Overview of Hemostatic Systems Flashcards
hemostatic system
system designed to keep an individual from bleeding
3 main stages of the hemostatic system
- vasoconstriction of blood vessels
- formation of a platelet plug
- blood clotting which reinforces the platelet plug with a fibrin mesh
how is blood maintained in a fluid state?
balance b/w procoagulant and anticoagulant forces
what does the endocrine mechanism do? (in relation to hemostasis)
increases blood volume following a tissue injury
what does the neural mechanism do? (in relation to hemostasis)
increases cardiac output and increases blood pressure following a tissue injury
tissue injury leads to…
decreased blood pressure and blood volume
vasoconstriction
contraction of smooth muscle cells of vessel walls to restrict the loss/flow of blood at site of injury
what triggers the reflexive contraction of vascular smooth muscle?
sympathetic nerves
serotonin
made and released by platelets and at NMJs
2 actions of serotonin
- direct action as vasoconstrictor when present in high concentrations @ sites of injury
- indirectly, can act as a vasodilator when stimulates nitric oxide release
endothelin-1
made and released by damaged endothelial cells
what happens when endothelin-1 is overexpressed?
can contribute to high BP and heart disease
histamine
binds to 1 of 4 different histamine G-protein coupled receptors
located in GI, uterus, lung, and vascular smooth muscle cells
histamine actions
causes vasodilation of vasculature
causes vasoconstriction of alveolar airways
prostacyclin (PGI2)
a prostaglandin or eicosanoid
prostacyclin (PGI2) actions
inhibits platelet activation
vasodilator
-cause more blood flow
thromboxane A2
made and released by activated platelets and endothelial cells
a prostaglandin
thromboxane A2 actions
stimulates activation of new platelets & increases platelet aggregation
vasoconstrictor
thromboxane A2 half-life
30 sec- SUPER SHORT
limits action to near site of an injury
drugs should be undetectable after how many half-lives?
5
constrictor influences do what?
increase vascular tone
dilator influences do what?
decrease vascular tone
vascular tone should be…
balanced
do not want vascular tone changing all the time
what happens if you have chronically low blood volume?
body adjusts- constricts more to keep the blood pressure in normal range
cell stressors facilitate the formation of…
prostaglandins
prostaglandin formation
- constitutive and inducive enzymes produce prostaglandin through PGH2
- cell-specific isomers are formed
- cell-specific isomers will act as vasodilators or vasoconstrictors depending on where you are in the body
where is blood made?
bone marrow
pluripotent hematopoietic stem cell can become….
any of the blood cells needed by the body
what forms platelets?
megakaryocytes
macrophage function
phagocytosis and activation of bactericidal mechanisms
&
antigen presentation
macrophage
-present in almost all tissues
-mature form of monocytes
-orchestrate immune responses & help induce inflammation
neutrophils function
phagocytosis and activation of bactericidal mechanisms
neutrophils
-primary cells recruited into site of acute inflammation
mast cells function
release of granules containing histamine and active agents
what is histamine derived from?
histadine
erythropoiesis
production of erythrocytes
stem cell for production of erythrocytes
hemocytoblasts
where does hematopoiesis take place during prenatal?
-liver
-spleen
-yolk sac
which bones are typically involved in hematopoiesis?
big bones –> more marrow
platelets are also called…
thrombocytes
are platelets true cells?
no
they do not have a nucleus
platelets are normally kept in what state?
inactive
platelets are _____ with different kinds of signaling molecules
rich
signaling molecules contained in platelets
-coagulation factors
-adhesion molecules
-chemokines
-regulators of growth & angiogenesis
-immunological molecules
what is the “first responder”?
platelets
how quickly does a platelet plug form?
within 2-4 minutes
inflammation
body’s process of fighting against things that harm it in an attempt to heal itself
too much inflammation can cause….
many problems
cardinal signs of inflammation
-pain
-heat
-redness
-swelling
-loss of function
examples of acute inflammation
-allergic reaction
-burns
-infection
-cuts
-trauma injury
examples of chronic inflammation
-diseases (cardiovascular, neurological, autoimmune)
-cancer
-rheumatoid arthritis
acute inflammation
generally helpful
chronic inflammation
generally unhelpful
3 major components of acute inflammation
- vascular changes- increased blood flow (vasodilation), increased vascular permeability
- cellular events- migration of leukocytes into the site of injury
- mediators- derived from plasma cells and proteins
healing cascade
- inflammation (48h post injury)
- proliferation (3-10 days post injury)
- remodeling (21 days post injury)
exudate
high protein
>1.02
transudate
low protein- albumin
<1.01
increased hydrostatic pressure & decreased osmotic pressure
pus
enriched in neutrophils
type I hypersensitivity disease
anaphylactic
*very quick
ex: allergies
type II hypersensitivity disease
antibody-dependent
cell membrane antigens can be altered to “non-self”
type III hypersensitivity disease
immune complex type
often cause tissue damage
type IV hypersensitivity disease
cell-mediated
*delayed response
ex: graft rejection, TB
most common drug that fights inflammation
non-steroidal anti-inflammatory drugs (NSAIDs)
NSAIDs
relieve pain & reduce swelling (inflammation)
ex: aspirin, ibuprofen
corticosteroids
highly effective at reducing inflammation bc they are similar to cortisol (hormone produced by adrenal glands)
*suppress the activity of a person’s immune system
