Physiology Unit 4: Endocrine System
Which hormone interaction is described in the situation below Glucagon increases blood sugar levels; insulin decreases blood sugar levels
Antagonism
Hormones released into the circulation can circulate either freely or bound to carrier proteins, also known as? what is the free or unbound hormone known as?
BINDING PROTEINS . The free or unbound hormone is the active form of the hormone, which binds to the specific hormone receptor.
what are the causes of growth hormone deficiency? what does a growth hormone deficiency result in?
Causes •Hypothalamic disorders •Mutations: GHRH receptor, GH gene, GH receptor, IGF-1 receptor •Combined pituitary hormone deficiencies (panhypopituitarism - a secondary disorder) •Radiation •Psychosocial deprivation Clinical manifestations Depend on the time of onset and the severity of hormone deficiency • Complete GH deficiency •slow linear growth rates •normal skeletal proportions •pudgy, youthful appearance (decreased lipolysis) •in the setting of cortisol deficiency à hypoglycemia
What is cortisol and what does it do?
Cortisol is a hormone produced by the adrenal cortex that is produced in response to stress and restore homeostasis. - Secreted with any stress! - Causes mobilization of energy stores and suppresses the immune response. Types of stress that increase cortisol release include: Trauma of almost any type Infection Intense heat or cold Injection of norepinephrine Surgery Hypoglycemia Psychological stress Almost any debilitating disease Cortisol secretion also peaks in the AM - it is secreted in a circadian rhythm.
what are the hormones that fall under the group steroid hormones? can they travel freely in the blood?
Derivative of Cholesterol 1. Cortisol 2. Aldosterone 3. Testosterone 4. Estradiol 5. Cholesterol are all very hydrophobic, so they CANNOT travel freely in the blood. They need the help of binding proteins
what can also occur because of type I diabetes
Diabetic Ketoacidosis (DKA) - it is due to increase lipid break down so the liver starts making more ketoacids pretty much your cells are starving for nutrients so your liver tries to help out by releasing ketones in the blood, but the ketone levels get really high because the cells aren't getting the glucose they need so just know what one of the things that is really common in type I is DKA and this causes the pH of the blood to fall (normal is 7.35-7.45) so DKA is when its below 7.35 DKA occurs predominantly in patients with Type I DM. DKA can occur due to omission or reduced insulin injections, occlusion of insulin pump, infection, major trauma, surgery, etc. - because remember, stressors such as infection, trauma, surgery, these also stimulate the secretion of cortisol which increase glucose and decreases insulin, so in someone with type I, in situations like these, you would have to give them more insulin
what can cortisol be converted into in each zone?
Each zone takes in cortisol and depending on the zone converts it into a different hormone 1. Zona Glomerulosa --> mineralocorticoids - secrete aldosterone which effects the Na+ and K+ levels in the blood 2. Zona Fasciculata --> glucocorticoids - secretes cortisol - in some peripheral tissues (not in the adrenal cortex) cortisol can be converted to cortisone (for example in the kidneys) - the enzyme HSD11B2 is what converts cortisol to cortisone. Cortisone can be converted back to cortisol in the skin by the enzyme HSD11B1 3. Zona Reticularis --> androgens - secretes androstenedione which is a precursor for testosterone
what are the two different types of diabetes mellitus?
Energy metabolism impaired 1. Insulin deficiency (Type 1 Diabetes Mellitus) 2. Deficient insulin response (Type II Diabetes Mellitus) - insulin resistance, so you have insulin in type II but the target cells do not respond appropriately to it.
how is diabetes mellitus identified?
FPG: fasting plasma glucose - which should be below 100 2-h-PG: 2-hour post-prandial glucose A1C: hemoglobin A1C; a measure of long term blood glucose levels - around 5.6 increases in these numbers would indicate possible diabetes
what is Diabetes Mellitus (DM) Type II?
Fasting hyperglycemia (higher then normal glucose levels in the plasma) despite availability of insulin-Insulin resistance WAS called non-insulin dependent diabetes or adult onset diabetes. Both misnomers, type II DM may require insulin and occurs in children. Strong genetic component
what are the control points at which calcium is regulated?
