Exam 4 Flashcards
Define hemostasis. .
-Process which causes bleeding to STOP Prevents hemorrhage (massive decrease in blood volume)
Describe step 1 of hemostasis- vascular constriction
a. Local myogenic spasm b. Local autacoid factors from the traumatized tissues and blood platelets c. Nervous reflexes
Where are thrombocytes formed?
red bone marrow
Thrombocyte production is regulated by?
Thrombopoietin (liver and kidney)
List the contents/functions of thrombocyte membrane receptors and cytoplasm.
Adhesion proteins- vWF, fibronectin, collagen, fibrinogen Actin and myosin Phospholipids
Which substances activate platelets?
1.ADP released from damaged erythrocytes 2.Exposed collagen fibers 3.Thromboxane A2
What are the antithrombotic (anti-platelet) properties/functions of the endothelium?
1.Covers highly thrombogenic basement membrane -Uninjured endothelium does not bind platelets 2. PGI2 (prostacyclin) and NO from uninjured endothelium inhibit platelet binding 3. ADPase counters the platelet aggregating effects of ADP
Describe step 2 of hemostasis- platelet plug formation.
- Platelet adhesion -Subendothelial protein layer exposed -Platelets bind to subendothelial vWF, and collagen via surface glycoproteins -Platelets swell 2. Platelet release reaction -Release platelet agonists from granules 3. Platelet aggregation
Blood Coagulation.
Blood Clotting (Step 3 of hemostasis)
What is a blood clot?
1.Blood that has been converted from a liquid to a solid state 2. Formed elements trapped in insoluble fibrin threads
List the substances required for blood clotting.
Ca2+ Enzymes synthesized by liver cells Substances released by platelets or damaged tissues
Why is blood coagulation described as a cascade of reactions?
Each clotting factor activates the next in a fixed sequence
What is the end result of blood coagulation?
formation of insoluble fibrin threads
Describe step 3 of Hemostasis: Blood Coagulation
3 pathways 1. Extrinsic 2.Intrinsic 3. Common
Type of damage that activates the extrinsic pathway?
Tissue Trauma causes tissue factor (thromboplastin to leak into the bloodstream)
Type of damage that activates the intrinsic pathway?
endothelial damage occurs and platelets come in contact with exposed collagen fibers Phospholipids are released from damaged platelets
What ion activates the clotting factors in the extrinsic pathway?
Ca2 and clotting factors combine to create Prothrombin Activator (Prothrombinase)
What ion activates the clotting factors in the intrinsic pathway?
Ca2+ and clotting factors combine to form Prothrombin Activator (Prothrombinase)
Prothrombin activator forms in seconds or minutes in the extrinsic pathway
Prothrombin Activator forms in seconds Faster process
Prothrombin activator forms in seconds or minutes in the intrinsic pathway
Prothrombin Activator forms in several minutes
Is Less or More steps involved in the extrinsic pathway?
Less
Is Less or More steps involved in the intrinsic pathway?
More
What enzyme is produced at the end in the extrinsic pathway?
Prothrombin Activator (Prothrombinase)
What enzyme is produced at the end in the intrinsic pathway?
prothrombin Activator (Prothrombinase)
Describe what is occurring during the common coagulation pathway.
- Prothrombin Activator and Ca2+ -Catalyzes the conversion of Prothrombin to Thrombin 2. Thrombin -Soluble Fibrinogen + Ca2+ = Insoluble Fibrin Threads Positive feedback effects -Accelerates formation of Prothrombinase -Activates platelets to release phospholipids
Describe what is occuring during step 4 of hemostasis- clot retraction and blood vessel repair.
Blood clot plugs the ruptured area of blood vessel Platelets pull on fibrin threads causing clot retraction Actin and Myosin -Squeezes serum from the blood clot blood clot shrinks Trapped platelets release factor XIII stabilizing the fibrin threads Edges of damaged vessel are pulled together Fibroblasts and endothelial cells repair the blood vessel
What are the two normal hemostatic control mechanisms?
