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Test 2

What were the first 3 steps to studying endocrine function? 1- Separate the gland in question from the body. 2- Replace the gland at another site to see if the body function returns after the gland is restored. 3- Inject the gland to see if the body functions return after the gland is restored.
What were the last 3 steps to studying endocrine function? 4- Purify the glandular extract and identify the active component (using an assay). 5- Synthesize the hormonal substance in a lab. 6- Determine the hormones effect on the body and how it controls body function.
When and what did Berthold do? 1849. First demonstrated gonad had endocrine function.
When and what did Brown-Sequard do? 1890. Cyclic Theory (1910).
When and what did PE Smith do? 1930s. Removed the pituitary gland, ground it up, gave it back. Keyed the term gonadotropin.
When and what did Moore and Price do? 1930. Founded the negative feedback loop.
Does the simple neural reflexes have direct or indirect innervation of a target cell? How do they communicate? Direct -- afferent/efferent neurons & neurotransmitters
Do neuroendocrine reflexes have a direct or indirect innervation of a target cell? How do they communicate? Indirect -- neurosecretory cells & neurhormones
Is the nervous system a fast response or a slow response? Fast
Is a simple neural reflex or a neuroendocrine reflex quicker? Why? Simple Neural Reflex. Neuroendocrine reflex has to send neurohormones through the blood to the target where the simple is directly innervated.
What are the clusters of nerve cell bodies in the hypothalamus called? Hypothalamic nuclei
What are the functions of the hypothalamic nuclei? Respond to different stimuli
What is the bone that surrounds the pituitary gland? Sella Turcica
Where do the two parts of the pituitary gland come from? Diencephalon comes from the brain and Rathke's pouch comes from the roof of the mouth.
What is part of the adenohypophysis? Pars Distalis (anterior pituitary), Pars Intermedia, Pars Tuberalis
What is the median eminence? Region where hypophysis and hypothalamus come together
What is part of the neurohypophysis? Pars Nervosa (posterior pituitary) and Infundibulum
What are the two areas in the brain that secrete GnRH? Surge Center (preoptic area) and Tonic Center (Arcuate Nuceli)
Does GnRH flow to the Pars Distalis or the Pars Nervosa? Pars Distalis?
Where do surge center and tonic center cell bodies extend into? The HPP System
What is the order of the Hypophyseal vessels? Superior Hypophyseal Artery (SHA) --> Median Eminence --> Primary Portal Plexus (PPP) --> Portal Vessels (PV) --> Secondary Portal Plexus (SPP) --> systemic capillary --> main system
Where will oxytocin be released from? Posterior Pituitary
What are neurons that reside in the hypothalamus that are associated with oxytocin? Paraventricular nuclei (PVN)
What does hormone mean? To excite or arouse
What is a hormone? Chemical substance released into the blood stream that binds to a specific target to result in a specific action. Chemical Messenger. Actions take time. Action only occurs after binding to a specific receptor. Not food.
What are functional characteristics of a hormone? quick or slow, travel through blood, all cells in body are equally exposed, only those with specific receptors will respond, tissues respond differently to different hormones, effects of hormones depend on dose (amplitude) and time (frequency)
Describe different time scenarios for a hormone. Quick - oxytocin; hours - glucose homeostasis; days- menses; years - puberty
Where is DNA converted to mRNA? Nucleus
Where is mRNA converted to prohormone? rough ER
Where is prohormone converted to hormone? Smooth ER, Golgi Apparatus
What is negative feedback? Secretion of one hormone reverses the secretion of a 2nd hormone
What is positive feedback? Secretion of one hormone causes the secretion of a 2nd hormone to increase, unstable
What are some actions of hormones? Release of other hormones (GnRH), stimulate gonads (gonadotropins), sexual promotion (testosterone), pregnant maintenance (progesterone), luteolysis
What is luteolysis? What influences this? It is CL regression. Prostaglandin F2-alpha influences.
