Exam 1 Lecture 4 Hormonal Communication

Describe a simple endocrine pathway

- Endocrine cells respond directly to an internal or environmental stimulus by secreting a particular hormone. - The hormone travels in the bloodstream to target cells, where it interacts with its specific receptors. - Signal transduction within target cells brings about a physiological response

Explain negative feedback control of tropic hormone release

- External conditions can either stimulate or inhibit the hypothalamus - The hypothalamus may release a releasing hormone that travels in the portal blood system to the AP - The AP is then stimulated to release a tropic hormone - This tropic hormone reaches a target endocrine gland and cause it to release a hormone or some other action that results in physiological responses - This hormone released by the target endocrine gland, in the general circulation, may reach the hypothalamus and the AP, which have receptors for this hormone - This, by negative feedback control, will prevent the hypothalamus from producing the releasing hormone and the AP from secreting the tropic hormone, so the pathway is turned off

Explain how the thyroid hormone cascade pathway works and its self-regulation

- External conditions like coldness stimulate the release of TRH by the hypothalamus - The TRH travels through the portal blood vessels to the AP where it triggers the release of TSH into the general circulation - The TSH travels in the bloodstream until it reaches the thyroid gland's receptors - This triggers the release of thyroxine by the thyroid gland, which will go into the general circulation and generate multiple physiological responses - When the level of thyroxine becomes high enough, it will bind to receptors in the hypothalamus and AP, inhibiting the release of TRH and TSH respectively

Give 3 examples of rhythmic hormones

- GH and cortisol secreted rhythmically: GH secreted mostly in the night, cortisol secreted mostly when we wake up - melatonin release, which is produced by the pineal gland in brain, occurs in the dark, marking the length of night. exposure to light inhibits melatonin release - sometimes people take melatonin before bed for jet lag and insomnia

Describe an example of a hormone cascade pathway

- If the level of thyroid hormone in the blood drops, the hypothalamus responds by initiating a hormone cascade pathway - The hypothalamus secretes thyrotropin-releasing hormone (TRH), causing the anterior pituitary to secrete a tropic hormone known as either thyroid-stimulating hormone (TSH) or thyrotropin - TSH stimulates release of thyroid hormone by the thyroid gland, an organ in the neck consisting of two lobes on the ventral surface of the trachea. - As thyroid hormone accumulates, it increases metabolic rate, while also initiating negative feed- back that prevents its overproduction

Describe the hormones of the posterior pituitary

- Neurosecretory cells of the hypothalamus synthesize the two posterior pituitary hormones: antidiuretic hormone (ADH aka vasopressin -- for water reabsorption in the kidney) and oxytocin (stimulates labor contractions, milk release) - these are transported to the posterior pituitary, where they are stored - Nerve signals from the brain trigger release of these neurohormones.

How did the Chernobyl disaster impact the thyroid gland of some people?

- One of the radioactive isotopes released through the explosion and spread across Europe was iodine-125 - As people are exposed to I-125, it is very dangerous bc it becomes concentrated in your thyroid gland - Its radioactivity pings away at the DNA in the thyroid gland, typically resulting in thyroid cancer

Describe the action of ADH in the kidney's reabsorption of water

- Osmoreceptors in the hypothalamus monitor blood osmolarity via its effect on the net diffusion of water into or out of the receptor cells. - When blood osmolarity rises above set point (high = too salty, low = too watery) bc of sweating profusely for ex., signals from the osmoreceptors in hypothalamus trigger a release of ADH from the posterior pituitary, as well as thirst - Within the kidney, the main targets of ADH are the collecting ducts. There, ADH brings about changes that make the epithelium more permeable to water, allowing water reabsorption that helps prevent further osmolarity increase - Also, Drinking water reduces blood osmolarity to set point, inhibiting further ADH secretion and thereby completing the feedback circuit - Homeostasis: Blood osmolarity (300 mOsm/L) - Release of ADH is blocked by ethanol in the pituitary gland, so water is not reabsorbed in the collecting ducts, causing dehydration

Describe the unintentional experiment in endocrinology with Kleinfelter's Syndrome

- Rare syndrome that bc of a mistake in meiosis person ends up with XXY - This causes the testes to function very poorly - This causes low testosterone levels and reduced negative feedback - secondary sex characteristics are much reduced: even though they have a Y chromosome and penis, have a lot of female characteristics (breasts, female pubes, wide hips, small testicles, etc.)

