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CBL endocrine > lecture 2 > Flashcards

lecture 2 Flashcards

1
Q

Thyroid gland location

A 
IN the neck 
2 lobed structure 
Lateral lobes connected by an isthmus 
Floor of pharynx 
Rich blood supply
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2
Q

Parathyroid glands location

A

Behind the lateral lobes of the thyroid

4 glands: 2 Pairs( superior and inferior)

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3
Q

What cells does the thyroid consist of

A

Parafollicular cells scattered

Follicle consisting of single layer of cuboidal epithelial cells, called follicular cells, surrounding central colloid

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4
Q

Iodine and thyroid

A

Requires iodine for normal hormone production

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5
Q

Hormones that the thyroid makes

A

Thyroxine( t4)
Tri-iodothyronine ( t3)
Calcitonin

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6
Q

Calcitonin

A

Involved in calcium metabolism

Secreted by parafollicular cells

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7
Q

t3 and t4

A

Secreted by follicular cells

Derived from tyrosine

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8
Q

Colloid

A

Glycoprotein called thyroglobulin, synthesised by epithelial cells

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9
Q

t3 and t4 synthesis

A 
Active uptake of iodide 
Production of thyroglobulin 
Iodination of tyrosine on thyroglobulin ( colloid)
Reabsorption of thyroglobulin 
Secretion of t3 and t4
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10
Q

Difference between active and inactive thyroid

A

Cells less flat when active

Less colloid- released thyroid hormones

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11
Q

Control of thyroid function

A

Regulated by the hypothalamic pituatry thyroid axis
TRH from hypothalamus stimulates tyrotrope cells of the anterior pituitary to release TSH
TSH acts on the thyroid follicular cells binding to the G protein couples receptor

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12
Q

Actions of TSH

A

Increasing activity of iodine pump
Stimulating synthesis of thyroglobulin
Increasing thyroid blood flow

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13
Q

Low t3 and t3

A

negative feedback
High amounts of TRH
High amounts of TSH
stimulates increase in t3 and t4

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14
Q

high t3 an t4

A

low TRH

Low tSH

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15
Q

How are thyroid hormones bound

A

99% is reversibly bound to proteins- TBG - provides store and limits renal excretion biologically inactive
1% is free and determines everything

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16
Q

How does t3/t4 effect things

A 
Oxygen consumption and BMR 
Metabolism 
CVS effects 
Growth and differentiation of tissues 
Growth and development of CNS 
Neuromuscular effects 
Fertility and GI motility
17
Q

Euthyroid state

A

Hypothalamus releases TRH
Pituatry thryotroph releases TSH
Stimulates the thyroid gland to release t3 and t4

18
Q

hypothyroidism

A

LOW levels of t3 and t4
Hypothalamus produces more TRH
Pituauatry thyrotroph produces more TSH
Doesn’t produce enough t3 and t4

19
Q

Hyperthyroidism

A

TOO MUCH t3 and t4

20
Q

Iodine deficiency and goitre

A

hen blood levels of TSH rise, the thyroid gland uses iodine to make thyroid hormones. However, when your body is low in iodine, it can’t make enough.
To compensate, the thyroid gland works harder to try to make more. This causes the cells to grow and multiply, eventually leading to a goiter.

21
Q

Features of hypothyroidism early in developmemt

Cretinism

A

Neurological deficits
Small stature
Puffy hands and face
Delated puberty

22
Q

HYpothryoidism in adulthood

A 
Low BMR and cold sensitivity 
Bradycardia 
Slow speech 
Weight gain 
Constipation
Dry thickened skin 0 myxoedema 
Menstrual abdonormalities
23
Q

Hyperthryoidism - thyrotoxicosis

A 
Nervousness 
High metabolic rate 
Raised temp 
Tremors 
Tiredness 
Increases bwoel movements 
Common type is graves disease
24
Q

Role of calcium

A 
Bone strength 
Blood coagulation 
Neuromuscular excitability 
Enzyme regualtion 
Contraction
25
Q

CAlcium balance

A

Daily intake at gut
Daily output at kidney
Storage in bone
Net zero bone calcium balance

26
Q

Plasma calcium is controlled by what 3 hormones

A

PTH
Calcitonin
Vitamin D

27
Q

What does PTH do to calcium levels

A

INCREASE

28
Q

What does calcitonin do to calcium levels

A

DECREASE

29
Q

Decrease in plasma ca2+

A 
Parathyroid glands ( chief cells) increase PTH 
Ca2+ uptake from kidneys, vitamin D increases uptake in intestines, release from bones
30
Q

Increase in plasma ca2+

A

Thyroid parafollicular C cells increase calcitonin

Ca2+ deposition I. bones, reduces ca2+ uptake in kidneys

31
Q

Hypocalcaemia

A 
Decreases calcium 
Causes by hypoparathyroidism following removal of parathyroid glands 
Increased excitability 
Twitching 
Coma 
Muscle cramps
32
Q

Hypercalcaemia

A

Increased Ca2+
Malignancy
Stones bones and groans
Sluggish, decreases neuronal membrane permeability to Na+
Polydipsia and polyuria- impairs ADH effect
Coma

CBL endocrine (8 decks)

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