By C. Kohn, Waterford WI Wounds & Hemostasis. Normal Blood Flow To have normal blood flow, blood...
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- Slide 1
- By C. Kohn, Waterford WI Wounds & Hemostasis
- Slide 2
- Normal Blood Flow To have normal blood flow, blood must be kept
at an exact viscosity (thickness) Too thin, and the smallest cuts
would cause a pet to bleed to death Too thick, and the blood would
not flow Anticoagulants keep the blood thin and allow it flow under
normal circumstances Injury changes the situation Blood must not be
allowed to flow freely everywhere or the wound would never
heal
- Slide 3
- 4 Types of Open Wound Abrasions-injuries destroying only
surface layers of the skin. Incisions- wounds produced by sharp
instruments these types of cuts usually have smooth edges. Puncture
Wounds- penetrations of the superficial (surface- layer) tissue.
Lacerations- cuts with irregularly torn edges. oSlide courtesy of
Texas A&M
- Slide 4
- Hemostasis The series of chemical reactions needed to stop
bleeding is called hemostasis Hemostasis has three steps Step 0:
Injury Step 1: Vasoconstriction blood vessels constrict (or shrink)
to slow blood flow at the site of injury Step 2: Platelet Plug
formation the wound is corked, or covered with sticky platelets
Step 3: Formation of a fibrin blood clot a more sturdy solution is
created
- Slide 5
- Step 1: Vasoconstriction In vasoconstriction, the walls of the
blood vessels shrink to reduce the size of the area that blood can
flow through. The muscles surrounding the vessel will contract,
shrinking the vessel
- Slide 6
- Step 2. Platelet Plug Formation At the site of injury, collagen
will help platelets to stick to the site of the injury Collagen is
sort of like branches that the platelets can grab onto as they pass
in the bloodstream
- Slide 7
- Platelets Platelets are formed in the bone marrow and live in
your bodys circulatory system for roughly a week Platelets arent
really cells they do not have a nucleus and cannot divide Platelets
do have a coat made of a particular protein that prevents a
platelet from sticking to anything other than injured tissue
Platelets contain contractile proteins (like those in your muscle
cells) These proteins enable a platelet to expand and contract
Inside the platelet are special chemicals that aid in the formation
of the platelet plug (explanation on next slide).
- Slide 8
- Clot Contraction & Repair About 30-60 minutes after a blood
clot has formed, the platelets within the clot contract Like muscle
cells, platelet cells can shrink due to actin and myosin
contractile proteins This contraction pulls on the wound from the
inside; bringing the edges of the wound closer together The blood
clot is temporary at the same time of contraction, the tissue
surrounding the damaged site begin to divide and repair via
mitosis.
- Slide 9
- RBC WBC Platelet
- Slide 10
- Degranulation: A Feed Forward Mechanism The platelets release
granules that enable more platelets to get stuck. The more
platelets that get stuck, the more granules are released the
promote more platelets to get stuck. This is a feed-forward
mechanismthe process becomes stronger as it happens more.
- Slide 11
- Step 3: Coagulation The platelet plug will become reinforced
with a fibrin mesh net This fibrin net also traps red and white
blood cells in order to from a blood clot over the site of the
injury The red blood cells will form a solid plug The white blood
cells will aid in fighting infectious agents that are able to make
it inside the body.
- Slide 12
- Review: 3 Steps of Hemostasis 1. Vasoconstriction the muscles
of the damaged blood vessel contract to reduce the amount of blood
flowing through it by reducing the size of the blood vessel 2.
Platelet Plug Formation collagen fibers protruding from the site of
the injury catch platelets and form a plug. Platelets contract and
shrink the wound 3. Formation of a Blood Clot a fibrin mesh catches
red and white blood cells to form a clot and prevent infection.
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re/tr/m1/s7/trm1s7_3.htm
- Slide 13
- Prevention of Infection Once bleeding has been controlled, the
next step is stopping infection The blood vessels that were
constricted now dilate (open up) to bring white blood cells rushing
to the scene. The process in which the wound swells and becomes
inflamed is called inflammation.
- Slide 14
- White Blood Cells White blood cells engulf and destroy any
germs that may have gotten into the body through the open wound.
This process of destroying germs creates heat This causes the
trademark symptoms of serious wounds swelling, redness, tenderness,
and heat. The worse the infection, the greater the inflammation and
heat.
- Slide 15
- Fibrinolysis 2 days after clotting the fibrin mesh that holds
the clot together is dissolved This process is called Fibrinolysis
Source: thrombosisadviser.com
- Slide 16
- Stuff You Should Know: Warfarin Warfarin (or Coumadin) is a
blood thinner. It was originally a rat poison, and is still widely
used for this method Rats that eat food laced with Warfarin die
from blood loss because their blood is unable to coagulate
Warfarin, in much lower doses is one of the most widely prescribed
medications in the world. Warfarin can help dangerous clots from
forming in heart attack and stroke victims Warfarin is named for
WARF, or the Wisconsin Alumni Research Foundation. This is the
agency that funds all research at the University of Wisconsin.
- Slide 17
- Review What is necessary for normal blood flow? What is an
anticoagulant? What are the four types of open wounds? What is
hemostasis? What are the 3 steps of hemostasis? What is
vasoconstriction and how does it happen? What is a platelet and how
does it help a wound heal? How do they know where to go when there
is an injury? How is a platelet different from other kinds of
cells? What is a fibrin blood clot made from? (i.e. what is a
scab?) How does it form? How does an open wound close? Why do open
wounds sometimes swell, become hot, and look red? What is
fibrinolysis? How does a wound know how to heal? What is Warfarin
and what does it do?