lecture 4 - blood

Question 1

what are the functions of blood?

Answer 1

transport, maintain body temp, controls pH, regulation of body fluid electrolytes, regulates blood clotting, removes toxins from the body

Question 2

what are erythrocytes?

Answer 2

red blood cells

Question 3

what are leukocytes?

Answer 3

white blood cells

Question 4

what are thrombocytes?

Answer 4

platelets

Question 5

what are blood constituents?

Answer 5

55% plasma, 1%WBCs, 44%RBCs

Question 6

what is plasma?

Answer 6

90% water, transports materials carried in the blood, waste products, dissolved gases

Question 7

why do erythrocytes have an indented, disc shaped cells?

Answer 7

efficient o2 transport

Question 8

what is the erythrocytes structure/function?

Answer 8

transports o2 in the haemoglobin they contain

Question 9

what are globins?

Answer 9

4 protein chains - alpha, beta, gamma and delta

Question 10

what is haemoglobin?

Answer 10

goes red when combined with o2 and blue when deoxygenated

Question 11

what is sickle cell anaemia?

Answer 11

RBCs trapped within small blood vessels and blocks them - deprives the downstream tissues of 02

Question 12

what are the steps involved inn haemostasis?

Answer 12

1) vascular spasm (blood vessel constriction)

2) formation of platelet plug

3) blood coagulation
- platelets have a role in all these steps

Question 13

what is blood vessel constriction?

Answer 13

The smooth muscle layer surrounding a cut or torn blood vessel immediately constricts slowing blood flow through the defect and minimizing blood loss

Damaged cells and platelets at cut site release potent vasoconstrictors such as serotonin

As the ends of the endothelial (inner) surfaces are pushed together (by this spasm) they become sticky and adhere to each other

Question 14

what is the platelet plug?

Answer 14

Platelets stick to each other using von Willebrands factor, Causes a rapid build up of platelets at the site of injury so that a platelet blocks the site

Question 15

what is blood coagulation (clotting)?

Answer 15

conversion of fibrinogen (a large soluble plasma protein) into fibrin (an insoluble thread like molecule)

Question 16

what are the 2 control processes which inhibit coagulation?

Answer 16

1) anti-thrombin – inhibits many of the clotting factors and especially thrombin – its activity is enhanced by heparin which is normally present on endothelial cells

2) thrombomodulin – proteins C and S - endothelial cells also express thrombomodulin that can bind thrombin, this binding eliminates thrombins coagulant effects and also activates protein C – in addition to these controls which try to slow or prevent clot formuation there is a whole system for fibrinolysis – breakdown of a fibrin clot

Question 17

what is thrombus?

Answer 17

blood clot within a vessel/ heart

Question 18

what is embolus?

Answer 18

detached mass able to travel in a vessel

Question 19

what is embolism?

Answer 19

the lodging of an embolus

Question 20

what is thrombo-embolism?

Answer 20

blockage by a thrombus that has travelled

Question 21

what are blood groups?

Answer 21

Blood groups are inherited and represent contributions from both parents. An individual almost always has the same blood group for life but it may change due to infection, malignancy, autoimmune disease or after BMT

Question 22

what is the clinical relevance of ABO groups?

Answer 22

Because mismatching of blood groups will result in a haemolytic transfusion reaction, donated blood must be carefully matched before any transfusion, Patients with group AB are ‘universal recipients’, Patients with blood group O are ‘universal donors’