Physiology Flashcards
Substances responsible for the vasoconstriction as part of acute inflammatory response
“Vasoconstriction is stimulated by vasoactive agents such as catecholamines, serotonin, bradykinin, and prostaglandins that are released from surrounding tissues and by norepinephrine released by the sympathetic nervous system.15”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
Substances associated with vasodilation as a result of acute inflammation include
“Vasodilation is induced by vascular smooth muscle changes mediated by nitric oxide, histamine, leukotrienes, prostaglandins, and complement factors.”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
Name the four phases of acute vascular response to inflammation and briefly outline their mechanism and importance
Vasodilation - follows a brief period of vasoconstruction. Mediated by nitric oxide, histamine, leukotrienes and complement factors. Allows increased blood flow and delivery of soluble mediators and inflammatory cells.
Permeability - increase in the number of intercellular endothelial gabs mediated by serotonin and histamine. Allows the formation of transcytoplasmic channels for transcytosis of plasma products onto the site of inflammation.
Stasis - Secondary to fluid loss to hemoconcentration. Allows greater contact time in between erythrocytes /leukocytes and the endothelial membrane
Leukocyte extravasation - promoted by the interaction of endothelial adhesion glycoproteins called “selectins” and their corresponding ligands on leukocytes. Adhered Leukocytes migrate to the outside of vessels (particularly peripheral venules) through the process known as diapedesis.
Discuss the mechanism and anatomy of a left-to-right and a right-to-left (reverse shunt) in a patient with PDA
The ductus arteriosus is a fetal vessel communicating the descending aorta and the main pulmonary artery, allowing shunting of fetal oxygenated placental blood from the pulmonary artery to the systemic circulation and bypassing the non-functioning fetal lung. This structure quickly contacts due to increase oxygen tension and is meant to undergo fibrosis and necrosis within a few weeks after birth. If the ductus remains patent, blood continues to partially bypass the lungs in a left to right pattern (Aorta to pulmonic artery, due to higher pressure gradient) leading to a murmur, increased pulmonary blood flow and gradual left ventricular eccentric hypertrophy that may evolve into ventricular failure and pulmonary edema. Common clinical features include a bounding pulse and loud murmur. Reverse shunting (pulmonic artery to aorta, or right to left) occurs when there is an increase in the pulmonary vasculature. These dogs have diminished pulmonary flow, small left ventricle and marked hypertrophy of the right ventricle (due to increased pulmonary vascular resistance). Clinical features are very different from those of the most common left to right shunt, and include a soft or no murmur, differential cyanosis (cyanosis of caudal mucous membranes with pink cranial membranes) and secondary polycythemia/hyperviscosity due to renal hypoxemia.
Discuss the mechanism and anatomy of a left-to-right and a right-to-left (reverse shunt) in a patient with PDA
The ductus arteriosus is a fetal vessel communicating the descending aorta and the main pulmonary artery, allowing shunting of fetal oxygenated placental blood from the pulmonary artery to the systemic circulation and bypassing the non-functioning fetal lung. This structure quickly contacts due to increase oxygen tension and is meant to undergo fibrosis and necrosis within a few weeks after birth. If the ductus remains patent, blood continues to partially bypass the lungs in a left to right pattern (Aorta to pulmonic artery, due to higher pressure gradient) leading to a murmur, increased pulmonary blood flow and gradual left ventricular eccentric hypertrophy that may evolve into ventricular failure and pulmonary edema. Common clinical features include a bounding pulse and loud murmur. Reverse shunting (pulmonic artery to aorta, or right to left) occurs when there is an increase in the pulmonary vasculature. These dogs have diminished pulmonary flow, small left ventricle and marked hypertrophy of the right ventricle (due to increased pulmonary vascular resistance). Clinical features are very different from those of the most common left to right shunt, and include a soft or no murmur, differential cyanosis (cyanosis of caudal mucous membranes with pink cranial membranes) and secondary polycythemia/hyperviscosity due to renal hypoxemia.
