Practice Test

📝 Explanation:

The correct answer for the MCQ is option 1: Pernicious anemia results from vitamin B12 deficiency resulting from inadequate intrinsic factor. This is because pernicious anemia is specifically caused by the body's inability to absorb vitamin B12 due to a lack of intrinsic factor, which is required for the absorption of vitamin B12 in the small intestine. Folic acid deficiency, while it can also cause megaloblastic anemia, is not directly associated with intrinsic factor and is a separate entity from pernicious anemia.

1. Vitamin B12 deficiency resulting from inadequate intrinsic factor:
Vitamin B12 is an essential nutrient that plays a critical role in the production of healthy red blood cells. It is involved in the synthesis of DNA and the metabolism of fatty acids and amino acids. Intrinsic factor is a protein produced by the parietal cells of the stomach that binds to vitamin B12, allowing it to be absorbed in the small intestine. When there is a deficiency of intrinsic factor, vitamin B12 cannot be effectively absorbed from food, leading to vitamin B12 deficiency anemia. This is the most common cause of pernicious anemia.

Pernicious anemia is an autoimmune disorder where the body's immune system mistakenly attacks the stomach cells that produce intrinsic factor. Without sufficient intrinsic factor, vitamin B12 cannot be absorbed, resulting in a decrease in the number of red blood cells produced. The red blood cells that are formed are abnormally large and immature, known as megaloblasts. These cells are not efficient at carrying oxygen and are destroyed more quickly than normal cells, leading to the symptoms of anemia such as fatigue, weakness, and pallor. The deficiency in vitamin B12 can also affect the nervous system, causing neuropathy, cognitive impairment, and other neurological symptoms.

2. Folic acid deficiency resulting from inadequate intrinsic factor:
Folic acid is another B-vitamin essential for the production of red blood cells and is involved in DNA synthesis. However, folic acid deficiency is not directly caused by a lack of intrinsic factor. Folic acid is absorbed in the small intestine through a different mechanism than vitamin B12. While folic acid deficiency can also lead to megaloblastic anemia, it is not typically referred to as pernicious anemia. Pernicious anemia is specifically associated with vitamin B12 deficiency due to intrinsic factor deficiency or malabsorption.

3. Vitamin B12 deficiency resulting from inadequate extrinsic factor:
The term "extrinsic factor" is not commonly used in the context of vitamin B12 deficiency. Vitamin B12 is derived from dietary sources such as meat, fish, and dairy products. In the context of pernicious anemia, the issue is with the intrinsic factor, which is necessary for the absorption of vitamin B12. Therefore, this option is not accurate for explaining the cause of pernicious anemia.

📝 Explanation:

Chicken pox presents with multiple dermal lesions characteristically with vesicles, pustules which may secondarily ulcerate

📝 Explanation:

The correct answer is: 1. Progression �� vascularization �� invasion �� detachment �� embolization.

Explanation of the stages for a malignant tumor cell:

1. Progression: This is the initial stage of tumor development where the cells acquire the ability to proliferate in an uncontrolled manner. This can be due to genetic mutations that alter the normal regulatory mechanisms that control cell division. The tumor grows locally within the tissue or organ of origin.

2. Vascularization: Also known as angiogenesis, this stage involves the formation of new blood vessels that supply the tumor with nutrients and oxygen, which is essential for its continued growth and progression. The tumor cells secrete factors that stimulate the growth of blood vessels into the tumor mass.

3. Invasion: The malignant tumor cells develop the capability to invade surrounding tissues. They secrete enzymes that degrade the extracellular matrix and basement membrane, allowing them to move through these barriers and invade neighboring tissues and organs.

4. Detachment: During this stage, tumor cells detach from the primary tumor site. This is facilitated by the loss of cell-to-cell adhesion molecules and the degradation of the extracellular matrix by proteolytic enzymes.

5. Embolization: Detached tumor cells can then enter the lymphatic system or bloodstream. This process is known as intravasation. They travel through these vessels as emboli and can potentially form new tumors at distant sites, which is the process of metastasis.