Calcium channel blockers Flashcards
- What is the importance of calcium in the body?
- What are the functions of calcium in the body
- What can calcium prevent and decrease risk of ?
- what happens if there is too little calcium?
- calcium out of bones into the blood as needed to maintain a steady calcium level in the blood.
- too much calcium is mobilized from the bones, weakening them.
- Osteoporosis can result.
- What is rickets?
- What else is low calcium absorption associated with?
- What does calcium do as an electrolyte?
Calcium is one of the body’s electrolytes, which are minerals that carry an electric charge when dissolved in body fluids such as blood, but most of the body’s calcium is uncharged.
- Where is calcium stored?
- About 99% of the body’s calcium is stored in the bones, but cells, particularly muscle cells, and blood also contain calcium.
- What is calcium essential for?
- Calcium is essential for the following:
- Formation of bone and teeth
- Muscle contraction
- Normal functioning of many enzymes
- Blood clotting
- Normal heart rhythm
- How do we maintain a normal level of calcium?
- To maintain a normal level of calcium in the blood without weakening the bones, people need to consume at least 1,000 to 1,500 milligrams of calcium a day.
- How is The level of calcium in the blood is regulated
Parathyroid hormone and Calcitonin
What is the role of the parathyroid hormone?
- Parathyroid hormone is secreted from four parathyroid glands, which are small glands in the neck. Parathyroid hormone regulates calcium levels in the blood, largely by increasing the levels when they are too low. It does this through its actions on the kidneys, bones, and intestine
- What impact does the parathyroid hormone have the bones, kidneys, and intestine?
- Bones – parathyroid hormone stimulates the release of calcium from large calcium stores in the bones into the bloodstream. This increases bone destruction and decreases the formation of new bone.
- Kidneys – parathyroid hormone reduces loss of calcium in urine. Parathyroid hormone also stimulates the production of active vitamin D in the kidneys.
- Intestine – parathyroid hormone indirectly increases calcium absorption from food in the intestine, via its effects on vitamin D metabolism.
- How does the parathyroid hormone work in relation to low and high calcium?
Parathyroid hormone is mainly controlled by the negative feedback of calcium levels in the blood to the parathyroid glands.
- Low calcium levels in the blood stimulate parathyroid hormone secretion
- high calcium levels in the blood prevent the release of parathyroid hormone.
- What happens when there is too much parathyroid hormone?
producing too much parathyroid hormone causes raised calcium levels in the blood (hypercalcaemia) and this is referred to as primary hyperparathyroidism.
- What disease can be developed by hyperparathyroidism?
tertiary hyperparathyroidism that causes hypercalcaemia due to excess parathyroid hormone production on the back drop of all four glands being overactive.
- What happens when there is too low calcium and what disease is developed?/ what is the condition that has low calcium levels and causes another disease as a result?
Too little parathyroid hormone or hypoparathyroidism, is a rare medical condition. It can result in low levels of calcium in the blood (hypocalcaemia).
This can lead to Secondary hyperparathyroidism which occurs in response to low blood calcium levels and is caused by other mechanisms, for example, kidney disease and vitamin D deficiency.
- What would be the treatment for mild primary hyperparathyroidism?
Treatment may be by surgical removal of the affected gland(s) (parathyroidectomy).
- What is Calcitonin
- works to control calcium and potassium levels. It does this by inhibiting the activity of the osteoclasts, the cells that break down bone. When the osteoclasts break down bone tissue, the calcium enters the bloodstream. By preventing the breakdown of bone, calcitonin lessens the amount of calcium in the blood.
- decreases the amount of calcium the kidneys can re-absorb, lowering levels further.
- To make sure that each cell contracts at the right moment, the heart uses an electrical signal that moves from cell to cell.
How do we treat hypocalcaemia?
It is usually treated medically with oral calcium and vitamin D analogues but the availability of parathyroid hormone replacement therapy may change the approach to treatment for some patients
What is the role of calcium in heart function and blood circulation?
To make sure that each cell contracts at the right moment, the heart uses an electrical signal that moves from cell to cell.
- Calcium particles are responsible for the link between electrical activation and mechanical contraction.
- Calcium particles, which have an electrical charge, enter the heart muscle cells during each beat and contribute to the electrical signal.
- calcium particles initiate contraction by binding to specialized machinery within the cell. When the calcium binds, the machinery starts to move and makes the cell squeeze together.
- What happens when calcium particles are removed from the heart?
When the calcium particles are removed from the heart cells, this triggers relaxation, allowing the heart to be refilled with blood before the start of the next heartbeat. Thus, without calcium, our hearts would stop beating immediately.
What is the physiological role of Calcium channels in muscle contraction?/ how do calcium channels work in muscle contraction?
- Name the different types of calcium channel blockers?
voltage gated channel blocker - L type. T-type, N P AND R Type
receptor operated channel blockers
stretch operated channel blockers
- What is the most important calcium channel blocker?
L type
L-type calcium channel, also known as the dihydropyridine channel (DHP) channel is part of the high-voltage activated family of voltage-dependent calcium channel. The L stands for long-lasting referring to the length of activation.
- What is the most important calcium channel blocker?
L type
L-type calcium channel, also known as the dihydropyridine channel (DHP) channel is part of the high-voltage activated family of voltage-dependent calcium channel. The L stands for long-lasting referring to the length of activation.
- What do the calcium channel antagonists do and why are these effects useful?
The calcium channel antagonists
- interfere with cellular calcium uptake.
- arterial dilatation and, to a varying extent, depression of myocardial contraction and conduction.
- They also have an intrinsic diuretic effect.
- These actions are useful for :
- management of hypertension and angina
- supraventricular arrhythmias and peripheral vasospasm
- what are the adverse effects of calcium channel antagonist?
- They are dose dependent.
- flushing, headaches and peripheral oedema (particularly with the dihydropyridines) due to vasodilatation, and depression of myocardial function (particularly verapamil and, to some extent, diltiazem).
- What can shorter-acting dihydropyridines cause?
(particularly nifedipine) can cause reflex-mediated cardiac stimulation which may be dangerous.
What is the benefit of longer acting and slow release formulations?
The availability of slow-release and longer-acting formulations has improved tolerability and compliance
- What conditios does CCAs treat?
- Hypertension
- angina pectoris
- paroxysmal supraventricular tachycardias
- hypertrophic cardiomyopathy
- Raynaud phenomenon
- pulmonary hypertension
- diffuse esophageal spasms
- what are the three main classes of CCAs?
Calcium antagonists as a group are heterogeneous containing:
- Phenylalkylamines
- Benzothiazepines
- Dihydropyridines
What do calcium channel agonists do?
block the influx of calcium into the heart and arterial blood vessels
- what are the three main classes of CCAs?
Calcium antagonists as a group are heterogeneous containing:
- Phenylalkylamines - verapamil
- Benzothiazepines -Diltiazem
- Dihydropyridines - amlodipine, nifedipine and felodipine
- ## what is the main function of Calcium antagonists
lower blood pressure mainly through vasodilation and reduction of peripheral resistance.
- They maintain blood flow to vital organs.
- The calcium channel antagonists inhibit calcium uptake into cells through a channel in the cell membrane, which is specific for the entry of divalent cations, particularly calcium. The result of this inhibition is to reduce the availability of intracellular calcium and thus interfere with the cellular processes dependent on calcium.
- How do these classes of drug work?
- The members of each class bind to a different receptor site within the calcium channel. The three classes are represented by verapamil, diltiazem and the dihydropyridines: nifedipine, felodipine and amlodipine.
- Calcium channels at different sites throughout the body have variable concentrations of the three receptor sites