Phases and sub phases of healing
Phase 1 - Inflammation
Sub-phase a) Hemostasis
b)cell migration
c) debridement
Phase 2 - Proliferation
Sub-phase a) fibroblast proliferation
b) capillary proliferation
c) epithelial proliferation
Phase 3 - Remodeling
The phase and sub phases of healing when granulation tissue is formed
Second phase (proliferation), sub-phases fibroblast and capillary proliferation.
How long it takes for epithelial cells to migrate across and completely cover a properly closed surgical wound?
48 hours
The percentage point by which soft tissue wounds remain weaker than the original tissue. Two exceptions to this rule.
Most wounds remain 15 to 20% weaker than the original tissue. The urinary bladder and the bone regain 100% strength
Expected electromyographic change seen with demyelinizing disease
“The duration, or the time between the initial baseline deflection of the M-wave and the time it takes to return to a flat baseline, can be prolonged. These changes are indicative of a demyelinating process.”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
Conditions possibly responsible for a decrease in the amplitude of M-wave during electromyogram
“A decrease in M-wave amplitude is a nonspecific finding, in that it may be seen in neuropathies or myopathies (those involving the muscle used to record the M-wave). In addition, loss of as few as two consecutive internodes of myelin results in the conduction block of a neuron, so diminished amplitude may also be seen with demyelination. This phenomenon (conduction block) can be seen in other situations as well: (1) when metabolic insults occur in a nerve with preservation of axons (neurapraxia) or (2) before completion of Wallerian degeneration in a recently injured axon (axonotmesis).”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
What are the two primary components of the innate immune system?
Phagocytes and natural killer cells
What are the primary components of the acquired immune system?
B & T lymphocytes
Cell line responsible for carrying out immune surveillance throughout the body
Lymphocytes
Eight classes of central nervous system pathology
1) Contusive
2)Compressive
3) inflammatory
4) vascular
5) metabolic
6) toxic
7) degenerative
8)neoplastic
List six possible causes of thrombocytopenia caused by decreased production of platelets.
“Drug-induced disorders
Immune-mediated megakaryocytic hypoplasia
Viral (feline leukemia virus [FeLV], feline immunodeficiency virus [FIV])
Chronic rickettsial disease (ehrlichiosis)
Estrogen-secreting neoplasm
Myelodysplasia
Megakaryocytic leukemia
Cyclic thrombocytopenia (Anaplasma platys)
Radiation
Idiopathic bone marrow aplasia
Postvaccination”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
List five possible causes of thrombocytopenia caused by increased destruction of platelets
“Immune-mediated thrombocytopenia
Primary
Idiopathic
Evans syndrome (immune-mediated thrombocytopenia and immune-mediated hemolytic anemia)
Systemic lupus erythematosus (SLE)
“Secondary
Drugs
Live virus vaccination
Tick-borne disease
Neoplasia
Bacterial infection
Nonimmune disorders
Drug-induced
Ehrlichiosis
Rocky Mountain spotted fever
Dirofilariasis”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
List six possible causes of thrombocytopenia caused by increased consumption or sequestration of platelets
“Disseminated intravascular coagulation
Microangiopathies
Splenic torsion, hypersplenism
Sepsis
Hepatic disease
Severe acute hemorrhage
Severe hypothermia
Hemolytic uremic syndrome”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
List six possible causes of acquired thrombopathia.
