Exam 1 - Lecture VI (Basically all things Thyroid) Flashcards
Why are the 2 reasons the thyroid gland is important in anesthesia?
1) controller of metabolic rate
2) anatomy and location
7:00
What ligament can be covered up by the thyroid gland?
Why is this ligament important?
What is a main concern when cutting into this area?
Cricothyroid ligament, we use this for an invasive airway (EMERGENCY OPTION) 😅
The thyroid is VERY vascular and you are concerned about bleeding. 🩸
7:45
The _______ ________ artery feeds the thyroid from the ________ carotid artery.
The ______ nerve runs down the carotids.
The left _________ _________ nerve branches off & wraps around the aorta.
The right _______ _______ nerve branches off and wraps around the right carotid artery.
(These run btwn the thryroid and trachea.)
Where is the endpoint for these two nerves?
superior thyroid, external
vagus, left recurrent laryngeal nerve, right recurrent laryngeal nerve
Endpoint: voice box
10:00
What structure(s) give us the ability to speak?
The voice box and all of the skeletal muscles inside, innervated by the two recurrent laryngeal nerves.
*injuries to these nerves can make us lose our voice 🗣️
(surgical cutting or inflammation)
11:30
Enlarged thyroid glands can compress on the recurrent laryngeal nerves and make us lose our voice.
What else is the CRNA concerned about with an enlarged thyroid, or goiter, from an anatomical standpoint?
Getting in the way of your airway! Harder to intubate.
*large goiters can also compress tracheal ligaments to the point of collapse 😳
12:00
What two structures control the thyroid gland?
Which structure senses & decides what to release?
Pituitary gland and hypothalamus
“Hypothalamic Pituitary control system”
Hypothalamus is the boss!
15:00
How do hormones travel from the hypothalamus to the ANTERIOR pituitary gland?
Via a portal circulation system that is a few cm long.
16:00, Guyton pg. 931
What hormone does the hypothalamus release? (Full name and accronym)
Where are the receptors for this hormone?
TRH (Thyrotropin-releasing hormone)
It travels to the TRH receptors on the pituitary gland.
16:45
TRH causes release of _____ from the anterior pituitary gland. This hormone then travels to the _____.
TSH, thyroid stimulating hormone
thyroid gland
17:20
TSH causes release of hormones from the thyroid gland.
What two compounds are considered true thyroid hormones? What do they derive from?
T3 and T4 -circulating thyroid hormones
Derivatives of Tyrosine (amino acid)
18:30
What is added to the Tyrosine molecule to create T3 and T4?
Iodine (or Iodide)
19:15
What is the name for the molecule with ONE iodine added to a tyrosine?
Two Iodines?
How do you produce T3? What is the formal name for T3?
How do you produce T4? What is the formal name?
Monoiodotyrosine (T1), Diiodotyrosine (T2)
T3 recipe = T1 + T2, Triiodothyronine
T4 recipe = T2 + T2, Thyroxine
19:40
What is the main difference btwn a -tyrosine named molecule and a -thyronine?
The added benzene ring.
(from the 2 tyrosine molecules)
21:45
We get iodine from iodized table salt.🧂This is absorbed from our GI tract and then used.
Later, on the basal surface of the thyroid gland cell, Iodine is pumped into the cell via what kind of pump on the basal membrane?
Where does this pump derive its energy from?
Iodine-Na+ symporter
(this uses two Na+ for one Iodine)
Derives energy from the Na-K-ATPase pump 🙃
22:00, Guyton pg. 942
Does sea salt have iodine in it?
How much Iodine do we need a year?
NO!
50mg/yr (1mg/week) -doable.
*also, please enjoy salt bae (a Turkish chef)
24:00
What enzyme is responsible for the reaction used to oxidize iodine for it to connect with Tyrosine?
Peroxidase, uses H2O2 (hydrogen peroxide)
*Oxidative stress is a good thing here!
