Parathyroid And Thyroid Flashcards
Where is the parathyroid gland located?
It is located below the larynx on each side of and interior to the trachea.
What is the parathyroid gland composed of?
The right and the left loops, which are United by the isthmus.
Superior parathyroid gland
Inferior parathyroid gland
Closed follicles filled with secretary substances called COLLOID.they are lined with cuboid epithelial cells.
What is the Job of the follicular cells?
They are responsible for the trapping of iodine which they secrete alongside the thyroglobulin.
What are the parafollicular cells and what is their main function?
These are also known as c cells
-they secrete the hormone calcitonin and it is a peptide hormone that works by lowering the plasma calcium concentration and has has opposite effects to those of the PTH.
What is said about the capillaries surrounding the parathyroid gland?
There is a dense capillary network running through this and has a high blood flow compared to other tissues.
Where is the venous return?
By the thyroid vein which drains into the internal jugular veins.
What stimulates the thyroid stimulating hormone and where are they both released from?
Thyrotropine releasing hormone (TRH) secreted by the hypothalamus, stimulates the production of thyroid stimulating hormone (TSH) secreted from the anterior pituitary
What are the two main thyroid hormones?
T4(thyroxine) , 90% =inactive
T3 (triiodothyronine) ,10% =active
Where do these thyroid hormones bind to?
Bound to:
-thyroxine binding globulin (TBG) carries 70% of T4 and T3
-thyroxine binding prealbumin( TBPA) binds 10% of circulating T4 and lesser amounts of T3
-albumin, binds 15% of circulating T4 and T3
Unbound form =active
Bound form= reservoir
What is the main function of thyroid hormone?
-growth
-maturation of tissues
-cell metabolism
-heat production
-oxygen consumption
-mental development
What are the parathyroid glands?
These are small glands that are located behind the upper and lower poles of the thyroid gland
What are the main functions of the parathyroid glands?
They produce parathyroid hormone
-they regulate serum calcium by secreting calcitonin from the parafollicular cells (c cells)
Why is calcium important in our bodies?
Calcium is important in the conduction of electrical impulses in nervous and muscular systems and it is the only element that has its own regulatory system which is the parathyroid glands.
If there is a decrease in calcium in serum what happens?
There is increased PTH secretion
-it acts on the kidney, gut and the bones
-to increase serum calcium level it does this by ….
THIS LEADS TO OSTEOCLAST ACTIVATION and releasing free calcium
What is the maintenance of plasma calcium?
9-10mg/dl
-40% calcium is tightly bound to plasma proteins
-10% is combined to unionised salts
-50% is free 5mg per dl
Where is calcium absorbed?
In the small intestine
How is calcium homeostasis maintained?
The absorption of calcium from the intestine is balanced by daily calcium loss through renally excretion (0.2g per day) and through saliva and bile eliminated in the faeces (0.2g per day)
What body processes is calcium important for?
-neurotransmitter release
-muscle contractions
-blood coagulation
What is the conversion factor to convert mg/dl into mmol/l?
0.250
What’s happens if the parathyroid gland releases PTH?
It will activate the osteoclast formation where it will go on to degrade bone matrix and release calcium into the blood causing an increase in the calcium level.
What will happen if calcitonin is released from the parathyroid gland?
The parathyroid gland recognises that the calcium serum level has been risen it releases calcitonin which stimulates calcium deposition in bone and therefore is a decrease in the free calcium in serum.
What is primary hyperparathyroidism?
This means that there is a fundamental increase in the amount of PTH that’s is secreted from one or more glands
-this means there is abnormally high levels of calcium
-bone degradation leading to osteoporosis
-development of kidney stones
-begin growth of parathyroid gland
What is secondary hyperparathyroidism?
This is when there is an increase in the PTH level to chronic disease
What are signs and symptoms of hyperparathyroidism?
-fatigue
-muscle weakness
-vomiting
-hypertension
-demineralisation of bones
-development of kidney stones
-apathy (loss of movement)
What is a hypercalemic Crisis?
This is when the calcium serum levels are over 15mg/dl
This can develop into neurological, cardiovascular and renal symptoms
How do we decrease calcium levels in the body?
Give :
-IV fluids to flush the calcium out
-phosphate therapy, as the calcium is increased there is a decrease in phosphate so if we increase phosphate levels we can decrease the calcium levels
-calcitonin, to store calcium in bones
-dialysis
What is hypoparathyroidism?
This is abnormally low PTH levels, so low calcium levels
This is usually caused by damage of the thyroid or surgery of the thyroid gland
What are the signs and symptoms of hypoparathyroidism?
-neuromuscular irritability ( cramps, spasms etc)
-numbness
-tingling
-bronchospasm