure in plasma/capillaries decreases as more water forced out.
3. Proteins trapped in plasma -> incr. conc & osmolality due to loss of water.
4. Colloid (protein) osmotic pressure higher in plasma -> water diffuses back into capillaries by osmotic gradient.
Describe epithelial transport of solutes using an example.
- Side of epithelial cell facing Inside -> Apical.
Outside -> Basolateral. - Cells -> selectively permeable
-> Tight junctions -> nothing can pass between cells
-> must go through - Na+ & glucose transporters transport ions from gut into
epithelial cells.- Creates osmotic gradient so water follows.
3. Glucose transporter transports glucose down conc gradient.
- Creates osmotic gradient so water follows.
- Na+/K+ pump -> Transport Na+ ions out of epithelial cell -> Water moves down osmotic gradient.
-> Enables easier absorption of water using transportation of ions than water alone.
- Na+ & glucose transporters transport ions from gut into
Describe movement of water in epithelial transport.
- Water also flows in opp direction on basolateral side of epithelial cell.
1. Na+/K+/Cl- co-transporter takes up ions.
2. Water moves into intestinal epithelial cell down osmotic gradient.
3. Cl- channel on apical side of epithelial cell -> enables diffusion of Cl into gut lumen.
4. Water moves into gut lumen down osmotic gradient. - > Enables diffusion of water into small intestine -> aid physical transport of food to lower intestine. -> Reabsorbed in large intestine.