What is luteotropic? Affinity for the CL -- hCG and progesterone
What are 3 ways hormones are classified? Source, Mode of Action, Biochemical classification
What are hypothalamic hormones? produced by neurons in the hypothalamus -- releasing hormones (RH) -- target adenohypohysis -- result in release of other hormones
What are pituitary hormones? released from the pituitary into the blood -- Adenohypophysis releases gonadotropins and neurohypophysis releases oxytocin
What are gonadal hormones? Originate in gonads (estrogen and testosterone) -- feedback on hypothalamus, pituitary, repro tract
What are 2 other hormonal sources? Uterus (PGF 2-alpha) and Placenta (Estrogen, Progesterone, hCG, eCG)
What is the mode of action for neurohormones? RH? Gonadotropins? Sexual Promoters? Human Equine chorionic gonadotropin? Pregnancy Maintenance Hormones? Luteolytic hormones? RH (GnRH) stimulate other hormones, gonadotropins (LH/FSH), sexual promoters (e2, p4) regulate gonads, hypothal, pars distalis. H/E chorionic gonado released from placenta and stimulates CL, pregnancy maintenance (progesterone & placental lactogen)
What is the purpose of placental lactogen? gets mammary glands ready for lactation
what is the outermost layer of trophoblast? chorion -> secretes hormones
Why is a miscarriage around 4 months possible? transition from progesterone in CL to progesterone in placenta -- the switchover sometimes can be messed up
What are the biochemical units of hormones? peptides
What are the subunits of glycoproteins? Which unit is more common? Alpha and beta subunits. Alpha is more common. Beta is different and unique.
Why shouldn't you take progesterone when you are pregnant? Progesterone can be converted into testosterone.
What enzyme is necessary to convert testosterone into estradiol? Aromatase
What are eiconsanoids derived from? Arachidonic Acid
What is arachidonic acid? 20 carbon polyunsaturated fatty acid
Do eicosanoids act in a paracrine or autocrine manner? Why? paracrine due to quickly degrading
Do eicosanoids bind to the cell membrane or the nuclear membrane? Receptor on cell membrane?
What is the enzyme necessary to make AA? Phospholipase A2
What are the 2 main PG? PGF-synthase PGE- synthanse
What 4 things does the strength of a hormone action depend on? pattern and duration of secretion, half-life, receptor density, receptor-hormone affinity (strong or weak)
Why can't Estrogen-alpha feto-protein not enter the brain? There is a blood brain barrier that the estrogen bound to alpha feto-protein cant pass through
Can testosterone pass through the blood brain barrier? Yes.
Where is alpha feto-protein made? in the liver
What does estrogen do to the male surge center of the hypothalamus? Defeminizes it
Is GnRH released in high or low frequency? High or low amplitude? High frequency, high amplitude. From surge center.
What does LH do when GnRH is release? Follows in a similar surge pattern
When does the LH surge happen in humans? Day 14 of cycle
How is GnRH released in a post-pubertal male? LH? Testosterone? Tonic, episodic , no LH surge , steady release of testosterone
What is happening in the female tonic center during post-puberty? Low GnRH release, but at high frequency. Leads to follicular growth.
What is the surge center in the female post puberty responsible for? Ovulation
What is happening with the males surge center during post puberty? Nothing, does not develop
What is happening with the males tonic center during post puberty? Low GnRH release, No LH release, rest. High frequency, low amplitude
What is similar in the tonic center between all of the amplitudies? All amplitudes are low inside the tonic center.
What happens to LH when glucose is taken away? It has lower levels.
Does testosterone mimic or differ from LH? Mimics
What is puberty? an event that creates an ability to accomplish reproduction successfully
Pubscere - what does it mean and where does the word originate? latin - to be covered in hair
What are the requirements for pubertal onset? Appropriate frequency and amplitude of GnRH
What is the criteria of puberty for females? 1. Age of first estrus 2. Age of first ovulation (you can check physically or hormonally) 3. Age at which female can support pregnancy (body weight, metabolic threshold must be crossed)
What is the criteria of puberty for males? 1. Age when behavioral traits are exposed. 2. Age of first ejaculation. 3. Age when sperm first appear in ejaculate. 4. Age at which spermatozoa first appear in urine. 5. Age when ejaculate contains a threshold number of spermatozoa.
