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28 Cards in this Set
- Front
- Back
- 3rd side (hint)
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How much of the average adult body is water? |
50-65% |
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What is the average water intake, per day, via what? |
Diet and drinks: 2300ML Metabolic (from cells): 200ML per day |
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What is the average water loss, per day, via what? |
Kidneys: 1.5L per day Skin: 600ML per day Lungs: 300ML per day GIT: 100ML per day |
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How is our fluid compartmentalised, the largest divisions? Then an additional divide? |
2/3 intercellular / ICF 1/3 Extracellular / ECF (aka blood) Then ECF splits into interstitial fluid (80%) + plasma (20%) |
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What does water move via, and what is it driven by? |
Moves via osmosis Driven by the concentration of solutes. |
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What does osmolarity describe? What does it mean when something has a low osmolarity?
What does it mean when something has a high osmolarity? |
The total solute concentration of a solution Low solute concentration (hypotonic) High solute concentration (hypertonic) |
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What does it mean when there is an increase in plasma osmolarity, and it turns hypertonic? |
Increased solute concentration outside of the cell in the ECF - this draws out the water from the cell (osmosis) |
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What does it mean where there is a decrease in plasma osmolarity, and it turns hypotonic? |
Decreased solute concentration outside the cell / in the ECF - water is rushing into cell. Cell can burst! |
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What is it called when a cell has the ideal about of h2o? |
Isotonic! |
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What does overhydration/water intoxication cause in the plasma? What does it cause in the body? |
- Decrease in plasma osmolarity making it hypotonic - welling, convulsions, coma & death |
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What happens in the plasma in dehydration? What happens to the cells in dehydration? What is greater than what? |
- Increased plasma osmolarity = hypertonic - cells shrivel as water leaves the cell by osmosis - water loss is greater than water gain |
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1. What are physical causes of dehydration? 2. What decreases when dehydrated? (4) |
1. fever, burns, vomiting, diarrhoea, hemorrhage 2. Saliva production (dry mucosa in mouth + pharynx), urine output, blood volume, blood pressure |
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What is stimulated when you're dehydrated? (2) What is activated when you're dehydrated? (1) |
Stimulated: 1) ADH secretion from the PP 2) Thirst centre in the hypothalamus Activated: 1) Renin-angiotensin pathway (JG cells notice low BP/BV) |
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When is the thirst mechanism unreliable? |
In the: elderly very young mentally confused |
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When is ADH secretion stimulated? (provide examples - 5) |
When anything means increased fluid loss. E.g. fever, burns, vomiting, diarrhoea, haemorrhage. |
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What electrolytes exist in the ICF? Give 3. |
Potassium Proteins Phosphates |
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What electrolytes exist in the EXF? Give 2. |
Sodium Chloride |
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What are the (2) fundamental difference between electrolytes and non-electrolytes? Give an example of each substance. |
- Electrolytes have ionic bonds that dissasociate in water into positive & neg ions e.g. NaCl = Na+ & Cl- - Non-electrolytes have covalent bonds and do not dissasociate in water e.g. Glucose, urea, creatinine |
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What is osmotic pressure? What is it directly influenced by? What has more influence over osmotic pressure, why? |
The pressure countering osmosis (water from low to high). Directly influence by the amount of solute in the system. Electrolytes have much control over OP (they are ionic bonds + disassociate into more "bits") |
Water wants to move from low to high - osmotic pressure forces it to aim to "even out" and stay on the low side! |
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What controls the osmosis of water? |
Sodium ions! |
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What causes a change in extra cellular volume? Where can it move to/from? Is this okay? |
Sodium shift Can move from ECF to ICF and back = needs to be balanced |
Sodium ions= ++ water. |
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Why do we need to keep Na+ levels at normal range? (2) |
1) High Na+ levels = high BP 2) Extremely high or extremely low levels affect brain + other organ functions. |
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Describe the steps in the homeostatic regulation of sodium ion concentration (increased Na+) (7) |
1. HOMEOSTASIS (normal Na+ concentration in ECF) 2. HOMEOSTASIS DISTURBED (Increased Na+ concentration in ECF) 3. Osmoreceptors stimulated 4. Increased ADH release. Increased thirst. 5. Decreased urinary water loss. Increased water gain. 6. Additional water dilutes ECF, volume increased. 7. HOMEOSTASIS RESTORED. |
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Describe the steps in the homeostatic regulation of sodium ion concentration (decreased Na+) (7) |
1. HOMESTASIS (normal Na+ concentration in ECF) 2. HOMESTASIS DISTURBED. Decreased Na+ concentration in ECF. 3. Osmoreceptors inhibited. 4. Decreased ADH release. Decreased thirst. 5. Increased urinary water loss. Decreased water gain. 6. Water loss concentrates ECF, volume reduced. 7. HOMESTASIS RESTORED. |
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What isn't normally found in filtrate? |
Protein |
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What does ADH do to the collecting ducts? |
Increased the permeability. |
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The primary function of the proximal convoluted tubule is... |
the reabsorption of ions, organic molecules, vitamins, and water |
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What is the main force that causes filtration in the nephron? |
Glomerular hydrostatic pressure. |
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