BISC 276 Exam 2- Dynamic Study Modules and Learning Catalytics
In comparing a solution to a fluid in a cell, a hypertonic solution always has what?
A higher concentration of non-penetrating solutes than that in the cell.
What condition would lead to the fastest rate of oxygen diffusion into a cell?
A large concentration gradient and a thin membrane.
All cells that respond to proteins have what?
A receptor protein that has a specific binding site for that hormone
An intracellular signaling molecule produced by the binding of a ligand to a membrane-bound receptor is called what?
A second messenger- a first messenger molecule stays outside the cell but can still crease an intracellular chemical signal called a second messenger to create the cellular response Ex: a paracrine molecule is a signal molecule secreted by one cell to a neighboring cell, and a carrier protein moves molecules across the cell membrane
If you take a stressed person who is secreting a lot of the "override hormone" arginine vasopressin (AVP), causing high levels of cortisol, and then give them prednosolone, what will happen?
ACTH levels are high due to stimulation from AVP, and so ACTH levels will remain high
What are some examples of responses to ligands binding to a receptor?
Activating inactive enzymes, causing the synthesis of new enzymes, opening ion channels, phosphorylation of proteins inside the cell, and synthesis of cAMP
Which organs produce and release steroid hormones?
Adrenal cortex, gonads, and placenta -adrenal cortex produces mineralocorticoids (aldosterone- regulates sodium reabsorption and potassium secretion by the kidney tubules) and glucocorticoids (cortisol and corticosterone- help the body to adapt to stress by raising blood glucose levels and promoting the catabolism of protein and fat) and androgens (dehydroepiandrosterone, androstenedione- promote sex drive) -gonads produce estrogen (promotes development of the ovarian follicle and promotes development of secondary sex characteristics), progesterone (responsible for stimulating the growth of the endometrium should implantation of a zygote occur), testosterone and androstenedione (required for sperm development in teh testes, as well as development of male secondary sex characteristics) -placenta produces estrogen and progesterone
What is a true statement about amino acid-derived hormones?
Amino acid-derived hormones can be transported by being dissolved in plasma or bound to carrier proteins- thyroid hormones (hydrophobic and must be attached to a carrier protein) and catecholamines (hydrophilic and travel well in plasma without any assistance).
What is an example of a cortisol hypersecretion scenario that points to an example of a primary endocrine disorder?
An adrenal tumor-induced increase in cortisol, followed by decreased CRH, leading to decreased ACTH- a primary endocrine disorder is due to an abnormality occurring the endocrine gland that secretes the hormone.
Which androgens are secreted by both the adrenal cortex and the testes?
Androstenedione- promotes sex drive (in both males and females)
The interaction between the hormones insulin and glucagon can be described as what?
Antagonistic- insulin, secreted by the beta cells of the pancreas, lowers blood glucose concentrations by promoting the synthesis of proteins, triglycerides, and glycogen; glucagon, secreted by the alpha cells of the pancreas, elevates blood glucose concentrations by promoting both glycogenolysis and gluconeogenesis.
Which of the following hormones is NOT synthesized by the anterior pituitary gland (adenophypophysis)? A. Antidiuretic hormone (ADH) B. Follicle-stimulating hormone (FSH) C. Thyroid-stimulating hormone (TSH) D. Adrenocortocotropic hormone (ACTH)
Antidiuretic hormone (ADH)- secreted from the hypothalamic nerve terminals in the posterior pituitary, and is produced in the cell body of the neurons located in the hypothalamus and shuttled down the axon to be stored in axon terminals located in the posterior pituitary gland; causes the insertion of aquaporins in the collecting duct of the kidney, increasing water retention and decreasing urine output, as well as stimulates the constriction of arterioles.
In order for water to be absorbed by epithelial cells, what does there need to be?
Aquaporins must be present in the cell membranes and the concentration of impermeable solutes must be higher on the inside of the cell.