Functions of calcium in the body: -In the Extracellular Matrix: •Calcified matrix of bone and teeth -In the Extracellular Fluid: •Neurotransmitter release at the synapse •Influences excitability of neurons •Myocardial and smooth muscle contraction •Cofactor in blood coagulation •"Cement" of tight junctions -In the Intracellular Fluid: •Muscle contraction •Signal in second messenger pathways Control points for calcium and phosphate •Absorption - via intestines •Excretion - via urine (calcium and phosphate) and feces (calcium only) •Bones - hydroxyapatite of ground substance
what is released and from where to stimulate or inhibit the release of growth hormone? where is GH released from? what does it stimulate the release of?
GHRH from the hypothalamus stimulates GH from the anterior pituitary gland. Somatostatin (SST) inhibits GH secretion. GH acts directly on target tissues and as a trophic hormone to the liver, which releases Insulin-like Growth Factor (IGF).
What is a goiter and what causes it?
GOITER is an enlarged thyroid that does not indicate functional status. Seen in Hypothyroidism, Hyperthyroidism, Euthyroidism (normal thyroid gland)
what happens when you have excess growth hormones?
Gigantism in Children Acromegaly in Adults Coarse facial features, large fleshy nose, frontal bossing, jaw malocclusion.
what are the different names calcitriol goes by? how do we make it? what regulates its release?
Has 3 different names 1,25-Dihydroxycholecalciferol / Calcitriol / Vitamin D3 How do we make 1,25-Dihydroxycholecalciferol? - You just need to know that sunlight starts the process (not long periods, but about 10 minutes of sunlight) which produces vitamin D3 in the skin, next the liver takes over in the synthesis, then finally the kidneys produce the 1,25-(OH)2D - You can also make it by taking dietary vitamin D2 or D3 but you still need the liver and kidneys to make the fully functional 1,25-(OH)2D Regulation The production of calcitriol is regulated at the kidney by the action of PTH. High PTH levels stimulate calcitriol synthesis. Prolactin (which comes from the anterior pituitary), a hormone responsible for milk production in lactating women stimulates calcitriol synthesis aswell - this is bc a lactating mom needs to absorb more Ca+2 into the blood to have milk ready for the baby
what are the two common causes of hypothyroidism?
Hashimoto's thyroiditis autoimmune destruction of thyroid gland - Autoimmune reaction against thyroid gland destroys gland rather than stimulating it. - Most common cause of hypothyroidism - Most patients first exhibit autoimmune "thyroiditis," thyroid inflammation - Inflammation leads to fibrosis of thyroid resulting in decreased secretion of thyroid hormone. - a primary disorder Iodine deficiency Goiter is in picture - a person with Iodine deficiency would also have hypothyroidism considering you need iodine to make T3 and T4 - this person would also have gotier due to high levels of TRH - a primary disorder
Hydrophilic hormones circulate in the blood in their ___ form while hydrophobic hormones circulate in the blood in their ____ form.
Hydrophilic hormones circulate in the blood in their free form while hydrophobic hormones circulate in the blood in their bound form. Hydrophilic Hormones (ex. Insulin) circulate in their free form. Steroid (cortisol, estrogen, etc.) and thyroid hormones circulate bound to specific transport proteins. Some binding proteins are specific for a given hormone but some plasma proteins, such as globulin and albumin can bind to many hormones. - these hormones are unable to travel freely in the blood due to hydrophobic properties. (bc remember plasma is mostly water) - Because most binding proteins are synthesized in the liver, changes in liver function (ex. cirrhosis) may alter binding-protein levels and could indirectly affect plasma hormone levels. the free hormone is what is released when it gets to its target cell and binds to its receptor. (the free form is considered the active form)
Some organs contain endocrine cells that secrete hormones even though their primary function is not endocrine regulation. what are some of these organs?
Hypothalamus (TRH, CRH, etc.) Skin (Vitamin D) Adipose Tissue (Leptin) Thymus (Thymosin) Heart (Atrial Natriuretic Peptide) Liver (Insulin-Like GF1) Stomach (Gastrin) Pancreas (Insulin, Glucagon) Small Intestine (Secretin, CCK) Kidney (Renin, EPO, Vitamin D) Gonads (Testes, Ovaries) Yellow are the ones we are going to focus on
Overall, what are the actions of calcitonin?
IT DECREASES CALCIUM LEVELS
what is the role of calcitonin in the blood? where is it secreted?
