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VET SCI II
ENDOCRINOLOGY
113
Veterinary Medicine
Undergraduate 3
07/29/2020

Additional Veterinary Medicine Flashcards

 


 

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Term
Endocrine and Nervous System Functions
Definition
control all body functions
maintain homeostasis
Term
Homeostasis
Definition
the tendency of an organism to maintain a constant internal environment. Bodies internal environment works constantly to remain WNL
Term
Nervous System Attributes
Definition
controls homeostasis
nerve impulses conducted along axons of neurons
stimulates or inhibits release of neurotransmitters
Term
Endocrine System Attributes
Definition
controls homeostasis through the release of hormones into bloodstream thereby delivering hormone to the target cell throughout the body
Term
Target Cells
Definition
can be anywhere in the body
hormones attach to receptor on cell (lock and key)
if no receptor, hormones flow by cell
Term
Cell Affected by the Nervous System
Definition
other neurons, muscle cells, gland cells
Term
Endocrine System Cells Affected
Definition
Target cells
Term
Time to Onset of Action and Duration (Nervous)
Definition
milliseconds
very brief duration
Term
Time to Onset of Action and Duration (Endocrine)
Definition
seconds to hours to days
long duration
Term
Hormones
Definition
a chemical messenger that alters physiological activity of target cells in the body
Term
Action of Hormones on Target Cells
Definition
1. stimulates or inhibits target cell
2. stimulates or inhibits release of other hormones
onset of effects are slower but longer in duration than neurotransmitters
Term
Endocrine vs. Exocrine Glands
Definition
endocrine glands secrete hormones directly into the bloodstream, exocrine glands secrete products (enzymes, sweat, tears) into ducts that deliver into body cavities
Term
Lipid Soluble Hormones
Definition
Steroids, thyroid hormones, and nitric oxide
Enter target cells, combine with receptors in nucleus to form complexes which activate specific genes
Term
Water Soluble Hormones
Definition
prostaglandins and leukotrienes
protein and peptide hormones that attach to cell membrane but do not enter the cell
Term
Chemistry of Hormones
Definition
each hormones has a special molecular structure, is potent, attaches to receptors on target cell
Term
Control of Hormonal Secretion
Definition
concentration of each hormone precisely regulated, normal ranges can be very narrow, body constantly working to achieve homeostasis. Homeostasis monitored using feedback systems and direct stimulus
Term
Feedback System
Definition
Cycle of events in which status of body is continually
monitored, evaluated, changed, re-monitored, re-evaluated
Term
Components of a Feedback System (Variable)
Definition
Variable being monitored. Example is blood pressure
Term
Components of a Feedback System (Stimulus)
Definition
disruption that changes controlled condition
ex - decrease in BP due to hemorrhage
Term
Components of a Feedback System (Receptor)
Definition
structure that monitors condition
ex - baroreceptor in aorta
Term
Components of a Feedback System (Control Center)
Definition
sets range of values at which controlled condition should be maintained
evaluates input from receptors and generates output commands
ex - cardio center in medulla
Term
Components of a Feedback System (Output)
Definition
Nerve impulses, hormones or other chemical signals
ex - increased sympathetic impulses, decreased parasympathetic impulses, increased secreations of epi and norepi
Term
Components of a Feedback System (Effector)
Definition
body structure that recieves output from control center
e.g. - cardiac and smooth muscle increases heart stroke and volume, constricts blood vessels
Term
Negative Feedback
Definition
typically how hormone secretion is controlled
reverses original stimulus
ex - temp
Term
Positive Feedback
Definition
enhances or intensifies original stimulus
ex - parturition
Term
Direct Stimulation
Definition
stimulation comes directly from the nervous system
ex - fight or flight response
Term
Hypothalamus
Definition
integrating link between nervous and endocrine systems, receives sensory signals,regulates hunger, thirst, sleep cycles, aggressive behavior.