Intracellular calcium levels are kept in the submircomolar range by what mechanism(s)?
Binding to cytosolic proteins, active transport across the cell membrane, active transport into the mitochondria, and active transport across the cell membrane and active transport into mitochondria- the cytosol and its organelles transport and store calcium ions as required to maintain normal concentration gradient across the membrane that facilitates cell functions and interactions with cellular neighbors
What can be treated with hormones, hormone agonists, or hormone antagonists?
Breast cancer, prostate cancer, inflammation, diabetes, high blood pressure, fertility, infertility, osteoporosis, etc.
If the level of ACTH in the bloodstream decreases, the secretion of what will increase?
CRH- released from the hypothalamus, travels to the anterior pituitary gland via the hypothalamic-pituitary portal system and promotes the release of ACTH; as ACTH travels through the blood, it will stimulate the adrenal cortex to release cortisol, which inhibits future release of CRH and ACTH through negative feedback loops.
The difference between carrier and channel proteins is what?
Channel proteins create a continuous passage between intra- and extracellular compartments, can be leak or gated channels. Carrier proteins require that the substance crossing the membrane bind to a specific site on the carrier, which causes a conformation change causing the carrier to open to the other side of the cell and allowing the substance to move between the intracellular and extracellular compartments.
What hormones are secreted by the small intestine?
Cholecystokinin (CCK), secretin, and glucose-dependent insulinotropic peptide (GIP) -CCK is secreted by the duodenum and jejunum of the small intestine in response to the presence of fat or protein in the digested food in the duodenum, responsible for regulating the motility and secretions of the small intestine -secretin is secreted by the duodenum and jejunum of the small intestines in response to acid in the duodenum; actions of this hormone include inhibiting motility and secretions of the stomach, stimulating pancreatic secretion of bicarbonate, and stimulating bile secretion by the liver GIP- inhibits the motility and secretions of the stomach, and stimulates the pancreas to secrete insulin
What are some hormones that affect metabolism?
Cortisol, glucagon, growth hormone- cortisol, secreted by the adrenal cortex, raises blood glucose concentrations, as well as glucagon (by different means), and growth hormone regulates the metabolism of proteins, carbohydrates and triglycerides to ensure adequate energy is available for growth of bones and soft tissue.
Hormones that can have an affect on glucose levels in the blood include what?
Cortisol, insulin, and glucagon- cortisol raises blood glucose concentrations and promotes the catabolism of protein and triglycerides, glucagon elevates blood glucose concentrations by promoting both glycogenolysis and gluconeogenesis, and insulin lowers blood glucose concentrations by promoting the synthesis of proteins, triglycerides, and glycogen.
Which of the following is not a peptide hormone? A. Epinephrine B. Oxytocin C. Atrial natriuretic peptide D. Prolactin
Epinephrine- an amino acid-derived hormone, not a peptide hormone -hormones are classified as protein hormones (water-soluble: insulin, glucagon, oxytocin), steroid hormones (estrogen, cortisol, aldosterone, testosterone), or amino acid-derived hormones (epinephrine, norepinephrine, dopamine).
The concentration of inhibin in the bloodstream is regulated by what?
FSH and GnRH- GnRH from the hypothalamus promotes the secretion of FSH from the anterior pituitary gland; FSH then travels via the blood to the ovaries and testes, promoting the secretion of inhibin -> inhibin then exerts negative feedback on future release of GnRH and FSH. -inhibin is a gonadal hormone that inhibits secretion of FSH (follicle stimulating hormone)
You get the blood work results back for your patient. She has abnormally high levels of the pituitary hormone TSH. What is a possible explanation for her results?
Failure of negative feedback, reduced sensitivity to thyroxine, reduced output of thyroxine by the thyroid gland, or iodine deficiency.
What reproductive hormone(s) is/are released by the anterior pituitary?
