Chapter 16: The endocrine System
For each of the following statements, indicate whether it applies more to the endocrine system or the endocrine system: rapid; discrete responses; controls growth and development; long-lasting responses.
The endocrine system is more closely associated with growth and development, and its respones tend to long-lasting,
nervous system responeses tend to be rapid and discrete.
Which two endocrine glands are found in the neck?
The thyroid and parathyroid glands are found in the neck.
What is the difference between a hormone and a paracrine?
Hormones are released into the blood and transported throughout the body,
paracrines act locally, generally within the same tissue.
Name the two major chemical classes of hormones. Which class consists entirely of lipid-soluble hormones?
Name the only hormone in the other chemical class that is lipid soluble.
The two major chemical classes of hormones are amino acid-based hormones and steroids.
Steroids are all lipid soluble.
Thyroid hormones are the only amino acid-based hormones that are lipid soluble.
Consider the signaling mechanisms of water-soluble and lipid-soluble hormones.
In each case, where are the receptors found and what is the final outcome?
Water-soluble hormones act on receptors in the plasma membrane coupled most often via regulatory molecules called G proteins to intracellular second messengers.
Lipid-soluble hormones act on intracellular receptors, directly activating genes and stimulating synthesis of specific protiens.
What are the three types of stimuli that control hormone release?
Hormone release can be triggered by:
What is the key difference between the way the hypothalamus communicates with the anterior pituitary
the way it communicates with the posterior pituitary?
The hypothalamus communicates with the anterior pituitary via hormones released into a special portal system of blood vessels.
it communicates with the posterior pituitary via action potentials traveling down axons that connect the hypothalamus to the posterior pituitary.
Anita drank too much alcohol one night and suffereed from a headache and nausea the next morning.
What caused these "hangover" effects?
Drinking alcoholic beverages inhibits ADH secretion from the posterior pituitary
causes copious urine output and dehydration.
The dehydration causes the hangover effects.
List the four anterior pituitary hormones that are tropic hormones and name their target glands.
LH and FSH are tropic hormones that act on the gonads,
TSH is a tropic hormone that acts on the thyroid,
ACTH is a tropic hormone that acts on the adrenal cortex.
(If you said growth hormone, that's also a good answer, as GH causing the liver to release IGFs might also be considered a tropic effect.)
What is the major effect of thyroid hormones? Parathyroid hormone? Calcitonin?
Thyroid hormone increases basal metabolic rate (and heat production) in the body.
Parathyroid hormone increases blood Ca2+ levels in a varietyways.
Calcitonin at high (pharmacological) levels has a Ca2+ lowering, bone-sparing effect.
(at normal blood levels its effects in humans are negligible.)
Name the cells that release the thyroid hormones, parathyroid hormones, and calcitonin?
Thyroid follicular cells release thyroid hormone,
parathyroid cells in the parathyroid gland release parathyroid hormone, and
parafollicular (C) cells in the thyroid gland release calcitonin.
List the three classes of hormones released from the adrenal cortex and for each briefly its major effect(s).
Glucocotrticoids are stress hormones that, among many effects, increase blood glucose.
Mineralocorticoids increase blood Na+ (and blood pressure) and decrease blood K+.
Gonadocorticoids are male and femal sex hormones that art thought to have a vriety of effects
(for example, contribute to onset of puberty, sex drive in women, pubic and axillary hair development in women.)
Synthetic melatonin supplements are available, although their safety and efficacy have not been proved. What do you think they might be used for?
melatonin is used by some individuals as sleep aid, particulary to counter jet lag.
You've just attended a football game with your friend, Sharon, who is diabetic.
While Sharon drank only one beer during the game, she is having trouble walking straight, her speech is slurred, and she is not making sense.
What does it mean when we say Sharon is diabetic?
What is the most likely explanation for Sharon's current behavior?
How could you help her?
When we say Sharon is diabetic, this means that she has indufficient insulin action in her body.
The most likely explantion for Sharon's behavior is that she has taken too much insulin and is experiencing hypoglycemia.
You could help her by making sure she immediately ingest a sugary snack or drink.
Diabetes mellitus and diabetes insipidus are both due to lack of a hormone.
Which hormone causes which? What symptom do they have in common?
What would you find in the urine of a patient with one but not the other?
Diabetes mellitus is due to a lack of insulin production or action, whereas diabestes insipidus is due to a lack of insulin production or action,
diabetes insipidus is due to a lack of ADH.
Both conditions are characterized by production of copius amounts of urine.
You would find glucose in the urine of a patient with diabetes mellitus, but not in the urine of a patient with diabetes insipidus.
Which of the two chemical classes of hormones introduced at the beginning of this chapter do the gondadal hormones belong to?
Which major endocrine gland secretes hormone of the this same chemical class?
The gonadal hormones are steroid hormones.
A major endocrine gland that also secretes steroid hormones is the adrenal cortex.
Which hormone does the heart produce and what is its function?
The heart produces atrial natriuretc peptide (ANP).
ANP decreases blood volume and blood pressure by increasing the kidneys' production of salty urine.
What is the function of the hormone produced by the skin?
Vitamin D3, produced in inactive form by the skin, increases intestinal absorption of calcium.
In the elderly, the decline in levels of which hormone is associated with muscle atrophy? With osteoporosis in women?
The decline in growth hormone with age contributes to muscle atrophy.
The decline in estrogen contributes to osteoporosis in women.