Physiology Flashcards

Question

Describe how the integrity and strength of the sutured anastomosis changes over the timeline from incision to wound maturity. (7 marks)

Answer 1

Immediately following surgical incision, the strength of the wound is reliant upon the holding power of the sutures upon the collagen-rich layer (submucosa), as well as on a relatively fragile fibrin seal. Significant collagen breakdown occurs in the first 4 days due to upregulation of MMP’s, leading to relevant decrease in the strength of anastomosis (up to 70% for small intestines and colon). This is when dehiscence is most likely to occur. Risk factors include hypotension, poor O2 saturation, infection, excessive tissue trauma and tissue tension. Around 1 week post-surgery the intestines will have regained nearly 100% of the original bursting strength, but the strength of the scar will continue to increase for several months.

Answer 2

“BER = (30 × (BW in kg) + 70.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 3

“albumin, α- and β-globulins, prothrombin and fibrinogen. Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 4

“The normal portal pressure in dogs is 8 to 13 cm H2O, which is 7 to 8 cm H2O higher than the systemic venous pressure ” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 5

“If mineralocorticoid secretion is suppressed, hyponatremia, hyperkalemia, acidosis, and/or azotemia may occur.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 6

“A protective steroid release normally occurs during surgery that prevents circulatory collapse; however, animals with hypoadrenocorticism may be unable to respond appropriately and often require glucocorticoid supplementation before and during surgery. When minor elective surgery is performed in animals with adrenocortical insufficiency, glucocorticoid therapy may be given intravenously before induction of anesthesia (Box 22.1). The same dose can be given intravenously or intramuscularly after recovery from anesthesia, and the animal is returned to its oral maintenance glucocorticoid therapy the day after surgery. A similar protocol is used for major surgery, except that glucocorticoid therapy is continued at approximately five times the maintenance dose for 2 to 3 days (Box 22.2). Normal maintenance doses are then reinstituted. Once the animal is eating, medications can be given orally (Box 22.3).” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 7

“1. Prior to surgery give double the maintenance dose of oral glucocorticoids. 2. If oral supplementation is not reliable or feasible, then give: • Prednisolone sodium succinate 1 mg/kg IV or • Hydrocortisone sodium succinate 2 mg/kg IV 3. As soon as the patient can reliably take oral medications, repeat oral prednisolone. ” “Dexamathasone is more ulcerogenic than other steroids and should be used with caution.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 8

“They may have connective tissue abnormalities and muscle wasting, resulting in a pot-bellied appearance, redistribution of fat, and thin, fragile skin. Pyodermas are common in affected dogs, which may cause postoperative suture line healing to be compromised. Affected dogs may pant because of their catabolic state, but intraabdominal fat deposition plus abdominal muscular weakness sometimes causes ventilatory abnormalities. Hypernatremia, hypokalemia, and alkalosis may be present; substantial abnormalities should be corrected before surgery. Concurrent abnormalities (e.g., congestive heart failure, diabetes mellitus [DM]) increase the patient's anesthetic risk. Cardiovascular abnormalities may occur secondary to hypervolemia and hypertension; a thorough preoperative cardiac examination including blood pressure measurement is appropriate. Animals with HAC are at increased risk for postoperative pulmonary thromboembolism (PTE). If hypercoagulability is suspected, preventive measures may be indicated before surgery. For prevention of PTE, animals may be started on heparin during surgery and continued on it postoperatively (see Box 29.1) or they may be administered clopidogrel (2–3 mg/kg per day in dogs); however, prospective studies are needed to determine the relative benefit of these therapies. Many animals with HAC have clinically silent urinary tract infection; therefore urine culture is indicated in all patients, regardless of urinalysis findings.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 9

“• Clinical signs associated with hypoglycemia (usually neurologic abnormalities) • Fasting blood glucose concentrations of ≤40 mg/dL • Relief of neurologic signs with feeding or glucose administration” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 10

“Glucocorticoid therapy (Box 22.12) may help prevent hypoglycemia caused by islet cell tumors by increasing hepatic glucose production and decreasing cellular glucose uptake” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 11

“glucocorticoids, phenobarbital, and carprofen” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 12

