Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

MEH > Session 7 > Flashcards

Session 7 Flashcards

(145 cards)

Start Studying
1
Q

Where is the thyroid gland located?

A

Against and around the front larynx and trachea
Below thyroid cartilage
Just above the suprasternal notch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The thyroid gland lies against and around the front __________ and ___________

A

Larynx

Trachea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The thyroid gland is located below the…

A

Thyroid cartilage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The thyroid gland is located just above the…

A

Suprasternal notch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The thyroid gland consists of 2 lobes joined by…

A

Isthmus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The thyroid gland has which rough shape?

A

Bow tie shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Are the parathyroid and thyroid glands the same?

A

No, two distinct glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The isthmus extends from which rings of the trachea?

A

From the 2nd to the 3rd rings of the trachea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the first endocrine gland to develop?

A

Thyroid gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When does the thyroid gland first appear during embryological development?

A

3-4 weeks gestation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does the thyroid gland first appear (at 3-4 weeks gestation)?

A

An epithelial proliferation in the floor of the pharynx at the base of the tongue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does the thyroid gland develop from being an epithelial proliferation in the floor of the pharynx at the base of the tongue (at 3-4 weeks gestation) to its final position?

A

Descends as diverticulum through the thyroglossal duct and migrates downwards in front of the hyoid bone. Connection to the tongue by the thyroglossal duct degenerates and detached thyroid continues to its final position over the following two weeks.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

During embryological development, the thyroid gland descends as _____________ through the __________________ duct and migrates downwards in front of the __________ bone

A

Diverticulum

Thyroglossal

Hyoid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the histology of thyroid tissue

A

Follicular cells arranged in spheres called thyroid follicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

In the thyroid gland, thyroid follicles (formed from follicular cells arranged in spheres) contain…

A

Colloid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is colloid? Where is it found? Is it extracellular or intracellular?

A

Deposits of thyroglobulin

In thyroid follicles

Extracellular (but within thyroid follicles)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Are the thyroid and parathyroid glands distinct glands?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe the cells of the parathyroid gland and the hormone they produce

A

Principal cells produce parathyroid hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which cells produce parathyroid hormone in the parathyroid gland?

A

Principal cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What hormone is released from the principal cells of the parathyroid gland?

A

Parathyroid hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What two types of cells are found in the thyroid gland?

A

Follicular cells

Parafollicular cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Thyroid follicular cells in the thyroid gland produce…

A

Thyroid hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Thyroid parafollicular cells produce…

A

Calcitonin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Colloid in the thyroid gland follicles stores…