Follicle-stimulating hormone (FSH- in women, stimulates estrogen secretion and growth/development of follicles in ovaries; in males, promotes production of sperm by the testes) and luteinizing hormone (LH- in women, stimulates ovulation, conversion of follicle into the corpus luteum and secretion of estrogen and progesterone; in men, stimualtes release of testosterone by the testes)- released from anterior pituitary gland upon stimulation from gonadotropin-releasing hormone (GnRH), which travels via the hypothalamic-pituitary portal vein to the anterior pituitary.
What reproductive hormone(s) is/are released in both males and females?
Follicle-stimulating hormone (anterior pituitary), luteinizing hormone (anterior pituitary), inhibin (testes and ovaries), and dehydroepiandosterone (adrenal cortex)
At what level can signal amplification occur?
G protein, protein kinase, and second messenger Ex: cAMP signal amplification shows a progressive increase in the output of phosphorylated proteins
Examples of hormones that are released by the hypothalamus include what?
Gonadotropin-releasing hormone (GnRH)- released by hypothalamus and travels via the hypothalamic-pituitary potal vein to the anterior gland and stimulates the releease of luteinizing hormone (LH) and follicle-stimulating hormone (FSH)
The release of growth hormone by the anterior pituitary is inhibited by what?
Growth hormone-inhibiting hormone/somatostatin- the hypothalamus releases growth hormone inhibiting hormone, which travels via the hypothalamic-pituitary vein to the anterior pituitary gland and inhibits growth hormone secretion.
What hormones does the heart, liver, and pancreas produce?
Heart- atrial natriuretic peptide Liver- insulin-like growth factors Pancreas- insulin and glucagon
In order for a molecule to be considered a hormone, it must meet certain criteria, which does NOT include what? What DO the criteria include?
Hormones are very small, water-soluble molecules- false statement Criteria for classifying hormones include: -the hormone must travel in the blood to the target organ -the effects of the hormone are usually seen in many areas in the body -the on set of the hormonal effects is slow compared to the effects of the nervous system
A signal molecule enters a cell, binds to the DNA and affects DNA transcription >> this molecule must be what?
Hydrophobic
In people with diabetes mellitus, glucose is not being transported into cells at the normal rate. This buildup of glucose in the plasma causes the extracellular fluid to become what?
Hypertonic and hyperosmotic- in this case, glucose is a non-penetrating solute that is trapped in the extracellular fluid, making the solution both hyperosmotic (since glucose can't move out, water does) and hypertonic.
Corticotropin releasing hormone (CRH) is secreted by what?
Hypothalamus- secreted by the hypothalamus and travels via the hypothalamic-pituitary vein to the anterior pituitary to stimulate the release of adrenocorticotropic hormone (ACTH)
A cell placed in a solution of unknown composition soon swelled up and burst, so the solution must have been what to the cell when it was originally placed in the solution?
Hypotonic and of an undetermined relative osmolarity (not given information on the total number of solutes in solution- no osmolarity conclusions)
The level of calcium in the cytosol can be raised by activating what?
IP3 and phosphlipase C
What is a statement provides an accurate comparison between facilitated diffusion and simple diffusion?
In both facilitated and simple diffusion, substances move down their concentration gradient. In simple diffusion, substances will move across the membrane without any protein transporters, they simply pass through the plasma membrane directly. In facilitated diffusion, substances will travel across the membrane through a channel protein or carrier protein.
Up regulation allows a target cell to do what?
Increase the sensitivity of a target cell to a ligand- up regulation refers to an increase in the number of receptors compared to normal conditions, occurring when cells are exposed to low messenger concentrations for a prolonged period of time; the probability of a target cell being ligated by a messenger molecule is improved as more receptors for that molecule are produced by the cell and inserted into its membrane, increasing the sensitivity of a target cell to a ligand.
What hormone(s) directly cause(s) bone growth?
Insulin-like growth factor (IGF)
To make thyroid hormone (thyroxine), the thyroid gland need what substance from the diet?
