Week 7 - Thyroid gland

Question 1

Where is the thyroid gland located

Answer 1

Inferior to the Larynx and anterior to the trachea

Question 2

What does the thyroid gland secrete and its %

Answer 2

Thyroid hormones (90%)

90% made up of T3 - Triiodothryonine (10%) and T4 - Thyroxine (80%)

Calcitonin 10% (parathyroid gland)

Question 3

What are the follicles made up of

Answer 3

Colloid (gelatinous fluid) which is composed of thyroglobin and this stores thyroid hormone

Question 4

What cells secrete Calcitonin in the thyroid gland

Answer 4

Parafollicular cells

Question 5

Hormones secrete in order from hypothalamus to thyroid gland

Answer 5

TRH by hypothalamus, TSH by AP, T3 and T4 by thyroid gland

Question 6

What do T3 and T4 do in the body?

Answer 6

They go to most cells in the body. Regulates metabolism, alters the metabolic rate, affects body temperature due to heat production from higher metabolism, growth and maturation of organs (bone, hair, nervous tissue, connective tissue)

Question 7

What happens when there is too much TH in the body (Hypersecretion)

Answer 7

Increased metabolic rate, increased heat production = elevated body temperature, weight loss, increased appetite, rapid heart rate, enlarged thyroid gland (Goiter)

Question 8

What happens when there is not enough TH in the body (Hyposecretion)

Answer 8

Decreased rate of metabolism, low body temperature, weight gain, decreased appetite, reduced heart rate, abnormal growth, decreased maturation and nervous system development.

Question 9

Calcitonin stimulation, target tissue, response

Answer 9

Stimulation: secreted tin response to high blood calcium (Ca2+) levels

Target tissue: bone

Response: Decreases osteoclast cell activity (bone reabsoption) and lengthens the life of osteoblast cells (bone formation. This decreases Ca2+ and phosphate levels in the blood

Question 10

2 types of cells in the parathyroid gland and their functions

Answer 10

Chief cells - secrete Parathyroid Hormone (PTH)

Oxyphils cells - function unknown

Question 11

PTH (assists with the regulation of Ca2+ levels) stimulation, target tissue, and response

Answer 11

Stimulation: a decrease in blood Ca2+ levels

Target tissue: bone, kidneys, small intestine

Response: Bone: binds to osteoblast receptors which increase osteoclast activity and number, this increases bone reabsorption, in turn bringing Ca2+ and phosphate into the blood

Kidneys: Stimulates Ca2+ uptake in the kidneys, less Ca2+ in urine

Small intestine: Increased absorption in the small intestine of Ca2+ and phosphate