OP-L3 Flashcards
Fluid distribution
ICF> ECF( Interstitial. fluid> plasma)
What ions have a higher concentration in the ICF than in the ECF?
Mg2+, K+ , Phosphate
(Remember MGK singer +phosphate)
total body water of a 70 kg human
42 L
Do adipocytes have more or less water
less
How much total body water is lost per day
How much is lost in the following:
- Kidneys
- lungs
- skin
- digestion
2.5 L
- Kidneys – 1.5 L
- lungs – 0.3
- skin– 0.6
- digestion – 0.1
Total ICF and ECF?
ICF = 28 L (2/3rds)
ECF = 14 L (1/3rds)
why no net movement of water btwn ICF and ECF?
same osmolarity
Plasma membrane functions:
- cell adhesion
- cell communication
- Transportation of substances in and out of the cell
- Cell recognition via surface antigens
- Enzymatic activity
- Determination of cell shape
Structure of glycolipids?
2 fatty acyl chains linked to carbohydrate polar head groups
types of plasma memb proteins?
Integral, lipid-anchored or peripheral
what do non-antibiotic drugs target
G-protein coupled receptors
Mechanisms of memb. transport - types of memb transport proteins
- AQPs –> water transport channels - regulated by number of channels or channel permeability (pH)
- Ion channels –> classified by selectivity – specific ions or non-specific cations
- solute carriers : Uniporters, antiporters, symporters
- ATP dependent transporter (ATP pumps)
- Endocytosis
- Exocytosis
- Diffusion
which one can water cross
-epithelia
- lipid bilayer
epithelia
how does water get in and out if it cant cross the cell membrane (lipid bilayer) in the kidney
- Thru the pores in the glomerulus during blood filtration
- thru aquaporins in the collecting ducts and the loops of henle and tubules
Significance of ADH in the reabsorption of water in the kidneys? + what process inserts the aquaporin channels into the membrane?
- AQP 1 is always inserted into the basolateral membrane of collecting ducts while AQP-2 is present in the cytoplasm of the collecting duct cells
- If ADH is secreted then AQP-2 will be inserted into the apical membrane of the collecting ducts via exocytosis of vesicles containing AQP-2 channels.
- If AQP-2 channels are inserted then water is reabsorbed
- more concentrated urine - increased reabsorption
– If dehydration - ADH secreted
– If hydrated – no ADH - no AQP-2 inserted into the apical membrane thus no reabsorption of water thus dilute urine
What disorder is associated with AQP-2 channels - explain what happens
If two defective alleles for AQP-2 channels
Then diabetes insipidus
Problems with water reabsorption as despite ADH secretion AQP-2 channels arent inserted into the apical membrane
where in the brain is the sensor that monitors osmolarity?
The hyppothalamus
osmolarity?
Concentration of osmotically active ions and molecules in plasma
Explain the mechanism of maintaining plasma homeostasis by ADH
Dehydration –> low blood vol +high osmolarity –> stimulates the osmoreceptors in the hypothalamus -> stimulates the release of ADH by the pituitary gland and also stimulates thirst –> ADH goes to kidneys –> water reabsorbed and less excreted
is osmolarity high or low if you’re dehydrated?
high
why is water not reabsorbed when you drink alcohol?
blocks pituitary gland from secreting ADH
what are some negative feedback loops? diseases due to problems with negative feedback loops?
Production of sweat when it gets too hot –> the body does so in order to cool down the body
Shivering when its very cold –> does so in order to warm up the body with increased kinetic energy.
–If this negative feedback response was absent a person could get hypothermia
(sensor–> controller–> effector –> stimulates negative feedback response)
Cancer - dysregulated cell division
Fever - dysregulated body temp
Cystic Fibrosis - airway surface liquid composition
Cholera - dys. water balance
positive feedback example
Blood clot formation
Increase in clotting factors stimulates more clotting factors
How do you calculate total body water?
Assumptions in total body water calculation
- solute is not broken down by body (like glucose by insulin)
- Equilibration is complete within 24 hours
- There is no water intake during this period
- Correction for water loss is accurate