A

Thyroglobulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Describe the general structure of thyroid hormones
Two tyrosine linked together + iodine at three (T3) or four (T4) positions on the aromatic rings
26
T3 is also known as...
Triiodothyronine
27
From which molecules is T3 (triiodothyronine) formed?
From MIT + DIT
28
From which molecules is T4 (thyroxine) formed?
DIT + DIT
29
What is another name for T4?
Thyroxine
30
What is the function of thyroglobulin in the thyroid gland? What does it contain?
Acts as a scaffold on which thyroid hormones are formed Tyrosine residues
31
What two processes occur on thyroglobulin?
Iodination and coupling
32
What is thyroid peroxidase?
Membrane bound enzyme that regulates three separate iodine involving reactions
33
Which enzyme in the thyroid gland regulates iodine involving reactions?
Thyroid peroxidase
34
Name three functions of thyroid peroxidase
Oxidation of iodide to iodine Addition of iodine to tyrosine acceptor residues on thyroglobulin Coupling of MIT or DIT to generate thyroid hormones on the thyroglobulin
35
The oxidation of iodide to iodine by thyroid peroxidase requires...
Hydrogen peroxide
36
Name some common dietary sources of iodine
Dairy products Grains Meat Eggs
37
What happens to dietary iodine consumed in the diet? Where is it absorbed?
Reduced to iodide before absorption Mainly in small intestine
38
Nearly all the iodine in the body is found in the...
Thyroid gland
39
How is iodide taken up from the blood into the thyroid gland?
By thyroid epithelial cells using a sodium-iodide symporter
40
Which transporter on thyroid epithelial cells takes up iodide from the blood?
Sodium-iodide symporter
41
Name the three main processes involved in thyroid hormone synthesis
Iodide oxidation Iodination of tyrosine acceptor residues on thyroglobulin Coupling of DIT with DIT (T4) (or MIT with DIT - T3)
42
Most of the thyroid hormone secreted is...
T4
43
Does T3 or T4 have greater biological activity?
T3 (up to 4x greater)
44
Most T4 is converted to T3 in the...
Liver and kidneys
45
Both T3 and T4 are transported in the blood bound to...
Thyroxine-binding globulin
46
Regulation of thyroid hormone secretion is via ___________ feedback
Negative
47
Thyroid cells affect which cells in the body?
Virtually every cell in the body
48
What effect do thyroid hormones have on the cells of the body? (2)
Effects on cellular differentiation/development | Effects on metabolic pathways
49
Describe the structure of thyroid stimulating hormone
Glycoprotein hormone composed of 2 non-covalently bound subunits (alpha and beta)
50
Which subunit of thyroid stimulating hormone provides its unique biological activity?
Beta subunit
51
Which hormone is the trigger for thyroid hormone release? Where is it released?
Thyroid stimulating hormone Anterior pituitary
52
Which hormone triggers the release of thyroid stimulating hormone from the anterior pituitary? Where is this hormone released?
Thyrotropin releasing hormone Hypothalamus
53
TSH specifically stimulates... (5)
``` Iodide uptake/oxidation Thyroglobulin synthesis/iodination Colloid pinocytosis into cell Cell metabolism and growth Proteolysis of thyroglobulin ```
54
TSH can couple to which GPCRs?
G-alphaQ | G-alphaS
55
Activation of GalphaQ GPCRs results in increased activity of... and production of... Activation of GalphaS GPCRs results in increased activity of... and production of...
Phospholipase C ---> DAG + IP3 Adenylyl cyclase ---> cAMP
56
cAMP activates which late effector?
Protein kinase A
57
Name three general actions of thyroid hormone
Increase in basal metabolic rate and heat production Stimulation of metabolic pathways Sympathomimetic effects
58
Thyroid hormone results in an increase in basal metabolic rate and heat production in most parts of the body but excluding the... (3)
Brain Spleen Testis
59
How does thyroid hormone result in an increase basal metabolic rate/heat production? (2)
Increases number/size of mitochondria | Stimulates the synthesis of enzymes in the respiratory chain
60
Does thyroid hormone generally stimulate catabolic or anabolic metabolic pathways more?
More catabolic pathways
61
Give two examples of metabolic pathways that can be affected by thyroid hormone
``` Lipid metabolism (increased lipolysis/b-oxidation) Carbohydrate metabolism (increased gluconeogenesis/glycogenolysis ```
62
Describe the sympathomimetic effects of thyroid hormone
Can increase target cell response to catecholamines by increasing receptor number on target cells
63
How can thyroid hormones increase target cell response to catecholamines?
By increasing receptor number on target cells
64
Describe the specific effect that thyroid hormone can have on the CVS
