AD Lecture #5

What is hemostasis?

The ability to form a clot.

What three things does the body's ability to form a clot depend on?

1. Vessel walls (endothelium): inside lining

2. platelets (# and functions

3. coagulation factors, tissue factors

What is primary hemostasis?

A platelet plug (unstable) formed at the site of a vessel injury.

What is secondary hemostasis?

The strengthening of the platelet plug by the addition of fibrin

- Stable platelet plug

- Coagulation cascade

What is the main difference between primary hemostasis and secondary hemostasis?

- Primary hemostasis is an unstable platelet plug

- Secondary hemostasis has fibrin and a stable platelet plug

Primary hemostasis disorders involve what type of cell

platelets

What is a purple top tube used for?

It is used for CBCs and contains EDTA coagulant.

What are petecchiae?

Pinpoint hemorrhages seen on mucosal surfaces and hairless areas of skin.

What are petechial hemorrhages a clinical sign of?

Platelet disorders

What is purpura?

Large red/brown/purple spots on skin caused by bleeding underneath the skin's surface due to ruptured small blood vessels (capillaries)

What is a hematoma?

A blood blister or blood swelling.

What stabilizes a clot?

Fibrin

What does thrombin convert?

Thrombin converts fibrinogen to make fibrin.

Secondary hemostasis disorders involve what problem

the body's coagulation factors

What is epistaxis?

a nosebleed

What are the coagulation factors in the intrinsic pathway?

Factors 12, 11, and 9.

What are the coagulation factors in the extrinsic pathway?

Factors 3 and 7.

What are the coagulation factors in the common pathway?

Factors 10, 5, 1, and 2.

What test is done in the intrinsic pathway?

PTT, APTT, ACT coagulation time

What test is done in the extrinsic pathway?

PT

What test is done in the common pathway?

PT

What color top tube is used for coagulation studies?

Sodium citrate, blue top tube

What is a thrombus?

A blood clot that forms in the bloodstream or circulatory system (stationary)

What is ischemia?

A condition that restricts blood supply and oxygen to parts of the body

What are the three characteristic factors for Virchow's triad?

1. Hypercoagulable

2. Abnormal Blood Flow

3. Endothelial injury

What is hypercoagulability?

A change in the viscosity of the blood or thickening of blood

What is sludging?

The slow movement of blood.

What is abnormal Blood Flow?

Turbulence of the blood which bounces platelets, WBCs and RBCs off of the vessel walls which causes damage

What is endothelial injury?

Narrowing of the vessel and trauma that causes tissue factors and clotting factors to be released into circulation

Can the three Virchow's triad factors work independently?

Yes, they can work independently.

What is an infarct?

Tissue death.

What happens if thrombi act like an infarct?

It causes occlusion of blood supply and localized ischemia.

What is an embolus?

A moving blood clot.

What are some examples of an embolus?

- Fat (gain access to circulation due to trauma)

- bacteria (septicemia)

- parasites (HW)

- Neoplasia (tumor spreading)

- foreign bodies (catheter)

- air bubbles

What percent of emboli are actually thrombi?

99%

What disease do cats have that can cause saddle thrombi?

Hypertrophic cardiomyopathy (HCM).

What is hypertrophic cardiomyopathy?

A condition where the walls of the ventricles thicken, reducing blood flow.