- Fibrinolytic system 2. Anticoagulants Present In Blood to Prevent Intravascular clotting
What is the function of plasminogen?
Becomes Plasmin (Fibrinolysin) which digests fibrin threads
What is the function of Plasmin?
digest fibrin threads
Is plasminogen an active or inactive enzyme?
inactive
Is plasmin an active or inactive enzymes?
active
What is the function of prostacyclin produced by wbc’s and endothelial cells?
Opposes thromboxane A2 Inhibits platelet adhesion and release
What is a thrombus?
Blood Clot Decreased blood flow allows clotting factors to build up locally activates coagulation cascade
What is a embolus?
Thrombus may dissolve spontaneously or dislodge and travel Blood clot, air bubble or fat from broken bone in the blood
What are the vitamin K dependent clotting factors?
Factors II (Prothrombin), VII, IX and X
Where are the vitamen K clotting factors produced?
hepatocytes
Why are people prescribed Coumadin (Warfarin)?
vitamin k antagonist
What is the function of anticoagulants and thrombolytic agents?
Suppress or prevent blood clotting
Describe the Fibrinolytic System in normal hemostatic control
- Dissolves small, inappropriate clots and clots at a site of a completed repair 2. Inactive plasminogen is incorporated into the clot -Activation occurs with factor XII, thrombin, and t-PA -Plasminogen becomes Plasmin (Fibrinolysin) which digests fibrin threads 3. Clot formation remains localized -Fibrin absorbs thrombin -Blood disperses clotting factors -Endothelial cells and WBC’s produce Prostacyclin -Opposes thromboxane A2 -Inhibits platelet adhesion and release
What does Fibrinolysis mean?
To dissolve the clot
Describe what anticoagulants do in the blood to prevent intravascular clotting
Normal Hemostatic control mechanism -Anti-thrombin: Blocks X, XII, and II -Heparin Mast cells (in tissue) and Basophils (in blood)
Where is vitamin K produced?
bacteria in large intestine
If you select a esogeal tube that is too big for an animal what does it do to the deadspace?
Increases it and their will not be enough air.
Hemostasis needs to be ______,______, and ________.
Rapid, localized and reversible
what happens when something hemorrhages?
A massive decrease in blood volume
Blood must be______and ______ at appropriate time
Fluid, coagulate
What are the 3 major functions of the respiratory system?
- Supply O2 to the Tissues 2. Remove CO2 from the Tissues 3. Acid/Bases Balance
List the four major functional events of the respiratory system.
- Pulmonary Ventilation (Breathing) 2. Diffusion of O2 and CO2 between alveoli and blood (high to low) 3. Tranport of CO2 and O2 to and from tissues (Hemoglobin) 4. Regulation of Pulmonary secretion
Describe how the lungs can be expanded and contracted in two ways.
- change vertical Diameter 2.changing the anterior posteri diameter of the thoracic cavity.
What are the lungs made of?
Elastic Tissue -want to collapse when air is let out
What is visceral pleura?
Covers the Lungs
What is parietal pleura?
Covers the Internal Surface of the Thoracic Cavity
What is the pleural Cavity?
Inbetween visceral and pareital pleura
What is pleural fluid?
A small volume of fluid between layers of the pleura
What is the function of pleural fluid?
To Lubricate and reduce friction during breathing Can have adhesion if missing
What is pleural pressure?
Pleural pressure is a ballance of pressure between visceral and pareital pleura
Is Plural Pressure normally negative or Positive compared to atmospheric pressure?
Negative (-5 to -4)
Does pleural pressure increase or decrease during inspiration?
It decreases or becomes more negative due to chest wall and lung expansion (lung volume increases)
Does pleural pressure increase or decrease during expiration?
Increasing but lung volume decreases
What is alveolar pressure?
Pa-The amt. of pressure within the alveolis. Inspiration 0 to -1 cm h20
Does alveolar pressure increase or decrease during inspiration?
