Circulatory

What is the primary function of the vascular system?

The vascular system is a transportation system for cells, nutrients, and wastes, crucial for maintaining normal fluid and electrolyte balance.

List the basic structural components of the vascular system in order.

Artery – arteriole – capillary – venule - vein.

What are the main components of blood?

Red blood cells (erythrocytes, RBCs), White blood cells (leukocytes, WBCs), Platelets (or thrombocytes), Plasma.

What is serum?

Serum is the fluid component of blood without clotting proteins. It is plasma with clotting proteins removed.

Name the major protein components of plasma.

Albumin, Clotting proteins, and Globulins (including immunoglobulins).

What type of cells form capillaries?

Endothelial cells.

How is blood flow regulated at the capillary bed?

Blood flow is regulated by the arteriole.

Define vasoconstriction and vasodilation.

Vasoconstriction: Constriction of the arteriole, reducing blood flow. Vasodilation: Dilation of the arteriole, increasing blood flow.

What two factors primarily determine arterial blood pressure (BP)?

Cardiac output and peripheral resistance (PR).

State the formula relating blood pressure (BP), cardiac output, and peripheral resistance (PR).

BP = Cardiac output x PR.

What are Starling's forces, and what do they determine?

Starling's forces are counteracting forces at the capillary level that determine the movement of fluid in the capillary bed.

Name the two types of hydrostatic pressure involved in Starling's forces.

Capillary pressure and Interstitial fluid pressure.

Name the two types of colloidal osmotic pressure involved in Starling's forces.

Plasma colloidal osmotic pressure and Interstitial colloidal osmotic pressure. Albumin is a key protein contributing to plasma colloidal osmotic pressure.

What is the net fluid movement at the arterial end of a capillary? What about the venous end?

Arterial end: Net movement of fluid from the blood vasculature into the tissue. Venous end: Net flow of water back into the vascular system.

What system is responsible for removing excess fluid from the extravascular space?

The lymphatic system.

What is hyperemia? What is a common cause?

Hyperemia is a state of more blood in capillaries due to increased inflow. A common cause is vasodilation of arterioles. Blushing is an example.

What is congestion? What is a common cause?

Congestion is a state of more blood in capillaries due to reduced outflow. A common cause is post-capillary obstruction or venous pressure increase.

What is ischaemia? What are some common causes on the arterial side?

Ischaemia is reduced blood in capillaries due to reduced FLOW of blood. Common causes on the arterial side include vasoconstriction and a blood clot.

What can ischaemia on the venous side be due to?

Vascular congestion – outflow obstruction.

Define infarction.

Death of tissue due to ischaemia (reduced flow).

What are the two main types of infarcts, based on their appearance?

Arterial (white) infarct and venous (red) infarct.

In what type of circulatory systems do infarcts commonly occur? Give examples.

Infarcts commonly occur in end-artery systems (no collaterals). Examples include the heart, brain, and kidney. Myocardial infarct is an example of a white infarct.

What is oedema (edema)? What type of fluid is it?

Oedema is excess interstitial fluid. It is a transudate (low protein content).

Differentiate between exudate and transudate.

Exudate is effusion with high protein content, while transudate is effusion with low protein content. Edema is a transudate.

Give examples of conditions involving oedema.

Ascites, hydropericardium, hydrothorax, peripheral oedema.

What are the two main categories of oedema?

Inflammatory oedema and noninflammatory oedema.

What is the primary mechanism of inflammatory oedema?

Increased permeability of endothelium.

List some mechanisms and causes of noninflammatory oedema.

Increased venous hydrostatic pressure (e.g., heart failure, postural oedema), Reduced colloidal osmotic pressure (hypoproteinaemia/hypoalbuminaemia, e.g., kwashiorkor), Lymphatic vessel obstruction (e.g., removal of lymph node), Increased total body water.

What is haemorrhage?

Escape of blood from the vasculature.

External haemorrhage

Bleeding outside the body, including into the stomach and intestines.

Define internal haemorrhage and list the locations it can occur.

Bleeding into cavities (haemoperitoneum, haemopericardium) or into tissues.

Define haematoma, ecchymosis, and petechia.

Haematoma: Swelling of blood in tissues [-oma = swelling]. Ecchymosis: Group of petechia appearing as a paintbrush haemorrhage. Petechia: Pinpoint haemorrhages in tissues.

What is haemostasis?

The stopping of haemorrhage, a normal function of the blood.

Name the three major components involved in haemostasis.

Endothelial cells, platelets, and coagulation proteins.

What is the normal role of endothelial cells in haemostasis? What happens when they are injured?

Normally anticoagulant. When injured, they become procoagulant.

What are platelets and what is their role in haemostasis?

Cell fragments of megakaryocytes. They adhere, change shape, and recruit other platelets to form a primary plug.

What is the role of coagulation proteins in haemostasis?

They are activated in a cascade to form a fibrin mesh (secondary plug).

What is a thrombus? How does it differ from a postmortem clot?

A thrombus is a blood clot that develops within the vessels of a living organism. A postmortem clot forms in vessels after death.

Define thrombogenesis.

The process whereby blood clots (thrombi) are formed.

List three main factors that contribute to thrombogenesis.

Endothelial injury, Altered blood flow (stasis, turbulence), Hypercoagulability.

What is embolism?

A clustering or aggregation of a substance within the bloodstream that can cause obstruction.

Give examples of different types of emboli.

Thrombi (thrombotic), gas, air, marrow, neoplastic cells. Pulmonary embolism is a common type.

Define shock in the context of circulatory disturbances.

Widespread hypoperfusion of tissues resulting from reduced cardiac output and/or reduced effective circulating blood volume.

Name the three main categories or causes of shock.

Cardiogenic, Hypovolemic, Blood Maldistribution.

Give examples of conditions that can lead to hypovolemic shock.

Haemorrhage (less blood) or dehydration, protein loss (less plasma).

List the three types of shock categorized under blood maldistribution.

Neurogenic shock (spinal cord trauma), Septic shock (inflammatory mediators), Anaphylactic shock (hypersensitivity reaction).