Why the children are more prone to be dehydrated compared to adults.

 

• Dehydrations reduction of body water level in the extracellular compartment sometimes accompanied with intracellular compartment due to excessive water loss or lack of water intake.

 

• The signs of dehydration are;
• Decrease skin turgor.
• Dry lips & tongue.
• Decrease blood pressure.
• Increase heart rate & pulse .
• Sunken eyeballs.
• Sunken fontanelle (infants).

 

• The symptoms of dehydration are;
• Dry throat and mouth.
• Difficulty in speech.
• Decrease urine output.
• Lethargy.
• Weight loss.

Physiological basis of giving normal saline to a patient with isosmotic dehydration.

o   Dehydration is a decrease in ECF volume due to loss of H₂O and solutes such as Na⁺.

o   In isoosmotic dehydration loss of H₂O is equal to the loss of solutes.

o   Loss of isotonic fluid from plasma causes a loss of fluid from interstitium to plasma to maintain hydrostatic balance between the compartments.

o   But there is no change in the osmolality in the ECF compartment because the fluid lost is isotonic.

o   Thus there is no shift of fluid into or out of ICF because there is no change in ECF osmolality.

Up regulation and down regulation with examples

Down regulation

o   Is the process by which a cell decreases the quantity of a cellular component, such as RNA or protein in response to an external variable.

o   There are several ways in which a cell down regulates its cellular components.

1.      Receptor mediated endocytosis.

Occurs when the material to be transported into the cell binds to certain specific molecules in the membrane. Common cause for down regulation in membrane receptor. 

2.      Internalization.

Ligands bind to their receptors and ligand-receptor complex move laterally in the membrane to coated pits where they are taken into the cell by endocytosis. Some receptors are recycled and some replaced by de nova synthesis. 

The main characteristics of the erythrocyte cell membrane and relate these to the function of erythrocyte.

Organization of erythrocyte membrane

 

Human erythrocytes are small cells that lack nuclei when mature they appear as circular biconcave discs.

• The membrane structure agrees with the Fluid Mosaic Model.
• “the membrane protein ,intrinsic proteins(integral) deeply embedded and peripheral proteins loosely attached, that in an environment of fluid phospholipid bilayer.”
• Fluidity of the membrane largely depends on the lipid composition of the membrane
•  Due to presence of phospholipids erythrocyte membrane has high fluidity & flexibility.
  

The main sub cellular features of a protein secreting cell.

o   A protein secreting cell is metabolically very active

o   It receives signals via G protein coupled receptors.

o   It has a prominent nucleus which takes a large space of the cell. (Transcription, translation occurs in it.)

o   RER supports in synthesis of protein. So it is prominent in the cell. (RER has ribosome on its surface which involve in polypeptide synthesis using amino acids)

o   More mRNA, tRNA & rRNA make cytoplasm basophilic.

o   From RER synthesized polypeptides sent to Golgi apparatus for further modifications via vesicles. So large number of vesicles can be seen.

o   Well developed Golgi apparatus can be seen for post translational modifications of synthesized polypeptides.

o After that finished proteins exit from the cells by a secretory vesicles made out of Golgi apparatus, so large number of secretory vesicles can be seen.