What determines whether a fetus develops into a male or female? How?

- Sex steroids determine this -- until seventh week of an embryo's development, either gender may develop - Female is default system, but if a Y chromosome is present, it will cause the gonads to start producing androgens in the 7-week-old embryo, and the male reproductive system develops from the female default system - if no androgens, the female default reproductive system develops

Give examples of how melatonin and seasonality result in changes to organisms

- Siberian hamster changes color based on season for camouflage (white in winter, darker in summer) - sheep and deer breed in autumn, small rodents breed in spring (so that offspring is born in summer) - Syrian hamster testicles are bigger in spring when they are reproductively active but smaller in fall when they are inactive

Describe the pituitary gland

- Signals from the hypothalamus travel to the pituitary gland, a gland located at the base of the hypothalamus - has discrete posterior and anterior parts, or lobes, which are actually two fused glands that perform very diff. functions - posterior pituitary is an extension of the hypothalamus. Hypothalamic axons that reach into the posterior pituitary secrete neurohormones synthesized in the hypothalamus. - anterior pituitary is an endocrine gland that synthesizes and secretes hormones in response to hormones from the hypothalamus

Describe a hormone cascade pathway

- The stimulus is received by a sensory neuron, which stimulates a neurosecretory cell. - The neurosecretory cell then secretes a neurohormone, which diffuses into the bloodstream and travels to endocrine cells. - Endocrine cells respond directly to this stimulus by secreting a particular hormone. - The hormone travels in the bloodstream to target cells, where it interacts with its specific receptors. - Signal transduction within target cells brings about a physiological response

Describe a simple neuroendocrine pathway

- The stimulus is received by a sensory neuron, which stimulates a neurosecretory cell. - The neurosecretory cell then secretes a neurohormone, which diffuses into the bloodstream and travels to target cells. These also include more than one cell type

What are the two different types of thyroxine? What is different in their structure? Which one does the thyroid mostly produce? Which is more active and why? How can they be converted to each other?

- Triiodothyronine (T3) and Thyroxine (T4); - They are both made from tyrosine but T3 has 3 iodine atoms while T4 has 4 iodine atoms - The thyroid mostly produces T4 - T3 is the more active form bc receptors have a higher affinity for it - T4 can be converted to T3 by an enzyme in the blood and/or target cells

Describe the pathway cortisol release and its regulation

- a frightening stimulus elicits release of corticotropin-RH (CRH) from the hypothalamus - CRH travels through portal blood system to other cells in AP, which stimulates the release of the tropic hormone adrenocorticotropin (ACTH) from the AP - ACTH goes into the general circulation and reaches the adrenal cortex, and stimulates the release of cortisol from the adrenal cortex into the bloodstream general circulation - high cortisol levels in blood, by negative feedback, can inhibit release of CRH by hypothalamus or ACTH by AP

Describe the unintentional experiment in endocrinology with body building by steroids

- a man starts shooting up a lot of synthetic androgens (anabolic steroids) - this will exaggerate secondary sex characteristics like body strength and muscle development - bc of the negative feedback mechanism, the now very high levels of testosterone will inhibit the release of GnRH, LH, and FSH - this nullifies the role of the testes, causing it to shrink. also many other very harmful side effects. results in the enhancement of secondary sex characteristics at the expense of primary sex characteristics like spermatogenesis, etc. - in women, this can cause reduced breast size, enlarged clit, facial and body hair, deep voice, etc.