Iodine
A cell containing 300 mOsm of non-penetrating solutes per liter is placed in a solution containing 200 mOsm of non-penetrating solutes per liter and 100 mOsm of the penetrating solute urea per liter. The solution can said to be what with respect to the cell?
Iso-osmotic (same number of non-penetrating solutes/tonicity) and hypotonic (in terms of all solutes.
What is a peptide hormone characteristic?
It forms a hormone-receptor complex on the cell membrane in order to trigger the appropriate changes in cellular activities.
Aldosterone is a BLANK, and is secreted by what?
It is a mineralocorticoid, and it is secreted by the adrenal cortex- stimulates sodium reabsorption and potassium secretion in the kidney
What is a characteristic of the second messenger DAG?
It is membrane-bound- DAG stands for diacylglycerol, and after binding with the membrane receptor, it triggers steps that lead to activation of protein kinase C, which in turn leads to the desired cell response.
The blue light emitted from laptops, tablets and cell phones is thought to disrupt patterns when these devices are viewed at night because the blue light suppresses what hormone?
Melatonin
An increase what would increase the rate of diffusion of oxygen molecules across pulmonary cell membranes?
Membrane surface area, the oxygen concentration inside the lung, and temperature.
Cox-2 (cyclooxygenase 2) inhibitors, such as Vioxx and Celebrex are what?
More specific than aspirin, which inhibits both Cox-1 and Cox-2, do not produce stomach upset like aspirin because they do not inhibit PGE2 (prostaglandin E2) the way aspirin does (PGE2 indirectly protects the stomach lining from acid), and can increase the risk of heart attack and stroke in susceptible individuals- Cox-2 is a chemical compound that is activated when damaged tissue cells associated with pain and inflammation release agents known as prostaglandins, and the Cox-2 inhibitors interfere with this process and produce relief of pain more directly than Cox-1 inhibition by aspirin; reduction of thromboxane that occurs in Cox-1 inhibition reduces the risk of blood clots when Cox-2 inhibitors are used, and irritation of the stomach lining is reduced, which is desirable (however, the use of Cox-2 inhibitors raises the risk of heart attacks and stroke in individuals who are predisposed to heart disease)
Which of the following molecules would not diffuse through cell membranes easily? A. Na+ ions and glucose B. Cholesterol C. Steroids D. Na+ ions E. Glucose
Na+ ions and glucose- one has a charge and the other is a large molecule, and so they require assistance.
If a cell's Vm = -70 mV and ENa+ = +50 mV, which way will Na+ ions move across the cell membrane?
Na+ ions will move into the cell- Na+ has a higher concentration out of the cell than in and it is positively charged (equilibrium potential is +50)
An endocrine organ's release of a hormone can be effectively controlled by what?
Negative feedback loop mechanisms.
Which of the organ systems is known for producing more focused, direct and the fastest responses from target cells?
Nervous system- the endocrine and the nervous systems are both crucial to exerting both communication and control functions over all the other organ systems in the body, but the one that possesses the attributes described best is the nervous system.
If a patient is given an intravenous solution that is 0.9% NaCl (300 mOsm/L NaCl), his or her red blood cells will do what?
Not change size or shape- the solution introduced is isotonic to the blood
What does not require the use of ATP out of the following? A. Osmosis B. Active Transport C. Exocytosis D. Endocytosis
Osmosis- exocytosis involves breakdown and reassembly of proteins, requiring energy; endocytosis involves engulfing substances, involving breakdown and reassembly, also requiring energy.
Which of the following types of molecules would be most likely to pass through the membrane by means of simple diffusion? A. Oxygen - nonpolar B. Water - polar C. Na+ - polar D. An amino acid - polar E. Glucose - polar
Oxygen- simple diffusion is a form of passive diffusion whereby solutes move from areas of high concentration to low concentration through the membrane without the assistance of a membrane transporter, and in order for something to pass through the membrane unassisted, it must meet certain criteria, including being nonpolar.
