Thyroid And Parathyroid Glands Week 1 FINISHED Flashcards
What is the largest endocrine gland? How big is it?
Thyroid gland
20-25grams
What does thyro mean?
Shield
Where does the thyroid gland lie?
Between C5 and T1 vertebra
What muscles does the thyroid gland lie deep to?
Sternothyroid and sternohyoid muscles
What unites the 2 bilateral lobes of the thyroid?
The isthmus
What is the location of the lobes and isthmus of the thyroid?
The lobes are found lateral and anterior to the larynx and trachea between the level of C5 and T1. The isthmus is found anterior to the 2nd and 3rd tracheal rings
What % of people have a pyramidal lobe of the thyroid?
50%
What surrounds the thyroid gland?
A fibrous capsule which sends septa deep into the gland. Connective tissue then attaches the thyroid to the cricoid cartilage and superior tracheal rings.
What is external to the capsule that surrounds the thyroid gland?
Deep pretracheal cervical fascia
What is the arterial supply for the thyroid gland? Where does each of these arteries originate?
Superior thyroid artery - arises off the external carotid artery
Inferior thyroid artery - arises off the thyrocervical trunk off the first part of the subclavian artery.
Where do the arteries for the thyroid run in relation to the other capsules of the gland?
Between the fibrous capsule and the pretracheal cervical fascia
What are the 3 pairs of veins that drain the thyroid? Which part of the gland does each drain and where do they drain into?
Superior thyroid veins: drain the superior pole of the thyroid gland and empty into the internal jugular vein
Middle thyroid veins: drain the middle pole of the thyroid gland and empty into the internal jugular vein
Inferior thyroid veins: drain the inferior pole of the thyroid gland and empty into the left brachiocephalic vein
What is the nerve supply for the thyroid gland? What is their function in the gland?
SNS: Superior, middle and inferior cervical ganglion
- cause blood vessel constriction
PSNS: vagus
- unclear
How is secretion by the thyroid gland monitored?
By the pituitary gland
What is the function of the thyroid gland?
It is an endocrine gland which secretes hormones, mostly the thyroid hormone (most commonly thyroxine) and calcitonin
What are some of the functions of thyroxine in the body?
•Affects body temperature •Regulation of protein, fat and carbohydrate metabolism •Maintains growth hormone secretion •Skeletal maturation •Cardiac rate, force and output •Promotes CNS development •Stimulates the synthesis of many enzymes •Necessary for mm tone Increases rate of metabolism
What is the function of calcitonin in the body?
Participates in the regulation of the blood level of calcium, and stimulates bone mineralisation
Reduces blood levels of calcium
Inhibits bone reabsorption
What is the size, shape, colour and location of the parathyroid glands? How many do people usually have and what % usually have more?
6mm x 4 mm oval shaped, reddish brown glands situated on the posterior surface of the thyroid gland lobes. Most people have 4. Only 5% of the population have more than 4.
Are the parathyroid gland internal or external to the fibrous capsule of the thyroid gland?
External
What is the arterial supply for the parathyroid glands?
Usually the inferior thyroid arteries but may be supplied by other nearby arteries such as superior thyroid, laryngeal, tracheal and oesophageal.
What is the venous drainage of the parathyroid veins?
Drain into the venous plexus on the anterior surface of the thyroid gland, which then empties into the thyroid veins.
What is the function of the parathyroid gland?
To secrete parathyroid hormone, which acts to increase blood calcium and increase bone reabsorption
How do calcitonin and parathyroid hormone help to maintain homeostasis in the body?
If blood calcium levels rise beyond a set point, calcitonin is released from the thyroid gland which cause blood calcium levels to drop
If blood calcium levels fall beyond a set point, parathyroid hormone is released from the parathyroid glands which cause blood calcium levels to rise
What kinds of glands are the thyroid and parathyroid glands?
Both are endocrine glands