Describe portal blood vessels

- a system of blood vessels in the microcirculation at the base of the brain, connecting the hypothalamus with the anterior pituitary - fxn is to quickly transport and exchange hormones between the hypothalamus arcuate nucleus and anterior pituitary gland

Describe hormones

- are chemical signals - are secreted by endocrine cells - are transmitted locally (autocrine or paracrine) or secreted into the circulatory system for long distance communication - may reach all cells in the body, but only those cells with the appropriate receptors can respond - can regulate lots of different responses, but more slowly than the responses regulated by the nervous system - can regulate a variety of different responses, but more slowly than responses regulated by the nervous system

What is the therapy for type II diabetes like?

- bc insulin resistance is the problem, injecting insulin won't help - but, by putting people on an exercise regimen and a fasting diet, that helps type II diabetes a lot. insulin sensitivity comes back often after reducing obesity

What happens to sex development during puberty?

- before puberty, set point of GnRH release in hypothalamus is very low bc hypothalamus is very sensitive to any feedback from secondary sex hormones - at puberty, set point of GnRH changes to a much higher, less sensitive level so more GnRH, LH, FSH arer produced so more sex steroid hormones are produced and released

Describe the pancreatic cells relating to blood glucose control

- beta cells produce and secrete insulin - alpha cells produce and secrete glucagon (antagonist of insulin, remember it activates same cAMP as epinephrine w/ a diff GPCR)

What are some female secondary sex characteristics?

- breast development - longer legs - wider pelvis - subcutaneous fat in butt, thighs, hips

Describe hypothyroidism. What causes it? What are its symptoms in adults and children?

- can result from iodine deficiency and/or inherited conditions of thyroid deficiency, which results in there not being enough active thyroxine - symptoms in adults include goiter, low metabolism, intolerance of cold, general physical and mental sluggishness - symptoms in children include retarded growth and poor mental development, causing cretinism (can cause dwarfism, retarded sexual development, puffy features, etc.)

In Type I diabetics, what do some of their cells use for fuel? What old treatment did this lead to?

- cells not taking up glucose use fat and protein for fuel, resulting in body wasting away and tissue and organ damage; - led to treatment with starvation diet before 1922 -- these ppl died early and were discriminated against

How does the melatonin profile vary in animals that breed rhythmically?

- changes in day length (photoperiod) change melatonin profiles -- more in long nights of winter, less in short nights of summer - these melatonin changes elicit changes in the plant or animals that are seasonally appropriate. - the onset of reproductive behavior is often controlled seasonally bc the change in melatonin profile is the seasonal stimulus for reproduction in some animals and plants - the reproductive organs will be affected as a response

What are pheromones? Give examples

- chemical signals that are released into the air and that communicate information from one individual to another and act through the olfactory system; - synchronization of menstruation among human females living together in dormitories, dogs marking territory by urination, mate attraction in arthropods

What are testosterone and estradiol synthesized from (give steps)?

- cholesterol converted to progesterone and then into androstenedione or directly into androstenedione - androstenedione is converted into testosterone - testosterone is converted into estradiol

Describe the hypothalamus

- coordination of endocrine signaling relies heavily on this region of the brain - receives information from nerves throughout the body and, in response, initiates endocrine signaling appropriate to environmental conditions

How does an iodine deficiency affect the thyroid gland?

- deficiency leads to the production of inactive thyroxine (non-iodinated), which cannot turn off production of TRH by negative feed back. - thus, the thyroid cannot stop making inactive thyroxine and works too hard and swells, causing goiter bc the thyroid gland has swollen

Summarize what the hypothalamus does in response to a stress stimulus

- direct nervous linkage to adrenal medulla triggers its secretion of epinephrine and norepinephrine -- very fast response - releases CRH to the AP, AP triggered to release ACTH, ACTH triggers adrenal cortex to secrete glucocorticoids like cortisol, these glucocorticoid then go to target tissues -- have slow response

What are some male secondary sex characteristics?