Drugs (NSAIDS, Abx, heparin)
Uremia
Anemia
Hepatic disease
Hypothermia
Colloid hemodilution
Myeloproliferative disorders and paraproteinemias
Ehrlichiosis
Snake venom
Disseminated intravascular coagulation”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
List 2 of the most common inherited Thrombopathias of dogs and cats
“von Willebrand disease (many dog breeds, rare in cats)
Signal transduction disorders (Basset Hound, Spitz)
Glanzmann’s thrombasthenia (Otterhound, Great Pyrenees)
Chédiak-Higashi syndrome (gray Persian cats)
Selective adenosine diphosphate (ADP) deficiency (Cocker Spaniel)
Cyclic hematopoiesis (gray Collie)
Procoagulant expression disorders (German Shepherd Dog)
Macrothrombocytopenia (Cavalier King Charles Spaniel)”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
List five possible causes of acquired secondary coagulopathy (secondary hemostasis)
“Vitamin K deficiency
Hepatopathy
Disseminated intravascular coagulation
Pharmacologic anticoagulants
Hemodilution (dilutional coagulopathy)
Severe hypothermia
Acidemia
Shock
Massive trauma”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
Name the end products of primary and secondary haemostasis and briefly describe how they are formed. (8 marks)
Primary hemostasis – end product: platelet clot; Endothelial disruption exposes subendothelial collagen to which platelets adhere via platelet glycoprotein VI receptor and to collagen-bound Von Willebrand’s factor via glycoprotein Ib receptor. Adherence stimulates the release of platelet cytosolic granular contents (ADP) which stimulate arachidonic acid metabolism and production of prostanoids like Thromboxin A2, recruiting and activate further platelets.
Secondary Hemostasis – end product: fibrin mesh; Simultaneously with platelet aggregation, blood cells are exposed to Tissue Factor (TF) immediately after tissue injury. TF is a cofactor to Factor VII, which then activated factors IX and X leading to the activation of prothrombin to generate thrombin. Thrombin is the central protein in the coagulation cascade, cleaving fibrinogen into fibrin and activating further platelets.
Describe the clinical signs expected in animals with significant defects in primary and secondary haemostasis. (8 marks)
Primary Hemostasis: Petechia, mucosal damage, prolonged bleeding at injury sites.
Secondary Hemostasis: hematomas, hemarthrosis, intramuscular hemorrhage, effusions.
State the beneficial properties of transfusions of fresh frozen plasma, fresh whole blood and packed red blood cells and give an example of a surgical clinical situation in which each of these products could be used
Fresh Frozen Plasma (FFP): contains all constituents of plasma, including coagulation proteins, vWF, natural anticoagulants, albumin and globulins. Indicated for inherited or acquired coagulation disorder, vWD and hypoproteinemia. Example: Doberman Pincher with vWD, presented with GDV.
Fresh Whole Blood: Same as FFP but including RBC’s. Low platelet concentration, requiring large volume to affect platelet levels. Example: Hemoabdomen (replaces volume, RBC’s and “some” platelets and clotting factors. Supplementation with FFP or Cryoprecipitate likely necessary depending on the level of platelet/clotting factor consumption).
Packed Red Blood Cells (pRBC’s): Does not contain clotting factors, vWF, natural anticoagulants, albumin or globulins. Exposes recipient to large amounts of RBC antigens. Example: Anemic but normovolemic patient who requires a surgical procedure (avoids fluid-overload); anemic patient with cardiac disease who needs surgery (volume -sensitive).
Describe how the integrity and strength of the sutured anastomosis changes over the timeline from incision to wound maturity. (7 marks)
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.
What is the basic formula to calculate basal energy requirement (BER) in patients greater than 2 kg?
“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.
What are the four primary types of plasma proteins produced by the liver?
“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.
What are the normal H2O systemic venous pressure and normal portal pressure for dogs?
“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.
What are the Four major metabolic abnormalities frequently observed in the biochemistry profile of a patient with mineralocorticoid deficiency?
“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.
What precautions should be taken prior to anesthetizing patients with hypoadrenocorticism for minor versus major surgical procedures?
“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.
Patients affected by Addison’s disease should receive corticosteroids prior to surgical procedures. What is the recommended corticosteroid form and what concerns can be associated with the use of dexamethasone?
“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.
“Patients with HAC are catabolic and often protein depleted; this may adversely affect wound healing. Discuss the typical musculoskeletal changes associated with his condition and their metabolic impact.
“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.
What is the Whipples triad and what does it indicate?
“• 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.
What is the mechanism by which glucocorticoids help prevent hypoglycemia in patients with insulinoma?
“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.
List three drugs which may adversely affect the results of thyroid function tests in dogs?
“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.
How can hypothyroidism affect a patient’s anesthetic in surgical status?
“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.
