Physiology Year One (1st Semester) Instruction: Answer five (5) Questions only. 1. Briefly describe Erythrocyte based on its (i)shape, (ii) contained organelles, (iii) site of production, (iv) life cycle and (v) functions (2 marks each).

Electrolytes are minerals in the body that carry an electric charge when dissolved in water. They are essential for nerve and muscle function, hydration, and maintaining the body's pH levels.

• Cations: Ions that carry a positive electrical charge. They are formed when an atom loses one or more electrons.
• Anions: Ions that carry a negative electrical charge. They are formed when an atom gains one or more electrons.

• Extracellular cations: Sodium ($\text{Na}^+$), Calcium ($\text{Ca}^{2+}$).
• Intracellular cations: Potassium ($\text{K}^+$), Magnesium ($\text{Mg}^{2+}$).

• Extracellular anions: Chloride ($\text{Cl}^-$), Bicarbonate ($\text{HCO}_3^-$).
• Intracellular anions: Phosphate ($\text{HPO}_4^{2-}$), Proteins.

• Most common extracellular cation: Sodium ($\text{Na}^+$)
• Most common intracellular cation: Potassium ($\text{K}^+$)
• Most common extracellular anion: Chloride ($\text{Cl}^-$)
• Most common intracellular anion: Phosphate ($\text{HPO}_4^{2-}$)