Increase
What is Boyle’s law?
The volume of a gas varies inversley with pleural pressure assuming Temp. is constant
Does alveolar pressure increase or decrease during expiration?
Decrease
What is transpulmonary pressure (recoil pressure)?
Measurement of the elastic forces in the lungsthat tends to collapse the lungs during expiration
Define lung compliance.
-Measure of how easy it is to inflate the lung -Relates lung volume changes to changes in transpulmonary pressure (Slope of the P-V curve)
How much PTP does it take to expand only the lungs?
200 ml/cm H2O pressure required to inflate the lungs only
How much PTP does it take to expand the lungs and thoracic cage
110 ml/cm H2O pressure required to inflate the lungs and thoracic cage = * ½ as much pressure is required to inflate the lung
Describe what happens to volume and pressure if an alveolus is more compliant.
The more compliant an alveolus is, the less pressure is required to fill it with larger volumes of air.
Give some examples of decreased lung or thoracic cage compliance
Scar tissue from Tuberculosis Pulmonary edema Surfactant deficiency Paralysis of intercostal muscles
Give some examples of decreased lung or thoracic cage compliance
Scar tissue from Tuberculosis Pulmonary edema Surfactant deficiency Paralysis of intercostal muscles
How much PTP does it take to expand the lungs and thoracic cage?
110 ml/cm H2O pressure required to inflate the lungs and thoracic cage = * ½ as much pressure is required to inflate the lung
Describe what happens to volume and pressure if an alveolus is less compliant.
The less compliant an alveolus is, greater pressures are required to fill it with smaller volumes of air.
Describe the two elastic forces of the lungs.
- 33% of elastic forces of the lung tissue are caused by the elastic tissues of the lung (elastin and collagen fibers interwoven with lung parenchyma. 2. 67% is caused by surface tension at air fluid interface
What is surface tension?
A strong collapsing force within the lung
Name the types of alveolar cells.
Alveolar Epithelial Cells: Type I and Type II Alveolar Macrophages (Dust Cells)
What is the Law of Laplace?
As radius decreases, surface tenrion decreases
What is the equation?
P= 2 x Surface Tension)/radius of alveoli (r)
How does the Law of Leplace work during inspiration and expiration?
During exhalation, reduced surface tension causes alveoli to assume the smallest diameter possible (prevent collapse) so as r gets smaller surface tention gets smaller as well so P is adequate for small alveoli to stay open - During inhalation, surface tension must be overcome to expand the alveolus
What is respiratory distress syndrome?
Breathing disorder of premature newborns Alveoli cannot remain open due to lack of surfactant Great effort is needed to inhale in order to reopen the collapsed alveoli
What are the treatments for respiratory distress syndrome?
Supplemental oxygen CPAP (Continuous Positive Airway Pressure) Surfactant administered into lungs via trachea
How is surface tension reduced?
Reduced by surfactant Phospholipid + protein molecule
What is the function of a spirometer?
Measures volume changes of gas during inspiration and expiration
What is a spirogram?
Lung Volumes (ml) Y-axis) x-axis-Time Lung Capacities (ml (Plot)
Name the 4 major volumes of the lung.
- Tidal Volume (Vt) 2. Inspiratory Reserve Volume (IRV) 3. Expiratory Reserve Volume (ERV) 4.Residual Volume (RV)
What is Tidal Volume (Vt)?
One breath, either inspired or expired (500 ml)
What is Inspiratory reserve volume (IRV) ?
Volume that can be inspired voluntarily after a normal inspiration (3000 ml)
What is Expiratory Reserve Volume?
Volume that can be expired voluntarily after a normal expiration (1100 ml)
What is Residual Volume?
Volume of gas left in the lung after the maximum forced expiration (1200 ml)
Know the Graph
Draw a graph and explain how alveolar ventilation (hypoventilation and hyperventilation) affects PAO2 and PACO2
