Pathology Flashcards
Definition: edema
Increased interstitial fluid
Terms regarding other sites of increased fluid:
- Hydrothorax
- Hydropericardium
- Hydroperitoneum
Causes of edema
- Increased hydrostatic pressure
- Reduced plasma osmotic pressure
- Lymphatic obstruction
- Sodium retention
- Inflammation
Increased hydrostatic pressure causes edema through ___
Impaired venous return
Arteriolar dilation
What is hyperemia?
What kind of process? (Active or passive)
Arteriolar dilation leads to increased blood flow and engorgement of vessels with oxygenated blood
Active process
What is congestion?
What kind of process? (Active or passive)
Reduced outflow of blood causes increased volumes of deoxygenated blood, increased pressure, and stasis
Passive process
Classic sites of congestion
Lungs
Liver
Extremeties
Definition: hemorrhage
Hemorrhages in skin, mucous membranes, or serosal surfaces have specific names:
A release of blood into extravascular space
Petechiae 1-2 mm
Pupura >3 mm
Ecchymosis >1-2 cm
Clinical significance of hemorrhage depends on ___ and ___
Volume and rate of blood loss
Virchow’s Triad
- Endothelial injury
- Stasis or turbulent blood flow
- Hypercoagulability
Thrombosis: excessive clotting
Thrombi on heart valves are ___
Vegetations
Thrombi are usually attached __
and tend to propagate towards __
Attached at their site of origin
Propagate towards the heart
What happens to thrombi?
Propagate Embolism Dissolve Organize/recanalize Microbial seeding >> mycotic aneurysm (rare)
Definition: emboli
Detached intravascular solid, semisolid, or gaseous mass carried by the blood to a site distant from the point of origin
Pulmonary emboli usually originate from __
DVT of leg above the knee
Fat emboli usually originate __
From marrow of broken long bones
Fat emboli are sometimes accompanied by __
Rash
Air emboli causes?
Decompression sickness from gas bubbling in tissues (esp. nitrogen)
Introduction of >100 cc of air into a vessel during a procedure
Amniotic fluid emboli causes
Rupture of membranes and concurrent year of uterine vessels
High maternal mortality rate
Pathognomic: items present in amnion (fetal squames, lanugo hairs, etc) are present in embolus
Definition: infarct
Coagulation necrosis corresponding to a particular vascular distribution caused by either arterial or venous occlusion
99+% are thromboembolic
Types of infarcts:
Red (hemorrhagic)
- venous
- loose tissues
- tissues with dual circulation (liver, lung, bowel)
- congested tissues
- can occur when flow is re-established to a site
White (occlusive)
- arterial
- more “solid” organs
Factors that influence the development of an infarct:
- Nature of vascular supply
- Rate of development of the occlusion
- Tissue vulnerability to hypoxia
- Oxygen content of blood
Definition: shock
Circulatory collapse with resultant hypo-perfusion and decreased oxygenation of tissue
Causes of shock:
Decreased cardiac output
Widespread peripheral vasodilation
4 major types of shock
- Hypovolemic
- Cardiogenic
- Septic
- Neurogenic
Hypovolemic shock
What is it?
Causes?
Circulatory collapse resulting from acute reduction of circulating blood volume
Caused by:
- Severe hemorrhage or massive loss of fluid from the skin(injury, burns, trauma)
- Loss of fluid from GI tract (vomiting, diarrhea)
Cardiogenic shock
What is it?
Cause?
Circulatory collapse
Resulting from:
Pump failure of the left ventricle
Most often caused by massive myocardial infarction
Septic shock
What is it associated with?
Gram - infections
Cause gram - endotoxemia
- also occurs with gram + infections
- TSS - staph aureus
What is MODS?
Multiple organ dysfunction syndrome
Can be an outcome of septic shock
Characterized by systemic shut down of vital processes
Requires major intervention
Neurogenic shock is most often associated with ___
Severe trauma
and
Reactive peripheral vasodilation
Stages of shock:
- Nonprogressive (early) stage
- Progressive stage
- Irreversible stage
Non progressive (early) stage of shock Characteristics
Compensatory mechanisms:
- Increased heart rate
- increased peripheral resistance
Maintain perfusion of vital organs
Progressive stage of shock
Characteristics
Tissue hypoperfusion
Circulatory and metabolic imbalance
-metabolic acidosis from lactic academia
*compensatory mechanisms are no longer adequate
Irreversible stage of shock
Characteristics
Organ damage and Metabolic disturbances are so severe that survival is not possible
Morphologic manifestations of shock
ACUTE TUBULAR NECROSIS OF THE KIDNEY
Others: Brain necrosis Liver necrosis Fatty change in heart or liver Patchy mucosal hemorrhages in colon Depletion of lipid in adrenal cortex Pulmonary edema
What is DIC?
Disseminated Intravascular Coagulation
Widespread microvascular thrombi because of endothelial damage
Causes of DIC
- Major trauma (esp crush injuries)
- Overwhelming infections (often gram -)
- Obstetric complications
- Mucin-secreting adenocarcinomas
- Prostatic surgery
- Venomous snake bites
