lecture 3 endocrine structures and anatomy

Question 1

location of the thyroid gland

Answer 1

is in the lower neck in front of the trachea/behind the Adam’s apple.
- There are two lobes connected by the isthmus which lie over the trachea.

Question 2

major hormones secreted by the thyroid gland

Answer 2

• Thyroxine (T4) – contains four iodine atoms (DIT + DIT)
• Triiodothyronine (T3) – contains three iodine atoms (MIT + DIT)
• Calcitonin – peptide hormone

Question 3

control pathways for hormone secretion of the thyroid gland

Answer 3

The hypothalamus secreted Thyrotropin releasing hormone (TRH) which then stimulates the anterior pituitary to secrete the Thyroid stimulating hormone (TSH), which then goes to the thyroid gland to produce and release thyroid hormones T3 and T4. T3 and T4 will then give feedback to the hypothalamus to tell it what to do.

Question 4

primary targets and effects of the pituitary gland on thyroid hormones

Answer 4

T3 and T4– primary targets of virtually everywhere in the body
 Effects metabolic regulation, growth and development, cardiovascular system
Calcitonin – primary targets are the bones and kidneys
 Effects calcium regulation

Question 5

the anatomy of the parathyroid gland

Answer 5

is touching the thyroid gland, however, is typically embedded in the tissue on the back of the thyroid.

Question 6

major hormones secreted by the parathyroid gland

Answer 6

Parathyroid hormone – is regulated through levels of calcium in the blood.

Question 7

control pathways for hormone secretion of the parathyroid gland

Answer 7

When there are low blood calcium levels in the body the parathyroid hormone recognizes this and responds by secreting more of PTH, which increases calcium levels in the blood. If calcium levels in the blood are too high the parathyroid gland responds by inhibiting release of PTH.

Question 8

primary targets and effects of the parathyroid gland

Answer 8

• Bone – to increase activity of osteoclasts so that the bones can break down and release more calcium
• Kidneys – to increase calcium absorption if needed (reduces urine output with calcium)
• Intestines – the active form of Vitamin D (calcitriol) is produced in response to the parathyroid hormone

Question 9

anatomy of the adrenal cortex and adrenal medulla

Answer 9

o The adrenal cortex is the outer portion of the adrenal gland. Primarily regulate long-term stress responses, metabolism, electrolyte balancing, and sexual development.
o The adrenal medulla is in the center of the adrenal gland and is surrounded by the adrenal cortex. Primarily responsible for immediate responses and short-term stress responses.

Question 10

location of the adrenal medulla

Answer 10

located on top of the kidneys and shaped like a hat
the inner portion of the adrenal gland

Question 11

location of the adrenal cortex

Answer 11

located on top of the kidneys and shaped like a hat
the outer portion of the adrenal gland

Question 12

major hormones secreted from the adrenal medulla

Answer 12

Secretes catecholamines (epinephrine and norepinephrine)
- These are involved in the body’s stress response and work to help the fight or flight response function

Question 13

the control pathway for secretion for the adrenal medulla

Answer 13

Catecholamines (epinephrine and norepinephrine) are controlled by direct sympathetic nervous system stimulation.

Question 14

the control pathway for secretion for the adrenal cortex

Answer 14

Mineralocorticoids (aldosterone) are controlled by the RAAS (renal system).
Glucocorticoids (cortisol) are controlled by the HPA axis (hypothalamus-pituitary-adrenal).
Sex hormones (androgens) are influenced by ACTH.

Question 15

zona glomerulosa of the adrenal cortex

Answer 15

the outermost layer
Aldosterone is the primary thing released. The target is the kidneys, and it works by regulating sodium and potassium balances by promoting sodium reabsorption and potassium excretion to help control blood pressure and fluid balance.

Question 16

zona fasciculata of the adrenal cortex

Answer 16

the middle layer
Mainly production of glucocorticoids. The primary target is the live, muscles, fat, and the overall immune system. Cortisol (stress hormone) mainly helps in regulation of metabolism by increasing blood glucose, promoting fat breakdown, and suppressing the immune responses.

Question 17

zona reticularis of the adrenal cortex

Answer 17

innermost layer
Sex hormones (DHEA, and other androgens), with the primary target being the reproductive organs.