Human Physiology and Anatomy

The average human heart beats about 72 times per minute at rest, which is considered a normal resting heart rate for adults.

Each human foot contains 26 bones, including the tarsals, metatarsals, and phalanges. This is a well-established anatomical fact.

The average thickness of human skin varies but is generally around 2 to 3 millimeters, with 3mm being a common estimate for average skin thickness. Options B and D (centimeters) are too large for skin thickness. Therefore, 3mm (option C) is the most accurate answer.

Vitamin K is essential for normal blood circulation because it plays a critical role in blood clotting, which helps prevent excessive bleeding and supports vascular health.

The average brain weight of a newborn baby is approximately 300 grams. Option A correctly reflects this typical value, while option B (400 grams) is higher than the average newborn brain weight.

The percentage of blood cells, specifically red blood cells, in human blood is approximately 45%, known as the hematocrit value. This is a standard physiological measure.

The femur is the longest and strongest bone in the human body, supporting the weight of the body and enabling leg movement. The stapes is the smallest bone, and the tibia is strong but not longer than the femur.

RBCs stands for Red Blood Cells, which are scientifically called Erythrocytes. The other options are incorrect as Leucocytes are white blood cells, Nucleotides are building blocks of nucleic acids, and AOT is unrelated.

White Blood Cells (WBCs) are also known as leukocytes, which are cells of the immune system involved in protecting the body against infections. Lymphocytes are a type of WBC, nucleotides are building blocks of nucleic acids, and erythrocytes are red blood cells.

The normal human body temperature is approximately 37 °C, which the body maintains despite minor fluctuations due to homeostasis.

The liver is the largest gland in the human body, responsible for many vital functions including detoxification, protein synthesis, and production of biochemicals necessary for digestion.

Prolactin is the hormone responsible for stimulating milk production in the mother's breast. Oxytocin, while important for milk ejection, does not initiate milk production. FSH and ADH are unrelated to lactation.

Plasma constitutes about 55% of human blood by volume, making option B the correct answer. The other options are either too low or too high compared to the accepted average percentage.

Karl Landsteiner discovered the ABO blood group system in 1901, which was a groundbreaking finding in immunology and transfusion medicine. This discovery allowed for safer blood transfusions by matching compatible blood types.

Xerostomia is the medical term for dry mouth, which occurs due to reduced or absent saliva flow. This condition is commonly recognized and distinct from dryness of skin, nose, or head.

The skin is the largest organ of the human body by surface area and weight, serving as a protective barrier. Other organs like the liver and heart are internal and smaller in size compared to the skin.

The fluid part of blood is called plasma, which is a yellowish liquid that carries blood cells, nutrients, hormones, and waste products throughout the body. Platelets and blood cells are components suspended in the plasma, not the fluid itself.

White blood cells (WBCs) generally have a lifespan ranging from 1 to 5 days, depending on the type. Some WBCs may live longer, but the typical range is 1-5 days, making option A the most accurate.

The average adult human has a blood volume of about 5 to 6 liters, with 6 liters being a commonly accepted average for a typical adult. Therefore, option C (6 liters) is the most accurate choice.

Addison's disease, also known as primary adrenal insufficiency, is caused by the failure of the adrenal glands to produce sufficient hormones, primarily cortisol and aldosterone. This failure is most commonly due to autoimmune destruction of the adrenal cortex. The pituitary gland produces adrenocorticotrophic hormone (ACTH), which stimulates the adrenal glands to produce these hormones. In Addison's disease, the adrenal glands fail despite normal or elevated ACTH levels. Therefore, the disease is caused by adrenal hormone deficiency, not ACTH deficiency. However, among the given options, ACTH (option D) is the hormone most closely related to adrenal function regulation. The other options (Antidiuretic Hormone, Luteinising Hormone, Melanophore Stimulating Hormone) are unrelated to Addison's disease. Hence, option D is the best choice given the options, but it should be understood that Addison's disease results from adrenal gland hormone deficiency, not ACTH deficiency.

Individuals with the AB+ blood group are considered universal recipients because they have all A, B, and Rh antigens, allowing them to receive red blood cells from any blood type without immune reaction.

Digestion of food is completed in the small intestine, where enzymes break down nutrients for absorption. The stomach initiates digestion, the large intestine absorbs water, and the liver produces bile but does not digest food directly.

Individuals with blood group O are called universal donors because their red blood cells lack A and B antigens, allowing their blood to be safely transfused to people of any other blood group without causing an immune reaction.

The liver is the largest gland in the human body, responsible for numerous vital functions including detoxification, protein synthesis, and production of biochemicals necessary for digestion.

The pituitary gland is known as the master gland because it controls the functions of many other endocrine glands by releasing various hormones.