25:00, Guyton Pg. 942-943
What happens if peroxidase becomes overwhelmed or is missing?
We lose the ability to create thyroid hormone.
25:45, Pg. 943
What is this showing?
Tyrosine being attached to iodine(s) to create all the numerous thyroid hormones.
26:00
Thyroid hormones are lipophilic (fat soluble).
This means they need LIVER transport proteins to travel throughout the CV system. 👬
What are these transport proteins (3), starting with the primary?
Primary: TBG (Thyroxine binding globulin) -MAIN transporter
2nd: Thyroxine binding pre-albumin
3rd: Albumin
*Think about liver failure patients here…might not be able to transport thyroid hormone sufficiently.
28:00
In the circulation, T3 makes up ___% and T4 (Thyroxine) makes up ___%.
___ is more active and ____ is the main circulatory hormone.
T3 - 7%, T4 - 93%
T3 more active.
T4 is main circulatory hormone.
31:00, Pg. 944
Thyroid hormones: A short story.
Due to the lipophilic properties of T3 and T4, when they come into close proximity of their target cell, they release from the carrier protein and move through the cell wall.
Once they’re across the wall, they bind to intracellular proteins & eventually become FREE!
Once free, where do they go?
Why do they go there?!
Is T3 or T4 (thyroxine) more active intracellularly?
Into the nucleus!
Elicit response: ⬆️ gene TRANSCRIPTION!
T3 - more active
33:00
T3 (Triiodothyronine) is the most active form but we only have ~7% floating around.
What is the body’s mechanism for giving us more T3 at the cellular level?
(HINT: its an enzyme)
If the thyroid gland only makes 15% of our T3 utilized, how much is made at the cellular level?
Deiodinase!
This strips an iodine from T4 and creates T3 intracellularly.
(most of what is delivered is T4)
85% of T3 is created this way 😁
34:20, pg. 944
After new protein synthesis, list the outcomes thyroid hormone would have on metabolism. (HINT: power house, MVP pump, endocrine)
⬆️ metabolism (need more energy, nutrients)
- ⬆️ mitochondria - become larger and amount = ⬆️ ATP!⚡️
- ⬆️ Na-K-ATPase activity (bc of an ⬆️ in cell permeability to Na+; uses ATP, too)
- ⬆️ glucose metabolism
–⬆️ glucose absorption (from GI)
–⬆️ gluconeogenesis (creation of)
–⬆️ glycolysis rate
–⬆️ circulating insulin (⬆️ activity of ENDOCRINE system)
38:00
After new protein synthesis, list the outcomes thyroid hormone would have on CV. ♥️ (cholesterol & triglycerides, too)
-⬆️ HR + ⬆️ SV = ⬆️ CO!
-⬆️ PP (related to ⬆️ SV & ⬆️ sBP but ⬇️ dBP)
-⬇️ Cholesterol (result of using it for energy & ⬆️ excretion of it via GI tract w/ bile)
-⬇️ Triglycerides
44:00
After new protein synthesis, list the outcomes thyroid hormone would have on the CNS. 🧠
What would happen in the instance of extreme hyperthyroidism?
⬆️ alertness & awareness (insomnia??)
⬆️ Neuromuscular activity/transmission (⬆️ tremors)
–IF very elevated hyperthyroidism = NMJ deficits (overactivity - motor disfunction)
51:45
How long do thyroid issues take to develop? Why?
~2-3 days
Gene Transcription takes time, girl!
*NOT everything takes this long but the majority of metabolic demands takes awhile…
55:00
Exopthalamus is caused by _____thyroidism.
Why do patients suffer eye damage from this?
Hyperthyroidsim;
Eyelids don’t close completely in sleep.
58:00
List the 3 things that can cause hyperthyroidism from lecture.
1) Tumors
2) Autoimmune - Graves Disease
3) 💊 Rx drugs (not clear how)
59:00
Describe Graves disease.
