hemostatis till the end of chal Flashcards
Normally, blood flows smoothly past the ___________ of blood vessel walls.
intact lining (endothelium)
But if a blood vessel wall breaks, a series of reactions is set in motion to accomplish _________
hemostatis
stoppage of bleeding
hemostatis
This response, which is fast and local-ized, involves many substances normally present in plasma, as well as some that are released by platelets and injured tissue cells.
Hemostasis
Hemostasis involves three major phases, which occur in rapid sequence:
1) vascular spasms
2) platelet plug formation
3) coagulation or blood clotting
Blood loss at the site is permanently prevented when __________ grows into the clot and seals the hole in the blood vessel.
fibrous tissue
The immediate response to blood vessel injury is vasoconstric-tion, which causes that blood vessel to go into spasms. The spasms narrow the blood vessel at that point, decreasing blood loss until clotting can occur: (Other factors causing vessel spasms include direct injury to the smooth muscle cells, stimulation of local pain receptors, and release of serotonin by anchored platelets.)
Vascular Spams occur
The immediate response to blood vessel injury is _________.
vasoconstriction
causes that blood vessel to go into spasms.
vasoconstriction
The_________ narrow the blood vessel at that point, decreasing blood loss until clotting can occur:
spams
Platelets are repelled by an intact endothelium, but when it is broken so that the underlying collagen tibers are exposed, the platelets become “sticky” and cling to the damaged site. Anchored platelets release chemicals that enhance the vascular spasms and attract more platelets to the site. As more and more platelets pile up, a small mass called a platelet plug, or white thrombus, forms.
Platelet Plug forms
_______ are repelled by an intact endothelium, but when it is broken so that the underlying _______ are exposed, the platelets become “sticky” and cling to the damaged site.
Platelets;
collagen fibers
____________ release chemicals that enhance the vascular spasms and attract more platelets to the site.
Anchored platelets
As more and more platelets pile up, a small mass called a __________, or __________, forms.
platelet plug or white thrombus
At the same time, the injured tissues are releasing tissue factor (TF), which interacts with PF3, a phospholipid that coats the surfaces of the platelets. This combination interacts with other blood protein clotting factors and calcium ions (Ca?+) to form an activator that leads to the formation of thrombin, an enzyme. Thrombin then joins soluble fibrinogen (fi-brin’ o-jen) proteins into long, hairlike molecules of insoluble fibrin.
Fibrin forms a meshwork that traps the RBCs and forms the basis of the clot (Figure 10.7).
Within the hour, the clot begins to retract, squeezing serum (plasma minus the clotting proteins) from the mass and pulling the ruptured edges of the blood vessel closer together.
coagulation events occur
the injured tissues are releasing _________, which interacts with PF3
tissue factor (TF)
a phospholipid that coats the surfaces of the platelets.
PF3,
This combination interacts with other blood protein clotting factors and calcium ions (Ca?+) to form an activator that leads to the formation of _______, an enzyme.
thrombin
Thrombin then joins soluble ________ proteins into long, hairlike molecules of insoluble fibrin.
fibrinogen
Fibrin forms a meshwork that traps the ________ and forms the basis of the clot
RBCs
Within the hour, the clot begins to retract, squeezing ________ (plasma minus the clotting proteins) from the mass and pulling the ruptured edges of the blood vessel closer together.
serum
plasma minus the clotting proteins
serum
Normally, blood clots within ___ to ____ minutes.
3 to 6
Once these events of the clotting cascade were understood, it became clear that placing a _________ over a cut or applying _________ to a wound would speed up the clotting process.
sterile gauze
or
pressure
gauze provides a ________ to which the platelets can adhere, and the pressure _____ cells, increasing the release of tissue factor locally.
rough surface;
fractures
The two major disorders of hemosta-
sis— _______________ and ____________
undesirable clot formation
and
bleeding disorders
Despite the body’s safeguards against abnormal clotting, undesirable clots sometimes form in intact (unbroken) blood vessels, particularly in the ______.
legs
A clot that develops and persists in an unbroken blood vessel is called a _________
thrombus
TRUE OR FALSE
if the blockage forms in the blood vessels serving the heart (coronary thrombosis), the consequences may be death of heart muscle and a fatal heart attack.
TRUE
Smooth muscle contracts, causing _______.
vasoconstriction
TRUE OR FALSE
Injury to lining of vessel exposes collagen fibers; platelets adhere.
