final exam old material Flashcards
can hormones affect behavior
yes
can behavior affect hormones
yes
How can extirpation and hormone replacement be used to study the physiological role of hormones?
A hormonally dependent behavior should be altered or disappear when the source of the hormone is removed or the actions of the hormone are blocked; restoration of the hormone should reinstate/normalize the behavior; hormone concentrations and the behavior should be covariant
What is the definition of a hormone?
is an intercellular (between cells) chemical signal that is secreted by one cell of the body and modifies the function of another cell of the body that reaches its target cells by traveling through blood vessels
What distinguishes a hormone from a neurotransmitter?
mode of delivery to the target cell; neurotransmitters diffuse through a synapse and hormones travel through blood vessels
What are some advantages and disadvantageous of endocrine versus paracrine intercellular signaling in the body?
The advantages to hormone (endocrine) signaling are that they can have widespread effects because they travel in the bloodstream. Cons are that they travel slower than paracrine (NT) signaling and are less specific than neurotransmitters.
What is meant by the phrase that “many hormones are systemic”?
Many hormones circulate throughout the entire body
What determines whether or not a particular cell in the body is a target for a systemic hormone?
Whether or not a particular cell expresses receptors for that specific hormone
What is the group of hormones that we have discussed this semester that are not systemic hormones, and why are they not systemic?
Releasing factors or release control hormones are not systemic because they are not released in large enough amounts to travel far distances, they only travel to the pituitary to release another hormone
What is an effector hormone?
An effector hormone is a hormone that produces a regulatory effect on physiological/psychological function and is not a releasing factor
What is a releasing hormone?
A releasing hormone is a hormone that acts on endocrine cells to regulate the release of other hormones
Which neurohormones are effector hormones?
Vasopressin and Oxytocin
Are vasopressin and oxytocin produced in magnocellular or parvocellular neurons? Where are the cell bodies and axon terminals located of these neurons?
Produced in magnocellular cells in the SON and PVN of the hypothalamus and their axon terminals are located in the posterior pituitary
Which neurohormones are releasing hormones?
GnRH, TRH, GHRH, somatostatin, dopamine, CRH
Are releasing hormones in magnocellular or parvocellular neurons? Where are the cell bodies and axon terminals located of these neurons?
Produced in parvocellular neurons in the hypothalamus and their axon terminals are located in the median eminence
What type of endocrine cells are present in the anterior pituitary, and what hormones do they produce and secrete?
Basophils, acidophils, and chromophobes are endocrine cells located in the anterior pituitary.
Basophils: gonadotrophs (LH, FSH) and thyrotrophs (TSH)
Acidotrophs: somatotrophs (GH) and lactotrophs (prolactin)
Chromatophobes: corticotrophs (ACTH, beta endorphin) and melanotrophs (MSH)
What are 2 examples of a first order neuroendocrine arrangement?
Vasopressin and oxytocin release to the posterior pituitary
What are 5 examples of a second order neuroendocrine arrangement?
GHRH → GH
Somatostatin → GH (decreases)
Dopamine → prolactin (decreases)
GnRH → FSH (males only)
CRH → beta endorphin
What are 5 examples of a third order neuroendocrine arrangement?
GnRH → LH → testosterone
GnRH → FSH → estradiol
GnRH → LH → progesterone
TRH → TSH → T3, T4
CRH → ACTH → cortisol
What is a prohormone?
A precursor molecule that may have some hormonal function of its own but can be converted into another hormone
What is a carrier protein?
A protein that binds to a hormone molecule and escorts it around in the bloodstream, usually to help prevent degradation
What is the principle glucocorticoid hormone found in humans?
cortisol
What is the principle estrogen hormone found in humans?
estradiol, E2
What is the principle androgen hormone found in humans?
testosterone
What is the biological factor(s) that regulates testis growth?
Gonadotropins (LH and FSH) because trophic factors
What happens to the amount of that biological factor(s) immediately after removal of 1 testis?
GnRH, LH, FSH secretion levels will increase because there is less testosterone
What causes the amount of that biological factor(s) to change immediately after removal of 1 testis?
Decreased testosterone
Why does long-term treatment with a GnRH receptor agonist produce “chemical castration”?
Because it will shut down LH, FSH, and testosterone secretion because of the downregulation of GnRH receptors
Compare the water solubility, ability to pass through cell membranes and ability to penetrate the blood brain barrier of proteins and peptides versus steroids and thyroid hormones. How do these differences affect whether these hormones can be stored in vesicles and/or interact with intracellular receptors?
