Unit 2 [Thyroid Dysfunction and Endocrine Response to Stress]

Question 1

hypothyroidism

Answer 1

• too little TH
• characterized by plasma concentrations of thyroid hormone chronically BELOW normal
• causes: iodine deficiency, thyroid damage, autoimmune destruction (rarely pituitary or hypothalamus destruction)
• symptoms: low metabolism, weight gain, coldness, low blood pressure/HR, stunted growth
• goiter

Question 2

hyperthyroidism

Answer 2

• conditions characterized by plasma concentrations of TH that are chronically ABOVE normal
• causes: tumors or autoimmune disease, Graves’ for example (TSI antibodies stimulate the TSH receptor on the thyroid gland and have no negative feedback)
• symptoms: high metabolism, weight loss, more appetite, running hot/increased HR, anxiety, GOITER

Question 3

goiter

Answer 3

• hypothyroidism: TSH is tropic/trophic, meaning less negative feedback will be sent to hypothalamus
• enlarged thyroid gland due to increase in size and # of follicular cells
• excess TSH receptor activation (DIETARY IODINE DEFICIENCY IN MOTHER)
• hyperthyroidism can also result in this, lack of negative feedback!

Question 4

stress

Answer 4

• in physiologic terms, refers to any real or potential threat to homeostasis in the body
• ex: surgery, temperature drops, exercise, shock, starvation, fear…
• adrenal glands secrete hormones involved in the stress response

Question 5

adrenal gland location and anatomy

Answer 5

• below the lungs and above the kidneys
• have a cortex and medulla
• cortex split into zonas glomerulosa, fasciculata, and reticularis (all of which secrete steroids, while medulla secretes catecholamines)

Question 6

zona glomerulosa

Answer 6

• secretes aldosterone (mineralocorticoid), which regulates concentrations of sodium and potassium and thereby blood volume

Question 7

zona fasciculata

Answer 7

• mostly glucocorticoids (CORTISOL)

Question 8

zona reticularis

Answer 8

• secretes sex steroids (androgens), contributing to puberty and sex characteristics

Question 9

adrenal medulla and amine hormones

Answer 9

• adrenal catecholamines
• modified sympathetic ganglion without postganglionic fibers
• releases directly into the bloodstream!
• still binds to alpha (smooth muscle contraction), beta 1 (cardiac muscle), and beta 2 (smooth muscle relaxation) adrenergic receptors
• neurohormones result in delayed onset action