In the presence of calcitonin Ca+2 levels decrease 1. Ca+2 and phosphate reabsorption decreases in the kidneys 2. decrease bone resorption in the bones 3. decrease intestine absorption in the intestines (think N for NO MORE Ca+2, so Ca+2 levels decrease) it is secreted by Parafollicular cells (C cells) of the thyroid gland. really just need to know it decreases Ca+2 levels and its not a major controller of Ca+2 in humans
what are incretins?
Incretins include GIP (Gastric Inhibitory Peptide) and GLP (Glucagon-Like Peptide). So there are two different types 1. GIP 2. GLP they are both released by your small intestine - Incretins are secreted by cells in the duodenum and jejunum. incretins stimulate insulin secretion a good ex of feedforward regulation - imagine we are in the small intestine, and there is glucose in the lumen of the small intestine, there are cells that line the small intestine that can sense that glucose is there so they release the incretins, these incretins travel to the pancreases to say "hey you should release insulin because glucose is coming" - this is a preparatory mechanism and these cells are in the first two sections of your small intestine called the duodenum and jejunum.
how does insulin cause glucose uptake in muscle and adipocyte cells?
Insulin binding to its receptor causes more GLUT-4 transporters to be inserted into the cell membrane of the muscle and adipocytes. - when insulin binds to its receptors, a signal transduction mechanism causes vesicles that have GLUT-4 transporters to merge with the membrane via exocytosis. This adds the GLUT4 transporters to the membrane can causes more glucose to be taken in by passive transport (which requires no energy because glucose is going from high concentration to low) since we have more transporters in the membrane we can also make Vmax increase
what are the hormones that fall under the group peptide and protein hormones? can they travel freely in the blood?
Insulin, Glucagon, TRH, CRH, GHRH, GH, ACTH, Prolactin, FSH, LH, ADH, Oxytocin Do not usually need binding proteins made in a version called a pro-hormone first which gets packaged and cleaved to become a hormone
What is required for thyroid hormone synthesis?
Iodide (I-) so thyroid follicular cells actively transport it
When do the levels of glucagon dominate? what does glucagon stimulate?
Its levels dominate in the fasted state - so in between meals It stimulates INCREASES in 1. glycogenolysis 2. gluconeogenesis 3. ketogenesis so it stimulates the breakdown of glucagon, the production of glucose, and the production of ketone bodies
when does insulin levels dominate? what does insulin stimulate?
Its levels dominate in the fed state - so after a meal It stimulates INCREASES in 1. glucose oxidation 2. glycogen synthesis 3. fat synthesis 4. protein synthesis Insulin is the hormone of plenty: if you have lots of nutrients you are going to store them for later
what is the response to insulin in the muscles, adipocytes, and liver?
Muscle - glucose comes in and we utilize it, then amino acids come in and we make proteins Adipocytes - glucose comes in and these cells utilize its carbon skeleton along with fatty acids to make triglycerides (which is our storage form of lipids) Liver - glucose comes in and we utilizing it can storing it as glycogen Note we are not doing what follows the red dashed lines but we are doing the green lines
Is calcitonin a thyroid hormone?
NO it is a hormone that is made by cells in the thyroid gland but is not a thyroid hormone. on the outskirts of the thyroid follicles there are Parafollicular cells (next to the follicle) which release calcitonin which regulates calcium
Which hormone interaction is described in the situation below Thyroid hormone causes expression of B adrenergic receptors in bronchiolar smooth muscle
Permissiveness
Furthermore, endocrine pathologies can be considered primary disorders or secondary disorders. What is the difference?
Primary Disorders Abnormality in the last endocrine organ secreting the hormone leading to either hypo- or hyper-secretion. Causes of Primary Hyposecretion: (1)Partial destruction of the gland (2)Dietary Deficiency (3)Enzyme deficiency required for hormone synthesis A tumor in an endocrine gland can cause Primary Hypersecretion. Secondary Disorders Abnormality in tropic hormone leading to either hypo- or hyper-secretion A lack of sufficient tropic hormone leads to Secondary Hyposecretion. A tumor (either in an endocrine gland that secretes tropic hormones or in non-endocrine tissue (lung)) can secrete hormones and cause Secondary Hypersecretion
What are the actions of insulin?