works and acts on pituitary which releases 9 hormones
Term
TSH (Thyroid-Stimulating Hormone)
Definition
Source - Anterior pituitary
Target - thyroid gland
Effect - stimulates growth and development of thyroid and secretion of thyroid hormones T3 and t4
Term
ACTH (Adrenocorticotropic Hormone)
Definition
Source - Anterior pituitary
Target - cortex of the adrenal gland (adrenal cortex)
Effect - stimulates the growth development of adrenal cortex and the production of aldosterone and cortisol
Term
FSH (Follicle-Stimulating Hormone)
Definition
Source - anterior pituitary
Target in Female - ovaries
Effect in female - stimulates follicle growth and development
Target in Male - testes
Effect in male - stimulates sperm production
Term
LH (Luteinizing Hormone)
Definition
Source - anterior pituitary
Target in females - ovaries
Effect in females - causes ovulation of the mature follicle
Target in males - testes
Effect in males - stimulates production of testosterone
Term
Prolactin
Definition
source - anterior pituitary
target - mammary glands
effect - stimulates milk production in mammary glands of lactating females
Term
GH or STH (Growth Hormone)
Definition
Source - anterior pituitary
Target - bones and skeletal muscle
effect - stimulates growth and development of bones and skeletal muscle, regulates some aspects of metabolism
Term
MSH (Melanocyte-Stimulating Hormone)
Definition
Source - anterior pituitary
Target - melanocytes in skin
Effect - stimulates increased pigmentation
Term
Posterior Pituitary Hormones
Definition
two hormones produced by the hypothalamus and secreted by posterior pituitary are ADH and Oxytocin
Term
ADH (Anti-Diuretic Hormone)
Definition
Source - posterior pituitary
Target - kidneys
Effect - causes retention of water which decreases urine output
Term
Oxytocin
Definition
Source - posterior pituitary
Target - uterus and mammary glands
Effect - stimulates milk letdown, uterine contractions that expel fetus or retain spermatozoa
Term
Pineal Gland or Pineal Body
Definition
produces melatonin that affects mood and sleep-wake cycles
not a well-understood gland
Term
Thyroid Gland
Definition
composed of two lobes that sit on either side of the neck below the larynx. produces thyroid hormone and calcitonin
Term
Thyroid Hormone (T3/T4)
Definition
Source - Thyroid gland
Target - all cells in the body
Effect - increases rate of metabolism, needed for normal growth and development and maturation of the nervous system
Term
Calcitonin
Definition
Source - Thyroid gland
Target - osteoblasts in the bone
Effect - decreases blood calcium levels by stimulating uptake of calcium into bone
Term
Parathyroid Glands
Definition
attached to the lateral lobes of the thyroid glands, produces PTH
Term
PTH (Parathyroid Hormone)
Definition
Source - Parathyroid Gland
Target - acts on osteoclasts of the bone + kidneys and intestines
Effect - increases blood calcium levels by stimulating the breakdown of bone, causes kidneys to conserve Ca, causes intestines to absorb Ca from food
Term
Adrenal Glands
Definition
located near cranial end of the kidneys
made up of a cortex and medulla
Term
Hormones of the Adrenal Medulla
Definition
epinephrine and norepi
Source - adrenal medulla
Target - CVS, RS, liver
Effect - increases HR/BP, increases RR, liver breaks down stored glycogen and releases glucose in blood, fight or flight response
Term
Hormones of the Adrenal Cortex (Mineralocorticoids)
Definition
Aldosterone
Source - adrenal cortex
Target - kidneys
Effect - conservation of Na and water and excretion of K to help maintain BV and pressure
Term
Hormones of the Adrenal Cortex (Glucocorticoids)
Definition
cortisol and cortisone
Source - adrenal cortex
Target - immune system, liver, heart and uterus
