BIOL10003 Lecture Notes - Lecture 14: Metabolic Water, Water Potential, Fluid Compartments
cLecture 14 – Regulating Body Fluids
Regulation of body fluid is one of the most important body functions.
Physiology rule of 3
3 minutes without oxygen
3 days without water
3 weeks without food
If human lose: ** 50- 70 % of body weight is made of water
1% water – feel thirsty
2% water – may lose appetite
3% water – a’t futio ell phsiall
4% water – ausea, a’t oetate
10% water – muscle spasms/delirium
20% water – death
Water intoxication: Too much water (over 30 litres)
kidneys (produce urine) a’t ope with filtering all the water in the cardiovascular system
Organs swell due to the fluid in the cardiovascular system leaking into the tissue disrupting
their function
Brain becomes compressed in the skull
Seizures, confusion, blurred vision, pain, cramps, death
too much water dilute the environment needed for homeostasis
Life began in the Cambrian period is watery and salty environment. We share a lot of ions with
this environment
Osmosis
eae hee thee is o a it’s goig to get a
–
does’t eet a osoti pessue as it’s the sae as
it’s oetatio gadiet.
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–
–
–
– a’t futio ell phsiall
– ausea, a’t oetate
–
–
a’t o
Osmosis
Water diffuses through a semi-permeable membrane from an area of low osmotic
concentration (low osmolarity/ high water potential) to an area of high osmotic concentration
(high osmolarity/low water potential). Evens out the concentration.
Osmolarity (Osmotic concentration) = Osmoles (OSM) L-1
e.g. 1M solution of CaCl2 has a osmolarity of 3 Osm/L when it dissociates there are 1 Osm/L for
Ca2+ and 2 Osm/L for CL-1 ions giving 3.
Solutes can move in or out of cells by active transport against a concentration gradient
(requires energy). Cells manipulate osmolarity by regulating the concentration of those salts to
regulate body fluids.
Tonicity
Measure of effective osmotic pressure, exerted by non-permeate solutes only, across a semi-
permeable membrane. Like Osmolarity, except considers only non-permeable solutes (cannot
diffuse across).
solution that will eventually diffuse across has an osmotic draw to it. Molecules on one side of a
eae hee thee is o a it’s goig to get aoss) will have a bigger osmotic draw.
Impermeable membrane will more likely draw water across the membrane.
hospital drips – isotonic saline and it has no effect on the size of your cells. Isotonic solution
does’t eet a osoti pessue as it’s the sae as the solution inside our cells (no net gain
of water).
Hypertonic solution: cells crenate. water moves from the inside of the cells to the outside down
it’s oetatio gadiet. Too much salt in cell
Hypotonic solution: water moves from the distilled water outside and into the cell. Cells swell
and could potential burst.
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Isotonic environment are the ideal environment for blood and other bodily cells.
WHY REGULATE BODY WATER AND SOLUTES
• To ahiee hoeostasis- constancy of the
extracellular environment
• All organisms contain:
- water((50-70% of ost ogaiss’ od eight
- Ions (e.g. Na +,K+, Cl-)
- Organic solutes (e.g. glucose, amino acids)- need in particular osmotic concentration
• Eat ad elatie oentrations of solute in body fluid (osmotic concentration) critical for
proper chemical functioning
•Ho a aial egulates osoti oetatio is deteied suoudig eioet.
Aquatic Animals
Osmoconformer: osmotic concentration of internal environment=external environment (iso-
osmotic to their environment)
Marine invertebrates & non-bony fish
Stenohaline species– they cannot cope with large changes in body salinity therefore must live
in environment where salinity and temp changes little.
The do not waste any energy on regulating change and cannot.
Osmoregulator: Osoti oetatio of iteal eioet ≠eteal eioet body
fluid osmoconcentration is regulated compared to their environment)
Marine and freshwater vertebrates (bony fish, birds, mammals etc)
Euryhaline species – Organisms that can cope with a wide range of salinities
Marine vertebrate osmoregulators in hypertonic solution
Lose water from body fluids to seawater, gain ions from the seawater.
Body fluid is hypotonic to seawater
• Bod fluid is hpetoi to fesha
• Gai ate ososis, lose solutes diffusio
• Pole: too uh ate, too fe solutes solutio: podue lots of dilute uie, do’t
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Document Summary
Regulation of body fluid is one of the most important body functions. If human lose: ** 50- 70 % of body weight is made of water. Water intoxication: too much water (over 30 litres) Kidneys (produce urine) (cid:272)a(cid:374)"t (cid:272)ope with filtering all the water in the cardiovascular system. Organs swell due to the fluid in the cardiovascular system leaking into the tissue disrupting their function. Seizures, confusion, blurred vision, pain, cramps, death. Too much water dilute the environment needed for homeostasis. Life began in the cambrian period is watery and salty environment. We share a lot of ions with this environment. Water diffuses through a semi-permeable membrane from an area of low osmotic concentration (low osmolarity/ high water potential) to an area of high osmotic concentration (high osmolarity/low water potential). Osmolarity (osmotic concentration) = osmoles (osm) l-1 e. g. 1m solution of cacl2 has a osmolarity of 3 osm/l when it dissociates there are 1 osm/l for.
