Calcium And Phosphorus Metabolism Knowledge Test

An increase in PTH (parathyroid hormone) has a net effect of increasing plasma calcium levels. PTH stimulates the release of calcium from the bone, increases calcium absorption in the intestine, and enhances calcium reabsorption in the kidneys. As a result, more calcium is available in the bloodstream, leading to increased plasma calcium levels.

Calcitriol, PTH, and calcitonin are the three principal hormones that regulate calcium levels in the body. Calcitriol helps in the absorption of calcium from the intestines, PTH increases calcium levels in the blood by stimulating the release of calcium from bones, and calcitonin helps to decrease calcium levels by inhibiting the release of calcium from bones. Therefore, all three hormones play a crucial role in maintaining calcium homeostasis in the body.

Osteoblasts are responsible for bone mineralization, which is the process of depositing minerals, such as calcium and phosphate, into the bone matrix. These cells are involved in bone formation and play a crucial role in maintaining bone health. Osteoblasts secrete proteins and other substances that help build and mineralize the bone, making it strong and rigid. They work in coordination with osteoclasts, which are responsible for bone resorption, to maintain a balance between bone formation and resorption, ensuring proper bone remodeling and repair.

PTH, or parathyroid hormone, is responsible for causing decalcification or demineralization of bone. It acts on osteoclasts, which are cells that break down bone tissue. PTH stimulates osteoclast activity, leading to the release of calcium and phosphate from the bone matrix into the bloodstream. This process helps to maintain calcium homeostasis in the body by increasing the levels of calcium in the blood. Calcitriol, on the other hand, is the active form of vitamin D and is involved in the absorption of calcium from the intestines. While calcitriol plays a role in calcium metabolism, it does not directly cause decalcification or demineralization of bone.

Osteoclasts are responsible for bone resorption. These cells are specialized in breaking down and absorbing old or damaged bone tissue. They release enzymes and acids that dissolve the mineralized matrix of the bone, allowing for the removal of calcium and other minerals. This process is essential for bone remodeling and repair, as well as for maintaining calcium homeostasis in the body. Osteoblasts, on the other hand, are responsible for bone formation, synthesizing and depositing new bone tissue.

Percutaneous coronary intervention (PCI) is indeed a non-surgical method used to open narrowed arteries that supply blood to the heart muscle. It involves the use of a catheter to insert a balloon or stent into the blocked artery, thereby restoring blood flow. This procedure is commonly performed to treat coronary artery disease and relieve symptoms such as chest pain or discomfort. Therefore, the given answer "True" is correct.

Ca (calcium) activates ATPase, which is an enzyme that hydrolyzes ATP to provide energy for muscle contraction. When ATP is hydrolyzed, it releases energy that allows the interaction between actin and myosin, the two proteins responsible for muscle contraction. Therefore, the statement that Ca activates ATPase and increases the interaction between actin and myosin is true.

Calcitriol, PTH, and calcitonin are hormones that work together to regulate the levels of calcium in the blood within a specific range. Calcitriol helps increase calcium absorption from the intestines, PTH increases calcium release from bones, and calcitonin decreases calcium release from bones. This coordinated action ensures that the plasma calcium levels remain within a narrow range, which is necessary for proper functioning of various physiological processes in the body. Therefore, the statement is true.

Low serum calcium causes an increase in 1,25-dihydroxy Vitamin D3 (Calcitriol) levels. This is because when serum calcium levels are low, the parathyroid gland releases parathyroid hormone (PTH), which stimulates the production of 1,25-dihydroxy Vitamin D3 in the kidneys. This active form of Vitamin D helps to increase calcium absorption from the intestine and reabsorption from the kidneys, ultimately increasing serum calcium levels and restoring calcium homeostasis in the body.

ADH (Antidiuretic hormone) acts through cAMP (cyclic adenosine monophosphate) and then Ca (calcium). This means that ADH stimulates the production of cAMP, which in turn activates protein kinase A and leads to the release of calcium from intracellular stores. Calcium then acts as a second messenger to carry out various physiological effects of ADH, such as water reabsorption in the kidneys. Therefore, the given statement "ADH acts through cAMP & then Ca" is true.