“Hypothyroidism may be manifested as lethargy, exercise intolerance, weight gain, constipation, nonpruritic symmetric alopecia, peripheral neuropathies (e.g., laryngeal paralysis, vestibular deficits), reproductive problems, cardiovascular changes (i.e., bradycardia and weak apex beat), and/or coagulopathies. Hypothyroidism may also result in diminished activity of factor VIII or of factor VIII–related antigen, which may predispose animals with von Willebrand disease (vWD) to spontaneous bleeding or serious hemorrhage during surgery. The mean von Willebrand factor/antigen (vWF) concentration in hypothyroid dogs has been found to be significantly reduced compared with that in euthyroid dogs. It appears that reduced concentrations of plasma vWF can be found in dogs in association with congenital vWD or with vWD acquired through hypothyroidism. Animals with untreated severe hypothyroidism and bleeding tendencies undergoing emergency procedures should be given oral L-triiodothyronine (Box 22.16) three or four times a day, or a single IV dose of L-thyroxine. Elective procedures should be postponed until replacement therapy has been maintained for a minimum of 2 weeks. If excessive bleeding is noted despite thyroid supplementation, whole blood, plasma, or cryoprecipitate should be given (see Box 4.1 and Table 4.5).” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 13

“Thyroid secretions (T4, T3, and calcitonin)” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 14

“In adults, it causes an increase in the overall metabolic rate; in juveniles, it stimulates growth. Calcitonin (formed by parafollicular C cells) lowers blood calcium by stimulating calcium uptake.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 15

“Excessive circulating T4 causes multisystemic organ dysfunction. Thyrotoxicosis increases the metabolic rate and sensitivity to catecholamines and causes significant cardiovascular and metabolic abnormalities. Up to 80% of affected cats may have thyrotoxic heart disease; approximately 20% of these may have congestive heart failure. Hypertension is sometimes identified but does not appear to be as common as cardiac disease. Multifactorial mechanisms may cause neuromuscular and CNS dysfunction in some hyperthyroid cats. Neurologic signs associated with feline hyperthyroidism are listed in Box 22.17. T4 and T3 bind to receptor sites in the sarcoplasm that increase skeletal muscle heat production and mitochondrial oxygen consumption. The hyperthyroid state may reduce muscle contraction by uncoupling oxidative phosphorylation. Thyroid hormones may lower the threshold for cerebral tissue activation, may alter the activity of some brain enzymes, and may interact with catecholamines to alter the mental state of some affected animals. Abnormalities of the CNS may include hyperexcitability, irritability, aggression, seizures, confusion, and stupor.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 16

“• Generalized weakness • Neck ventroflexion • Fatigue • Muscle tremors • Ataxia • Incoordination • Inability to jump • Muscle atrophy • Breathlessness (due to weakness of intercostal muscles) • Collapse” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 17

Hypertrophic cardiomyopathy leading to cardiomegaly

Answer 18

“Thyroid scintigraphy is the optimal diagnostic test because it can both definitively identify hyperthyroidism and locate functional ectopic thyroid tissue.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 19

“Hyperthyroidism increases glomerular filtration rate (GFR), which may lessen azotemia and thereby mask clinical signs of chronic kidney disease (CKD). This is important because successful therapy of hyperthyroidism may result in clinical manifestation of CKD. At the same time, CKD may lower serum TT4 concentrations (i.e., euthyroid sick syndrome) into the reference range, making diagnosis more difficult. The combined measurement of fT4 and TT4 may be necessary when trying to determine if cats with moderate to severe CKD have hyperthyroidism.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 20

“If in doubt as to the safety of thyroidectomy or 131I therapy, one may first administer a course of methimazole and monitor serum creatinine and blood urea nitrogen concentrations to see how the patient will tolerate euthyroidism. For cats that develop overt renal failure after establishment of euthyroidism, withdrawal of methimazole should result in improved renal function. Hypokalemia and concurrent muscle weakness may occur in cats with hyperthyroidism.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 21

“hepatopathy, thrombocytopenia, and agranulocytosis occur with long-term therapy.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 22

“Measurement of PTH in animals with normal renal function is a sensitive test. High-normal or increased serum concentrations of PTH in hypercalcemic animals with normal renal function are strongly suggestive of hyperparathyroidism. ” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 23

(1) overload of the lymphatic system (2) inadequate collection by the lymphatic terminal buds (3) abnormal lymphatic contractility (4) insufficient lymphatic (5) lymph node obstruction (6) central vessel (i.e., thoracic duct) defects.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 24

“Regardless of the cause, edema results when capillary filtration exceeds the combined resorptive capabilities of the venous and lymphatic systems. This edema is relatively protein rich (2–5 g/dL). Because of the resultant high osmotic pressure, additional fluid is pulled into the interstitial space, worsening the edema. If the lymphatic system cannot adequately drain this interstitial fluid, collagen deposition and fibrosis may result. Hence, although the early stages are reversible, chronic edema is associated with thickening and fibrosis of tissue, making treatment difficult. The domestic species most commonly reported to have lymphedema is the dog.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 25

Primary lymphedema - caused by an abnormality or disease of lymphatic vessels or lymph nodes. Possibly due to congenital or hereditary diseases. Secondary lymphedema - Occurs as a result of lymphatic obstruction of nodes or vessels by neoplasia, infection ( filariasis), Lymphoproliferative disorder‘s or surgical trauma.