- facial/body hair - balding - deeper voice - subcutaneous fat in abdomen

What produces the sex steroid hormones? What are the different types?

- gonads (testes and ovaries) produce steroid hormones from cholesterol - androgens are male steroids, the main being testosterone - main female steroid hormones are estrogen and progesterone

Describe hyperthyroidism. What does it do to the hormone cascade pathway? What is one cause of it? What are its symptoms?

- hyperthyroid goiter results when the negative feedback mechanism fails even though blood levels of thyroxine are high -- too much active thyroxine - one cause is an autoimmune disease like Graves Disease, in which an antibody was made that binds to the TSH receptor, activating the secretion of thyroxine (acts as an agonist to the receptor) - the thyroid remains maximally active and grows larger, causing symptoms associated with high metabolic rates like nervousness, "jumpiness", feeling hot, and a buildup of fat behind eyeballs

Describe the unintentional experiment in endocrinology with operatic castrati

- in 1700s, boy sopranos with a great voice were castrated before puberty so their voice wouldn't deepen: called operatic castrati - grew to be an adult but voice never changed - their secondary sex characteristics were similar to Kleinfelter's

Describe the pathway of how norepinephrine and epinephrine are formed

- in the adrenal medulla: tyrosine (an AA) --> L-dihydroxyphenylalanine (L-Dopa) --> Dopamine --> Norepinephrine --> Epinephrine

Describe the hormones of the anterior pituitary

- lots of hormones synthesized in AP - Tropic hormones are those released from the AP that regulate the activity of other endocrine glands - Non-tropic hormones directly influence tissues that are not endocrine glands - Hormones secreted by the hypothalamus into portal blood vessel control the release of all anterior pituitary hormones

What are the adrenal glands made of? What does each respective part produce?

- made up of the adrenal medulla and the adrenal cortex: each adrenal gland is a fused endocrine and neuroendocrine gland - medulla develops from the nervous system and remains under its direct control: produces the amines epinephrine and norepinephrine - cortex is under hormonal control, mainly by adrenocorticotropin (ACTH) from the AP: produces cortisol

What are rhythmic hormones? What does this mean about the set point we want for homeostasis? Give two examples

- many hormones are controlled by our daily biological clock that regulates many activities: responsible for jet lag, shift-work adaptation problems, etc. - this means that the set point to achieve homeostasis is not always constant, can be modulated rhythmically

Name the different organs of the endocrine system

- pineal gland - hypothalamus - pituitary gland - thyroid gland - adrenals - pancreas - ovaries - testes - parathyroids

Describe the hormone pathway behind estrogen production and its regulation in females

- release by hypothalamus of Gonadotropin-releasing hormone (GnRH) into portal blood system - GnRH travels to AP and triggers release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) into the general circulation bloodstream - these travel to the ovaries and trigger the synthesis and release of estrogen -- physiological response is development of secondary sex characteristics - high estrogen levels in bloodstream, by negative feedback, can inhibit GnRH release by hypothalamus or LH & FSH release by AP. also, during one phase of the menstrual cycle, estrogen can have a positive feedback effect (opposite of normal negative feedback)

Describe the hormone pathway behind testosterone production and its regulation in males

- release by hypothalamus of Gonadotropin-releasing hormone (GnRH) into portal blood system - GnRH travels to AP and triggers release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) into the general circulation bloodstream - these travel to the testes and trigger the synthesis and release of testosterone -- physiological response is development of secondary sex characteristics - high testosterone levels in bloodstream, by negative feedback, can inhibit GnRH release by hypothalamus or LH & FSH release by AP

Describe endorphins, non-tropic hormones

- the body's natural opiates - these hormones bind to pain receptors in the brain and dull the perception of pain - "runner's high" may result from release of endorphins when stress and pain in the body reaches critical levels - morphine/opium/heroin are mimics of endorphins

How do beta blockers work? What is a commonly prescribed beta blocker?