The hormones secreted by the hypothalamic nerve terminals in the posterior lobe of the pituitary include what?
Oxytocin (suckling and sensory stimuli from stretch receptors in teh cervix stimulate secretion) and antidiuretic hormone (elevated blood osmolarity and low blood pressure stimulate secretion; regulates water in the body)- both hormones are produced in the cell body of the neurons located in the hypothalamus and shuttled down the axon to be stored in the axon terminals located in the posterior pituitary gland, and hence, the function of the posterior pituitary gland is storage of these two hormones
Release of a neurotransmitter by a nerve cell is an example of what kind of signaling?
Paracrine
Thyroid hormone is required for the production of beta adrenergic receptors in the smooth muscle of the bronchioles. Once the beta adrenergic receptors are produced, epinephrine can bind to these receptors, inducing dilation of these tubules. This hormone interaction can be described as what?
Permissive- occurs when the presence of one hormone is needed for another to exert its actions. -antagonistic hormones are those that oppose the actions of each other (insulin and glucagon) -additive hormones are when they produce the same type of response in the body and the net effect equals the sum of the individual effects -synergistic hormones are when they produce the same response in the body and the net effect of the two hormones exceeds the sum of the individual effects
The cellular response to the second messenger cAMP can be inhibited by activating what?
Phosphodiesterase and Gi Protein (inhibitory G protein)- intereference with Gi protein will block successive events Ex: when cholera toxin attach to lumen epithelia of the small intestine, and phosphodiesterase in breakdown of cGMP in retina of eye
Oxytocin is secreted by what?
Posterior pituitary (neurohypophysis)- it is produced in the cell body of the neurons located in the hypothalamus and shuttled down the axon to be stored and secreted from the axon terminals located in the posterior pituitary gland.
Passive membrane transport does not use energy in the form of ATP in order to move substances across biological membranes. That doesn't mean, however, that there is no energy used in the movement of ions across the membranes. How would you classify the type of energy required in order for a neutral substance to move via either simple or facilitated diffusion.
Potential energy in the form of a concentration gradient.
An increase in the concentration of LH in the blood will result in the secretion of what?
Progesterone and testosterone- LH is produced by the anterior pituitary gland, and stimulates the ovaries and testes to secrete said hormones; progesterone responsible for stimulating growth of endometrium should implantation of zygote occur, and testosterone is required for sperm development and as well as secondary sex characteristic development in males.
What influences the amount of prolactin released by anterior pituitary cells?
Prolactin-releasing hormone, prolactin-inhibiting hormone/dopamine- the hypothalamus secretes prolactin-releasing hormone, which travels via the hypothalamic-pituitary vein to the anterior pituitary gland and stimulates prolactin secretion; the hypothalamus may also inhibit the anterior pituitary secreting prolactin by secreting prolacin inhibiting hormone (dopamine) -prolactin is responsible for the ability for female mammals to produce milk
Lipophobic chemical messengers are also hydrophilic. The following choices all describe lipophobic chemical messengers except which one? A. Secretion by diffusion B. There is a fast onset time to response C. Receptors are located on plasma membrane D. They activate membrane-bound enzymes E. There is a relatively short duration of response
Secretion by diffusion- lipophilic
An otherwise healthy patient with osteoporosis has been taking 500 mg of Calcium 3x a day for months. However, a DEXXA scan of her bone density shows her bone mass is continuing to decrease. What could be true of this patient?
She is vitamin D deficient, she has high levels of parathyroid hormone, her blood calcium levels are in normal range, or she could benefit from treatment with a parathyroid hormone inhibitor (antagonist) combined with vitamin D supplements (can't be low Ca++ levels because that would put her in respiratory failure)
A beaker containing two fluid compartments separated by a semipermeable membrane is filled with distilled water. In compartment A you place 15 mM of NaCl and in compartment B you place 25 mM of NaCl. The membrane is permeable to both sodium and chloride. Initially, which side has higher osmotic pressure? As time goes on, will the water levels change, and if so, how?
