Chapter 7 review questions Flashcards
Level 1:
The study of hormones is called .
endocrinology
List the three basic ways hormones act on their target cells.
Alter the rate of enzymatic reactions, control transport of molecules into and out of cells, or change gene expression and protein synthesis in target cells.
List five endocrine glands, and name one hormone secreted by each. Give one effect of each hormone you listed.
See Fig. 7.2.
Match the following researchers with their experiments:
a. Lower
b. Berthold
c. Guillemin and Schally
d. Brown-Séquard
e. Banting and Best
- isolated trophic hormones from the hypothalami of pigs and sheep
- claimed sexual rejuvenation after injections of testicular extracts
- isolated insulin
- accurately described the function of the pituitary gland
- studied comb development in castrated roosters
(a) 4, (b) 5, (c) 1, (d) 2, (e) 3
Put the following steps for identifying an endocrine gland in order:
a. Purify the extracts and separate the active substances.
b. Perform replacement therapy with the gland or its extracts and see if the abnormalities disappear.
c. Implant the gland or administer the extract from the gland to a normal animal and see if symptoms characteristic of hormone excess appear.
d. Put the subject into a state of hormone deficiency by removing the suspected gland, and monitor the development of abnormalities.
(d), (b), (c), (a)
For a chemical to be defined as a hormone, it must be secreted into the for transport to a(n) and take effect at concentrations.
blood, distant target, very low
What is meant by the term half-life in connection with the activity of hormone molecules?
the time required for half a dose of hormone to disappear from the blood
Metabolites are inactivated hormone molecules, broken down by enzymes found primarily in the and , to be excreted in the and , respectively.
kidneys and liver, urine and bile
Candidate hormones often have the word as part of their name.
factor
List and define the three chemical classes of hormones. Name one hormone in each class.
Peptides—three or more amino acids; example: insulin. Steroids—derived from cholesterol; example: estrogen. Amino acid–derived—made from single amino acids; example: thyroid hormone
Decide if each of the following characteristics applies best to peptide hormones (P), steroid hormones (S), both classes (B), or neither class (N).
a. are lipophobic and must use a signal transduction system
b. have a short half-life, measured in minutes
c. often have a lag time of 90 minutes before effects are noticeable
d. are water-soluble, and thus easily dissolve in the extracellular fluid for transport
e. most hormones belong to this class
f. are all derived from cholesterol
g. consist of three or more amino acids linked together
h. are released into the blood to travel to a distant target organ
i. are transported in the blood bound to protein carrier molecules
j. are all lipophilic, so diffuse easily across membranes
(a) peptide, (b) peptide, (c) steroid, (d) peptide, (e) peptide, (f) steroid, (g) peptide, (h) all classes, (i) steroid, (j) steroid
Why do steroid hormones usually take so much longer to act than peptide hormones?
Steroid hormones usually initiate new protein synthesis, which takes time. Peptides modify existing proteins.
When steroid hormones act on a cell nucleus, the hormone-receptor complex acts as a(n) factor, binds to DNA, and activates one or more , which create mRNA to direct the synthesis of new .
transcription factor, genes, proteins
Researchers have discovered that some cells have additional steroid hormone receptors on their , enabling a faster response.
cell membrane
Melatonin is made from the amino acid _____________, and the catecholamines and thyroid hormones are made from the amino acid ______________.
tryptophan, tyrosine
A hormone that controls the secretion of another hormone is known as a(n) hormone.
trophic
In reflex control pathways involving trophic hormones and multiple integrating centers, the hormones themselves act as signals, suppressing trophic hormone secretion earlier inthe reflex.
negative feedback
What characteristic defines neurohormones?
synthesized by and secreted from neurons
List the two hormones secreted by the posterior pituitary gland. Towhat chemical class do they belong?
oxytocin and vasopressin, both peptide neurohormones
What is the hypothalamic-hypophyseal portal system? Why is it important?
The portal system is composed of hypothalamic capillaries that take up hormones and deliver them directly to capillaries in the anterior pituitary. The direct connection allows very small amounts of hypothalamic hormone to control the anterior pituitary endocrine cells.
List the six hormones of the anterior pituitary gland; give an actionof each. Which ones are trophic hormones?
See Fig. 7.9.
Explain long-loop negative feedback.
A hormone from a peripheral endocrine gland decreases pituitary and hypothalamic hormone secretion.
When two hormones work together to create a result that is greaterthan additive, that interaction is called . Whenhormone A must both be present to achieve full expressionof hormone B, that interaction is called . When hormone activities oppose each other, that effect is called .
synergism, permissiveness, antagonistic
Level 2:
Compare and contrast the terms in each of the following sets:
a. paracrine signal, hormone, cytokine
b. primary and secondary endocrine pathologies
c. hypersecretion and hyposecretion
d. anterior and posterior pituitary
(a) Paracrines—local; cytokines—local or long distance; hormones—long distance. Cytokines—peptides; hormones—peptides, steroids, or amines. Cytokines—made on demand; peptides—made in advance and stored. (b) Primary pathology arises in the last endocrine gland of the pathway. Secondary pathology arises in a gland secreting a trophic hormone. (c) Hypersecretion—too much hormone; hyposecretion—too little hormone. (d) Both secrete peptide hormones. Anterior pituitary gland—true endocrine gland; posterior pituitary—neural tissue.
