UPSC-CMS 2022 — Physiology

Q: The least marked function of a human spleen is

reservoir function. ***Reservoir Function*** - In **humans**, the spleen stores only a **minimal amount of blood** (~30-40 ml of RBCs), unlike in animals like dogs and horses where it serves as a major blood reservoir - While it does store some **platelets and monocytes**, the reservoir function is the **least marked** among the spleen's primary functions in humans - This function is relatively insignificant compared to the spleen's other critical roles *Filter Function* - The spleen is a **major blood filter**, removing **old and damaged red blood cells**, bacteria, and cellular debris - Removes approximately **20-30 ml of aged RBCs daily** through selective filtration in the red pulp - This is one of the **most important** and highly marked functions of the spleen *Immune Function* - The spleen is a **major secondary lymphoid organ** containing **25% of the body's lymphocytes** - Produces **antibodies** (IgM and IgG) and responds to blood-borne antigens - Critical for fighting **encapsulated organisms** (Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis) - Post-splenectomy patients face risk of **OPSI** (overwhelming post-splenectomy infection), highlighting its crucial immune role *Pitting Function* - The spleen performs the unique **pitting function** by selectively removing intracellular inclusions (**Howell-Jolly bodies, Pappenheimer bodies, Heinz bodies**) from RBCs without destroying the entire cell - This specialized function helps maintain RBC quality and is particularly evident in splenectomized patients who show these inclusions in peripheral blood [Practice more Physiology PYQs on OnCourse]

Q: In hyperemesis gravidarum, Wernicke's encephalopathy is seen due to the deficiency of

vitamin B1. ***vitamin B1*** - **Wernicke's encephalopathy** is directly caused by a severe deficiency of **thiamine (vitamin B1)**. - In **hyperemesis gravidarum**, persistent vomiting leads to inadequate intake and absorption of this vital vitamin. *vitamin B6* - Deficiency of **vitamin B6 (pyridoxine)** can cause peripheral neuropathy, glossitis, and dermatitis. - While important for many metabolic processes, its deficiency is not directly linked to Wernicke's encephalopathy. *vitamin B12* - **Vitamin B12 (cobalamin)** deficiency primarily results in megaloblastic anemia and subacute combined degeneration of the spinal cord. - It does not cause the specific neurological triad of Wernicke's encephalopathy. *vitamin B9* - Deficiency of **vitamin B9 (folate)** leads to megaloblastic anemia and is crucial for neural tube development. - It is not associated with the pathogenesis of Wernicke's encephalopathy. [Practice more Physiology PYQs on OnCourse]

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The least marked function of a human spleen is

In hyperemesis gravidarum, Wernicke's encephalopathy is seen due to the deficiency of