- they inactivate only beta-adrenergic GPCR receptors so they can be used to reduce fight-or-flight responses to epinephrine - this prevents activation of adenylyl cyclase leading to cAMP production and the fight-or-flight responses, but leave the alpha receptors available to norepinephrine and its regulatory functions (esp. for blood pressure) - propranolol is commonly prescribed for reducing performance anxiety

What are the effects of glucocorticoids?

1. proteins and fats broken down and converted to glucose, leading to increased blood glucose levels 2. immune system may be suppressed

Describe circulating vs local hormones

Circulating hormones -- are secreted by the endocrine cell into the bloodstream which carries it to a specific target cell usually far away, where it then leaves the blood vessel and binds to a receptor on the target cell. One function of endocrine signaling is to maintain homeostasis Local hormones -- are either autocrine (self) or paracrine (nearby) signaling where the endocrine cell secretes the hormone nearby so it binds to its own receptor or a nearby target cell's receptor, reaches target solely by diffusion. play roles in many physiological processes, including blood pressure regulation, nervous system function, and reproduction. Local regulators that mediate such signaling include the prostaglandins

Explain how one hormone can have different potential responses in different cells

For example, epinephrine: - this hormone triggers glycogen breakdown in the liver. - however, epinephrine also increases blood flow to major skeletal muscles - and decreases blood flow to the digestive tract. - these varied responses enhance the rapid reactions of the body in emergencies. - A single hormone can elicit multiple responses if its target cells differ in their receptor type or in the molecules that produce the response - Target cells with the same receptor exhibit different responses if they have different signal transduction pathways or effector proteins; Target cells with different receptors for the hormone may also exhibit different responses

When was insulin therapy discovered?

In 1922, the role of insulin as a therapy for Type I diabetes was discovered by Banting and Best: by observing that dogs became diabetic when their pancreas was removed. They then used pancreas extracts to see what was important and found insulin. This dramatically improved life of diabetics, but they are still more likely to suffer from blindness, kidney failure, heart attacks, etc.

Why do people use iodinated salt?

In regions of the world where there isn't a lot of iodine around in their diet, so they become iodine deficient. Those ppl can get their necessary iodine through this salt so their thyroid can function properly

Describe how glucose levels in the blood are controlled

In the pancreas: - there is an ideal, homeostatic blood glucose level of about 90 mg/100 ml - after a meal, blood glucose levels rise, this stimulates the Beta cells to release insulin into general circulation. Insulin stimulates cells throughout body (especially muscle and liver cells) to take up glucose and convert it to glycogen and fat, reducing blood glucose levels - when blood glucose levels fall, to prevent becoming hypoglycemic, the pancreas stops releasing insulin, and cells switch to using glycogen and fat for energy to reach homeostatic level. if blood glucose levels falls too low, the Alpha cells release glucagon which stimulates liver to convert glycogen back to glucose

Describe the termination of hormonal signals

Intracellular termination: G-proteins, phosphatases, arrestins, etc (prev. discussed) Extracellular termination: 1. Degradation of hormone by enzymes in liver, blood, lymph (or converted to inactive form) 2. Removal of hormones (or their breakdown products) from blood by the kidneys and subsequent excretion. This is why many hormones can be discovered by a urine test

What are the different classes of hormones? Give examples

Polypeptides (hydrophilic): insulin, glucagon Steroids (hydrophobic, all lipids with 4 fused carbon rings): cortisol, estrogen Amines (can be hydrophobic but mostly hydrophilic, synthesized from a single AA): thyroxine, epinephrine

Where did our understanding of the molecular basis of the sleep/wake cycle in humans originate from? What discovery did it lead to?

Studies from activity/rest cycle in fruit flies; led to discovery of an inherited type of human insomnia (advanced sleep phase syndrome) now known to be caused by a mutation in a homolog gene (period gene) discovered in flies that regulates how fast our biological clock runs

What are TRH, TSH, and thyroxine?