Increases the heart responsiveness to catecholamines - --> Increasing cardiac output (increased HR/force of contraction) - --> Increasing peripheral vasodilation
65
What essential function does thyroid hormone have in the nervous system?
Increases myelination of nerves and development of neurones
66
What type of receptors does thyroid hormone bind to?
Intracellular nuclear receptors
67
TH receptors are effectively hormone activated transcription factors, what is meant by this?
They modulate gene expression
68
How do TH receptors affect gene transcription in the absence of thyroid hormone?
TH receptors bind DNA and repress transcription
69
What happens to the thyroid hormone receptor and gene transcription upon binding of thyroid hormone?
Conformational change of TH receptor Gene transcription activated
70
Thyroid hormone is _________ soluble and enters the cell through which transporters?
Lipid soluble Thyroid hormone transporters
71
Thyroid hormone receptor is pre-bound to specific DNA sequences on DNA called...
Hormone response elements
72
What are hormone response elements? Where are they found?
The specific DNA sequences where thyroid hormone receptor is pre-bound In the promoter region of thyroid hormone regulated genes
73
Give two examples of thyroid hormone activated genes
PEPCK Ca ATPase Na/K ATPase
74
What is RXR and its function?
Retinoid X receptor Forms dimer with thyroid hormone receptor
75
What are the normal plasma levels of... I) Free T4 II) Free T3 III) TSH ... in SI units
10-25 pM 3-8 pM 1-15 pM
76
What is goitre?
Enlargement of the thyroid gland
77
Goitre may accompany either _________________ or ______________
Hypothyroidism | Hyperthyroidism
78
Is goitre always present in hyper/hypo-thyroidism?
Not always present in either
79
When does goitre develop?
When the thyroid gland is overstimulated
80
Describe the levels of T3, T4 and TSH seen in hypothyroidism
Low T3 Low T4 High TSH
81
State some potential causes of hypothyroidism
``` Failure of thyroid gland TSH/TRH deficiency Inadequate dietary supply of iodine Autoimmune disease Anti-thyroid drugs Post surgery ```
82
Describe some general symptoms seen in hypothyroidism
``` Obesity Lethargy Intolerance to cold Bradycardia Dry skin Alopecia Hoarse voice Constipation Slow reflexes ```
83
Hypothyroidism can cause _____________ in infants and _____________ in adults
Cretinism Myxedema
84
Describe what happens in cretinism
Severely stunted physical/mental growth due to deficiency of thyroid hormone (hypothyroidism)
85
Myxedema is synonymous with which term?
Severe hypothyroidism
86
What is Hashimoto's disease?
Autoimmune disease resulting in destruction of thyroid follicles leading to hypothyroidism
87
Describe the levels of T3, T4 and TSH seen in Hashimoto's disease
Low T3 Low T4 High TSH
88
Is Hashimoto's disease more common in men or women?
Women
89
What is the treatment for Hashimoto's disease?
Oral thyroid hormone (T4)
90
What is the most common cause of hyperthyroidism?
Autoimmune Graves' disease
91
Excluding Graves' disease, name two other potential causes of hyperthyroidism
Toxic multinodular goitre | Thyroid carcinoma
92
Bulging eyes may be seen in some cases of hyperthyroidism or hypothyroidism?
Hyperthyroidism
93
Describe some general symptoms of hyperthyroidism
``` Weight loss Irritability Heat intolerance Sweaty, Warm Hands Tachycardia Fatigue Increased appetite ```
94
What is Graves' disease?
An autoimmune disease resulting in hyperthyroidism
95
What causes Graves' disease?
The production of thyroid stimulating immunoglobulin
96
TSI is produced in Graves' disease, how does it result in hyperthyroidism?
TSI continually stimulates thyroid hormone secretion outside normal negative feedback control
97
Describe the levels of T3, T4 and TSH seen in Graves' disease
High T3 High T4 Very Low TSH
98
What effect can Graves' disease have on BMR?
Increase in BMR
99
What nuclear medicine procedure is used to show functional thyroid tissue?
Thyroid scintigraphy
100
What material is used for the isotope scanning of the thyroid in a thyroid scintigraphy?
Technetium-99m
101
Describe the half life of technetium-99m. What are the implications of this?
Short half life - ~1/2 day Low radiation exposure
102
What is more commonly used to scan the thyroid rather than thyroid scintigraphy?
Ultrasound
103
What are antithyroid drugs used to treat?
Hyperthyroidism
104
How do antithyroid drugs work?
Block the formation of thyroid hormone
105
What is the most common antithyroid drug?
Carbimazole
106
How does carbimazole work as an antithyroid drug?
Converted to methimazole in the body. Prevents thyroid peroxidase action.
107
What is carbimazole converted to in the body?
