Blood & CV systems Flashcards by Lily Stuart

Functions of blood

Transports oxygen, carbon dioxide, water, hormones, nutrients, waste products, heat
Protects - blood clotting, immunity, inflammation
Regulates body fluid, pH, hormones, temperature

How well did you know this?

Not at all

Perfectly

Properties of blood

Viscosity (resistance to flow)

Osmololality (concentration)

How well did you know this?

Not at all

Perfectly

How many litres of blood does an average adult have?

4-6L
Plasma (55%) - clear extracellular fluid
Cells (45%)
Centrifugation separates cells from plasma

How well did you know this?

Not at all

Perfectly

What are the components of plasma?

Nutrients: glucose, gases, electrolytes, Na+ (90% of plasma electrolytes) hormones,
plasma proteins
Organic waste products:
Urea, creatinine, uric acid
toxic breakdown products removed by the kidneys

How well did you know this?

Not at all

Perfectly

Name the 3 plasma proteins found in the blood

Albumin - 
- most abundant plasma protein
produced by liver
- influences blood pressure, flow and fluid balance
Fibrinogen and clotting factors-
- produced by liver
- responsible for coagulation of the blood
Globulins -
- produced by plasma cells
- immunity

How well did you know this?

Not at all

Perfectly

Erythrocytes (RBC)

Gas transport: O2 and CO2 
Disc-shaped cell with thick rim =
increased surface area/volume ratio
No nucleus or organelles 
Cannot multiply (120 days life span)
Contain:
- haemoglobin 
- carbonic anhydrase enzyme
produces carbonic acid from CO2 and water

How well did you know this?

Not at all

Perfectly

Haemoglobin structure

4 protein chains (globins)
Each chain contains haem which allows oxygen to bind
Each Hb molecule can carry 4 oxygen molecules
Foetal Hb has a higher affinity to oxygen than adult Hb

How well did you know this?

Not at all

Perfectly

How do you measure erythrocyte concentration in clinical practice?

Haematocrit - packed cell volume (PCV)
Mean cell volume (MCV)
Erythrocyte count
Mean cell Hb (MCH)

How well did you know this?

Not at all

Perfectly

Define erythropoiesis

Process of the development of red blood cells from stem cells
Immature cells released into bloodstream as reticulocytes, and mature into erythrocytes

How well did you know this?

Not at all

Perfectly

What 2 things are required for blood cell synthesis?

Vitamin B12 and folic acid (have to be bound to intrinsic factor to allow absorption to take place

How well did you know this?

Not at all

Perfectly

Which hormone regulates red blood cell production?

Erythropoietin, produced in the kidneys

How well did you know this?

Not at all

Perfectly

What is haemolysis?

The breakdown of erythrocytes

How well did you know this?

Not at all

Perfectly

Leukocytes (WBC)

Important function in defence and immunity
Contain nuclei
Granulocytes:
> neutrophils - increase in bacterial infections, phagocytosis
> eosinophils - increase in parasitic infections eg. worms
> basophils - closely associated with allergic reactions (contain histamine), chicken pox
Agranulocytes:
> lymphocytes - increase in chronic infections and immune response, destroy foreign/virally cells, found in lymph nodes and spleen
> monocytes - become tissue macrophages, produce interlukin-1

How well did you know this?

Not at all

Perfectly

Platelets

Secrete:
- clotting factors
- factors for endothelial repair
- vasoconstrictors in broken vessels
Form temporary platelet plugs
Dissolve old blood clots 
Attract WBCs to sites of inflammation to phagocytose bacteria

How well did you know this?

Not at all

Perfectly

Define haemopoiesis

Production of blood cells

How well did you know this?

Not at all

Perfectly

What tissues produce blood cells?

