Endocrine System

Question 1

Describe negative feedback in the regulation of hormone release.

Answer 1

Low blood levels of a hormone causes a release of hormone by an endocrine gland. Once blood levels are high enough, it inhibits the further release of that hormone.

Question 2

Describe positive feedback in the regulation of hormone release.

Answer 2

Physical/mechanical stimulation causes a release of hormone, which leads to more physical/mechanical stimulation, which leads to release of more hormone, and so on.

Ex: oxytocin during labor; triggered by smooth muscle contractions in the uterus

Question 3

Where is the hypothalamus located?

Answer 3

Posterior to 3rd ventricle

Question 4

What hormone does the paraventricular nucleus of the hypothalamus produce?

Answer 4

oxytocin

Question 5

What hormone does the supraoptic nucleus of the hypothalamus produce?

Answer 5

Antidiuretic hormone (ADH or vasopressin)

Question 6

What are the four releasing hormones produced by the hypothalamus that influence the anterior pituitary?

Answer 6

Thyrotropin-releasing hormone (TRH)

Corticotropin-releasing hormone (CRH)

Gonadotropin-releasing hormone (GnRH)

Growth hormone-releasing hormone (GHRH)

Question 7

What are the two inhibiting hormones produced by the hypothalamus that influence the anterior pituitary?

Answer 7

Growth hormone-inhibiting hormone (GHIH)

Prolactin-inhibiting hormone (PIH)

Question 8

What effect does TRH have on the anterior pituitary?

Answer 8

Promotes secretion of thyroid-stimulating hormone (TSH) and prolactin

Question 9

What effect does CRH have on the anterior pituitary?

Answer 9

Promotes secretion of adrenocorticotropic hormone (ACTH)

Question 10

What effect does GnRH have on the anterior pituitary?

Answer 10

Promotes secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Question 11

What effect does GHRH have on the anterior pituitary?

Answer 11

Promotes secretion of growth hormone

Question 12

What effect does GHIH have on the anterior pituitary?

Answer 12

Inhibits secretion of growth hormone and thyroid-stimulating hormone

Question 13

What effect does PIH have on the anterior pituitary?

Answer 13

Inhibits secretion of prolactin

Question 14

What are the two lobes of the pituitary gland?

Answer 14

Neurohypophysis (posterior pituitary or pars nervosa)

Adenohypophysis (anterior pituitary or pars distalis)

Question 15

What are herring bodies?

Answer 15

Swollen axon terminals in the neurohypophysis filled with either oxytocin or ADH

Question 16

What effects does oxytocin have on the body?

Answer 16

Labor contractions, milk release; possibly involved in ejaculation, sperm transport in the female, sexual affection, and parent-offspring bonding

Question 17

What is the function of pituicytes in the neurohypophysis?

Answer 17

Maintainance and support of axons

Question 18

What are the three cell types of the adenohypophysis?

Answer 18

Acidophils

Basophils

Chromophobes

Question 19

What hormones do acidophils produce in the adenohypophysis? How do they usually present under the microscope?

Answer 19

Prolactin & growth hormone

Appear red due to binding of acidic dyes

Question 20

What hormones do basophils produce in the adenohypophysis? How do they usually present under the microscope?

Answer 20

1. Follicle-stimulating hormone
2. Luteinizing hormone
3. Thyroid-stimulating hormone
4. Adrenocorticotropic hormone

Appear purple or blue due to binding of basic dyes

Question 21

What are chromophobes in the adenohypophysis? How do they typically present under a microscope?

Answer 21

Acidophils or basophils that have released their product

Appear very pale blue or clear

Question 22

What are the principal effects of follicle-stimulating hormone (FSH)?

Answer 22

Female: growth of ovarian follicles and secretion of estrogen

Male: spermatogenesis

Question 23

What are the principal effects of luteinizing hormone (LH)?

Answer 23

Female: ovulation, production and maintenance of corpus luteum

Male: testosterone secretion

Question 24

What are the principal effects of thyroid-stimulating hormone (TSH)?

Answer 24

Growth of thyroid

Secretion of thyroid hormone

Question 25

What are the principal effects of **adrenocorticotropic hormone (ACTH)**?

Answer 25

Growth of adrenal cortex Secretion of glucocorticoids

Question 26

What are the principal effects of **prolactin (PRL)**?

Answer 26

Female: milk synthesis Male: increased LH sensitivity and testosterone secretion

Question 27

What are the principal effects of **growth hormone (GH****)**?