Methimazole
108
How would you carry out a thyroid examination?
Stand and feel around the thyroid area from behind the patient
109
What does a normal thyroid gland feel like on examination?
Not possible to feel a normal thyroid gland
110
What structure attaches the thyroid gland to the trachea/larynx? What implications does this have on the thyroid during swallowing?
Pre-tracheal fascia Moves upwards on swallowing
111
What is the most common way to examine the thyroid?
By ultrasound
112
What is a lingual thyroid? Where is it found? What causes it?
A type of ectopic thyroid Mainly in the tongue Lack of normal caudal migration of the thyroid gland
113
What happens in a thyroglossal duct cyst?
Remnants of the thyroglossal duct that connects the tongue to the thyroid during embryonic development remain and form a cyst near/within the body of the hyoid
114
Where is a thyroglossal duct cyst normally found? What swelling does it cause?
Near/within the body of the hyoid Swelling in the anterior of the neck - ON THE MIDLINE
115
Thyroglossal duct cysts can form a swelling in the anterior of the neck which is always...
ON THE MIDLINE OF THE NECK
116
What can cause upwards movement of a thyroglossal duct cyst?
Tongue protrusion
117
Is it common for a pituitary adenoma to produce TSH and lead to thyrotoxicosis?
No - extremely rare
118
What is an adenoma?
A benign tumour of glandular epithelial tissue
119
What is hyperthyroidism? What is thyrotoxicosis?
Over-activity of the thyroid gland (source is thyroid) Too much thyroid-like activity (e.g. Hyperthyroidism, Thyroxine Tablets)
120
The vast majority of hypo- and hyperthyroidism is due to a primary abnormality of the ______________ __________ itself
Thyroid gland
121
Describe the free T4 and TSH levels seen in... I) hyperthyroidism II) hypothyroidism
High T4, Low TSH Low T4, High TSH
122
Autoimmune endocrine diseases are generally more common in...
Women
123
Name an autoimmune condition of the Islets of Langerhans of the pancreas
Type 1 Diabetes
124
What is the name given to the autoimmune disease causing... I) hyperthyroidism II) hypothyroidism
Graves' disease Hashimoto's disease
125
What is the name given to autoimmune disease of the adrenal glands?
Addison's disease
126
Describe three different types of goitre
Diffuse Multinodular Single nodule
127
When can goitre occur with normal thyroid function?
In women during pregnancy/menopause/menarche
128
What are the two most commonest causes of goitre? Which is the most common cause globally and in the UK?
``` Iodine deficiency (Global) Multinodular goitre (UK) ```
129
How can iodine deficiency lead to goitre?
Reduced thyroxine levels ---> Increased TSH ---> Generalised thyroid enlargement (Goitre)
130
Describe the thyroid function status usually seen in multinodular goitre
Normal thyroid function
131
Iodine deficiency is particularly concerning during...
Pregnancy
132
An iodine deficient mother in pregnancy will result in an iodine deficient foetus. What can this result in?
Cretinism in the child. Mental retardation Abnormal gait Deaf mutism Short stature
133
What is a retrosternal multinodular goitre? What can it cause?
A multinodular goitre that enlarges inferiorly into the superior mediastinum Tracheal compression
134
Describe the specific hair loss that may be seen in hypothyroidism
Loss of the hair on the outer third of the eyebrows
135
State three potential causes of hypothyroidism
Autoimmune destruction of thyroid follicles (Hashimoto's disease) Severe iodine deficiency Post surgical removal of thyroid (with inadequate T4 replacement)
136
What is the normal treatment for hypothyroidism?
Oral thyroxine (T4)
137
State three potential causes of hyperthyroidism/thyrotoxicosis
Graves' disease Toxic multinodular goitre Toxic adenoma
138
State two unique symptoms/features of hyperthyroidism due to Graves' disease
Exophthalmos | Pre-tibial myxoedema
139
What is exophthalmos?
Bulging eyes
140
What is the usual treatment for hypothyroidism/thyrotoxicosis?
Carbimazole (anti-thyroid drug)
141
How does carbimazole work as an anti-thyroid drug?
Converted to methimazole in the body and blocks action of thyroid peroxidase reducing the production of thyroxine
142
Other than anti-thyroid drugs (e.g. Carbimazole) what other treatments are there for hyperthyroidism/thyrotoxicosis?
Surgical excision of thyroid - thyroidectomy
143
How does thyroid cancer present? Are they usually malignant?
As a thyroid nodule No very rarely malignant
144
Do thyroid cancers cause hypo/hyper-thyroidism?
No
145
Describe the prognosis for thyroid cancer
Excellent prognosis - very high cure rate

MEH (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions