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82 Cards in this Set
- Front
- Back
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Distant target cell
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Most common way an endocrine gland releases a hormone, goes into the circulation and acts upon a distant target cell
Ex: thyroid |
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Paracrine
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Paracrine cell releases a hormone and acts upon a nearby cell
Ex: ovary |
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Autocrine
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An autocrine cell secretes a hormone and it acts upon itself. Has an effect on self. Ex: insulin secreted by the pancreatic beta cell.
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Name the two ways hormones act in the blood stream and give examples.
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1) Free, unbound circulating hormones. Have shorter half life. Water soluable.
ex: pepetide hormones, protein hormones. Insulin 2) Attached to transport carriers circulating hormones. Lipid soluable. Longer 1/2 life. Ex: Steroid, thyroid hormones that are carried by a specific carrier protein synthesized in the liver. |
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Describe the characteristics of unbound hormones and how they are transported.
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Unbound hormones circulate unbound, are water soluble & have a short half life.
They require plasma cell membrane receptors and act through 2nd messengers (like cAMP) or by direct activation of the receptor that activates actions within the cell. |
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Describe the characteristics of bound hormones and how they are transported.
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Bound hormones are lipid soluble and use intracellular nuclear receptors.
B/c they are lipid soluble, they can diffuse through cell membranes. They act by causing nuclear transcription of specific genes to code for desired proteins by using intracellular receptors. |
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What is a second messenger and what is the most common one?
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A second messenger is used by unbound hormones (peptide hormones) to cause a response inside the cell (b/c the hormone can't get inside). This is an intracellular signal system. Hormone is considered 1st messenger. Most common 2nd messenger is cAMP. Hormones can make cAMP levels increase or decrease depending on the desired action of the hormone.
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What is the half life of a hormone?
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The time it takes for the body to reduce the concentration of the hormone by one half.
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What is receptor modulation?
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Regulation of target cell sensitivity. There can be up regulation and down regulation.
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Explain "up regulation" in response to hormone receptor modulation.
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Up regualtion is when a low amount of hormone is in the body and that low concentration stimulates the increase in number of hormone receptors on a cell to increase their chances of "up taking" that low amt of hormone into the cell. The "up" regulation refers to the number of receptors on the cell...not the hormone.
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Explain "down regulation" in response to hormone receptor modulation.
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Down regulation is when high concentrations of a hormone decrease the number of receptors per cell. This decreases our sensitivity to the high amounts of hormone floating around in the body and therefore the cell can't take up as much.
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Explain negative feedback in relation to hormonal regualtion.
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Hormonal regulation through negative feedback means target organ hormone inhibits secretions of relasing hormone and tropic hormone. Ex: Hypothalmus & Ant Pituitary stimulate production of cortisol. Once adequate levels of cortisol are reached, cortisol tells the hypothalmus and Ant. Pituitary to stop producing coristol.
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Explain positive feedback and give an example.
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Positive feedback is when a rise in one hormone causes a release of another. Example: Estrogen levels rise to cause an increase in LH.
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What does tropic hormone mean?
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Tropic mean "going forward". It is like a mediator b/t the begining releasing hormone and the target end organ.
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What is neural regulation of hormonal activity?
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Means there is involvement from the nervous system.
For example, when stress is applied to our bodies, epinephrine is released from the adrenal medulla under the sympathetic nervous system. This prepares our body for fight or flight response. |
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Give examples of endocrine gland hypofunction.
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1) Autoimmune destruction
-DM type 1-destruction of B-1 pancreatic cells 2)Other causes such as -tumors -inflammation -Ischemia |
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Give examples of endocrine gland hyperfunction.
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-hormone secreting tumors
-hyperplasia of the gland -autoimmune processes that stimulate rather than inhibit (Ex: Graves dx) -Exogenous hormone administration (Ex: Cushings) -Alteration in target tissue responsiveness/receptor sensitivity (Ex: DM 2) |
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Why is the pituitary gland called the "master gland"?
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Because it controls the pathways and functions of many hormones in the body. It is also attached to the hypothalmus which is involved in pituitary regulation. It is also near the optic nerve and can cause visual disturbances when issues with the pituitary arise.