Side B has a higher osmotic pressure (measure of the total number of solutes), and the water levels will not change.
What hormone is secreted by the delta cells of the pancreas?
Somatostatin- inhibits the secretion of pancreatic hormones and regulates digestion and absorption of nutrients by the digestive tract
The interaction between chemical messengers and their receptors is similar to the interaction between what?
Substrates and enzymes, glucose transporter proteins in the cell membrane, and ions and pore-type channels- each of these processes require the attachment of the items described to one another, all of them can demonstrate specificity, and water surrounds the cell membrane but does not have to attach to it in order to trigger a response on the part of the cell
What hormones does the thyroid gland secrete?
T3 (triiodothyronine) and T4 (tetraiodothyronine), as well as calcitonin -T3 and T4 are required for normal growth and development, and they increase basal metabolic rate; secretion stimulated by TSH from the anterior pituitary -calcitonin promotes calcium deposition in the bone, resulting in lower blood calcium concentrations; elevated blood calcium concentrations stimulate calcitonin release.
During primary hyposecretion of thyroid hormone (T3 and T4), what hormone levels are increased?
TRH (thyrotropin-releasing hormone) and TSH (thyroid-stimulating hormone)- primary hyposecretion refers to low hormone secretion as a result of a problem with the organ producing the hormone (the thyroid gland is not secreting adequate thyroid hormone); the hypothalamus secretes TRH, which travels via the hypothalamic-pituitary vein to the anterior pituitary gland and promotes the secretion of TSH, which is responsible for stimulating the thyroid gland to secrete thyroid hormone.
If thyroid hormone levels in the blood become too high, the secretion of which hormones will be inhibited?
TRH and TSH- the hypothalamus secretes TRH, which travels via the hypothalamic-pituitary vein to the anterior pituitary gland and promotes the secretion of TSH, which is responsible for stimulating the thyroid gland to secrete thyroid hormone; elevated plasma thyroid hormone concentrations inhibit future release of TRH and TSH through negative feedback.
In a G protein-coupled receptor, what happens to the G protein?
The G protein is released when a hormone binds to the receptor
Secondary endocrine organs include what?
The HEART (pumps blood), LIVER (produce bile, metabolic processing of nutrients, removal of old RBC, plasma protein production, waste elimination, and storage of essential vitamins and metals), and KIDNEY (maintains extracellular fluid volume and blood pressure, regulates erythropoiesis, eliminates waste, maintains appropriate electrolyte concentrations, plamsa osmolarity and plasma hydrogen ion concentrations)- if the secretion of hormone is secondary to the main functions of the organ, this organ is classified as a secondary endocrine gland
Sodium levels in the blood are regulated directly or indirectly by what?
The adrenal cortex- aldosterone, which is secreted by the adrenal cortex, is responsible for regulating plasma sodium concentrations by promoting sodium reabsorption in the kidney (water retention >> increased blood pressure).
Epinephrine is involved in the fight-or-flight response, and it is secreted by what?
The adrenal medulla- secreted by the adrenal medulla in response to sympathetic stimulation from a preganglionic neuron releasing acetylcholine, which binds to nicotinic receptors on the medulla
Glucagon is secreted by what?
The alpha cells of the pancreas.
What is a false statement about lipophilic hormones?
The effects of lipophilic messengers are short-lived- lipophilic molecules generate long-term effects; short-term effects describe lipophobic molecules.
During peptide synthesis, a propeptide may be found where?
The endoplasmic reticulum, Golgi apparatus, and secretory vesicle.
What is a true statement about the pancreas?
The exocrine pancreas secretes digestive enzymes, beta cells secrete insulin (endocrine function), and delta cells secrete somatostatin (endocrine function).
What is a true statement about insulin metabolism?