Answer 26

“Age of onset of clinical signs does not help distinguish between primary and secondary lymphedema because middle-aged animals may have acute signs of lymphedema that occur secondary to congenital lymphatic abnormalities. Although primary lymphedema is usually noted at birth or shortly thereafter, older animals may develop lymphedema associated with congenital abnormalities. In these animals, the lymphatic system functions normally until a precipitating cause (e.g., infection, trauma, or surgery) overwhelms the marginal lymphatic system. Congenital, hereditary lymphedema has been reported in bulldogs and poodles. A gender predisposition is not evident.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 27

“Lymphedema typically manifests as a spontaneous, painless swelling of the extremities with pitting edema. The onset may be insidious. The rear limbs are more commonly affected, and the swelling may be unilateral. Lymphedema usually begins in the distal extremity and progresses proximally. In severely affected animals, all four limbs and the trunk may be edematous. Although the patient may be less active than normal because of the weight of the limb or may carry the limb when ambulating, lameness and pain are uncommon without massive enlargement or cellulitis.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 28

“The key differential diagnosis is abnormality of the venous system, such as venous stasis or arteriovenous fistula. The physical examination should eliminate systemic causes of bilateral edema, including heart failure, renal failure, cirrhosis, and hypoproteinemia. Other differential diagnoses include trauma, neoplasia, and foreign bodies.” “Arteriovenous fistulae are vascular abnormalities in which a direct communication exists between an adjacent artery and vein. They may be congenital or acquired (e.g., after trauma, neoplasia, infection, or iatrogenic ligation of an artery and vein together). Clinical signs with arteriovenous fistulae vary depending on the location; however, palpation of strong pulsatile vessels, often of a fremitus or thrill, and auscultation of a machinery murmur (i.e., bruit) are classic findings. Angiography is necessary to confirm the diagnosis and determine the size, extent, and location of the fistula. ” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 29

“Lymphoscintigraphy involves intradermal injection of high-molecular-weight, radiolabeled colloids. A gamma camera is used to obtain images of the affected limb over time to observe the progression of radioactivity through the lymphatics. Primary lymphedema typically shows slow absorption of the radiopharmaceutical, reduced visualization of lymphatic vessels and lymph nodes, and no interstitial activity. Secondary lymphedema typically shows poorly visualized primary lymph vessels and dilated secondary lymph vessels. ” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 30

“Benzopyrones (Box 23.1) are a group of drugs that have been used to successfully treat experimental lymphedema in dogs and spontaneous lymphedema in human beings. All the drugs in this group appear to reduce high-protein edema. Their main action appears to be stimulation of macrophages, which promotes proteolysis. Protein fragments can then be reabsorbed into the blood. These drugs are active orally and topically, are inexpensive, and are relatively free of side effects. Included in this category of drugs are coumarin (5,6 benzo-[a]-pyrone), O-(β-hydroxy-ethyl)-rutosides, diosmin, and rutin.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 31

Replacement of clotting factors and ATIII

Answer 32

“Renal failure is when the kidneys are not able to maintain excretory, regulatory, and/or endocrine function, with subsequent retention of waste products and abnormalities in fluid, electrolyte, and/or acid-base homeostasis. This generally happens when 75% or more of the nephrons become nonfunctional. ” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 33

“Azotemia is defined as an increased concentration of nitrogenous waste products in the blood. Uremia is the clinical syndrome associated with sufficient loss of functional nephrons.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 34

“Chronic kidney disease (CKD), the most common renal disease of dogs and cats, refers to patients with a permanent loss of functioning nephrons that have had renal damage, with or without a decreased glomerular filtration rate (GFR) for at least 3 months, or that have had a 50% reduction of GFR for at least 3 months. ” “Chronic renal failure (CRF) is a progressive disease that occurs in patients with CKD with significant clinical signs (polyuria, polydipsia, weight loss, decreased appetite) and laboratory findings (azotemia, anemia, proteinuria).” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 35

