Physiologic Response to Surgery Flashcards
Define Stress Response
Hormonal & metabolic changes that are triggered by “stress”
Physiological Changes that Occur During the Stress Response
Hormonal
Metabolic
Immunological
Hematological
Psychological Changes that Occur During the Stress Response
Fatigue
Malaise
Depression
Behavioral Change that Occurs During the Stress Response
Reluctance to move
Hormonal Response to Stress
Activation of HPA axis & sympathetic nervous system
Receive input from area of trauma or injury
Normal feedback mechanism fails: system doesn’t get shut off
Sympathetic Nervous System Response to Stress
Adrenal medulla releases catecholamines
Increased norepinephrine from presynaptic nerve terminals
Leads to tachycardia & HTN
Renal Effects due to Activation of the Sympathetic Nervous System
Renin release causes conversion of angiotensin I to II
Aldosterone release leads to Na+ retention
Pancreatic Effects due to Activation of the Sympathetic Nervous System
Glucagon release
Decreased release of insulin
Some insulin resistance
Hepatic Effects due to Activation of the Sympathetic Nervous System
Glycogenolysis
Increased glucose & lactate concentration
Mobilization of FFA from lipid stores
Hormones Released by the Anterior Pituitary in a Stress Response
ACTH
GH
Prolactin
What releasing factors are released from the hypothalamus to trigger hormone release from the anterior pituitary?
CRH
GHRF
What is the posterior pituitary controlled by?
Hypothalamus: directly
Hormones Released from the Posterior Pituitary in a Stress Response
ADH
Changes in the Anterior Pituitary During a Stress Response
Increased ACTH
Increased GH
Increased prolactin
Increased ACTH Leads to
Increased release of cortisol & glucocorticoids from the adrenal medulla
Increased GH Leads to
Increased blood sugar
Antagonizes insulin
May have positive role in wound healing
Why is there increased prolactin in the stress response?
Decreased prolactin inhibiting factor
Increases in ADH Leads to
Further increase in ACTH
Function of Cortisol
Promotion of protein breakdown & gluconeogenesis
Inhibits glucose use & increases blood sugar
Promotes lipolysis further increasing blood glucose
Glucocorticoid anti-inflammatory effects
Mineralocorticoid effects causing fluid retention & potassium loss
Function of Insulin
Promotes uptake of glucose into muscle & adipose tissue
Coverts glucose into glycogen & triglycerides
Inhibits protein catabolism & lipolysis
Function of Increased Glucagon Release
Promotes hepatic glycogenolysis
Increases gluconeogenesis from amino acids in the liver
Has lypolytic activity
Effects of the Stress Response on Thyroid Hormones
Total & Free T3 decrease & return to normal after several days
TSH decrease for 2 hours & then return to normal
Carbohydrate Metabolism in a Stress Response
Glucose homeostasis mechanisms are ineffective
Lack of insulin to get sugar into the cells
Hyperglycemia Leads to
Wound infection
Impaired wound healing
Protein Metabolism in a Stress Response
Increased cortisol & cytokine concentration
Weight loss & muscle wasting
Can measure protein loos indirectly by nitrogen excretion in the urine
Increased Cortisol & Cytokine Concentration Leads to
Catabolism primarily from skeletal muscle
Albumin production reduced & alters extracellular volume