The half-life of insulin in the bloodstream is only a few minutes and insulin is removed from the blood by receptor-mediated endocytosis- in target tissues, insulin enters the cells by receptor-mediated endocytosis, and inside the cell, insulin is degraded to amino acids by insulin-degrading enzyme.
Atrial natriuretic peptide is secreted by what?
The heart- responsible for inhibiting sodium reabsorption by the kidney tubules
Where are the hormones of the posterior pituitary synthesized and packaged into vesicles?
The hypothalamus
The hormone erythropoietin is secreted by what?
The kidney- kidney releases erythropoietin in response to low blood oxygen levels and stimulates bone marrow to produce erythrocytes.
The rate of diffusion, or flux, of particles across a membrane is dependent upon what?
The membrane permeability, the surface area of the membrane, and the steepness of the concentration gradient across the membrane.
The term "simple diffusion" can be used to describe BLANK, from areas of high concentration to areas of lower concentration.
The movement of oxygen molecules across the cell membrane the the movement of oxygen molecules in air.
Why is breathing difficult with cystic fibrosis?
The osmotic pressure of the fluid on the luminal side of the respiratory surface favors water transport out of cells and the movement of Cl- ions is impeded due to a lack of chloride transporters, causing a build up of chloride, creating a mucus blockage. The oxygen permeability of the respiratory membranes is reduced due to the thickening of mucus in the lumen of the respiratory tract. So, in the end, due to the lack of chloride transporters, preventing electrical gradient for Na+ to move across and in, reducing the osmotic pressure in lumen to pull water across the membrane, thickening the mucus, and preventing the permeability to oxygen.
Estrogen and progesterone are secreted by what?
The ovaries
Estradiol is secreted by what?
The ovaries- estradiol is responsible for the development of the ovarian follicle and promotes the development of the secondary sex characteristics.
Facilitated diffusion differs from simple diffusion in what way(s)?
The rate of facilitated diffusion depends on the number of carriers in the membrane.
What is a true statement about facilitated diffusion?
The rate of facilitated diffusion is directly dependent on the number of carrier proteins for a solute and the rate of facilitated diffusion is directly dependent on the concentration gradient of the solute across the membrane.
Hormones can alter target cell operations by controlling what?
The rates of enzymatic secretions (CCK in the intestine), the transmembrane transport of chemical substances (insulin, antidiuretic hormone), and the process of gene expression and protein synthesis (lipophilic hormones promote- estrogen/testosterone)
1,25-dihydroxy vitamin D3 is secreted by several organs, one of which is what?
The skin- as a result of sunlight striking the skin, vitamin D3 is produced and released in the blood; the activation of this vitamin first occurs in the liver and is completed in the kidney, resulting in the production of the 1,25-dihydroxy vitamin D3 -> in this form, the vitamin promotes the calcium reabsorption in the kidney and calcium absorption in the small intestines.
Cholecystokinin (CCK) is secreted by what?
The small intestines in the presence of fat or protein in the digested food in the duodenum- responsible for regulating the motility and secretions of the small intestine, as well as stimulate enzyme secretion by the pancreas, bile secretion by the liver, and contraction of the gallbladder.
Where are the releasing hormones from the hypothalamus that control the anterior pituitary released from?
The upper capillary bed
As the solute concentration of a solution increase, what happens?
The water concentration decreases and the osmotic pressure increases.
If you take an unstressed person and give them prednisolone (cortisol agonist- acts like cortisol), what will happen?
Their levels of cortisol will go down due to negative feedback, their levels of ACTH will go down due to negative feedback, and their inflammation will be reduced.
In contrast to fast ligand-gated channels, slow ligand-gate channels differ because they what?
They are directly linked to enzymes such as guanylate cyclase and interact with G proteins- ligand-gated channels are activated by binding of a messenger molecule to a membrane surface receptor and classified as either fast or slow channels. In fast channels the receptor and channel are the same protein molecule; in slow channels the G protein couples the receptor protein to a separate channel protein and provides for responses that may last minutes, rather than fractions of a second.