TRH = TSH-releasing hormone, the first RH to be isolated from the hypothalamus TSH = thyroid-stimulating hormone, also called thyrotropin (a tropic hormone released by AP) Thyroxine (aka thyroid hormone) = increases the basal metabolic rate: exposure to cold stimulates release of TRH and ultimately thyroxine Ultimate responses of these hormones: upregulation of basal cell metabolism that creates heat, stimulation of fat breakdown, and protein synthesis

Give an example of a simple endocrine pathway

The control of pH in the duodenum, the first part of the small intestine. - The digestive juices of the stomach are extremely acidic and must be neutralized before further digestion can occur. - As the stomach contents enter the duodenum, their low pH stimulates endocrine cells in the lining of the duodenum to secrete the hormone secretin into the extracellular fluid. - From there, secretin diffuses into the blood. Circulating secretin reaches target cells in the pancreas, which respond by releasing bicarbonate into ducts leading to the duodenum. - This response—the release of bicarbonate—raises the pH in the duodenum, neutralizing the stomach acid.

What are catecholamines?

a class of amine hormones synthesized from the amino acid tyrosine: ex. epinephrine, norepinephrine, dopamine

What is diabetes mellitus?

a disease caused by a lack of the protein hormone insulin (Type I) or a lack of insulin receptors on target cells aka insulin resistance (Type II)

What is an agonist? What is an antagonist?

a molecule capable of binding to, and activating, a receptor; a molecule that opposes or reduces the action of an agonist, acts in opposite direction

What is norepinephrine?

a neurotransmitter produced in the medulla that is involved in physiological regulation (ex. to sustain blood pressure)

What type of hormones are epinephrine and norepinephrine? What types of receptors do they bind to? Describe the specific receptors and what they do?

amine hormones; they bind to two types of GPCRs in target cells -- alpha-adrenergic and beta-adrenergic; norepinephrine acts mostly on the alpha type, whereas epinephrine acts equally on alpha- and beta-receptors; Different cells express the various receptors differentially so responses will be tissue-specific: - alpha1-GPCRs are linked to Gq-protein that activate the Ca2+ pathway by acting on PLC - alpha2-GPCRs are linked to Gi-protein that inhibit adenylyl cyclase - beta1 and beta2-GPCRs are linked to Gs-protein that stimulate adenylyl cyclase, activating the cAMP pathway

What happens with overproduction of growth hormone in adulthood?

causes growth of the few tissues that are still responsive to GH: face, hands, feet, leading to Acromegaly

What cells does cortisol stimulate? What can it also be used to do and what is the tradeoff for this?

cells that are not critical to the emergency to decrease their use of glucose; can be used to reduce inflammation and allergy, but it blocks the immune system -- thus, long-term stress (leading to long-term elevated cortisol levels) can make us more susceptible to infections and disease

Why is the cortisol response slower than the epinephrine response?

epinephrine is under direct control of nervous system which is faster than the blood system

Describe the silkworm moth pheromones

female silkworm moth secretes pheromone from a gland on her abdomen that the male silkworm moth can detect through a very sensitive and elaborate antennae

What is a hormone that exhibits nontropic and tropic effects? Which ones only exhibit tropic effects? Which ones only exhibit nontropic effects?

growth hormone; follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TH), adrenocorticotropic hormone (ACTH); prolactin, melanocyte-stimulating hormone (MSH), endorphin

Sets of hormones from the hypothalamus, the anterior pituitary, and a target endocrine gland are often organized into a ________________________. Elaborate on this

hormone cascade pathway; Signals to the brain stimulate the hypothalamus to secrete a hormone that stimulates or inhibits release of an anterior pituitary hormone. The anterior pituitary hormone in turn acts on another endocrine organ, stimulating secretion of yet another hormone, which exerts effects on specific target tissues.