Answer 27

Widespread tissue growth, especially in: liver bone cartilage muscle fat

Question 28

What are the cell types of follicles in the thyroid (thyroid follicular cells)? Which ones are active and which ones are inactive?

Answer 28

Squamous: inactive Cuboidal: active

Question 29

What is **thyroglobulin**? Where is it produced?

Answer 29

Colloid precursor to thyroid hormone.

Question 30

What is the primary hormone produced by the thyroid follicular cells and what is its function?

Answer 30

Thyroxine (thyroid hormone): regulates cellular metabolism throughout the body stimulates prenatal and childhood brain development Promotes intestinal absorption Increases metabolic rate (increased body heat production)

Question 31

What are the two components of thyroxine?

Answer 31

Tetraiodothyronine (T₄) and Triiodothyronine (T₃)

Question 32

What is the primary hormone produced by the parafollicular cells? What is its function?

Answer 32

Calcitonin: regulates blood calcium levels during hypercalcemia in children (negligible effect in adults) \*indicated by arrows in image\*

Question 33

Describe **Grave's disease**

Answer 33

Most severe form of hyperthyroidism; produces antibodies against TSH receptors Causes rapid heartbeat, sweating, weight loss, bulging eyes, heat intolerance

Question 34

Describe **hypothyroidism**.

Answer 34

Reduction of thyroid hormone output Usually the result of a different autoimmune disease, lack of iodine, or thyroid cancer Causes lethargy, sleepiness, slow thinking, weight gain, cold intolerance

Question 35

What are the two cell types of the parathyroid gland?

Answer 35

Principle (chief) cells Oxyphil cells

Question 36

What is the function of principle cells?

Answer 36

Secrete parathyroid hormone, which: raises blood calcium levels and is antagonistic to parafollicular cells

Question 37

What is the function of oxyphil cells?

Answer 37

No known functions

Question 38

What are the two distinct layers of the adrenal gland?

Answer 38

Cortex Medulla

Question 39

What are the three layers of the adrenal cortex?

Answer 39

Zona glomerulosa Zona fasciculata Zona reticularis

Question 40

What is the precursor to ALL hormones of the adrenal cortex? What is this type of hormone called?

Answer 40

Cholesterol Corticosteroids or corticoids

Question 41

What family of hormones is secreted by the **zona glomerulosa**?

Answer 41

Mineralocorticoids Ex: aldosterone

Question 42

What family of hormones is secreted by the **zona fasciculata**? What are the cells of this zone called?

Answer 42

Glucocorticoids Ex: cortisol Spongiocytes

Question 43

What family of hormones is secreted by the **zona reticularis**?

Answer 43

Androgens and estrogens

Question 44

Describe **Cushing's Syndrome**

Answer 44

Lesion to the anterior pituitary; causes an increase in ACTH secretion, which leads to an increased cortisol secretion Symptoms: disruption of carbohydrate & protein metabolism, hyperglycemia, edema, loss of bone & muscle mass, and abnormal fat deposition in the face or shoulders

Question 45

Describe **Addison's Disease**

Answer 45

Under-production of cortisol; two subtypes: Primary adrenal insufficiency - damage to adrenal gland itself Secondary adrenal insufficiency - pituitary doesn't produce enough ACTH Symptoms: hypoglycemia, hypotension, weight loss, weakness, loss of stress resistance, darkening of the skin, and potentially fatal dehydration and electrolyte imbalances

Question 46

What are the secretory cells of the adrenal medulla? What hormones do they excrete?

Answer 46

Chromaffin cells: secrete epinephrine, norepinephrine, and a little dopamine

Question 47

Where is the pineal gland located?

Answer 47

Roof of 3rd ventricle, beneath the posterior end of the corpus callosum

Question 48

What are the secretory cells of the pineal gland? What do they secrete and what do they regulate?

Answer 48

Pinealocytes: secrete melatonin and regulate circadian rhythm

Question 49

Describe **brain (pineal) sand**

Answer 49

Corpora arenacea Benign calcified granules that accumulate in the pineal gland with age; visible on x-ray, enabling radiologists to determine the position of the gland

Question 50

What are the endocrine subunits of the pancreas? What are the cell types it contains?

Answer 50

Islets of Langerhans: α-cells β-cells δ-cells

Question 51

What do α-cells secrete? Function?

Answer 51

Glucagon - raises blood sugar Fuel for body between meals

Question 52

What do β-cells secrete? Function?

Answer 52

Insulin - lowers blood sugar Stimulates tissues and organs to take in sugar and nutrients to store or metabolize

Question 53

What do δ-cells secrete? Function?

Answer 53

Somatostatin - regulates speed of digestion