1.yolk sac (in embryo)
2. liver, spleen (until birth)
3. red bone marrow
produces RBCs, WBCs and platelets
4. lymphoid tissues
WBC production, maturation

Erythrocyte production

Erythropoiesis in red bone marrow produces  2.5 mil RBCs/second
Development takes 3-5 days
- reduction in cell size
- synthesis of Hb
- loss of nucleus

Recycling of erythrocytes

RBCs live for 120 days
- fragile membrane  
- cell bursts in narrow channels in the spleen
Macrophages in spleen &amp; liver
- digest cell components
- convert haem to bilirubin
- becomes bile product in faeces

Erythrocyte homeostasis

NEGATIVE FEEDBACK 
- drop in RBC count = hypoxemia to kidneys
- EPO production increases
- stimulation of bone marrow
- RBC count increases in 3-4 days
Causes of hypoxia:
Lung disease
smoking
high altitude
increase in exercise
bleeding

What is anaemia?

Inability of the blood to carry enough oxygen to meet body needs

low levels of haemoglobin
faulty haemoglobin
loss of blood
inadequate nutrition

Terms used to describe RBC characteristics

Normochromic - cell colour normal
Normocytic - cells normal size
Microcytic - cells smaller than normal
Macrocytic - cells bigger than normal
Hypochromic - cells paler than normal
Haemolytic - rate of cell destruction raised
Megaloblastic - cells large and immature

Types of anaemia

Diet induced:
eg. iron deficiency
eg. Vitamin B12/folic acid deficiency - pernicious (autoimmune) and dietary deficiency
Macrocytic/microcytic
Haemolytic - RBCs are destroyed or removed prematurely
Aplastic - bone marrow failure

Haemostasis

Primary haemostasis = temporary platelet plug

Secondary haemostasis = coagulation, stable clot

Vascular spasm

Prompt constriction of broken vessel
Triggered by:
> pain receptors (few mins)
> injury to smooth muscle (longer-lasting constriction)
> platelets release chemicals = serotonin
- provides time for other 2 mechanisms to work

Platelet plug formation

``` Injury = primary haemostasis - vasoconstriction (immediately) - platelet adhesion (seconds) - platelet aggregation (minutes) = > broken vessel, rough surface (collagen exposed) > platelets stick to it and other platelets > release a variety of substances (ADP) POSITIVE FEEDBACK ```

Coagulation

``` Clotting factors in plasma: - inactive form produced in liver - one factor activates the next = reaction cascade THROMBIN fibrinogen ------------------->> Insoluble fibrin polymerisation ```

Coagulation pathways

``` EXTRINSIC pathway = very fast - factors released by tissues start it INTRINSIC pathway - factors found only in blood cause it + occur together, converge in a common pathway, calcium required for both ```

Coagulation factors

``` Factor 1 = fibrinogen Factor 11 = prothrombin Factor 111 = thromboplastin Factor IV = Calcium Factor VIII = anti-haemophiliac factor A ```

How does a blood clot stop?

Platelets release chemicals to inhibit clotting Other substances eg. heparin also inhibit process Clot dissolves = fibrinolysis Plasmin = fibrin -dissolving enzyme/clot buster

What are clots not formed all the time?

- platelets don't stick to smooth vessel wall - clotting factors diluted by rapid blood flow (slow blood flow = DVT) - natural anticoagulants present in the blood > anti-thrombin produced by the liver > heparin secreted by basophils and mast cells

Blood groups

Antibodies in plasma cause agglutination in mismatched blood transfusions - don't have antibodies that would react with your antigens

ABO system

``` Group Antigen Antiobody A A Anti-B B B Anti-A AB A&B None o None Anti-A and Anti-B ```

RH group

``` D antigens on RBCs Anti-D body not normally present - forms only after exposure to Rh+ blood - pregnancy, transfusion O- packed cells can be given to any individual ```

What could happen in a mismatched transfusion reaction?

``` Agglutination = blockage of vessels Haemolysis = free Hb can block kidney tubules and cause death ```

Haemolytic disease of newborn

Causes severe anaemia and toxic brain syndrome (excess bilirubin) Prevention: - blood typing of pregnant women - Anti-D immunoglobulin given during pregnancy, after delivery, within 3 days of birth