18.7 Thyroid Gland

Question 1

Thyroid gland

Answer 1

Located inferior to larynx, composed of right and left lateral lobes, with a third small pyramidal lobe. Are all connected by the isthmus (passage).

Question 2

Thyroid follicles

Answer 2

Microscopic spherical sacs in the thyroid gland.

Question 3

Follicular cells

Answer 3

Compose wall of follicle

Question 4

Thyroid hormones

Answer 4

T3 and T4

Question 5

Parafollicular cells (C Cells)

Answer 5

Produce calcitonin- aids in calcium homeostasis

Question 6

8 functions of thyroid hormones:

Answer 6

1) increase basal metabolic rate
2) synthesis of Na+/K+ ATPase
3) increase body temp
4) stimulate protein synthesis
5) increase use of glucose and fatty acids for ATP production
6) stimulate lipolysis
7) enhance some actions of catecholamines
8) regulate development and growth of nervous tissue and bones

Question 7

Steps for Synthesis and secretion of thyroid hormone t3&t4

Answer 7

1) iodide trapping
2) synthesis of thyroglobulin
3) oxidation of iodide
4) iodination of tyrosine
5) coupling of T1 & T2
6) pinocytosis and digestion of colloid
7) secretion of thyroid hormones
8) transport in the blood

Question 8

Parathyroid hormone

Answer 8

Increases # of osteoclasts. Major regulator of levels of calcium, magnesium, and phosphate ions.

Question 9

4 types of parathyroid glands that make up thyroid glands

Answer 9

Left superior
Right superior
Left inferior
Right inferior

Question 10

Adrenal cortex

Answer 10

Produces steroid hormones for the body

Outer layer of adrenal gland

Question 11

3 zones of adrenal cortex

Answer 11

Zona glomerulosa -outer zone- “cells arranged in spheres “

Zona fasciculata- middle zone- “cells arranged in little bundles”

Zona reticularis - inner zone- “cells arranged in branches”

Question 12

Aldosterone

Answer 12

Major hormone secreted by outer zone of adrenal cortex. Regulates sodium and potassium ions.

Question 13

Angiotensinogen

Answer 13

A plasma protein produced by the liver

Question 14

Renin

Answer 14

An enzyme that converts angiotensinogen into

“angiotensin I”

Question 15

2 ways angiotensin II increases blood pressure

Answer 15

1) acts to constrict blood vessels by causing contraction of smooth muscle
2) stimulates secretion of aldosterone

Question 16

Glucocorticoids

Answer 16

Regulate metabolism and resistance to stress

Question 17

6 effects of glucocorticoids

Answer 17

1) protein breakdown
2) glucose formation
3) lipolysis
4) resistance to stress
5) anti inflammatory effects
6) depression of immune responses

Question 18

Negative feedback loop for glucocorticoid secretion

Answer 18

1) Stimulus
2) Controlled condition- glucocorticoid condition in blood
3) receptors- neurosecretory cells in hypothalamus
4) control center- corticotrophs in anterior pituitary
5) effectors- cells of zona fasciculata in adrenal cortex
6) response- increased glucocorticoid level in blood

All is back to normal…:)

Question 19

Androgens (DHEA mainly)

Answer 19

An androgen found in both sexes, insignificant in comparison to testosterone in men, but significant in woman.

Promotes sexual drive in women. Is the only source of estrogen in women.

Question 20

Adrenal medulla

Answer 20

Inner region of adrenal gland. Modified sympathetic ganglion of the ANS. The cells secrete hormones

Question 21

Chromaffin cells

Answer 21

Hormone producing cell

Question 22

Epinephrine and norepinephrine

Answer 22

Increase blood flow to the heart, liver, skeletal muscles and adipose tissue.