What is a hormone's half-life? What are epinephrine, cortisol, and thyroxine's half-lives?

length of time for the concentration of a hormone to drop one-half of the maximum (after active release from the endocrine gland is stopped); epinephrine's is 1-3 min (so it can be cleared from the blood very quickly bc it is hydrophilic), cortisol or thyroxine are on the order of days (can hang around for a long time bc it is hydrophobic and it is dissolved in cells around the body)

Define homeostasis

maintaining internal stability: ex. constant pH, osmotic pressure, Ca++, blood pressure, etc.

How is sex development different in birds from mammals?

males are default reproductive system, estrogen trigger female development -- opposite

Describe prolactin, a non-tropic hormone

mammalian females: stimulates breast development and milk production/secretion mammalian males: helps regulate endocrine fxn of the testes birds: regulates fat metabolism and reproduction amphibians: regulates timing of metamorphosis, also acts as a larval growth hormone fishes: regulates salt and water balance ancient hormone that has developed diff fxns over time

Opium comes from _______

poppies

What does the adrenal medulla secrete in response to stress?

produces epinephrine (aka adrenaline), initiating fight-or-flight reactions like: - increased heart and breathing rates - elevated blood pressure - glycogen breakdown - increased metabolism - changes in blood flow patterns

Each hypothalamic hormone is either a ________ hormone or an ________ hormone, reflecting its role in promoting or not promoting release of one or more specific hormones by the anterior pituitary

releasing; inhibiting

What are adrenal hormones typically involved in?

response to stress

Give an example of a neuroendocrine pathway

the regulation of milk release during nursing in mammals. - Suckling by an infant stimulates sensory neurons in the nipples, generating signals in the nervous system that reach the hypothalamus. - Nerve impulses from the hypothalamus then trigger the release of the neurohormone oxytocin from the posterior pituitary gland - In response to circulating oxytocin, the mammary glands secrete milk

Explain negative feedback control of hormone release

the response reduces the initial stimulus: by decreasing hormone signaling, negative feedback regulation prevents excessive pathway activity - homestasis is achieved by maintaining a variable at or near a particular value, set point. A fluctuation in the variable above or below the set point serves as the stimulus detected by a sensor. Upon receiving a signal from the sensor, a control center generates output that triggers a response, a physiological activity that helps return the variable to the set point

Describe the receptors for steroid hormones

they are cytoplasmic bc the steroid hormones are hydrophobic and can pass freely through plasma membrane

Receptors are ________ (for _______ hormones) or _________ (for ______ hormones

transmembrane; hydrophilic; cytoplasmic; hydrophobic

Describe the tropic and non-tropic effect of growth hormone

tropic: can act on the liver, responds to GH by releasing insulin-like growth factors (IGFs), which circulate in the blood and directly stimulate bone and cartilage growth non-tropic: can act on all cells in the body bc of AA uptake and promote growth of tissue

What are mineralocorticoids? What are glucocorticoids?

type of corticosteroid -- effects on mineral metabolism, act principally in maintaining salt and water balance. For example, the mineralocorticoid aldosterone functions in ion and water homeostasis of the blood type of corticosteroid -- have a primary effect on glucose metabolism. Augmenting the fuel-mobilizing effects of glucagon from the pancreas, glucocorticoids promote glucose synthesis from noncarbohydrate sources, such as proteins, making more glucose available as fuel. Also have variety of other fxns

What are the effects of under and overproduction of growth hormone in childhood?

under: pituitary dwarfism, can be treated if identified early over: gigantism, often happens bc of tumor on pituitary

What do adrenal cortex cells use to produce their hormones?

use cholesterol to produce their steroid hormones, including the main glucocorticoid, cortisol, that mediates the body's response to stress

Describe how diabetes impact blood glucose levels and what is causes

without insulin or the receptors for insulin, glucose accumulates in the blood (bc insulin pathway doesn't work properly) and when it gets to the kidneys, it gets filtered out and is lost in urine