Promotes the synthesis of energy storage molecules (anabolic reactions) and Promotes glucose uptake by body cells In Muscle - stimulates the uptake of glucose and use so stimulating the metabolism of glucose - synthesizing glycogen - uptake of amino acids - production of proteins so making proteins and glycogen (kinda stock pilling our extra resources for later) In adipocytes (fat cells) - stimulates the uptake of glucose and use so stimulating the metabolism of glucose - triglyceride synthesis for the storage of fat In Liver - synthesize glycogen - synthesize lipids (triglycerides) - decrease gluconeogenesis (so it decrease the amount of new glucose it is making) - prevents the release of ketones
how does the Calcitriol (vitamin D) hormone increase calcium levels?
Same as for PTH in that it increases Ca+2 levels, but calcitriol is the primary hormone that enhances intestinal absorption of calcium. so it increases Ca+2 levels through the intestines
What is aldosterone? what stimulates its secretion?
Secreted from the adrenal cortex and promotes sodium, chloride, and water reabsorption in the kidneys. - Increases renal tubular reabsorption of Na+ and secretion of K+. - Leads to an increase in EC fluid volume and Mean Arterial Pressure. Aldosterone secretion is stimulated by: 1. Angiotensin II, 2. increased K+ 3. decreased Na+ angiotensin II leads to vasoconstriction (increased BP) in the cardiovascular system and also helps you keep Na with helps retain water also leading an increased BP
Thyroid hormone stimulates energy utilization and raising the basal metabolic rate. What are the signs of hypothyroidism? What are the signs of hyperthyroidism?
Signs of hypothyroidism: weight gain, coarse and dry skin/hair, thinning of lateral eyebrows, decreased appetite, bradycardia, impaired growth (child), constipation, mental/physical sluggishness. Signs of hyperthyroidism: weight loss, thin and silky skin/hair, increased appetite, tachycardia and palpitations, accelerated growth (child), diarrhea, restlessness, irritability, anxiety
what happens to someones nerves if they have low levels of calcium? what about high levels?
Since Calcium is involved in so many different things in the body, its levels are tightly regulated! Too low = neuronal hyper-excitability Too high = neuronal depression this is the opposite of what you would expect it to be. it has to do with what extracellular K does to Na+ ability to move through its channels (they are both cations so if you have extra calcium it will make it harder for Na to move through its channels) which is why high calcium depresses nerve function
what stimulates the release of GH?
Stimulated by starvation (protein deficiency), fasting (hypoglycemia), stress, exercise, and excitement. Pulsatile secretion; lower concentrations during the day with highest levels a few hours after sleep. High secretion in neonatal period but decreases in childhood. Peak levels during puberty and then they decline with age.
Which hormone interaction is described in the situation below Glucagon, cortisol and epinephrine all increase blood glucose more than the sum of their individual effects
Synergistic
what is the relationship between insulin and glucagon?
THEY ARE ANTAGONIST As one increases the other decreases The combined actions of insulin and glucagon work to keep blood glucose in a set homeostatic range.
what happens to insulin levels as glucose levels rise?
THEY INCREASE but only up to a certain point as glucose levels increase, insulin levels increase but up to a limit where insulin can no longer compensate Below 100 mg/100ml or 100mg/dL is a normal plasma glucose level
How is T3 made in target cells?
Target cells make active T3 by using enzymes called Deiodinases/Iodinases that remove one iodine from T4. Individual target cells can alter their exposure to T3 by regulating their tissue Deiodinase synthesis. If a cell doesn't need to have as big of a response to the thyroid hormone it will not make as much enzyme iodinase (so there won't be as much T3) - this shows how cells can regulate their response through regulation of the enzyme iodinase
how is the adrenal cortex divided? what does each layer secret? what does the adrenal medulla secrete?
The ADRENAL CORTEX secretes corticosteroids, which are made from cholesterol. The cortex has three layers: 1. Zona Glomerulosa --> mineralocorticoids 2. Zona Fasciculata --> glucocorticoids 3. Zona Reticularis --> androgens Order from superfical to deep is GFR The Zona Fasciculata is the largest zone followed by Zona Glomerulosa then Zona Reticularis The ADRENAL MEDULLA is related to the sympathetic nervous system and secretes the catecholamines epinephrine and norepinephrine into the blood.
What is the difference between the anterior and posterior pituitary gland? what are their relationships with the hypothalamus?
