21-24 Flashcards
What does extracellular fluid composition show about historical settings?
that it was probably similar in composition
- so mainly a solution of sodium salts
- mainly NaCl
What is osmosis?
The tendency of a solvent to pass through a selectively permeable membrane from a dilute to a more concentrated solution
What is osmotic pressure (π)?
The pressure that has to be applied to a concentrated solution in order to stop solvent moving into is from a more dilute solution across a selectively permeable membrane
- colligative property
GRAPH
π = ρ x h x g
ρ=fluid density
What is water potential?
Suction needed to prevent movement of water into concentrated solution
= -π
What is an osmole?
1 mole of osmotically active particles
What is isomostic?
solutions with the same osmotic pressure
Hyperosmotic
if has higher osmotic pressure than the other
Hyposmotic
lower osmotic pressure compared to the other
What is an ineffective osmole?
When a solute cannot exert an effective osmotic pressure as it can move across the membrane
What is an effective osmole?
A solute that cannot pass through the membrane and so can exert an effective osmotic pressure
What is the tonicity of a solution?
The effect of a solution on the volume of a cell
- related to osmolality but depends on whether effective of ineffective osmoles are involved
What does isotonic mean?
Solution does not change volume of cell
Hypertonic?
Causes cell to shrink
Hypotonic?
Causes cell to swell
What is colloid osmotic pressure?
= oncotic pressure
The osmotic pressure exerted by colloidal molecules such as proteins
- one of starlings forces determining fluid movement in capillaries
What is the principle of balance?
The maintenance of homeostasis
- as substances added must equal rate at which they are removed
What are obligatory and regulated exchanges?
Obligatory = unregulated
- like tears, sweating, breathing, faeces
Regulated = urine
What are osmoregulatory organs?
Formed by ransport epithelia found in gills, skin, kidneys or gut
- functionally polarised so the two exposed surfaces have different roles
- OUTSIDE = luminal (apical)
- INSIDE = Adluminal (Basolateral)
Osmoregulatory organs in mammals.
Marine mammals survive on metabolic water alone
- KIDNEYYYY
Osmoregulation in a typical mammal
GRAPH
-
Osmoregulation in a desert mammal
PICTURE
The urinary system
PICTURE
Gross structure of the kidney
FIgure 5 pg 5
The renal tubule diagram
DIAGRAM
- Nephron (includes Bowman’s capsule)
- Collecting duct system
- Each human has roughly 1 million nephrons
- Proximal tubule = often convoluted and straight parts together