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Download MBBS Thyroid Lecture PPT

Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Thyroid Lecture PPT

This post was last modified on 30 November 2021


THYROID.

? LARGEST GLAND IN THE BODY.

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? FUNCTION =
1.Secretion of thyroxin.
2.Secretion of calcitonin.
SURGICAL ANATOMY.

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? Weight---------20----25gm.
? Right and left lobe connected by isthmus.

? SITUATION= C5 to T1 vertebra.

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? ISTHMUS = 2nd to 4th tracheal ring.

THYROID HORMONE.

? 1. THYROXINE (T4 ).

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? 2.TRIIODOTHYRONINE (T3 ).
? 3.TSH.
? 4.Free T3.
? 5.Free T4.

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HISTOLOGY

? FOLLICULAR CELLS------
? Lining the follicles

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and secretes T3 and T4.

? Active phase---columnar
? Resting phase ---cuboidal.
? Follicles contains COLLOID.

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? Parafollicular cells= secrete

CALCITONIN.

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? Promote hypocalcaemia and calcium

deposition in bone.

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? opposite to PTH.


Hormone synthesis.
HORMONE BIOSYNTHESIS.

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IODINE TRAPING



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FORMATION OF T3 and T4.

ORGANIFICATION

COUPLING REACTION.

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? Binding of iodine with TGB.

? MAJOR PRODUCT =

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? To form monoiodotyrosine

? THYROXINE

and diodotyrosine.

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? 2 Molecules of

diiodotyrosine

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? DIT + DIT = THYROXINE(T4).

? MIT + DIT = T3.
RELEASE OF T3 and T4.

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T3 and T4 DIFFUSES OUT OF THYROID

CELL INTO SURROUNDING

CAPILLARIES.

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PHYSIOLOGICAL ACTION.
REGULATION.

? Synthesis and liberation of thyroid hormone is

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controlled by TSH = From anterior Pituitary.

? Secretion of TSH depend on level of T3 and T4.

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= NEGATIVE FEEDBACK MECH........

? Regulation of TSH ----- By TRH From

HYPOTHALAMUS.

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HYPERTHYROIDISM.

? A form of thyrotoxicosis due to inappropriately
High synthesis and secretion of thyroid hormones

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by thyroid.

? Grave's disease is the most common cause, it is

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due to IgG auto-antibodies to TSH called LATS-

long acting thyroid stimulator. They bind to TSH

receptor and continuously stimulate it leading to

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increased T3 and T4 secretion.

? Toxic nodular goitre usually due to adenoma or

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cancer of the thyroid.


COMMON SYMPTOMS.

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? Excessive sweating
? Weight loss
? Heat intolerance
? Increased bowel movement
? Tremor

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? Nervousness/agitation
? Rapid heart rate/palpitation.
? Insomnia
? Breathlessness
? Irregular or scant menstrual periods

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Common signs

? Hyperactvity/hyperkinesis
? Sinus tachycardia
? Systolic hypertension

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? Warm, moist, soft and smooth skin, warm

hand.

? Excessive perspiration

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? Lid lag and stare(sympathetic overactivity)
? Fine tremor
Lab. Finding in hyperthyroidism.
DIAGNOSIS.

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? 1.Typical clinical presentation
? 2.markedly suppressed TSH( < 0.05)
? 3.Elevated FT4 and FT3.
? 4.Thyroid antibodies
? 5.ECG to demonstrate cardiac manisfestation

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? Nuclear scintigraphy to differentiate the cause.
role of imaging in hyperthyroidism.

? Thyroid ultrasound
? Colour doppler helpful.

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? May reveal nodular disease or increased vascularity

( seen in Grave's )

? Thyroid uptake and scan

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? High uptake
? Grave's, toxic MNG, Toxic adenoma
? Low uptake
? Thyroditis, iodine induced hyperthyroidism.

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