Patho Exam 3 - Hematologic System

What are the 4 components of hemoglobin?

RBC, heme group, O2 molecule, iron

Important things to know about hemoglobin

• iron allows hemoglobin to bind O2

• O2 had an increased affinity to iron

• O2 from lungs, enters RBC → O2 bonded to hemoglobin molecules → O2 released to tissue cells

What do peritubular interstitial fibroblasts do?

initiate a pathway for erythropoietin to be produced in a state of hypoxemia

Go through the process that keeps hemoglobin in homeostasis

1) STIMULUS - hypoxia (low blood O2) due to: decreases RBC count, decreased amount of hemoglobin, decreased availability of O2

2) KIDNEY - releases erythropoietin

3) ERYTHROPOIETIN - stimulates red bone marrow

4) INCREASING RBCs - enhanced erythropoiesis increases RBC count

5) CARRYING - O2 carrying ability of blood increases

Anemia

• a decrease in the oxygen carrying capacity of the blood

• this occurs secondary to fewer RBCs or a decrease in RBC function

• results in inadequate O2 delivery to the tissues

• carotid receptors sense the decreased O2 presence in the blood, stimulating the sympathetic NS

Pallor

looking very pale, even present in the eyes

Causes of anemia

• renal failure - no EPO secretion

• infiltrative process (leukemia) - cancer turns bone cells monoclonal, gets crowded

• aplastic anemia (viral or autoimmune) - stem cells stop producing blood cells

• nutrition deficiency - deficient in iron, B12, and folate

• RBC components - parts of the RBC are formed/shaped wrong (sickle cell)

• trauma or hemolysis to the blood vessel

Polycythemia

• an increase in RBCs

• results in more viscous blood and can result in thrombosis development and stroke

• caused by an increase EPO secretion due to chronic hypoxia, COPD, living at high altitude, sleep apnea

What is polycythemia vera caused by?

JAK2 mutation

What can a deficiency in either platelets or coagulation factors lead to?

excessive bleeding

An excess of platelets or deficiency in antithrombotic proteins can lead to what?

hypercoagulability (thrombus formation)

Platelets

• platelets adhere to a vessel wall and secrete substances that recruit more platelets to stick together to aggregate and form a clot

What protein helps a blood clot from and how does it do it?

• Von Willebrand’s factor

• helps a blood clot form by binding to platelets to encourage adhesion

*VW Factor deficiency is a genetic disorder (autosomal dominant or recessive) that results in increased bleeding

Thrombocytopenia

• decreased number of platelets

• causes: malignancy, radiation, drugs, infection

What causes platelets loss/destruction?

infection, drugs, autoimmune, overuse of available platelets resulting in inappropriate aggregation

Clotting Factors

are proteins made in the liver (vitamin K is necessary in this process)

What can alter clotting factors?

• liver failure, vitamin K deficiency, genetic protein mutation (hemophilia)

• any alteration in the clotting cascade can delay clotting, blood thinning meds are often used to intentionally avoid hypercoagulopathy

Thrombotic Thrombocytopenic Purpura (TTP)

• mutation where adamts13 protein does not break apart VW factor

• results in microclots and potentially larger clots

• causes petechial rash

Hypercoagulable states

• can lead to clot formation

• Protein C,S, and antithrombin III serve as check and balances for the clotting system to prevent venous thrombosis - mutations in any of these proteins can leave to deficiency and increased hypercoagulability

• Factor V (normally binds to platelets to induce clotting) Leiden Mutation causes factor V to be unable to be inactivated by protein C, resulting in hypercoagulability