“Very severe hypokalemia may cause ECG changes (e.g., flattened T waves, U waves) and skeletal muscle weakness.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 36

“urine output should be monitored during surgery, with a urine output goal of at least 0.5 mL/kg per hour. ” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 37

“Hyperkalemia can cause “tented” or spiked T waves, absent or flattened P waves, prolongation of the P-R interval, widened QRS complexes, and/or bradycardia, in addition to predisposing to cardiac arrhythmias. Potassium concentrations greater than 7 mEq/L may cause irregular idioventricular rhythm, and potassium concentrations exceeding 9 mEq/L commonly cause atrial standstill.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 38

“1. Dilute by giving physiologic 0.9% saline solution IV or, once the obstruction is relieved, LRS IV. 2. If necessary to lower potassium immediately, give sodium bicarbonate (see Box 4.1) or regular insulin 0.2–0.4 U/kg IV plus dextrose (2 g/U of insulin). 3. If hyperkalemia is immediately life threatening, may give 10% calcium gluconate (0.2–1.5 mL/kg) for transient cardiac protection. Give slowly (over 5–10 min) while monitoring the patient's ECG. 4. Provide intubation and controlled hyperventilation to rapidly reduce respiratory acidosis.” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 39

“Although seldom required, life-threatening hyperkalemia may be treated with IV sodium bicarbonate. Bicarbonate therapy drives potassium into cells in exchange for hydrogen ions. ” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 40

The increase my cardio oxygen consumption and may predispose to arrhythmias

Answer 41

“Because cats excrete the active form of ketamine in their urine, it should be avoided or used in lower doses if urinary obstruction or renal dysfunction is present. ” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 42

“The major rule-outs for hyperkalemia are obstructive uropathy, acute renal failure, uroabdomen, adrenocortical insufficiency, and iatrogenic potassium intoxication. ” Excerpt From Small Animal Surgery E-Book Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984 This material may be protected by copyright.

Answer 43

“β1-Receptor agonists primarily augment heart rate and contractility and ectopic pacemaker activity. ” Isoproterenol, Dopamine, Dobutamine, Epinephrine Excerpt From Small Animal Critical Care Medicine Deborah Silverstein & Kate Hopper https://books.apple.com/us/book/small-animal-critical-care-medicine/id903782830 This material may be protected by copyright.

Answer 44

“β2-Receptor agonist activity primarily causes vasodilation. ” Isoproterenol Epinephrine Excerpt From Small Animal Critical Care Medicine Deborah Silverstein & Kate Hopper https://books.apple.com/us/book/small-animal-critical-care-medicine/id903782830 This material may be protected by copyright.

Answer 45

Convection (direct contact with cooler surfaces) Evaporative cooling (air passage through airways)

Answer 46

High ambient humidity Upper airway obstruction Laryngeal paralysis Brachiocephalic airway syndrome Collapsing trachea Obesity Previous history of hyperthermia

Answer 47

Nonpyrogenic hyperthermia results from the body’s inability to dissipate heat adequately. Therefore, antipyretic agents are often ineffective in reducing body temperature and are actually contraindicated due to potentially adverse side effects of decreasing renal perfusion and increased chance of gastrointestinal ulceration.

Answer 48

The renin–angiotensin system (RAS), or renin–angiotensin–aldosterone system (RAAS), is a hormone system that regulates blood pressure, fluid and electrolyte balance, and systemic vascular resistance.[2] When renal blood flow is reduced, juxtaglomerular cells in the kidneys convert the precursor prorenin (already present in the blood) into renin and secrete it directly into the circulation. Plasma renin then carries out the conversion of angiotensinogen, released by the liver, to a decapeptide called angiotensin I.[3] Angiotensin I is subsequently converted to angiotensin II (an octapeptide) by the angiotensin-converting enzyme (ACE) found on the surface of vascular endothelial cells, predominantly those of the lungs.[4] Angiotensin II has a short life of about 1 to 2 minutes. Then, it is rapidly degraded into a heptapeptide called angiotensin III by angiotensinases which are present in red blood cells and vascular beds in many tissues. Angiotensin III increases blood pressure and stimulates aldosterone secretion from the adrenal cortex; it has 100% adrenocortical stimulating activity and 40% vasopressor activity of angiotensin II. Angiotensin IV also has adrenocortical and vasopressor activities Angiotensin II is a potent vasoconstrictive peptide that causes blood vessels to narrow, resulting in increased blood pressure.[5] Angiotensin II also stimulates the secretion of the hormone aldosterone[5] from the adrenal cortex. Aldosterone causes the renal tubules to increase the reabsorption of sodium which in consequence causes the reabsorption of water into the blood, while at the same time causing the excretion of potassium (to maintain electrolyte balance). This increases the volume of extracellular fluid in the body, which also increases blood pressure.

