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Question 1

What is the “false capsule” that covers the thyroid gland formed by?

Answer 1

pretracheal fascia

Question 2

What are the right and left lobes of the thyroid connected by and how does this structure extend?

Answer 2

They are connected by a narrow isthmus.

The isthmus continues upwards crossing the second and third tracheal cartilages.

Question 3

What is the structure that extends from the isthmus that is found in some people called?

Answer 3

Pyrimdal lobe that ascends towards the hyoid bone

Question 4

What are the posterior relations of the thyroid gland?

Answer 4

Trachea, esophagus, larynx, pharynx

Question 5

What are the two muscles that lie infront of the thyroid gland?

Answer 5

sternothyroid and sternohyoid muscles

Question 6

What are the vessels that lie postero-lateral to the thyroid gland?

Answer 6

Common carotid artery and internal jugular vein

Question 7

What arch is the trachea attached to and what unique feature does this give it?

Answer 7

Attached to the arch of the cricoid cartlige and moves up down while swallowing and osillatces while speaking

Question 8

What is the main arterial supply of the thyroid gland and where do those arteries lie and anastmose?

Answer 8

Main: Superior and inferior thyroid arteries

Lie Between the capsule and the pretracheal fascia

Anastmose inside the matter of the thyroid

Question 9

What is the superior thyroid a branch of and where does it descend?

Answer 9

It is a branch of the External carotid artery and it descends towards the superior lobe of the thyroid

Question 10

What is the inferior thyroid artery a branch of and how does it run?

Answer 10

It is a branch of thyro-cervical trunk

It runs superomedially posterior to carotid sheath reaches posterior aspect of the gland and supplies the inferior pole of the gland

Question 11

What nerve does the inferior thyroid artery have a relationship with?

Answer 11

Recurrent larygeal nerve

Question 12

What type of artery is found 10% of people that supplies the thyroid and what exactly does it supply?

Answer 12

Artery: Thyroid Ima Artery

Arises: From Aorta, brachiocephalic trunk, or internal carotid artery.

Supplies: Isthmus

Question 13

What are the nerves, arteries, and veins that are located posterior to the thyroid?

Answer 13

Common carotid artery

Internal jugular vein

Recurrent laryngeal nerve

Trachea

Thyroid cartlige

Superior laryngeal nerve

Vagus nerve

Question 14

What is the venous drainage of the thyroid?

Answer 14

Usually 3 veins on anterior surface

Superior thyroid veins Drain superior poles of thyroid

Middle thyroid veins Drain lateral poles

Inferior thyroid veins Drain inferior poles

Question 15

Where do the superior and middle thyroid veins drain?

Answer 15

Drain into the Internal jugular veins

Question 16

Where does the inferior thyroid vein drain?

Answer 16

Brachiocephalic vein

Question 17

What is the lymphatic drainage of the thyroid?

Answer 17

1. prelaryngeal lymph nodes
2. pretracheal and paratracheal lymph nodes.

Lateral lymph nodes: Drain into deep cervical lymph nodes

Finally: Into either brachiocephalic or thoracic duct

Question 18

What do the lateral lymph nodes that drain the thyroid run along?

Answer 18

Superior thyroid veins

Question 19

Where are the parathyroid glands embeded?

Answer 19

In the fibrous capsule

Question 20

How is the thyroid gland subdivided and what do these divisions contain

Answer 20

The thyroid gland is subdivided by
capsular septa into lobules
containing follicles.

Question 21

Label

Answer 21

Question 22

What do thyroid follicles contain?

Answer 22

colloid, a viscous gel consisting mostly of iodinated
thyroglobulin.

Question 23

What are the thyroid follicles surrounded by?

Answer 23

Thyroid follicles are enveloped by a layer of epithelial
cells, called follicular cells, which in turn are
surrounded by parafollicular cells.

Question 24

What is the function of follicular cells?

Answer 24

Synthesize and store thyroid hormones

Question 25

Label

Answer 25

Question 26

What type of epithelium do the follicular cells have?

Answer 26

Simple Cuboidal epithelium that becomes columnar when active and squamos when inactive

Question 27

What are the two major hormones that the thyroid secretes?

Answer 27

Thyroxine (T4) an Triiodothyronine (T3).

Question 28

What role does the pituitary gland have in regulating the thyroid?

Answer 28

It releases thyroid stimulating hormone that regulates Thyroid secretion.

Question 29

What else does the thyroid secrete?