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From what tissue is the anterior pituitary gland made up of?
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Developed from the glandular tissue.
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From what tissue is the posterior pituitary gland made up of?
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Developed from the neural tissue.
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Hypothalamic Hormones regualting the secretion of anterior pituitary hormones.
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-GH releasing hormone
-Somatostatin (inhibits GH + TSH) -Dopamine -Thyrotropin, corticotropin, gonadotropin ...releasing hormone |
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What is the hypothalamic-pituitary-target cell feedback mechanism.
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The hormones secreted by the hypothalmus have a direct function of either inhibiting or stimulating the hormones secreted by the pituitary. The hormones secreted by the pituitary has its effect on the target organ. Hormone levels from the target glands (organ) regulate the release of hormones from the anterior pituitary though a negative feedback system.
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Name the two primary hormones secreted by the posterior pituitary.
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1) Oxytocin
2) ADH (Antidiuretic hormone, vasopressin) |
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What is the alternative name for the posteior pituitary gland and what is its primary fuction?
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Neurohypophysis. Its primary function is to control the plasma osmolarity of ADH.
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Explain the functions of oxytocin and the primary target organ.
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Similar chemical structure of ADH. Primary target organ is myoepithelial cells in mammary tissue. Also stiumulates uterine contractions & may have role in sperm motility.
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Explain the functions of ADH and its effects on the body.
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Controls the serum osmolality by increasing water reabsorption in the distal tubules & collecting ducts of the nephron. Responds to multiple stiumuli.
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Explain SIADH (Syndrome of Inappropriate antidiuretic hormone)
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Too much ADH. "Low and wet". These patients have low sodium (dilution) and are fluid overloaded.
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What types of patients get SIADH?
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-From extopic secretion in several types of carcinomas.
-Post-op crani/pituitary surgery. -Medications, antidepressants, anesthetics, barbs, MSO4...etc. |
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How do you treat SIADH?
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You treat the underlying cause. Fluid restrict. Correct hyponatremia. Remember..."Low and wet"
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What is Diabetes Insipidus (DI)?
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Too little of ADH. So you are peeing your brains out. "High and dry" Pt's are dehydrated and have high sodium.
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How do you treat DI?
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Vasopressin or DDAVP.
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Name the two types of DI.
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1) Neurogenic DI
2) Nephrogenic DI |
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Explain Neurogenic (Central) DI.
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Distruption of the production of ADH which is produced by the posterior pituitary gland. Can be caused by things like head injury, tumor, infection, inherited as well. "High and dry"
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Explain Nephrogenic DI.
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Usually congenital and are caused by mutations in the genes which code for the V2 receptors & aquaporin-2 protein, rendering them inactive. Result is a kidney that is unable to reabsorb or concentrate urine.
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What is prolactin and where is it secreted from?
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Secreted from the anterior pituitary (adenohypophysis). Promotes breast development & lactation. Plays a role in fertility and testosterone.
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What is the most common anterior pituitary disorder caused by prolactin? What is it caused by and how is it treated?
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Hyperprolactinemia. Caused by a tumor or medications such as antipsychotics and tricyclic antidepressants. Treated with drugs that stimulate dopamine receptors in the brain.
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What is thyroid stiumulating hormone and where is it secreted?
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Secreted by the anterior pituitary. It stimulates secretion of thyroid hormones.
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What does an excess of growth hormone (GH, somatotropin) cause in children? In adults?
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In children causes proportional gigantism. Causes acromegaly in adults.
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What function does GH play in adults?
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Deficiency in adults associated with metabolic syndrome.
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What is the function of IGF-1 in relation to GH?
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GH can't directly produce growth-promoting actions, it has to act through IGF-1 which are produced by the liver. IGF is the one that makes the growth promoting action (ex bone growth) actually happen. IGF's are called somatomedins.
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Fucntion of luteinizing hormone and location of secretion.
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Anterior pituitary. Promotes growth of testicular tissue and stimulates ovulation.
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Function and location of secretion of Follicle stimulating hormone (FSH).
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Anterior Pituitary. Stimulates spermatogensis and testorsterone production. Estradiol and progesterone.