The Anterior Pituitary (adenohypophysis) is a true endocrine gland meaning it contains endocrine cells The Posterior Pituitary (neurohypophysis) is the site where hypothalamic neurons release neurohormones into circulation. - the site of releases of neurohormones - axons from neurons terminate in the posterior pituitary where there are also capillary beds The hypothalamus and pituitary gland are connected by the infundibulum.
Hormones can have many different interactions which one another. What are the 4 combined actions hormones can have?
The effects of combined actions: 1.Antagonism - For example, one increase something while another decreases 2.Additive 3.Synergistic - when a couple of hormones released at the same time give you a larger effect then what you would speculate based on their individual effects 4.Permissiveness - the presence of one hormone allows you to see the full effects of another hormone. (So one hormone is necessary for another to have its effects)
what are the effects of cortisol during stress?
The endocrine system responds to stresses on the body such as trauma, infection, pain, sleep deprivation, fright, and other emotional stresses by increasing the release of cortisol from the adrenal cortex and epinephrine from the adrenal medulla.
What is Grave's disease?
The most common cause of hyperthyroidism. It is an autoimmune disease. GD is an autoimmune disease where antibodies to TSH receptor called thyroid-stimulating immunoglobulins (TSIs) stimulate the thyroid gland to excess. - The immune system makes an antibody that acts just like TSH that is known as TSI. The thyroid gland responds to TSI just as it would to TSH. - since TSI is also stimulating the thyroid gland this will cause it to enlarge leading to goiter - this would also cause levels of T3 and T4 to be high TSI acts just like TSH. This causes lots of negative feedback so levels of TRH and TSH are low. BUT they cannot drop low enough because the TSI is a different hormone Side note: hyperthyroidism can also occur due to a tumor on the thyroid gland for example that causes over-secretion
What is the role of the pancreas with regards to endocrine secretion?
The pancreas contained cells called islets of langerhans which is the endocrine portion of the pancreas (a very small portion) - 1% of the pancreas is made up of endocrine cells, while 98% is made up of exocrine cells - the majority of your pancreas is not made up of islets, the majority of your pancreas is Acinar Cells that produce Digestive Enzymes (Exocrine Portion) - these acinar cells enter the duodenum through the pancreatic duct Inside the islets of langerhans are a verity of cell types which secrete different things
what is the parathyroid gland? what hormone(s) are produced by this gland? what cells secrete them? what the effects of the hormone(s) released from this gland?
The parathyroid gland sits on the back of the thyroid gland. - It is composed of 4-6 pea-sized glands on the posterior surface of the thyroid gland. It produces the parathyroid hormone (PTH) which is Secreted by the Chief Cells The PTH Regulates both calcium and phosphate levels by adjusting (1) Intestinal Reabsorption, (2) Decreasing Renal Excretion and (3) Exchange between the EC fluid and bone (causes bone breakdown) - again these are the three ways it increases Ca+2 SO OVERALL THE PTH INCREASE Ca+2 and DECREASES phosphate
What are the two thyroid hormones? what do they impact? where are they stored?
The two thyroid hormones are T4 and T3 The majority of the active hormones secreted by the thyroid gland are thyroxine (T4) while 7 % is Triiodothyronine (T3). - so the thyroid gland releases more T4 than T3 - T4 can be converted to T3 BUT T3 is more potent than T4 Thyroid hormones impact metabolism and growth/development. They also have permissive action on catecholamines. - because they increase the number of β receptors In the thyroid gland, there are thyroid follicles. In the center is the colloid - the colloid is where you make and store thyroid hormones - T thyrocytes make up the follicle
What is Addison's disease? come back to
Under secretion of the adrenal cortex. - the adrenal cortex is destroyed so you cannot make aldosterone, cortisol, testosterone Primary adrenal insufficiency Affects ALL layers of the adrenal cortex; autoimmune destruction the most common cause Chronic metabolic disorder that needs lifetime hormone replacement. Higher doses during stress. Need to have a regular schedule for meals and exercise. Limited ability to respond to infection, trauma and stress
What are the hormones that the hypothalamus releases? how do they affect the anterior pituitary and its hormones? Hypothalamic Hormones are Tropic Hormones? what about anterior pituitary hormone?
VERY IMPORTANT SLIDE Hypothalamic Hormones are Tropic Hormones A hormone that controls the secretion of another hormone is called a tropic hormone. All AP hormones, other than prolactin, are tropic hormones.