TRUE
_______ release chemicals that make nearby platelets sticky; platelet plug forms.
Platelets
Clotting factors present in plasma and released by injured tissue cells interact with Ca? to form ________
thrombin
the enzyme that catalyzes joining of fibrinogen molecules in plasma to fibrin
thrombin
_______ forms a mesh that traps red blood cells and platelets, forming the clot.
Fibrin
If a thrombus breaks away from the vessel wall and floats freely in the blood-stream, it becomes an _______
embolus
An ________ is usually no problem unless or until it lodges in a blood vessel too narrow for it to pass through.
embolus
TRUE OR FALSE
Undesirable clotting may be caused by anything that roughens the endothelium of a blood vessel and encourages clinging of platelets, such as severe burns, physical blows, or an accumulation of fatty material.
TRUE
___________, or __________, is another risk factor, especially in immobilized patients.
Slowly flowing blood
or
blood pooling
True or False
A number of anticoagulants, the most important of which are aspirin, heparin, and dicumarol, are used clinically for thrombus-prone patients.
TRUE
TRUE OR FALSE
The most common causes of abnormal bleeding are platelet deficiency (thrombocytopenia) and deficits of some of the clotting factors, such as might result from impaired liver function or certain genetic conditions.
TRUE
results from insufficient number of circulating platelets
thrombocytopenia
TRUE OR FALSE
even small movements cause spontaneous bleeding from small blood vessels
TRUE
small purplish blotches that evidenced thrombocytopenia
petechiae
Thrombocytopenia can arise from any condition that suppresses the ________, such as bone marrow cancer, radiation, or certain drugs
bone marrow
(needed by the liver cells to produce the clotting factors)
vitamin K
_________ applies to several different hereditary bleeding disorders that result from a lack of any of the factors needed for clotting.
hemophilia
Commonly called “bleeder’s disease”
hemophilia
TRUE OR FALSE
When a bleeding episode occurs, hemophiliacs are given a transfusion of fresh plasma or injections of the purified clotting factor they lack.
TRUE
AIDS
acquired immune deficiency syndrome
_______ is a condition of depressed immunity
AIDS
Losses of _______ percent lead to pallor and weakness.
15 to 30
Loss of ______ percent causes severe shock, which can be fatal.
over 30
_________ are routinely given to replace substantial blood loss and to treat severe anemia or thrombocytopenia.
Whole blood transfusions
The usual blood bank procedure involves collecting blood from a donor and mixing it with an ________ to prevent _______.
anticoagulant;
clotting
The treated blood can be stored (refrigerated at _____, or _____) for about _____ until needed.
4°C or 39.2°F;
35 days
True or False
The plasma membranes of RBCs, like those of all other body cells, bear genetically determined proteins (antigens), which identify each person as unique.
TRUE
__________ is a substance that the body recognizes as foreign; it stimulates the immune system to release antibodies or use other means to mount a defense against it.
An antigen
Binding of the antibodies causes the foreign RBCs to clump, a phenomenon called ______
agglutination
a phenomenon which leads to the clogging of small blood vessels throughout the body.
agglutination
*The RBC antigens that promote this clumping are sometimes called__________, and the antibodies that bind them together are called __________
agglutinogens;
agglutinins
TRUE OR FALSE
There are over 30 common RBC antigens in humans, so each person’s blood cells can be classified into several different blood groups. However, it is the antigens of the ABO and Rh blood groups that cause the most vigorous transfusion reactions.
We describe these two blood groups here.
TRUE
the ______ blood groups are based on which of two antigens, type A or type B, a person inherits.
ABO blood groups
TRUE OR FALSE
Absence of both antigens results in type O blood, presence of both antigens leads to type AB, and the presence of either A or B antigen yields type A or B blood, respectively.
TRUE
TRUE OR FALSE
In the ABO blood group, antibodies form during infancy against the ABO antigens not present on your own RBCs. As shown in the table, a baby with neither the A nor the B antigen (group 0) forms both anti-A and anti-B antibod-ies; those with type A antigens (group A) form anti-B antibodies, and so on.
TRUE
The Rh blood groups are so named because one of the eight Rh antigens (agglutinogen D) was originally identified in _____________.
Rhesus monkeys
rupture of RBCs
hemolysis
In situations in which the fetal RBCs are destroyed at such a rapid rate that the immature infant liver cannot rid the body of hemoglobin breakdown products in the bile fast enough, the infant becomes _______
jaundiced
This type of jaundice (sa baby) generally causes no major problems and is referred to as _________
physiologic jaundice
_________ is especially common in women because of their monthly blood loss during menses.
Iron-deficiency anemia
The young and the old are particularly at risk for ________
leukemia
The elderly are particularly at risk for ______ because the stomach mucosa (which produces intrinsic factor) atrophies with age)
pernicious anemia
helps treat severe anemia and thrombocytopenia
whole blood transfusion