Low serum calcium levels stimulate the release of calcitonin. Calcitonin acts to decrease serum calcium levels by inhibiting the release of calcium from bones, promoting the excretion of calcium in the urine, and reducing calcium absorption in the intestines. Therefore, an increase in calcitonin would counteract the low serum calcium levels and prevent them from decreasing further.

The statement is true because atherosclerosis is a gradual process that involves the buildup of plaque in the arteries over time. The plaque consists of cholesterol, fat, calcium, and other substances that can narrow and harden the arteries. The damage caused by this process, such as the formation of blood clots or the rupture of plaque, can lead to serious complications like heart attacks or strokes. Therefore, it is within the first 2-3 hours after the damage occurs that most of the harmful effects of atherosclerosis take place.

Women tend to have higher levels of high-density lipoprotein (HDL) cholesterol, also known as "good" cholesterol, compared to men. HDL cholesterol helps remove low-density lipoprotein (LDL) cholesterol, also known as "bad" cholesterol, from the arteries, reducing the risk of heart diseases such as heart attacks and strokes. Therefore, women are less prone to heart diseases compared to men.

The process of atherosclerotic plaque formation involves various cells, including lymphocytes, monocytes, macrophages, and smooth muscle cells. Atherosclerosis is a slow progression characterized by the accumulation of fatty deposits and inflammatory cells in the walls of arteries. Lymphocytes are involved in the immune response, while monocytes differentiate into macrophages that engulf and digest the accumulated lipids. Smooth muscle cells also play a role in plaque formation by proliferating and contributing to the formation of a fibrous cap over the plaque. Therefore, all the mentioned cells are involved in the process of atherosclerotic plaque formation.

The statement is true because the excretion of calcium does occur partly through the kidneys and mostly via the intestine. The kidneys play a role in regulating the levels of calcium in the body by filtering it from the blood and excreting any excess through urine. However, the majority of calcium excretion occurs through the intestine, where it is eliminated in the feces. This process helps maintain the balance of calcium in the body and prevent the buildup of excessive levels.

Hydroxyapatite is a compound that consists of calcium and phosphorous, and it plays a crucial role in forming the mineral component of bones and teeth. It provides the rigidity and strength to bones and teeth, making them hard and durable. Therefore, hydroxyapatite is the correct answer as it accurately describes the substance that makes up bone mineral and the matrix of teeth.

Parathyroid hormone does not inhibit calcium absorption. In fact, it plays a role in increasing calcium absorption from the intestines. The other factors listed, such as high content of dietary phosphate, the dietary ratio of calcium and phosphorus, alkaline condition, high content of dietary fiber, and the presence of phytates and oxalates, can inhibit calcium absorption.

High consumption of unsaturated fat is not a risk factor for atherosclerosis. Atherosclerosis is a condition characterized by the buildup of plaque in the arteries, leading to narrowing and hardening of the arteries. Risk factors for atherosclerosis include high consumption of saturated fat, diabetes, smoking, and obesity. However, unsaturated fats, particularly polyunsaturated fats, are considered heart-healthy and can actually help lower the risk of developing atherosclerosis. Therefore, high consumption of unsaturated fat is not a risk factor for atherosclerosis.

Abnormalities in calcium metabolism are primarily associated with alterations in parathyroid hormone (PTH). PTH is responsible for regulating calcium levels in the blood by stimulating the release of calcium from bones, increasing calcium reabsorption in the kidneys, and promoting the production of active vitamin D (calcitriol) which enhances calcium absorption in the intestines. Any imbalance in PTH levels can lead to disorders such as hyperparathyroidism (excessive PTH production) or hypoparathyroidism (insufficient PTH production), causing abnormal calcium levels in the body.

The normal concentration of plasma or serum calcium is 9-11 mg/dl (4.5 – 5.5 mEq/l).

Calcitriol is the active form of Vitamin D and it stimulates the uptake of calcium by osteoblasts, which are cells responsible for bone formation. It also promotes calcification or mineralization of bone, which is the process of depositing calcium and other minerals into the bone matrix to make it stronger and more rigid. PTH, on the other hand, primarily acts on the kidneys to increase calcium reabsorption and stimulates the release of calcium from bone, but it does not directly stimulate calcium uptake by osteoblasts or promote calcification. Therefore, Calcitriol is the correct answer.