Why do steroid hormones have a longer half-life than peptide hormones?
They are transported by carrier proteins in the blood and they can be stored temporarily in fat tissue and are protected from degradation- since steroid hormones are lipophilic, they do not travel well in the plasma (plasma is predominantly water), so for transport, these hormones bind to plasma proteins, which function as carriers, and this binding protects the hormones from degradation in the blood, lengthening their half-life.
What is a characteristic of lipophilic hormones?
They bind to receptors inside the cytoplasm or nucleoplasm- act as chemical messenger signals carried by bloodstream until they diffuse from the blood into the interstitial fluid, and there they are attracted to target cells and freely pass through the phospholipid bilayer and are further attracted by intracellular receptors of the cytosol or nucleus and bind to these receptors
How do steroid hormones work?
They elicit their physiological effect within the target cell's nucleus by initiating transcription and translation- because they are lipophilic, their receptors are found within the nucleus of the cell, and when a steroid binds to its nuclear receptor, transcription of the gene associated with the receptor occurs, and after undergoing transcription, translation will occur resulting in protein synthesis.
Thymosin is secreted by the BLANK, which is what kind of endocrine gland?
Thymosin is secreted by the thymus, and it is a primary endocrine gland- thymosin stimulates the production and function of the T lymphocytes, and primary endocrine glands are those whose main function is to secrete hormones.
Calcium levels in the blood may be affected by secretions from where?
Thyroid (calcitonin- lowers plasma calcium levels by promoting Ca deposition in the bone), parathyroid (parathyroid hormone- calcium release from the bone), and the skin (vitamin D3- promotes calcium reabsorption in the kidney and calcium absorption in the small intestines).
Triiodothyronine is another name for BLANK, which is secreted by what?
Thyroid hormone, which is secreted by the thyroid.
What happens in the secondary hypersecretion of a hormone?
Too much hormone is secreted from the anterior pituitary or hypothalamus.
Thousands of published studies of leptin ended up showing that leptin is not a treatment for obesity because obesity has similarities to what?
Type II diabetes (sensitization to insulin)
When are the receptor and transduction mechanisms contained within the same protein?
Tyrosine kinases (activated by binding of its chemical messenger) and fast ligand-gated channels (share both receptor and channel protein in same structure)
The greatest electrical driving force on an ion to move INTO a cell can be illustrated how?
Vm = -70 mV, ion = Ca2+ (ECa2+ = +110 mV)- versus smaller differences in numbers or opposite movement (reversed negative and positive)
Hormones known as catecholamines are what?
Water soluble derivatives of the amino acid tyrosine- tyrosine is a precursor molecule used to produce dopamine, norepinephrine and epinephrine
When does water toxicity occur?
When extracellular fluids becoming hypotonic, causing the cell to swell (less solute outside/more water outside, so water rushes in to correct ratio); water toxicity is when there is an excessive load of water in the extracellular fluid.
Steroid hormones found in the human body are varied, but the manner in which they act on target cells is quite similar, in that they have an affinity for binding sites located where?
Within the cytosol, on the outside of the plasma membrane, and in the nuclear envelope. They all trigger gene activation through dimerization.
Put the following events in the correct order: a. G protein activates phospholipase C b. Ligand-bound receptor activates a G protein c. PIP2 DAG + IP3 d. IP3 triggers calcium release from endoplasmic reticulum
b. Ligand-bound receptor activates a G protein a. G protein activates a phospholipase C c. PIP2 DAG + IP3 d. IP3 triggers calcium release from endoplasmic reticulum
What happens when adenylate cyclase is activated?
cAMP is formed by converting ATP to cAMP- the attachment of a chemical messenger to the surface cell membrane receptor specific to it initiates a sequence of chemical reactions that activates adenylate cyclase, which causes ATP to be converted to cyclic AMP, climaxing with the particular cell response called for by the second messenger system