How is adrenocortical hormones secretion regulated?
Zona glomerulosa secretes mineralocorticoids (aldosterone) & is primarily controlled via renin-angiotensin-aldosterone system (RAAS). Zona fasciculata secretes glucocorticoids (cortisol) & is controlled by hypothalamic-pituitary-adrenal axis (HPA), corticotropin-releasing hormone (CRH), and anterior pituitary hormone- ACTH. Zona reticularis secretes adrenal androgens (dehydroepiandrosterone) & is controlled by HPA.
what are insulins target cells?
adipocytes (fat cells), muscle cells, and the liver In adipocytes (fat cells) muscle cells when glucose levels are high, insulin makes these cells increase there glucose uptake, taking it out of the blood for storage Insulin also makes the liver stop putting glucose in the blood and instead take up glucose and store it as glycogen
what is glucagon? what is its primary target tissue? what does it cause?
an antagonist to linsulin Hormone of "starvation" or fasted state Primary target tissue is the LIVER, which increases blood glucose by: -Stimulating glycogenolysis (glycogen breakdown) & inhibiting glycogen synthesis -Increasing gluconeogenesis (makes new glucose) -Increases blood fatty acid & Ketoacid levels to provide more substrates for gluconeogenesis so glucagon increase the release of ketones which provide more substrates for metabolism and the production of glucose The liver functions like a buffer for blood glucose. Individuals with severe liver disease have difficulty maintaining a narrow plasma glucose range.
What is hypercortisolism?
an effect of increased cortisol levels - Pituitary form: Cushing's Disease - Adrenal form: Cushing's Syndrome - Ectopic: non-pituitary ACTH secreting tumor - Iatrogenic: long-term glucocorticoid therapy
What are tropic hormones?
are hormones that stimulate hormone secretion by another gland and also cause growth of the gland. tropic hormones stimulate other endocrine glands to release hormones and can also cause the growth of a gland
what happens to glucagon levels as glucose increases?
as glucose increases, glucagon decrease so when glucose decrease, glucagon is secreted by the islet α cells located in the pancreas overall the liver in response to glucagon increase glucose levels and ketone levels
how does the β cell know when to secrete insulin?
based on glucose levels in the blood (but there are also other ways to regulate insulin levels) 1. high glucose in the blood 2. more glucose enters the β cells 3. the β cells do metabolism and produce ATP 4. this closes a K+ channel 5. this causes depolarization 6. which opens a Ca+2 channel 7. and Ca+2 cause exocytosis of insulin as glucose levels go higher and higher, there is more ATP, more channel closure, more Ca+2 entry, allowing for the amount of insulin released to balance with the amount of glucose that is present
what is the cause of Diabetes Mellitus Type I?
damage of β cells - sometimes its autoimmune destruction of pancreatic beta cells Risk factors 1. there is a genetic predisposition that is linked to this type. - so there are some genes that increased susceptibility 2. Environmental triggers stimulate autoimmune response a. Viral infections (mumps, rubella) b. Chemical toxins 3. Usually develops < age 40, non-obese younger patients - so younger individuals fewer people take type I then type II
what would increase/stimulate the release of PTH? what does this lead to?
decreased levels of Ca+2 would stimulate its release this would cause three things 1. the kidneys to decrease their excretion of Ca+2 2. the intestines could increase Ca+2 absorption into the blood through the walls of the intestines 3. In the bones it will stimulate bone breakdown so that Ca+2 can be released into the plasma these three events would lead to Ca+2 levels rising back to normal
The concentration of each binding protein can change. If the concentration of a binding protein increases then the amount of the free hormone (the active form) __________
decreases also there are specific binding proteins for certain hormones. For example, plasma contains the binding protein albumin which acts as a taxi cab for things that are not hydrophilic and need a help to get into the plasma to get to where they need to go.
what are the 5 hormones that fall under the group amine hormones? can they travel freely in the blood?
derivatives of tyrosine - Thyroid hormones need binding proteins to help them travel in the blood 1. Thyroxine (T4) 2. Triiodothyronine (T3) 3. Norepinephrine 4. Epinephrine 5. Dopamine thyroid hormones Catecholamine Biogenic Amines
what hormones are secreted with the circadian rhythm?