Effects - anti-inflammatory, gluconeogenesis, breakdown of lipids and proteins, helps body resist stress, depresses immune system and delays wound healing
Term
Pancreas
Definition
endocrine and exocrine functions
located posterior to stomach, attached to duodenum
Term
Pancreas Endocrine Functions
Definition
secretes insulin and glucagon
Term
Insulin
Definition
Source - Pancreas
Target - cell membranes
Effect - causes cell membrane to become permeable to glucose, amino and fatty acids
decreases blood glucose levels
Term
Glucagon
Definition
Source - pancreas
Target - liver
Effect - stimulates breakdown of glycogen
increases blood glucose levels
Term
Ovaries and Testes
Definition
ovaries - secrete estrogen and progesterone
testes - secrete testosterone
Term
Estrogen
Definition
responsible for the development and maintanence of female reproductive structure
increases protein anabolism
lowers blood cholesterol
Term
Progesterone
Definition
hormone of pregnancy
prepares endometrium for implantation
prepares breasts to secrete milk
Term
Testosterone
Definition
activates spermatogenesis
responsible for development of secondary male sex characteristics, anabolic effect builds up muscles and bones, regulates libido
Term
Hypothyroidism
Definition
a deficiency of circulating T3/T4
Term
Etiology of Hypothyroidism
Definition
Hypothyroidism (primary) usually caused by the destruction of the thyroid gland where the immune system attacks the gland or the gland degenerates (atrophy)
Term
Primary Hypothyroidism
Definition
accounts for 95% of all hypothyroidism cases in dogs
Term
Secondary, Tertiary, and Congential Hypothyroidism
Definition
Secondary - dysfunction of the pitutary
Tertiary - congential defects of the hypothalamus
Congential - thyroid gland dysgenesis (defective development)
Term
Hypothyroidism and Iodine Deficiency
Definition
hypothyroidism can be due to insufficient iodine levels in diet but is rarely seen, iodine important in the function of T3/T4
Term
Signalment of Hypothyroidism
Definition
almost always dogs but can affect other species, usually middle-aged to older animals but can occur at any age.
Term
General Clinical Signs of Hypothyroidism
Definition
weight gain without increased appetite
lethargy
weakness
exercise intolerance
bradycardia
heat-seeking behavior
Term
Skin Disorders from Hypothyroidism
Definition
dull, dry, coarse coat
hyperpigmentation on flank, belly
skin becomes thick and oily
bilateral symmetrical alopecia
secondary skin infections
Term
Skin Disorders Associated with Hypothyroidism Cont.
Definition
alopecia typically the most observed clinical sign by owners
diminished T3/T4 affects hair growth
telogen phase - no follicle growth
decrease in SQ fatty acids/ vitamin E leads to scaly appearance and dry coat
Term
Ocular Disorders Associated with Hypothyroidism
Definition
KCS and uveitis though there is little clinical evidence to support this
Term
Reproductive Disorders Associated with Hypothyroidism
Definition
anestrus, abortion, decreased libido
Term
Testing of Hypothyroidism
Definition
Submit T3/T4/TSH sample to lab
thyroid medications such as levothyroxine may interfere with test results
periodic testing as pt will be on lifetime meds
Term
Tx of Hypothyroidism
Definition
daily oral hormone supp
must be continued for the animals whole life, usually use L-thyroxine
re-evaluation occurs 6-8 wks after initiation of tx, clinical signs should reverse with therapy
owners may notice change within first week of tx
Term
Hyperthyroidism
Definition
commonly called feline hyperthyroidism as its most commonly seen in cats
caused by increased T3/T4 in blood
Term
Etiology of Hyperthyroidism
Definition
caused most often by an adenoma of the thyroid gland, called functioning adenoma as it causes overproduction
Term
Etiology of Hyperthyroidism Cont.
