Human biology 1.1.3 preventing blood loss

  • Created by: Hannah
  • Created on: 13-05-13 17:08

Describe first aid procedure to prevent excessive

- put on pair of disposble gloves

- reassure person by telling them to sit/lie down

- check wound for any objects

- if none place large pad of clean cloth onto the wound and apply pressure firmly by using your hand 

- if object in wound do not remove it make a pad in shape of a ring around the object to surround object as it may be sealing a blood vessel and limiting the loss of blood

- if wound is arm/leg remove limb higher than as this lowers blood flow to the limb as the heart has to pump blood against gravity

- if blood soaks through pads do not remove them simply add another one as you could damage or remove the blood clot thats forming

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Outline mechanism of blood clotting?

tissue is damaged and collagen fibres are exsposed which causes platlets to stick to them and clump together to form a platelet plug

calcium is needed

white blood cells and platelets release enzyme thromboplastin which catalyses the conversion of prothrombin into thrombin

thrombin hydrolyses fibrinogen into smaller units

smaller unit polymerise to form insoluble stand of fibrin

fibrin fibres form a mesh over wound which blood cells get trapped in and form and blood clot

a scab is formed to prevent further blood loss

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State enzymes are globular proteins

enzymes are globular proteins with a specific tertiary structure  when an enzyme substrate complex is formed enables enzymes to exert forces on the substrate which lowers the activation energy

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Explain how structure of enzyme enables it to act

each enzyme only catalyses only reaction and can only accomodate one type of substrate molecule

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Describe conditions in which blood for transfusion

4 degress celcius 

buffer solution added- keeps ph of blood the same

calcium ions removed using sodium citrate as otherwise blood would clot

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What effect does changing the pH have on enzyme?

enzymes only work a certain pH as bonds that hold structure together rely on slighty negative and slighty positive charges.

The more acidic a solution is the more H+ ions it contains which affects the charges on the molecule causing weak bonds such as hydrogen to break.

alters enzymes tertiary structure and active site is no longer complementary to substrate so enzyme is denatured

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What affect does temperature have on enzymes?

Low temperatures mean less kinetic energy so less successful collisons slower rate of reactions. If too cold  ice crystals would form inside cells which would damage cell membranes so that cells would be destroyed when blood was thawed out

High temperatures lots of kinectic energy so therefore more successful collisons faster rate of reaction up until an optimun temperature which rate of reaction slows down as heat has caused weak hydrogen bonds to break altering tertiary structure of enzyme, active site no longer fits substrate and becomes denatured.

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Explain role of co-factors?

Co-factors are ions or molecules which bind to to enzyme before substrate does to allow it to catalyst a reaction otherwise the enzyme would be intact but non-functional

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What is whole blood and its uses?

whole blood contains eythrocytes,leucocytes, plasma and platelets

used for severe blood loss

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What is leuco-depleted blood and its uses?

blood is which as many leucocytes have been removed

important for people who receive repeated transfusion as wbcs would make antibodies which is dangerous for future transfusion

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What is packed red blood cells and its uses?

eythrocytes seperated from the rest of the blood and stored

when needed added salt and sugar solution

transfusion for anaemia or replace eythrocytes

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What are platelets uses?

Bone marrow failure

chemotherapy treatments for leukemia

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What are clotting factors and its uses?

plasma from donation processed into clotting factors.

individuals with haemophilia do not have factor 8 involved in blood clotting therefore factor 8 transfusion can be treatment

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What is plasma and its uses?

Blood with blood cells removed

cardiac surgery

 women with loss blood during childbirth

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Whats the affect of enzyme/substrate conc on enzym

higher concentration- more successful collisons as more substrate/ enzymes to be filled up so faster rate of reaction however when theres more substrate added than avaliable enzymes this will not affect the rate of reaction so it will stay constant.

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How is blood screened?

Small sample of blood taken

screened for hiv,hepatisis C 

by adding blood to antigens of the virus as if antibody attachs to antigen this mean individual has the virus

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When should you not give blood?


- have cough, sore throat, cold sore

-recent infection

- recent major sugery or serious illness

- taking antibiotics/other medication

- you do not weigh over 50 kgs

- had hepatitis or jaundice in last 12 months

- recently had tatoo/body peircing

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