What is metabolic threshold? Weight a person needs to reach to hold a baby -- this is usually genetically determined
Pre - Puberty - Female - Surge Center Low frequency, Low amplitude -- dormant
Pre-Puberty - Female - Tonic Center Always low amplitude, Low frequency -- no follicular development = no GnRH surge = no LH surge = no ovulation
Pre-Puberty - Male - Surge Center Defeminized by estrogen -- inactive
Pre-Puberty - Male - Tonic Center Low freq, Low Amp = no spermatogenesis = Low leydig cells, low testosterone
Why do you see a low frequency of estrogen during pre-puberty? Estrogen has a strong negative feedback on tonic center = very sensitive = low amp/low freq of GnRH
Over time, does the tonic center become more or less sensitive to estrogen? Less sensitive
What happens when the tonic center becomes less sensitive to estrogen? Causes GnRH to increase - low amp, high freq. = puberty (follicular development, spermatogenesis)
What are the main two limiting factors for pubertal onset? 1. GnRH estrogen sensitivity (tonic center) 2. Pre-synaptic GnRH neural connection must be fully formed
What do pre-synaptic neurons release? What are their functions? neural peptides -- some serve as brakes and some serve as gas
What three things are pre-synaptic neurons influenced by? Plane of nutrition, Exposure to environmental or social cues, genetics
What is plane of nutrition? Females must have a certain level of "fatness" -- glucose and fatty acid levels influence GnRH concentrations/secretion
When was leptin discovered? 1994
Where is leptin produced? Adipocytes
Where does leptin target? Hypothalamic receptors
What effect does leptin have? Decreases appetite
Does leptin directly or indirectly influence GnRH neurons? What effect does it have on pre-synaptic connections? indirectly -- may notify GnRH neurons that nutritional status is adequate -- may have effect on peptide production from presynaptic connections
Leptin is needed for ______ to occur. Leptin
What is a parabiotic experiment? When you connect two organisms together by blood supply, and see how things affect both mice.
Parabiotic experiment : Two mice are attached: One mouse does not have leptin, but one mouse does have leptin. What is the effect of this? The mouse that does not have leptin receives the leptin from the other mouse and it loses weight.
Parabiotic experiment: Two mice are attached: One mouse has a leptin receptor issue, but one mouse is normal. What is the effect? It has no effect? Even if the mouse with the leptin shares the leptin with the receptor issue mouse, the receptor issue mouse can't receive that leptin. Remains overweight.
What is the believed effect of Kisspeptin? Thought to regulate GnRH neurons/surge
What is photoperiod? duration of an organism's exposure to light
Exposure to certain environmental or social cues affects pre-synaptic neurons -- What are some of these cues? Season during animal is born, photoperiod of puberty, presence or absence of opposite sex, density of groups of same sex
Do deer, sheeps, goats have a short or long gestation? Short
Are deer, sheep, goats short or long day breeders? Short day breeders, light days shorter (fall/winter)
Are horses short or long day breeders? Long day breeders, spring/summer because they have a long gestation period
Which season do you want offspring to be born? Why? Spring because food is more plentiful
What is the difference in puberty ages depending on which season something was born? Born in spring = puberty earlier Born in fall = later puberty
When more females are put in the same pen, what is the effect on estrous? Go into estrous earlier, have shorter cycles
What is the effect on estrous when males are introduced into a pig pen? Estrous occurs earlier, shorter cycles
Does timing of estrous matter if males are in the pen with the females or if they are separated? It didn't matter, they both sped up the cycles
Genetics play a role in influencing pre-synaptic neurons. What about genetics does this? Male or female; breed of animals; multiple genes likely modulate onset and tempo of puberty
How does breed of animals effect puberty? It can speed up or slow down the age that puberty occurs at.
What is the MAIN factor controlling puberty? The ability of GnRH to produce appropriate gonadotropin secretion from Pars Distalis
Created by: 1363731667