1. When the action of one hormone is needed before a second hormone can produce
ID: 3474140 • Letter: 1
Question
1. When the action of one hormone is needed before a second hormone can produce an effect, the hormonal interaction i
synergistic
humoral
permissive
down-regulating
antagonistic
2. Which of the following is secreted in response to electrical signals traveling along the hypothalamo-hypophyseal tract?
adrenocorticotropic hormone
epinephrine
estrogen
oxytocin
thyroid-releasing hormone
3.Which of the following hormones reaches its target cells by traveling through the hypophyseal portal system?
cortisol
growth hormone
antidiuretic hormone
corticotropin-releasing hormone
insulin
a.synergistic
b.humoral
c.permissive
d.down-regulating
e.antagonistic
Explanation / Answer
1. There are a number of endocrine glands in our body which produce specific hormones and these hormones regulate our cell functions. Our cells do not respond to one hormone instead they respond to multiple hormones simultaneously. These hormones interact and also affect each other. To bring the body into the state of homeostasis a successful balance of the hormones are required. There are few effects possible when a cell receives signals from two hormones. Observe these steps option by option in the following steps:
a. When two hormones work in conjunction with each other and their net result is greater than the sum of their individual effects then such an effect can be described as synergistic.
Hence, the option (a) is not the correct answer.
b. Humoral response is an antibody mediated response. It involves B cells. Humoral response controls the release of a hormone in response to changes in extracellular fluids in the body.
Hence, the option (b) is not the correct answer.
d. When a hormone is in excess a cell decreases the quantity of a cellular component this is referred to as down regulation.
Hence, the option (d) is not the correct answer.
e. When one hormone opposes the effect of another hormone, the two hormones are called antagonistic.
Thus, the option (e) is also incorrect.
c. When the action of the first hormone is needed for the second to produce its effect then it is called permissive effect. It occurs when one hormone causes a greater activity in another hormone.
Hence, the correct answer is Option (c).
Note: When a cell receives instructions from the two hormones simultaneously then the interactions among these two hormones can have four possible effects: synergistic, permissive, antagonistic, or integrative.
2. The posterior region of the pituitary gland is an extension of the neurons of the paraventricular and supraoptic nuclei of the hypothalamus. These neurons cells have their cell body in the hypothalamus but their axons descend as the hypothalamic–hypophyseal tract within the infundibulum and finally, the axons end as axon terminals which extend down into the posterior pituitary.
The hormones travel down from infundibulum through hypothalamo-hypophyseal tract (are the bundle of axons) and are released from the axon terminals into the bloodstream. The electrical signals travel through these axons. The posterior pituitary does not produce any hormone but stores and secretes hormones produced by the hypothalamus. The paraventricular nuclei and supraoptic nuclei produce oxytocin and ADH respectively.
Hence, the options (a), (b), (c) and (e) are incorrect answers.
ADH and oxytocin are produced in neurons (called the neurosecretory cells) of the hypothalamus.
Hence, oxytocin, the option(d) is the correct answer.
3. The anterior pituitary gland produces hormones but their secretion is regulated by two classes of hormones. The first class of hormones is the releasing hormones secreted by the hypothalamus that stimulates the secretion of hormones from the anterior pituitary and the second class of hormone is the inhibiting hormones that inhibit secretion.
The hypophyseal portal system of the brain is a network of blood vessels that connects the hypothalamus with the anterior pituitary. It allows the transport and exchange of hormones between both the glands.
Both types of hypothalamic releasing and inhibiting hormones travel from a primary capillary plexus of the hypophyseal portal system to the portal veins, which carry them into the anterior pituitary gland. Hormones produced by the anterior pituitary (in response to releasing hormones) enter a secondary capillary plexus, and from there they enter the blood stream.
The anterior pituitary produces seven hormones. These are the growth hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone and luteinizing hormone,melanocyte-stimulating hormone, beta endorphin, and prolactin. Of all these hormones TSH, ACTH, FSH, and LH are collectively called tropic hormones which have other endocrine glands as their target.
Hence, the options (a), (c), (d) and (e) are incorrect answers.
Hormones that directly stimulate target cells to produce effects are called non-tropic hormones. They directly act on targeted tissues or cells, and not on another endocrine gland. Therefore, they do not stimulate the release of other hormones. Prolactin, MSH, and beta endorphin are non-tropic hormones of the anterior pituitary gland.
Growth hormone(GH) plays both tropic and non-tropic effects. It signals the liver to release insulin like growth factors that stimulate bone/cartilage growth(tropic action). It also exerts various metabolic effects that tend to raise blood glucose level (non-tropic action).
Hence, growth hormone, the option(b) is the correct answer.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.