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HUBS191 > L28 > Flashcards

L28 Flashcards

1
Q

What does calcitonin maintain?

A

Calcium levels (calcium homestasis)

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2
Q

What is the structure of the thyroid gland?

A

Follicles - Small spherical sacs
Follicular cells - Surround follicles
Clear cells - Lie in clusters between follicles

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3
Q

What are the steps of thyroid hormone synthesis?

A
  1. Iodine enters follicle
  2. Follicle cells release thyroglobulin (TGB), into the follicle
  3. Iodine reacts with tyrosine in the thyroglobulin molecules
  4. Iodised thyroglobulin moves into the follicular cells
  5. Thyroid hormones (T3 and T4) detach from TGB as needed
  6. T3 and T4 travel bound to a carrier protein (thyroid-binding globulin, TBG) to target cells
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4
Q

What are the two places thyroid hormone goes when it diffuses across the plasma membrane?

A

Mitochondria and the nucleus (to bind to DNA)

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5
Q

What role does mitochondria have in target cell activation by thyroid hormone?

A

It creates ATP to be used to aid target cell response

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6
Q

What is the response time of target cell activation by thyroid hormone?

A

45 minutes to days

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7
Q

How is thyroid hormone secretion controlled (what hormones are specifically secreted)

A

The hypothalamus secretes thyroid releasing hormone (TRH) into the blood, which initiates the anterior pituitary gland to secrete thyroid stimulating hormone (TSH) into the blood, which goes to the thyroid gland, allowing it to secrete thyroid hormones (T3 and, T4) into the blood)

It is controlled by a negative feedback loop of these hormones

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8
Q

What are the effects of thyroid hormones on metabolism?

A

The basal metabolic rate increases (by increased synthesis and activity of sodium potassium ion pump)

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9
Q

What are the other effects of thyroid hormones?

A 
Stimulates growth (for younger ages)
It is also for normal alertness and reflexes
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10
Q

What is Graves’ disease and what is its cause?

A

Hypersecretion of thyroid hormone.

It is an autoimmune disorder.

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11
Q

What are the symptoms of Graves’ disease?

A
  • High MR
  • Weight loss
  • Heat intolerant
  • Nervousness
  • Increased HR
  • Hair loss
  • Thyroid swelling
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12
Q

What stores the majority of calcium?

A

Bone

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13
Q

What are the three hormones involved in calcium regulation?

A

Parathyroid hormone, calcitriol and calcitonin

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14
Q

How is calcitonin made?

A

Calcitonin is made in the C cells (clear cells)

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15
Q

Who is bipedal stan?

A

You will never know

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16
Q

What is the stimulus and that initiates calcitonin secretion and the receptor that detects the stimulus?

A

A increase in blood calcium concentration is detected by the thyroid gland

17
Q

What is the calcitonin secretion pathway for an increase of blood calcium concentration?

A

Thyroid gland detects an increase in blood calcium concentration and secretes calcitonin. Calcitonin travels to bone and causes it to decrease bone breakdown and decrease release of calcium into blood.
Net effect is decrease blood calcium (restored to reference range/set point)

Controlled by negative feedback

18
Q

What is the calcitonin secretion pathway for an decrease of blood calcium concentration?

A

The parathyroid gland detects low blood calcium concentration and secretes parathyroid hormone (PTH)
It goes to the kidneys and bone.
The bone increases bone breakdown to release calcium into blood.
AND the kidneys increase calcium reabsorption, resulting in less urinary excretion of calcium. Vitamin D converts into calcitriol which results in increased calcium absorption in the intestine from food.
Net effect - Increase blood calcium (restores set point via negative feedback)

19
Q

What is the difference between calcitriol and calcitonin?

A
  • Calcitriol increases calcium absorption in intestine from food, resulting in an increase of blood calcium
  • Calcitonin Decreases bone breakdown to decrease release of calcium into blood, resulting in a decrease in blood calcium concentration
20
Q

What is hypocalcemia and what does it lead to?

A

Low blood calcium
Increased excitability of the nervous system
Leads to muscle tremors, spasms or cramps (tetany)

21
Q

What is hypocalcemia caused by?

A
  • Vitamin D deficiency
  • Diarrhoea
  • Thyroid tumors
  • Underactive (or removal of) parathyroid glands
  • Pregnancy and lactation
22
Q

What happens when blood calcium is too high?

A

Hypercalceamia

- Nerve and muscle cells less responsive and excitable

HUBS191 (3 decks)

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