growth hormone and cortisol growth hormone peaks at night and cortisol peaks in the morning
What happens once the iodide is inside the colloid?
it is converted to iodine (I2) Iodine is then added onto tyrosine by the enzyme peroxidase producing T3 and T4 - so it is peroxidase that does the oxidation step producing T3 (which has 3 iodines) and T4 (which has 4 iodines) T3 and T4 are then complexed with thyroglobulin (TG) to exit the cell
how does the Calcitonin hormone decrease calcium levels?
just know that Calcitonin (from the Parafollicular cells of the thyroid gland) decreases calcium levels Actions opposite of PTH so it reduces plasma calcium levels. side note: In addition to calcitonin, bone formation is stimulated by Insulin, GH, IGF-1, Estrogen and Testosterone
Overall, what are the actions of insulin?
notice that GH and Cortisol are antagonist to insulin considering they make glucose levels increase
What is myxedema?
severe hypothyroidism Treatment is administration of L-thyroxine (T4) -There is a dull, expressionless facies, with puffiness of eyelids. Skin appears swollen, cool, waxy, dry, coarse, and pale with increased skin creases Increased quantities of hyaluronic acid and chondroitin sulfate bound with protein plus water accumulate in skin. - Other symptoms of hypothyroidism: low BMR, mental capacity, body temp., appetite, HR, RR, BP; anemia, weakness, lethargy, wt. gain; increased cholesterol
what are the two different portions of the pituitary gland?
the anterior pituitary and the posterior pituitary
What are the five specialized endocrine glands?
their sole function is to secrete hormones 1. pituitary gland - anterior and posterior 2. pineal gland 3. thyroid gland 4. parathyroid gland - involved in calcium regulation 5. Adrenal gland - cortex: makes things like cortisol - medulla: epinephrine (things like neural hormones)
what are the three principle ketones
these are an alternate energy substate which is utilized. the liver will put these in the blood
so what is the difference between Type I and Type II? what do they lead to?
they both lead to hyperglycemia (higher than normal glucose levels) Type I is due to damage to the β cells which release insulin (therefore you can't really make insulin) Type II is insulin resistance, so you have insulin in type II but the target cells do not respond appropriately to it.
what can occur with regards to the sympathetic response if you have very high levels of thyroid hormone?
this has to do with the permissive effects when someone has very high levels of thyroid hormone it can lead to an enhanced sympathetic response (because you have more β receptors). This is called called a thyroid storm - its a concern for people who have hyperthyroidism considering during stressful situations, their sympathetic response can be to robust leading to excess vomiting, breathing, etc.
how doe the parathyroid hormone (PTH) increase calcium levels?
three different ways •Mobilizes calcium from bone •Enhances renal absorption of calcium •Increases intestinal absorption of calcium (indirectly) so it increases the Ca+2 levels in the bones, kidneys, and intestines (which is all three of our control points) In addition to PTH, bone resorption is stimulated by Cortisol and T3.
how do these hormones, ions or nutrients, and neurotransmitters regulate hormone secretion?
via negative feedback in this flow chart, we have the following endocrine glands: hypothalamus, anterior pituitary, and the thyroid gland The hypothalamus releases a releasing hormone which causes the anterior pituitary to release a stimulatory hormone causing the thyroid gland to secrete its hormone If there was an abnormality in the thyroid glands ability to secrete hormones, it would be considered a primary disorder If there was an abnormality in the hypothalamus or anterior pituitary's ability to secrete a hormone, it would be considered a secondary disorder
What are the symptoms of diabetes mellitus?
•Urinating often (Polyuria) •Feeling thirsty (Polydypsia) •Feeling hungry (Polyphagia) •Extreme fatigue •Blurry vision •Cuts/bruises that are slow to heal •Weight loss - even though you are eating more (Type I DM) •Tingling, pain or numbness in the hands/feet (Type II DM) The three P's are the most classic symptoms
What are the 6 hormones that are released by the anterior pituitary gland?
- The anterior pituitary is a true endocrine gland. - The hypothalamus secretes releasing or inhibiting hormones (tropic hormones) which regulate the secretion of the endocrine cells in the anterior pituitary gland. - The AP produces 6 hormones. (all of which are protein/peptide hormones) 1. FSH 2. LH 3. Growth hormones 4. TSH 5. Prolactin 6. ACTH
what is the target organ of 1,25-(OH)2H?
