Medical Terminology Quiz

Hemostasis

• Hemostasis is the process of blood clotting, preventing excessive bleeding after blood vessel damage.
• Inadequate hemostasis can lead to hemorrhage, potentially causing hypotension, shock, and death.
• Inappropriate clotting (thrombosis) or clot migration (embolism) can obstruct blood vessels.
• Ischemic cell death (infarction) is a potential consequence.
• Myocardial infarction, pulmonary embolism, and cerebrovascular accident are major causes of morbidity and death in developed countries, linked to thromboembolism.

Hyperemia and Congestion

• Hyperemia and congestion both involve increased blood volume in tissues but have different mechanisms.
• Hyperemia is an active process caused by arteriolar dilation and increased blood flow, seen in inflammation or exercise.
• Congestion is a passive process resulting from impaired outflow of venous blood. It can be systemic (e.g., heart failure) or local (e.g., venous obstruction).

Oedema

• Oedema is the abnormal accumulation of free fluid in interstitial tissue spaces and serous cavities.
• Free fluid in body cavities is called effusion (e.g., ascites in the peritoneal cavity).
• Free fluid in interstitial space is called oedema.
• Oedema can be localized (e.g., limb) or generalised (e.g., systemic).
• Oedema is caused by factors like increased capillary hydrostatic pressure, lymphatic obstruction, increased capillary permeability, and sodium/water retention.
• Transudates have low protein content and are often associated with cardiac or renal diseases.
• Exudates have high protein content and inflammation.

Dehydration

• Dehydration is a state of pure water loss, leading to sodium retention (hypernatremia).
• Clinical symptoms include intense thirst, mental confusion, fever, and oliguria.
• Causes include gastrointestinal losses (vomiting, diarrhea), renal losses (diabetes insipidus), excessive perspiration and through skin (burns, injuries).

Overhydration

• Overhydration is an increased extracellular fluid volume due to pure water excess or water intoxication.
• Symptoms include disordered cerebral function (nausea, vomiting, headache, confusion, and convulsions), potentially leading to coma/death.
• Causes include excessive unmonitored intravenous fluid infusions, and renal retention of sodium and water (e.g., congestive heart failure).

Disturbances in Blood Volume

• Hyperemia and congestion describe localised increases in blood volume within dilated vessels of an organ or tissue.
• Active (arterial) hyperemia results from increased blood inflow due to arteriolar dilation.
• Passive (venous) hyperemia arises from impaired venous drainage, leading to decreased outflow.

Active Hyperemia

• Active hyperemia is the increased blood flow due to vasodilation of arterioles and capillaries.
• The process is driven by sympathetic neurogenic mechanisms or vasoactive substances.
• Examples include inflammation (e.g., congested vessels in pneumonia) and blushing.

Passive Hyperemia (Venous Congestion)

• Passive hyperemia (congestion) refers to impaired venous drainage and accumulation of blood in veins and capillaries, leading to bluish discolouration (cyanosis) and swelling in tissues.
• Venous congestion can be local (e.g., portal obstruction) or systemic (e.g., heart failure).
• This condition can cause tissue damage and rupture of blood vessels.

Haemorrhage

• Haemorrhage is the escape of blood from blood vessels, either externally or internally into serous cavities.
• Haematoma is the extravasated blood collected in tissues, leading to swelling.
• Petechiae are small haemorrhages, purpura are larger, and ecchymoses are subcutaneous haemorrhages (bruises).
• Common causes include trauma, spontaneous haemorrhage (e.g., aneurysm), inflammation, and neoplasia.
• The severity of hemorrhage depends on the amount, speed of loss, and site of bleeding.

Haemorrhage Effects

• Haemorrhage effects depend on amount, speed, and location.
• Significant loss (over 20%) can lead to clinical effects, sudden/rapid loss over 33% may be fatal.

Hemostasis and Thrombosis

• Normal hemostasis maintains a clot-free state in vessels, promoting rapid clot formation at injuries.
• Thrombosis is the problematic counterpart, involving clot formation in intact vessels.
• Both processes involve the vascular wall, platelets, and the coagulation cascade.
• Injury to endothelium exposes sub-endothelial materials, triggering platelet activity and initiating the coagulation cascade.

Thrombosis

• Thrombosis involves the formation of a solid mass (thrombus) in blood from its constituents.
• Turbulence and stasis (slow blood flow) contribute to arterial and venous thrombosis, respectively.

Embolism

• An embolus is a solid, liquid, or gaseous mass carried by blood, causing blockage at a distant site from its origin.
• Common causes include dislodged thrombi, fat droplets, air bubbles, or nitrogen.

Infarction

• Infarction is the area of ischemic necrosis caused by reduced vascular supply, resulting in tissue death.
• Infarcts can be red (hemorrhagic) or white (anemic), depending on the cause (venous or arterial blockage).

Shock

• Shock is a systemic hypoperfusion of tissues due to decreased cardiac output or blood volume, leading to impaired tissue perfusion, cellular hypoxia, and potential organ dysfunction/failure.
• Types of shock include cardiogenic, hypovolemic, and septic.