Would you expect TSH & TRH to be ⬆️ or ⬇️ ?
autoimmune disorder; produces an overactive thyroid gland by stimulating TSH-r on the thyroid via autoantibodies.
*strange autoimmune disease bc the antibodies don’t destroy the receptor but only turn it on💡
Normal path: TRH (Hypothalamus) > TSH (APgland) > TSH-r (Thyroid gland) > ⬆️ thyroid hormone!
-TRH ⬇️
-TSH ⬇️
59:30 & 96:30
How do you treat hyperthyroidism?
1) 🔪 surgery - cut out tumor (risk for loss of speech)
2) shrink gland ☢️ (radioactive iodine - gets taken up by I-pumps VERY useful)
3) Drugs
63:00
For hyperthyroidism, Thiocyanate can be given.
How does this drug work? (Hint: looks like Iodine)
It outcompetes Iodine so TH can’t be produced! (🚫 ABSORPTION)
*this could cause a goiter
*drugs take long time to work
77:00, pg. 950
Propylthiouracil can also be given for hyperthyroidism.
Describe its MOA. (Hint: P for peroxidase)
It blocks peroxidase, thus no iodination of tyrosine to form T3 and T4 can happen. (🚫 OXIDATION)
*this could cause a goiter
*drugs take long time to work
78:10, pg 950
T/F?
Giving someone an egregious amount of Iodine (100x normal amount) can help treat hyperthyroidism. This can also be used in preparation of thyroidectomy.
True!
This ‘most likely’ overwhelms peroxidase step.
This will shrink the TG promoting a shorter surgery time and decrease the amount of bleeding during removal.
80:30, pg. 950
How much Iodine is in a 100mg dose of Amioderone?
35mg
Amioderone is 35% iodine.
*long term amio therapy??
*can cause hyper or hypothyroidism
81:30
What is Hashimoto’s thyroiditis?
Autoimmune disease that causes INFLAMMATION and DESTRUCTION ⚔️ of the TG and leads to HYPOthyroidism.
85:00, pg. 951
What do you worry about in a child born without a thyroid?
What is cretinism?
Growth and development (physical and cognition) 🧠
87:15, pg. 953
List 4 treatments for hypothyroidism.
Treat cause:
1) ⬆️ iodine in diet
2) Levothyroxine/Synthroid *give on empty stomach 🙃
3) steroids
4) Plasmapheresis (remove autoantibodies)
90:00
What would an adenoid tumor on the TG secrete?
How can this be diagnosed?
(HINT: NEGATIVE FEEDBACK)
It would secrete TH but you would have very low levels of
TRH and TSH. (NEGATIVE FEEDBACK)
94:00
You eat nothing but natural ol’ sea salt 🧂 and now you have an iodine deficiency & low T4 (Thyroxine) levels.
Would your TRH and TSH levels be ⬆️ or ⬇️?
TRH and TSH ⬆️ ⬆️ - negative feedback
*Stop being a hippie and get you some Morton’s.
*BTW Himalayan salt has a lil amount of natural iodine.
97:00
⬆️ Thyroxine will shut down the release of ____ from the ____ gland.
It will also _____ (directly/indirectly) shut down _____ secretion from the ________ d/t ⬆️ metabolism & body temp. 🌡️
TSH, anterior pituitary
Indirectly, TRH, hypothalamus
98:20
The anterior pituitary gland controls which hormones? (6)
Is ACH secreted by the pit gland?
1) prolactin
2) Lutenizing (LH)
3) FSH
4) Corticotropin -> stimulates Adrenal cortex -> ACH (⬆️ glucose = ⬆️ insulin)
5) GH
6) Thyrotropin
103:00
Where are T3 & T4 produced?
What happens when they need to be released?
Inside of Thyroglobulin proteins that are inside the thyroid gland. The protein serves as a storage site, holding ~60-70
The thyroglobulin protein dissolves when these need to be released.
106:00