Ca interacts with TROPONIN C to trigger muscle contraction. Troponin is a complex of three subunits: Troponin C, Troponin T, and Troponin I. Troponin C is the subunit that binds to calcium ions, which is crucial for muscle contraction. When calcium ions bind to Troponin C, it causes a conformational change in the troponin-tropomyosin complex, exposing the binding sites on actin for myosin. This allows myosin to bind to actin and initiate the sliding of the filaments, resulting in muscle contraction.

The Ca-Calmodulin complex is known to activate Ca dependent protein kinases and adenylate cyclase. This means that both enzymes are activated by the Ca-Calmodulin complex.

The correct answer is 15-20 mins. This is because irreversible cardiac injury occurs when the occlusion, or blockage, of blood flow to the heart is complete for a prolonged period of time. When blood flow is completely blocked for 15-20 minutes or longer, the heart muscle is deprived of oxygen and nutrients, leading to irreversible damage. This can result in a heart attack or myocardial infarction.

Phytates and oxalates are compounds found in certain foods that can bind to calcium and prevent its absorption in the intestines. Parathyroid hormone, acidity and lactose, lysine and arginine, and vitamin D all promote calcium absorption in different ways. Parathyroid hormone helps regulate calcium levels in the blood, acidity and lactose enhance calcium solubility and absorption, lysine and arginine increase calcium absorption in the intestines, and vitamin D stimulates the production of calcitriol, the active form of vitamin D, which promotes calcium absorption. Therefore, the correct answer is phytates and oxalates, as they do not promote calcium absorption.

PTH regulates plasma Ca level in the bone by causing decalcification or demineralization of bone carried out by OSTEOCLAST. This is brought about by PTH stimulated increased activity of pyrophosphatase and collagenase, which results in bone resorption.

Calcium (Ca) is an essential component in the coagulation process. It acts as a cofactor in all three coagulation pathways, namely the extrinsic pathway, intrinsic pathway, and common pathway. In these pathways, calcium is involved in the activation of various coagulation factors. Factor IV is the correct answer because it is another name for calcium in the context of coagulation.

Calcitonin is secreted by parafollicular cells of the thyroid glands and it promotes calcification by increasing the activity of osteoblasts. PTH (parathyroid hormone) is responsible for increasing blood calcium levels by stimulating the release of calcium from bones and decreasing calcium excretion by the kidneys. Calcitriol is the active form of vitamin D and it helps in the absorption of calcium from the intestines. Therefore, the correct answer is Calcitonin.

The extent of myocardial injury reflects the extent of the occlusion, the metabolic needs of the area deprived of perfusion, and the duration of the imbalance between coronary supply, substrate availability, and the metabolic needs of the tissue. Therefore, the correct answer is "none of the above."

Calcitriol is the correct answer because it stimulates calcium uptake by osteoblasts in bone, promoting calcification or mineralization (the deposition of calcium phosphate) and remodeling. Calcitriol is the active form of vitamin D and plays a crucial role in regulating calcium and phosphate levels in the body. It enhances the absorption of calcium from the intestines and promotes its reabsorption from the kidneys. This helps maintain adequate levels of calcium in the blood and supports bone health.

Hyperthroidism is not associated with atherosclerosis. Atherosclerosis is a condition characterized by the buildup of plaque in the arteries, leading to narrowed and hardened arteries. It is primarily caused by factors such as high cholesterol, high blood pressure, smoking, and diabetes mellitus. Hyperthroidism, on the other hand, is a condition where the thyroid gland produces an excessive amount of thyroid hormone. While hyperthroidism can have various cardiovascular effects, it is not directly linked to the development of atherosclerosis.

Heart failure is not a complication of atherosclerosis because it is primarily caused by other factors such as hypertension, coronary artery disease, or heart valve problems. Atherosclerosis is the buildup of plaque in the arteries, which can lead to blockages and restrict blood flow. This can result in complications like myocardial infarction (heart attack), aortic aneurysms, and stroke, but it does not directly cause heart failure.

Ca is needed for the direct activation of pancreatic lipase, ATPase, and succinate dehydrogenase. However, CPK does not require Ca for its direct activation. Therefore, the correct answer is CPK.