Human Physiology and Anatomy

Carbon is the most abundant element in the human body by mass, making up approximately 18% of total body weight. This is because carbon is the fundamental building block of all organic molecules - proteins (16% of body mass), fats, carbohydrates, and nucleic acids all contain carbon atoms in their backbone structures. While oxygen is the most abundant by number of atoms (65%), carbon-containing molecules have higher atomic mass.

Neurons (brain cells) have extremely limited regenerative capacity in adult mammals because they are post-mitotic cells that have exited the cell cycle. Once damaged, neurons rarely divide or replace themselves, which is why brain and spinal cord injuries are often permanent. In contrast, liver cells (hepatocytes) can regenerate extensively even after significant damage, muscle cells have satellite cells for repair, and some other cell types can divide throughout life.

The masseter muscle in the jaw generates remarkable force, capable of biting with pressures exceeding 200 pounds on the molar teeth. This evolutionary adaptation allows for efficient processing of tough foods, making it the strongest muscle based on maximum force generation.

The skin assists in the process of excretion of water, salts, etc. The human skin does not involve in absorption of water and minerals.

Heat is lost form our body through skin, lungs, urine and faeces, etc.

The main function of liver within the digestive system is to absorb nutrients from the small intestine. Bile from the liver secreted into the small intestine also plays an important role in digesting fat. The liver also detoxifies potentially harmful chemicals. It breaks down and secretes many drugs. 

It is the function of cement, a bone like structure covering and fixing the root in position. The function of the cement is not only to seal the restoration on the tooth, but also in some cases to support the retention of the restoration.

Malleus, incus, and stapes are the three ear ossicles (small bones in the ear).

The function of ear wax and tiny hairs in the ear canal is to trap dust and dirt that enters the ear.

Ears help in hearing and also in body balance.

Erythroblastosis fetalis (hemolytic disease of the newborn) is the condition caused by Rh factor incompatibility between mother and fetus. When an Rh-negative mother carries an Rh-positive fetus, her immune system may produce antibodies that attack fetal red blood cells, causing severe anemia. Hemophilia is a bleeding disorder, erythropoiesis is RBC production, and myxedema is a thyroid condition.

The gall bladder is located on the inferior surface of the liver, specifically in a fossa on the right lobe. It stores and concentrates bile produced by the liver, releasing it into the duodenum via the bile duct when needed for fat digestion.

Islets of Langerhans are present as a part of the pancreas. The islets of Langerhans are the regions of the pancreas that contain its endocrine cells. Discovered in 1869 by German pathological anatomist Paul Langerhans at the age of 22, the islets of Langerhans constitute approximately 1 to 2% of the mass of the pancreas.

Skin consists of two main layers: The outer layer, known as the epidermis and the inner layer, known as the dermis.

The upper surface of the tongue has small projections called papillae. This is the correct option.