Definition
can be caused by increased iodine levels in cat food
soy disrupts thyroid function
BPA - coating in cans that is an endocrine disrupter
1/300 cats diagnosed with hyperthyroidism
Term
Signalment of Hyperthyroidism
Definition
usually in middle-aged to older cats but can occur at any age
Term
Clinical Signs of Hyperthyroidism
Definition
significant weight loss (emaciation)
voracious appetite
tachycardia
hyperactivity
poor, rough hair coat
goiter - enlargement of one or both thyroid lobes
Term
Testing for Hyperthyroidism
Definition
differential dx may be obtained based on clinical signs, palpable thyroid nodule, increased serum T4 concentrations
Term
Tx for Hyperthyroidism (Medical)
Definition
Methimazole (Tapazole)
kills off part of the thyroid tissue
pt may not tolerate it well with V/D
Term
Tx for Hyperthyroidism (Surgical)
Definition
surgical removal of part of the thyroid gland that has the adenoma, critical that parathyroid glands aren't removed as well
Term
Tx for Hyperthyroidism (Radiation)
Definition
use of iodine 131
concentrates in the overactive tissue and kills abnormal tissue
must have nuclear license to admin
must isolate for 7-10 days
considered best option for tx
Term
Post Tx for Hyperthyroidism
Definition
hyperthyroidism can mask underlying kidney dz
increaed T3/T4 increases kidney metabolism
creatine levels would be elevated
Term
Hyperadrenocorticism
Definition
Also called cushings dz, it is the chronic overproduction of the glucocorticoid cortisol
Term
Cortisol
Definition
increases blood sugar, supresses immune system, metabolism of fats, carbs and proteins
Term
Three Forms of Hyperadrenocorticism
Definition
pitutary dependent
adrenocortical tumor
iatrogenic
Term
Pituitary Dependent (PDH)
Definition
comprises of 85-90% of cushings, 90% of those cases in dogs caused by pituitary tumors
causes excessive secretion of ACTH from anterior pituitary
results in hypertrophy of the adrenal glands, excessive production of glucocorticoids, negative feedback loop becomes ineffective
Term
Adrenocortical Tumors
Definition
comprises of 10-15% of naturally occurring cases, unrelenting production of cortisol from the tumor
renders negative feedback loop ineffective
Term
Iatrogenic Hyperadrenocorticism
Definition
caused by exogenous administration of corticosteroids, used for control of autoimmune disorders and chronic inflammation
natural cortisol production shut down due to negative feedback mechanism
Term
Signalment for Hyperadrenocorticism
Definition
usually middle aged to older dogs, commonly seen in poodles, dachshunds, terriers
males and females equally affected
Term
General Clinical Signs of Hyperadrenocorticism
Definition
pt may show one or multiple clinical signs, no one sign is diagnostic and absence of one or more signs does not rule out
onset of signs very slow, owner may not notice for months
Term
General Clinical Signs of Hyperadrenocorticism Cont.
Definition
distended, pendulous abdomen
weight gain, increased appetite
lethargy
PU/PD
poor hair coat, excessive bruising
recurrent skin/UT infections
Term
Dx of Hyperadrenocorticism
Definition
1. Bloodwork - all need baseline samples drawn
2. ACTH Stim - give an injection of ACTH, measures cortisol output which is greatly elevated in cushingnoid pt
Term
Dx of Hyperadrenocorticism LDDS
Definition
LDDS - animal is fasted, given an injection of Dex SP, follow-up samples taken 4-8 hrs later, cushingoid pts. will not suppress cortisol in response to injection
Term
Dx of Hyperadrenocorticism HDDS
Definition
used to differentiate between forms of cushings, dog with adrenal tumor will not suppress at all, dog with pituitary tumor should respond with suppressed cortisol levels
Term
Tx of Hyperadrenocorticism (Mitotane)
Definition
aka lysodren
selectively causes the necrosis of certain cells in the adrenal gland, but has no effect on pituitary tumors
Often used in the tx of PDH because of difficulty of surgical removal, instead, drug targets the hypertrophy of adrenal glands
