Endocrine System

Question 1

What is the endocrine system?

Answer 1

• chemical mediators called hormones are released from
  one part of the body and travel (usually via the blood) to another part of the
  body

Question 2

What are endocrine glands?

Answer 2

• secrete hormones into the blood

Question 3

What are exocrine glands?

Answer 3

• secrete substances into ducts that transport them to the external environment (e.g., sweat, saliva, digestive enzymes)

Question 4

What are artificial hormone analogues?

Answer 4

• some “mimic” the hormone and cause the cell to respond as if
  the hormone was present (“agonist”)
• some “block” the receptor thus preventing the hormone from
  binding, but will have no effect on the target cell (“antagonist”)

Question 5

What is tamoxifen?

Answer 5

• analogue of estrogen
• antagonist in breast tissue (used to fight breast cancer)
• agonist in uterine tissue (can cause uterine cancer)

Question 6

Describe water soluble hormones.

Answer 6

• must be injected as they are digested in the gut
• can travel through the blood in a free form
• receptors are located on the target cell’s cell membrane

Question 7

Describe lipid-soluble hormones.

Answer 7

• can be taken orally as they are not digested in the gut
• require a transport protein to carry them through the blood
• receptors are located inside the target cell

Question 8

What are some examples of stimuli that can induce a gland to secrete a hormone?

Answer 8

• signals from the nervous system
• levels of circulating ions or compounds in the blood
• the action of other hormones

Question 9

What re some of the important functions of hormones?

Answer 9

• regulate the growth and development of tissues and organs
• regulate metabolic processes
• regulate the chemical composition of the blood and internal environment
• cause contraction of cardiac muscle and smooth muscle

Question 10

How are hormones that are not used “deactivated”?

Answer 10

• deactivated by the liver and excreted by the kidneys

Question 11

What are some endocrine glands?

Answer 11

• parathyroid glands (4)
• pineal gland
• pituitary gland
• thyroid gland
• adrenal glands (2)
• hypothalamus
• pancreas
• ovaries
• testes

Question 12

Where is the hypothalamus and pituitary gland located?

Answer 12

• in the sella turcica of the sphenoid bones

Question 13

What does the anterior pituitary gland do?

Answer 13

• produces 7 hormones whose secretion is controlled by “releasing” and “inhibiting” hormones secreted by the hypothalamus

Question 14

What does the posterior pituitary gland do?

Answer 14

• Made up of the axons of hypothalamic neurons that produce 2 hormones

Question 15

How do hormones secreted by the pituitary gland enter the bloodstream?

Answer 15

• branches of the internal carotid arteries form capillary networks around the lobes of the pituitary.
• hormones enter the bloodstream via these capillary networks

Question 16

What are the seven hormones released by the anterior pituitary gland?

Answer 16

• Human growth hormone (hGH)
• Thyroid-stimulating hormone (TSH)
• Follicle-stimulating hormone (FSH)
• Luteinizing hormone (LH)
• Prolactin
• Adrenocorticotropic hormone (ACTH)
• Melanocyte-stimulating hormone

Question 17

What two hormones do the posterior pituitary gland release?

Answer 17

• oxytocin

- antidiuretic hormone (ADH)

Question 18

Where is the pineal gland located?

Answer 18

• small gland in the posterior portion of the roof of the third ventricle

Question 19

What does the pineal gland do?

Answer 19

• secrete melatonin, which
  induces drowsiness
• visual input from the eyes either stimulates (dark) or inhibits (light) the
  secretion of melatonin

Question 20

What does the thyroid gland produce?

Answer 20

• T4 and T3

- calcitonin

Question 21

Do fetuses produce T4 and T3?

Answer 21

• they don’t produce much of either in the first half of pregnancy
• they rely on their mothers production

Question 22

How is the parathyroid gland stimulated?

Answer 22

• by a drop in Ca++ in the blood

Question 23

What hormone does the parathyroid gland secrete?

Answer 23

• parathyroid hormone

Question 24

What is the main function of the parathyroid hormone?

Answer 24

• stimulates osteoclasts (bone)
• decreases Ca++ excretion (kidneys)
• increases Ca++ absorption (GI tract)

Question 25

Which hormones does the adrenal cortex stimulate?

Answer 25

• steroid hormones such as:
• mineralocorticoids (mineral homeostasis)
• glucocorticoids (glucose homeostasis)
• androgens (male sex hormones)

Question 26

Which hormones does the adrenal medulla secrete?

Answer 26

• epinephrine
• norepinephrine
• classified as catecholamines

Question 27

What stimulates the adrenal medulla?

Answer 27

• sympathetic preganglionic neurons causes the secretion of neurotransmitters into the blood

Question 28

What do acini cells of the pancreas secrete?

Answer 28

• secrete digestive enzymes into the GI tract

Question 29

What do islet cells of the pancreas secrete?

Answer 29

• secrete hormones into the bloodstream

Question 30

What are the two divisions of pancreatic islets?

Answer 30

• alpha cells and beta cells

Question 31

How are alpha cells of the pancreas stimulated and what do they secrete?

Answer 31

• stimulated by ↓ glucose in the blood

- secrete glucagon

Question 32

How are beta cells of the pancreas stimulated and what do they secrete?

Answer 32

• stimulated by ↑ glucose in the blood

- secrete insulin

Question 33

What hormones do the ovaries secrete?

Answer 33

• estrogen
• progesterone
• relaxin

Question 34

What are hormone do the testis secrete?

Answer 34

• testosterone

Question 35

What is hormone replacement therapy?

Answer 35

• the secretion of estrogen and progesterone drops significantly after menopause
• medications containing estrogen +/- progesterone are used to boost the
  levels of the hormones and counteract these effects