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Function and location of secretion of adrenocorticotropic hormone (ACTH).
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Anterior pituitary. Stimulates release of adrenal corticosteroids or androgens. Secreted in response to low cortisol levels, diurnal rhythms, stress.
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What are the two layers of the adrenal gland?
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1) Medulla (inner most layer)
2) Cortex (outer most layer with 3 different layers within it) |
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Name three horomes and their functions secreted from the adrenal cortex.
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1) Androgens and Adrenal estrogen- primary source of androgens for women
2) Mineralocorticoids-aldosterone, secreted in response to angiotensin II. Increases the activity of the Na+ pump (conservation of Na+ in the nephron) 3) Glucocorticoids: ex: cortisol. Numerous metabolic, anti-inflammatory & growth suppressing effects. |
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What are the immunologic and anti-inflammatory effects of glucocorticoids?
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-They decrease capillary permeability and stabilizes lysosomal membranes to block inflammation
-Reduces humoral & cell-mediated immune responses. -Suppresses fibroblast activity (decrease scar formation) -Inhibits prostaglandin synthesis (plays a role in anti-inflammation) |
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What are the two types of adrenal insufficiency?
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1) Primary-adrenal cortical hormones are deficient and ACTH levels are elevated b/c of lack of feedback inhibition.
Ex: Addison's Disease 2) Secondary-Disorder of the HPA system w/ resulting adrenal cortical atrophy and loss of cortisol production. |
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What is Addison's Disease?
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It is a primary adrenal insufficiency in which all the layers of the adrenal cortex are destroyed. Compensatory increase in ACTH secretion (no negative feedback mechanism b/c no cortisol being produced).
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What is the cause of Addison's Disease?
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Most likely caused by autoimmune destruction: 1) presence of autoantibodies
2) Deficient T suppressor cells |
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Explain the three possible causes of secondary adrenal insufficiency.
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1) Hypopituitarism
2) Adrenalectomy -can occur in both of these b/c if no pituitary gland or dysfct., no ACTH secreted. ACTH effect directly on the receptors of the adrenal cortex= low ACTH levels in secondary. 3) Iatrogenic (Addisonian Crisis)- Lifelong steroid treatment therapy. Can't just stop treatment b/c adrenal cortex has stopped making cortisol b/c has been given exogenously. Ex: Steroid taper |
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State the clinical manifestations of adrenal insufficiency.
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Weakness, GI disturbances, hyperpigmentation (if ACTH is increased), hypoglycemia, hypotension (most life threatening). Think of opposite of Cushing's syndrome.
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What are the two main differences between primary and secondary adrenal insufficiency?
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Primary has high ACTH (=tan appearance)
Secondary has low ACTH (=no tan appearance) |
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What is Cushing's Syndrome?
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Associated with high levels of cortisol due to various causes.
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Explain the relationships and mechanims behind CRH, ACTH and cortisol.
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Hypothalmus sends corticotropin-releasing hormone (CRH) to pituitary gland--> CRH causes pituitary to secrete andrenocorticotropin horomone (ACTH)--> ACTH stimulates adrenal glands to produce cortisol. Increased cortisol levels decrease CRH/ACTH, and decreased cortisol levels increase CRH/ACTH
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What are the two types of ACTH dysfunction that effect Cushing's syndrome?
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1) ACTH- independent (Excess cortisol secretion, decreased ACTH levels)
Ex: Excess glucocorticoid administration (prednisone). 2) ACTH-dependent (excess ACTH secretion) Ex: Pituitary tumor (Cushing's dx) |
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Explain the significance behind adrenal medulla hyperfunction and disease behind it.
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Problem b/c these hormones (epinephrine) are secreted elsewhere in the body causing HTN. Can be caused by Phochromocytoma: tumor the chromaffin cells that secrete these catecholamines.
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Name the three types of thyroid horomes and their functions.
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1) T4
2) T3 -both control rates of metabolic processes 3) Calcitonin-decreases serum calcium by inhibiting osteoclastic activity and increasing osteoblastic activity. |
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What is the role of iodine in relation to T3 and T4?