Answer 29

Calcitonin which plays a role in regulating calcium metabolism

Question 30

What is the structural difference between T3 and T4?

Answer 30

**The two active thyroid hormones are triiodothyronine (T3) and tetraiodothyronine, or thyroxine (T4). The structures of T3 and T4 differ only by a single atom of iodine, as shown in Figure 9.16. Although T3 is more active than T4, almost all hormonal output of the thyroid gland is T4. This “problem” of secreting the less active form is solved by the target tissues, which convert T4 to T3. A third compound, reverse T3**

Question 31

What is the functional difference between T3 and T4?

Answer 31

T3 is more active than T4 But T4 has a longer half life and is synthsized in greater amounts

Question 32

What are 2 causes of hyperthyroidism?

Answer 32

**Autoimmune disease** where antibodies (Thyroid-Stimulating Immunoglobulins: TSI) bind to the TSH receptor and induces continual activation (12 hours) of cAMP system. High levels of Thyroid hormone caused by TSI depress the pituitary gland secretion of TSH that drop to zero. **Thyroid adenoma:** cancer within a region of thyroid gland that secrete large quantities of thyroid. The healthy part of the gland will show reduction in thyroid secretion due to the feedback mechanism exerted on the pituitary gland (less TSH secretion).

Question 33

What are some symptoms of hyperthyroidism?

Answer 33

1- High state of excitability 2- Intolerance to heat 3- Increased sweating 4- Mild to extreme weight loss 5- Varying degrees of diarrhea 6- Muscle weakness 7- Nervousness 8- Extreme fatigue but inability to sleep 9- Tremor of the hands

Question 34

What is exothalmos and what is it caused by?

Answer 34

Protrusion of the eyeballs caused by swelling of the retro-orbital tissue and degenerative changes in the extraocular muscles. IgGs reacting with eye muscle

Question 35

What are diagnostic tests of hyperthyrodism?

Answer 35

**Direct measurement** of **free thyroxine** (sometimes **triiodothyronine**) in the plasma. Basal metabolic rate is increased +30 to +60. **Measuring plasma levels of TSH** (close to zero) or **TSI levels** (high in thyrotoxicosis, low in thyroid adenoma).

Question 36

What are the physiological treatments for hyperthyroidism?

Answer 36

Physiological treatment for hyperthyroidism primarily involves surgically removing most of the thyroid gland. Before surgery, patients typically receive propylthiouracil for 1 to 2 weeks to reduce metabolic activity. Alternatively, treatment can include administering 5 mCi of radioactive iodine, which is absorbed by the hyperplastic thyroid gland and destroys most of its cells. If the patient remains hyperthyroid after the initial dose, additional doses may be given.

Question 37

What is hashimoto disease?

Answer 37

Hypothyroidism caused by immune cells attacking the thyroid This will cause inflamation and fibrosis.

Question 38

What is thyroid goiter?

Answer 38

Hypothyroidism caused by thyroid hypertrophy

Question 39

What is endemic thyroid goiter caused by?

Answer 39

caused by dietary iodide deficiency: Deficiency in iodide > deficiency in thyroxine and triiodothyronine > increased TSH by pituitary gland increased Thyroglobulin in the thyroid follicle > enlarged thyroid follicle (10 to 20 X).

Question 40

What is Idiopathic Non-toxic Colloid Goiter?

Answer 40

Thyroiditis leading to decreased production of thyroid hormone which in turn leads to increased TSH which will lead to increased thyroglobulin which will lead to hypertrophy in non inflammed areas with nodular shape

Question 41

What are some of the symptoms of hypothyroidism?

Answer 41

Regardless the cause or type of hypothyroidism the physiological characteristics are similar: Fatigue and somnolence (12-14 hours of sleep) Extreme muscular sluggishness Slow heart rate Decreased cardiac output Decreased blood volume Sometimes increased body weight Constipation Mental sluggishness Depressed growth of hair and scaliness of the skin Froglike husky voice Edematous appearance throughout the body (myxedema)

Question 42

What is myxedema

Answer 42

Develops in patients with total absence of thyroid hormone function: 1- Bagginess under the eye 2- Swelling of the face Greatly increased quantities of Hyaluronic acid and chondroitin sulfate bound with protein from excessive tissue gel in the interstitial space leading to increased interstitial spaces. The nature of the excess fluid leads to nonpitting edema.

Question 43

GO back to slides and study the tables from first aid

Question 44

What is creatnism?

Answer 44

Severe hypothyroidsim in early childhood which causes mental retardation and failure of bodygrowth