occasionally used in tx of adrenal tumors in animals that are at poor surgical risk
Term
Tx of Hyperadrenocorticism (Ketaconazole)
Definition
common antifungal med but also inhibits the production of cortisol at high doses, used when there is an intolerance to lysodren
Term
Tx of Hyperadrenocorticism (Surgery)
Definition
may be indicated with adrenal tumors, but must leave some - animal can't live without adrenal glands
Term
Tx of Hyperadrenocorticism (Other)
Definition
anipryl - tx for PDH, reduces ACTH prod. by increasing dopamine, clinical trials however showed no consistent resolution in dogs
vetoryl - interferes with cortisol synth
Term
Hypoadrenocorticism
Definition
also called addisons dz
comes in primary and iatrogenic forms
Term
Primary hypoadrenocorticism
Definition
atrophy or destruction of the adrenal cortex, may be immune-mediated or iatrogenic
Term
Iatrogenic Hypoadrenocorticism
Definition
long-term admin of glucocorticoids causes atrophy of the adrenal cortex followed by a sudden stop of admin
Term
Etiology of Hypoadrenocorticism
Definition
decreased blood levels of aldosterone
results in oversecretion of Na and retention of K in bloodtsream
Term
Clinical Signs of Hypoadrenocorticism (The Great Pretender)
Definition
C/S mimic those of other disorders
intermittent V/D
acute weakness and depression leading to collapse
shock, decreased BP, coma
key signs - bradycardia, bloodwork shows increased K and decreased Na
Term
Addisonian Crisis
Definition
Hyperkalemia disrupts normal sinus rhythm which results in arrhythmia
decreased BP due to hypovolemia which can lead to renal failure/shock/death
Term
Dx of Addisons Dz
Definition
Difficult, rule out other diseases first
ACTH stim test - gold standard, results will indicate an abnormally decreased ACTH plasma cortisol concentration, blood samples obtained one hour prior and post ACTH stim
Term
Tx of Addisons
Definition
correct hypotension and electrolyte imbalances with Iv fluid therapy (no K)
obtain blood sample for ACTH
admin of glucocorticoids
DOCP - mineralocorticoid injections given monthly typically in combo with prednisolone
Term
Prognosis of Addisons
Definition
aggressive managment of addisonian crisis will result in stable pt within 24-48hrs, owners cont at home therapy and pt reevaluated once a month, then every 3-6 mo., clinical signs should cease if therapy is apporopriate
Term
Diabetes Mellitus
Definition
due to decreased blood levels of insulin. a group of disease entities characterized by a relative or absolute deficiency of insulin, results in decreased utilization of glucose, amino acids, and fatty acids, leads to hyperglycemia and glucosuria
Term
Normal Blood Glucose Levels
Definition
70-100 mg/dl
Term
Signalment of Diabetes Mellitus
Definition
Both dogs and cats, typically middle-aged to older animals
Term
Causes of Diabetes Mellitus
Definition
Primary - Islet cell destruction in pancreas (chronic or autoimmune)
Secondary - insulin resistance may be due to islet cell exhaustion/loss of function
Term
Clinial Signs of DM
Definition
overweight pts are pre-disposed but weight loss can occur in pts with prolonged DM
polyphagia
weakness/lethargy
PU/PD
hyperglycemia
glucosuria
increased healing time/susceptibility to infections
diabetic cataracts
Term
Tx of DM
Definition
admin of exogenous insulin
weight control and dietary management
Term
Complications
Definition
Overdose of insulin can lead to hypoglycemia
DKA
Term
Diabetes Insipidus
Definition
NOT a disease of the pancreas
symptoms - PU/PD, similar to DM so must be distinguished
occurs when posterior pituitary under produces ADH
Term
Diabetes Insipidus Results in
Definition
without adequate blood levels of ADH the kidneys will not reabsorb water causing PU/PD
Term
Tx of DI
Definition
Desmopressin/Vasopressin to supp hormone
lots of water
prognosis good as long as pet allowed unlimited access to water
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