Protein/peptide hormones: water/blood soluble; cannot pass through BBB; cannot cross the membrane; are stored in vesicles
Steroid/thyroid hormones: not soluble in blood so need carrier proteins; can cross membranes so receptors intracellular; not stored in vesicles; can cross BBB
Why do steroid hormone effects on target tissues often last a long time?
It lasts as long as the levels of regulated proteins remain altered
What determines whether an embryonic gonad develops into a testis or an ovary?
Expression of TDF
What determines whether the Wolfian duct or the Mullerian duct continues to develop/differentiate?
If testosterone and mullerian inhibitory hormone are present, the wolfian duct will develop but if no testosterone or mullerian inhibitory hormone are present than the mullerian duct will develop
What determines whether the genital skin differentiates into a vagina or a penis?
The presence of 5-alpha reductase that is able to convert testosterone into DHT
What is meant by “organizational” effects of hormones?
Relatively permanent effects of hormones on structure and function of the body. Often occur during a critical period of development
What is meant by “activational” effects of hormones?
Relatively immediate and temporary effects of hormones that come and go with the presence and absence of the hormone
What is the relationship between the activational and organizational effects of hormones on the nervous system?
William C Young hypothesis; during development, hormones can organize and determine the structure of the nervous system in a way that will determine how the nervous system responds to the activational effects of hormones throughout life
What are the mechanisms of action by which oral contraceptives prevent pregnancy?
They lock the cycle into the luteal phase (high progesterone) thereby preventing follicle maturation, the LH surge, and ovulation
What is a sexually dimorphic difference between males and females in the neurohormonal control of GnRH secretion?
Rats: only females have functional surge center in hypothalamus which is where the brain regulates the ovulatory cycle; pattern of HPG axis activity is dimorphic
Humans: females have positive feedback to high estrogen levels which produces the LH surge
What role does the enzyme, aromatase, have in organizational effects of testosterone on the rodent brain?
It converts testosterone into estradiol which inhibits the formation of a surge center
What are pheromones?
Pheromones are chemical signals emitted by one organism that affects the function of another organism
Lee-Boot effect
female mice housed together had lengthened diestrus (inactive) of up to several weeks
Whitten effect
female mice housed in the absence of males showed interruptions in estrous cycles
Bruce effect
placing pregnant females with strange males resulted in termination of pregnancy and mating with the new male
Vandenbergh effect
females housed with males attain puberty sooner than females housed without males and females housed with females attain puberty later than females housed by themselves
What is some evidence for a pheromonal contribution to the menstrual synchrony phenomenon in women?
In the 1998 study, the social component was taken away, leaving only the pheromonal component. In this study, menstrual cycles were still altered which provided evidence for a pheromonal component.
What is meant by a permissive effect of a hormone?
Means that the presence of the hormone is necessary but not sufficient for a particular effect
What are 3 primary processes that contribute to a considerable lag time in the onset of steroid hormone actions at target tissues after stimulation of CRH neurons or GnRH neurons in the hypothalamus? Which process is responsible for the greatest lag time?
Hormone into bloodstream in response to stimulus; production of steroid hormone ; process of hormone reaching cell, binding to receptor, modulating gene transcription; time for an actual change in cell function takes the longest
what is testicular feminization mutation
no functioning androgen receptor so even though person has testes, testosterone cannot bind
female external genitalia, no pubic hair
what is 5-alpha reductase deficiency
testosterone cannot change to DHT so external genitalia is female until puberty and then begins to develop as male
how would you study if a sexually dimorphic trait depended on organizational or activational effects of hormones
activational: look at effects after puberty and if it varies with menstruation, pregnancy, or menopause
organizational: are effects present in childhood ; compare children when one has a hormone deficiency and one doesn’t
what are the anatomical components of male and female rat mating behavior
male: MPOA, olfactory system, amygdala, BNST
female: ventrolmedial hypothalamus, locus coeruleus
what findings support/do not support the possibility that hormones contribute to sexual orientation or gender identity
male to female transgender have same size BST as females
males usually have bigger BST
3rd nuclei of INAH showed differences in size comparing attraction to different genders
what are the hormones and follicle like during menstrual phase
low estrogen, low progesterone
LH/FSH increase by day 5 which begins follicular phase
sloughing off of uterine lining
what are the hormones and follicle like during the follicular phase
increasing estrogen, low progesterone
day 13: LH surge
day 14: ovulation
development of follicles and mature egg
what are the hormones and follicle like during the luteal phase
increased estrogen after temporary dip, increased progesterone
preparation of uterus to receive fertilized egg
what triggers menstruation
withdraw of progesterone
low estrogen, low progesterone