Answer 49

An ACiD is a molecule that donates a hydrogen ion (h+) when a base molecule accepts one.

Answer 50

a BUffeR is a weak acid or base, which helps protect against large changes in ph. » The primary extracellular buffer is bicarbonate. » The intracellular buffers are phosphate, pro- teins, and hemoglobin. » Bone also acts as a buffer.

Answer 51

Acidemia is a blood ph < 7.35; Alkalemia is a blood ph > 7.45.

Answer 52

Henderson–hasselbach approach: 1.Metabolic acidosis: a primary gain in acid or loss of base 2.Metabolic alkalosis: a primary gain in base or loss of acid 3.Respiratory acidosis: retention of co2 due to co2 production outpacing alveolar ventilation 4.Respiratory alkalosis: removal of co2 (by ventilation) outpacing co2 production

Answer 53

Pao2 is a measure of oxygenation, not ventilation. PaCo2 provides the best measure of a patient’s ability to ventilate and determines whether respiratory acidosis or alkalosis is present. Remember that co2 is approximately 20× more diffusible than o2, making it easier for a patient to maintain normal co2 concentrations in the presence of lung disease. • PvCo2 is the partial pressure of carbon dioxide dissolved in venous blood. When the sample has been obtained properly, it measures a patient’s ability to ventilate, similar to Paco2.

Answer 54

Base excess/deficit (BE) » reflects the metabolic portion of the acid–base balance, which takes into account all of the body’s buffer systems » estimates how much base needs to be added or subtracted to achieve a normal ph at normal temperature » evaluates for metabolic acidosis or alkalosis.

Answer 55

While osmolality is a measure of all solutes in solution, tonicity refers only to the effective solutes in solution; that is, those that cannot cross a membrane and so exert an osmotic pressure.

Answer 56

Isotonic losses, such as those observed with vomiting and diarrhea, occur when the fluid being lost has an osmolality similar to that of plasma. With isotonic !uid loss, sodium concentrations are typically normal; however, if the animal is able to drink water, hyponatremia may result from replacement with a hypotonic fluid

Answer 57

Hypotonic losses occur when the type of fluid being lost has a higher concentration of water than plasma, such as with diabetes insipidus and panting. The loss of a hypotonic !uid, or water in excess of sodium, can result in hypernatremia. Although isotonic replacement !uids may bene$t some patients with hypotonic losses, others benefits from !uids that contain more free water.

Answer 58

Hypertonic losses, or loss of sodium in excess of water, are uncommon but can be seen with hypoadrenocorticism, third-space loss of fluid (such as pleural or peritoneal efusion), and diuretic administration.1 Excess loss of hypertonic fluid can result in hyponatremia.

Answer 59

Signs of overhydration include chemosis, serous nasal discharge, increased skin turgor, peripheral edema, ascites, pleural eusion, and pulmonary edema.

Answer 60

IV SQ intraosseous Enteric (considered ideal since most physiological. Even if through ET tube or similar)

Answer 61

More than 60% to 80% of a crystalloid solution distributes out of the intravascular space within 20 to 30 minutes.

Answer 62

Neonates are able to use lactate as a fuel source, making LRS the preferred fluid choice for young patients.

Answer 63

Lactate in LRS is metabolized by the liver; thus, it is a suboptimal choice for patients with hepatic dysfunction or diabetic ketoacidosis because they will not be able to convert lactate to bicarbonate.

Answer 64

Adults: 60% Neonates: 80%

Answer 65

75% intersticial 25% Intravascular Small amout is transcellular (synovial, CSF)

Answer 66

dogs: 110 days cats: 70 days

Answer 67

Upon vascular injury, platelets will release arachidonic acid which is converted into thromboxane by thromboxane synthase via COX-1. Thromboxane promotes vasoconstriction and coagulation. At the same time endothelial cells will use prostacyclin synthase to synthesize prostacyclin through COX-2, leading to vasodilation and anti-coagulation. This balance is fundamental to prevent excessive coagulation and thrombosis.