1,25-Dihydroxycholecalciferol / Calcitriol / Vitamin D3 the GI tract where causes the absorption of calcium in the intestines Vitamin D3's main action is to cause absorption of Ca2+ and PO43- by the intestines.
how are T3 and T4 secreted into the blood?
1. Colloid is internalized by endocytosis. - T3 and T4 are taken into the colloid droplet with TG 2. The vesicles fuse with lysosomes in the cell. 3. Proteases cleave T3 and T4 from TG. - a protease cleaves the thyroid hormones off of thyroglobulin (TG) so they can be secreted 4.T3 and T4 diffuse out of the cell and into capillaries. - because of T3 and T4s structure, they need help traveling in the blood so they bind to transport proteins ~99% of T3 and T4 bind with plasma proteins for transport Due to the strength of its binding to the transport protein, T4 has a long half-life. T3 doesn't bind as tightly so its half-life is only 2-3 days.
how do you control insulin secretion? what increase its secretion? what decreases its secretion?
1. High plasma glucose levels 2. High plasma amino acid levels 3. High parasympathetic activity - rest and digest 4. Incretins 5. sympathetic activity - the cells need glucose to deal with the fight or flight, therefore this decrease insulin levels because we do not want to store glucose in these situations but rather use it Increase insulin secretion decrease insulin secretion
What are the three things that are used to regulate hormone secretion?
1. Ions and nutrients 2. Neurotransmitters 3. Hormones
how do we get iodide into the colloid to make thyroid hormone?
1. Na+/I- symporter (NIS) - is capable of producing intracellular I- concentrations that are 20-40 times as great as the concentration in plasma. - this secondary active transporter brings in sodium and iodide. (bring in Na is energetically favorable) this allows you to build up high levels of iodide in the follicular cell with a goal of getting it into the colloid 2. Pendrin - Iodide must also exit the thyrocyte across the apical membrane to access the colloid, where the initial steps of thyroid hormone synthesis occur. Pendrin is a Cl-/I- exchanger. - Pendrin allows us to transport iodide into the colloid where it is converted into Iodine (I2)
What are the two hormones released from the posterior pituitary gland?
1. VASOPRESSIN or ANTI-DIURETIC HORMONE - causes water reabsorption in the kidney, and constriction of blood vessels. Increase blood pressure and decreases plasma osmolarity. 2. OXYTOCIN - causes ejection of milk from the breasts and uterine contraction during labor.
What are the two zones of the adrenal gland?
1. adrenal cortex 2. adrenal medulla
what are the three structural classes of hormones?
1. amine hormones 2. peptide and protein hormones 3. steroid hormones
the hypothalamus controls the anterior pituitary hormone secretion in two different ways. What are they?
1. short loop feedback 2. long loop feedback
Hormone levels must be kept in balance with negative feedback mechanisms. If this doesn't occur, endocrine disorders occur. All endocrine pathologies fall under three different categories. What are they?
1.Hormone HYPOsecretion: Too little Diabetes mellitus (DM) type I, Hashimoto's Thyroiditis, Addison's Disease, Central Diabetes Insipidus (DI) 2.Hormone HYPERsecretion: Too much Acromegaly/Gigantism, Grave's Disease, Cushing's Disease 3.Abnormal (increased or decreased) Target Cell Response DM type 2, Nephrogenic DI
what are the three hormones that regulate plasma calcium levels? which ones increase it? which decrease?
1.Parathyroid Hormone (PTH) 2.Calcitriol (1,25-dihydroxycholecalciferol or vitamin D3) 3.Calcitonin (from the Parafollicular cells of the thyroid gland) Increase calcium levels Decrease calcium levels
what is a normal fasting glucose level?
80-100 mg/dL
what are the different types of cells found in the islets of landerhans? what do they secrete?
A cells/α cells - Glucagon B cells/β cells - Insulin the majority of the cells are β cells
What is hypocortisolism?
Absence of cortisol contributes to circulatory failure due to loss of permissive action on catecholamines. - α1 response --> not getting as much of a sympathetic response therefore you have less vasoconstriction and a decreased blood pressure Lack of cortisol prevents mobilization of energy sources (glucose and free fatty acids) during stress and can result in fatal hypoglycemia.
