ANP 1115 - Blood (Pt. 2) & Intro to Heart Flashcards
What is Fibrinolysis?
Removal of clot when no longer needed
What is the Key enzyme for Fibrinolysis?
Plasmin (precursor is plasminogen - plasma protein that gets incorporated into the clot)
- Plasminogen is the inactive form of plasmin
- Plasmin breaks down blood clot
What is Plasminogen Activated by?
Activated by tPA - Tissue Plasminogen Activator
- released by endothelial cells
When does Fibrinolysis begin and end?
Begins within 2 days and continues until clot is dissolved
What are the two Homeostatic Mechanisms to Control Size of Clot?
- Swift removal of coagulation factors
- Inhibition of activated clotting factors
What does Clot Formation Require?
Requires [procoagulation factors] > [anticoagulation factors]
What is the Importance of Vascular Spasms in response to Injury?
flowing blood washes away procoagulants
- Vascular spasms cause vasoconstriction, hence decrease in blood flow to maintain [procoagulants]
What happens to Thrombin as it is formed?
As thrombin forms, it is adsorbed onto fibrin threads (limits clot size)
What is the Role of Antithrombin III?
antithrombin III (plasma protein) inactivates any escaping thrombin
- antithrombin III & protein C (plasma protein) inactivate many intrinsic pathway procoagulants
What is Heparin and its Role?
basophils & mast cells
- enhances activity of antithrombin III and inhibits intrinsic pathway
What does Smooth Endothelial Lining of undamaged blood vessels prevent?
prevents undesirable clotting
- no access to collagen
- endothelial-derived NO & prostacyclin
What is a Thrombus?
A clot that develops and persists in an unbroken blood vessel
- can block critical blood circulation to those tissues
What might promote Thrombus formation in an unbroken blood vessel?
What is an Embolus?
A thrombus which ha broken free
- can get stuck in a vessel of small diameter
e.g., pulmonary or cerebral emboli
How do you treat a Thrombus?
Treat with drugs such as tPA, streptokinase to dissolve clots via plasmin
Why is a low does of Aspirin a good Preventative Therapy in heart attack risk patients?
Aspirin interferes with the production of prostaglandins
- Low dose because you still need blood clotting
- Preventative measure
What are the Three Bleeding Disorders?
- Thrombocytopenia
- Impaired Liver Function
- Hemophilias
What is Thrombocytopenia?
Any condition harmful to bone marrow (malignancy, radiation, drugs)
- Interference with normal levels of production of platelets
- Easy bruising due to internal hemorrhage
- Petechiae: tiny area of damage to capillary
What is Hemorrhage?
Escape of blood from a ruptured blood vessel?
Why does Whole Blood Transfusion only give TEMPORARY relief for Thrombocytopenia?
Platelet life span is only 10 days
What are some Impaired Liver Functions?
Hepatitis, cirrhosis (procoagulants come from liver)
- Liver disease also associated with reduced bile production
- Bile is required to absorb vitamin k
What is the Role of Bile?
Assists with digestion of fats in GI system
What is Hemophilias?
Hereditary bleeding disorders due to deficiencies in intrinsic pathway factors
What is the Difference between Hemophilia A and Hemophilia B?
Hemophilia A (83% of cases): lack factor VIII
Hemophilia B: lack factor IX
- both sex-linked and require regular transfusion
How does the body compensate for Blood Loss?
- Generalized vasoconstriction to decrease blood vessel volume
- increasing the rate of erythropoiesis
What can a loss of 15-30% of blood cause?
weakness, pallor (paleness)
- loss of > 30% can induce shock
When is Whole Blood Transfusion performed?
If substantial blood loss or thrombocytopenia
- often packed red cells for anemia
What is the Donor’s blood mixed with?
donor blood mixed with an anticoagulant (citrate dextrose – a calcium chelator)
- can be stored several weeks @ 40C
What is the importance of Citrate Dextrose?
Binds calcium ions
- important cofactor in blood clotting
What do RBC Antigens promote?
Agglutination
What causes Agglutination problems during Transfusion?
Only the ABO and Rh antigens cause serious agglutination problems during transfusion
Why is Type O the Universal Donor?
No antigens
Why is Type AB the Universal Recipient?
No antibodies
Where was Rh D first identified?
Rh D first identified in Rhesus monkeys, then in humans (~85% North Americans Rh+
How do Rh Antibodies differ from those of ABO Antibodies?
Rh antibodies NOT spontaneously formed in blood of Rh- individuals
- individuals become sensitized upon first exposure to Rh antigens (transfusion, carrying an Rh+ fetus)
- antibodies will attack donor RBCs in response to second & subsequent exposures
How is erythroblastosis fetalis prevented in Rh- Mothers?
Rh- mothers carrying second Rh+ fetus treated with RhoGAM (anti-Rh serum) to prevent erythroblastosis fetalis (hemolytic disease of the newborn)
Why is the problem with transfusion the recipient’s agglutinins and not the donors?
Donors have a finite amount of antibodies
- recipients can produce more antibodies
What is Agglutination?
clogging of small blood vessels
What happens to Clumped RBCs?
Clumped RBCs rupture or are destroyed by phagocytes & Hb released
What is the Overall Result of Agglutination & Hemolysis?
- Blocked flow to tissues
- Reduced O2-carrying ability of blood
- Hb Precipitates / clogs kidney tubules (possible kidney failure)
What are the Symptoms of Agglutination?