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Iodine breaks down the thyroglobin to T4 and T3
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What is Grave's Disease?
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It is autoimmune disorder that leads to hyperthyroidism, goiter and opthalmopathy. Caused by an abnormal stimulation of the thyroid- There are thyroid stimulating antibodies which bind to the TSH receptors keeping them active and therefore result in hypermetabolic state.
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What is the most concerning effect of Grave's disease that you must watch out for and educate your patients?
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Thyrotoxicosis or thyroid storm. Symptoms, fever, tachycardia.
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What are some of the causes behind hypothyroidism?
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1) Congential defects in the thyroid hormone (can be treated sucessfully)
2) Autoimmune destruction (Hashimoto's) 3)Thyroiditis, 4) Iodine deficiency 5) Iatrogenic |
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What is a complication of hypothroidismt that can be life threatening?
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Myxedema which is "mucinous edema" for alteration in composition of dermis and other tissues. Myedema coma is a life threatening condition that is presented by hypothermia, progressive resp depression.
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What is the function of alpha cells in the pancreas?
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They secrete glucagon which increases blood glucose level.
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What is the functioin of beta cells in the pancreas?
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They secrete insulin which decreases blood glucose levels. No insulin being made.
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What type of disease if Diabetes Mellitus type one?
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Usually from cell-mediated autoimmune destruction of beta islet cells.
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What other hormones cause an increase in blood glucose levels other than glucagon?
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Epi, growth hormone, and gluccocorticoids.
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What is Diabetes Mellitus type two?
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A relative insulin deficiency OR insulin resistance with hyperinsulinemia & increased hepatic glucose production.
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Why do DM type II patients sometimes need exogenous insulin?
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Because sometimes when the beta islet cells have worked so hard to produce excess insulin (b/c of the decreased sensitivity), they eventually become exhausted and shut down completely.
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What sort of insulin levels can pts with DM II have?
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High, low or even normal. All has to do with the resistance to the insulin.
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What is insulin resistance syndrome, syndrome X or aka "Metabolic Syndrome"?
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Insulin resistance also contributes to other abnormalities such as obesity, high levels or TG's, low HDL, HTN. "Diabesity"
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What are some other problems associated with DM II?
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DM II is a vascular disease and r/t dyslipidemia, inflammation, endothelial dysfunct, hyperinsulinemia & insulin resistance.
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Whare are some common syptoms of both DM I & II?
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Polyuria, polydipsia and polyphagia.
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Describe the pathophysiology of DM I.
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DM I is characterized by lack of insulin>increased blood glucose>breakdown of body fats and proteins.
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What is insulin's function in relation to fat breakdown and ketosis?
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Insulin inhibits fat breakdown into fatty acids. Ketosis occurs when fatty acids released and converted into ketones by the liver.
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What is diabetic ketoacidosis?
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Hyperglycemia leads to osmotic diuresis, dehydration, loss of electrolytes.
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What are the clinical maifestations of DKA?
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Ketosis: Kussmaul's resp, fruity breath, nausea, abd pain.
Dehyration, lyte loss, poly-uria,dipsia, wt loss, dry skin, suken soft eye ball, lethary, coma, death. |
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What can DKA be precipiated by?
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Poor management of DM, infection, stress, trauma, surgery, MI, inadequate insulin dose.
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What is hyperglycemic hyperosmolar nonketototic syndrome (HHS or HHNK)?
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Not only limited to DM. Characterized by hyperglycemia, dehydration, absecne of ketoacidosis.
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What types of pts does HHS usually occur in?
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DM II (older pts), acute pancreatitis, infection, MI, poor PO intake, TPN admin.
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What are some maifestations of HHS?
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Neurologic (confusion, seizures, hemiparesis), dehydration, f/e imblance. BG > 600. High morality rate.
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What are chronic complications of DM?
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-Macrovascular, foot ulcers
-microvascular (in insulin independent tissues): retinopathy, nephropathy, neuropathy. |
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Polycystic Ovary Disease (PCOS)
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Related to obesity and insulin resistance. Endocrine disorder. Frequent cause of infertility. Pituitary is releasing large amount of LH.
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