Circulatory Disorder: Hemorrhage & Homeostasis Flashcards
Describe hemorrhage.
-escape of blood from blood vessels (extravasation)
>ext or int (tissue/body cavity)
>arterial, venous, capillary
*hyperemia & congestion = blood in vessel
Describe the 2 types of hemorrhage.
- Rhexis
-tear in vascular wall due to:
>trauma, necrosis of blood vessel wall, invasion of blood vessel by neoplasia - Diapedesis
-small defect in vessel wall or RBCs passing thru vessel wall in inflam or congestion due to:
>inflam, congestion, hypoxia, toxins, coagulation disorder
*wall is intact, but inc capillary permeability
Describe the causes of hemorrhage.
- Trauma
- Sepsis, viremia, bacteremia, toxic conditions -> necrosis & degen of endothelial cells
- Chemical agents
- Neoplasia
- Coagulation abnormalities
Describe hemorrhage classification based on size.
- Petechia = 1-2 mm
- Purpura = 3mm-1cm
- Ecchymosis = 1-2 cm
- Suffusive = larger than ecchymosis
- Paint brush
- Hematoma
- Linear
*Diathesis = inc tendency to bleed/bruise easily from insig injuries (platelet & coagulation disorders)
Describe hemorrhage classification based on location.
- Perivascular
- Sub-serosal
- Sub-mucosal
- Sub-capsular
- Subdural
-bleeding between arachnoid mater & dura - Epidural
-bleeding between dura mater & skull - Hemothorax
-blood in thoracic cavity - Hemopericardium
-blood within pericardial sac
-can lead to fatal cardiac tamponade - Hemoperitoneum
-blood in peritoneal cavity
Describe other areas of hemorrhage.
- Hemarthrosis = blood in joint space
- Hemopytsis = coughing up blood or blood stained sputum from lungs or airways
- Hyphema = blood in anterior chamber of eye
- Epistaxis = bleeding from nose
- Hematemesis = vomit up blood
- Hematochezia = fresh blood in stool
- Melena = tarry blood in stool
Describe hemorrhage resolution.
-result of hemostasis
-sm amount can be reabsorbed
-lg amount require phagocytosis & degradation by macrophage
-organizing hematoma = central mass of fibrin & RBCs surrounded by supportive vascular CT (fibrous) -> macs phagocytose lesion
Describe hemorrhage clinical significance.
- General (vol & rate) hemorrhagic shock
-profuse blood loss -> acute anemia -> hypovolemic shock -> death
-anemia bc repeated small hemorrhage - Location & severity compressive effects
-mechanical compression of organs due to a hematoma
-brain & heart = fatal
Describe hemostasis.
-keeps blood fluid clot free in blood vessel
-physiological response to vascular damage = rapid clot formation
-mechanisms to seal an injured vessel to prevent blood loss
Describe the mechanisms of hemostasis.
Describe the coagulation cascade.
-enzymatic conversions
>each step proteolytically cleaves inactive proenzyme into activated enzyme = thrombin formation
-conclusion of proteolytic cascade = thrombin coverts soluble plasma protein fibrinogen into fibrin
-coagulation factors are plasma proteins made by liver
Describe the end of the coagulation cascade.
- Stabilize clot by fibrin
- Contract fibrin platelet clot
- Reduce size of clot (restore flow)
- Draws damaged vessel edges closer (for healing)
Describe why coagulation would fail.
- Hepatic disease (cant make coagulation factors)
- Platelet defect
- Nutrition deficiency (vit K)
- Toxics (warfarin)
- Hemophilias (absence of coagulation factors)
- Bacterial invasion during clot formation