Fever, chills, nausea, vomiting, general toxicity
How is kidney failure prevented?
Critical to prevent kidney failure by administering alkaline fluids to dilute & dissolve Hb
- Diuretics also work
What is Autologous Transfusion?
Storage of patients own blood pre-surgery
e.g., 1 unit / 3-4 days before surgery
What is Blood Typing?
- Use serum containing anti-A or Anti-B agglutinins
- Similar procedure for Rh factor typing
What is the Heart?
simply a transport system pump
- hollow blood vessels provide delivery routes
What is the Heart enclosed by?
enclosed within mediastinum of thorax
- Region in the thoracic cavity that holds the heart
Where is the Base and Apex o the heart?
- broad, flat base toward right shoulder
- apex points toward left hip
What are the Three Layers of the Heart?
pericardium, myocardium, endocardium
What is the Pericardium?
Double-walled, firbo-serous sac
a) fibrous pericardium (thicker part)
b) serous pericardium (thinner part)
What is the purpose of Fibrous Pericardium of the Heart?
- protects and anchors heart
- prevents overfilling of heart (puts an upper limit on how much the heart can be filled to prevent tearing or damaging)
What is the Serous Pericardium?
parietal & visceral (epicardium) layers + fluid-filled pericardial cavity
- deep to the fibrous pericardium
What is the Pericardial Cavity?
Contains serous fluid to allow the heart to fill and contract comfortably
- frictionless surface
What is the Myocardium?
- cardiac muscle
- branching cardiac muscle cells arranged into bundles
What is cardiac muscle?
bulk of the heart
- very electrical
- conducts electrical impulses from one cell to the next
What is the role of Connective Tissue Wrappings of Cardiac Muscle bundles?
- Insulation around bundles to direct flow of electricity through the atria and ventricles of the heart
- reinforce myocardium internally
- anchor cardiac muscle fibers
- provide additional support for great vessels and valves
- direct spread of action potentials across heart to specific pathways
What is the Endocardium?
Layer of endothelium + CT layer on inner myocardial surface
- continuous with endothelium of vessels leaving & entering heart
What are the two Exterior Grooves?
- Coronary Sulcus
Anterior-Posterior Interventricular Sulcus
What is the Coronary Sulcus?
- runs horizontally
- provides a pathway to vessels for coronary circulation
What is the Anterior-Posterior Interventricular Sulcus?
- Passageway between left + right ventricles
- depression on surface of heart to provide passageway for coronary vessels
- branch into smaller vessels into muscular of the heart in order to develop
- deliver oxygen and nutrients
What are the Atria?
Receiving Chambers
- small, thin-walled
- need only convey blood to ventricles
Where does Deoxygenated, Systemic Blood enter?
Enters through right atrium via:
- Superior vena cava (receives oxygen poor blood from above the heart)
- inferior vena cava (receives oxygen poor blood from areas below the heart)
- Coronary sinus from myocardium (receives oxygen poor blood from the walls of the heart)
Where does Oxygenated blood enter?
Oxygenated blood to left atrium via 4 pulmonary veins
What are Pectinate Muscles?
muscle bundles found especially in the right atrium
- Fossa Ovalis
- Foramen Ovale
What is the Foramen Ovale?
Opening between left and right atrium in developing fetus that allow the two bloods to mix
What is the Foss Ovalis?
Closure of foramen ovale
- make shallow depression
What are Ventricles?
Discharging Chambers
- the real pumps of the heart
- walls much thicker (especially left ventricle - 3x thicker)
What do the Left and Right Ventricles pump?
Right Ventricle: pumps blood oxygen-poor to the pulmonary trunk
Left Ventricle: pumps oxygen-rich blood to the aorta
What are the Muscle Bundles of the Ventricles?
Internal walls have muscle bundles:
- trabeculae carneae
- papillary muscles (link the chordae tendineae)
What direction is blood flow?
Blood flow is unidirectional
- enforced by 4 valves
What is the importance of Chordae Tendineae and Papillary Muscles?
keeps valves closed
What are the Heart Valves?
- Atrioventricular Valves
- Semilunar Valves
What are the Atrioventricular Valves?
Paired between left and right
i) tricuspid valve: right atrium to right ventricle
ii) mitral (bicuspid) valve: left atrium to left ventricle
What are the Semilunar Valves?
Paired, from ventricles to either pulmonary or systemic circuits
i) Pulmonary valve: right ventricle to pulmonary trunk (then arteries)
ii) aortic valve: left ventricle to aorta
What are the Valve Problems?
Valvular Insufficiency: incompetent valves that don’t close 100%
Valvular Stenosis: valves stiff due to calcification and/or scar tissue; doesn’t open all the way
What is the difference between Pulmonary and Systemic Circuit?
pulmonary circuit (right ventricle): short, low-pressure circulation
systemic circuit (left ventricle): long pathway with 5X resistance
What is Coronary Circulation?
- shortest, but one of the most important, circulations in the body
- Left & right coronary arteries branch from the base of the aorta
- encircle the heart in the coronary sulcus (atrioventricular groove)
What are Anastomoses?
Vessels that join up together
- Provides alternate routes for nourishment if a given artery begins to be occluded (blocked)
What are the Diseases of Coronary Vessels?
Angina Pectoris: chest pains
- vessels narrow (many occlusions)
Myocardial Infarction: Heart attack due to total occlusion
- complete blockage of O2 and nutrients to particular area of heart muscle
