Structure and Function of Blood Flashcards
What are the constituents of blood? What order do they centrifuge?
Plasma (top centrifuge layer)
o FPP – (fibrinogen, clotting factors) for management of bleeding with abnormal coagulation
o Cryoprecipitate (fibrinogen)
Cells (bottom centrifuge layer)
o Platelets – correction of thrombocytopenia/abnormal platelet function with bleeding
o Granulocytes – therapy of infection
o Red cells – correction of anaemia
What percentage of extracellular fluid does plasma comprise? What is plasma made of?
20% of extracellular fluid
o Protein (8%)
Albumin (60%) (transport and oncotic pressure)
Globulin (36%) (immune)
Fibrinogen (4%) (blood haemostasis)
o Water (90%)
Solvent, lubricant, cushion, heat dissipator
Glucose, salts and other dissolved chemicals (2%)
What are the functions of plasma proteins?
Inflammatory response
o Complement proteins (permeability, opsonisation, chemotaxis, lysis)
o Cytokines e.g. interferons (released from lymphocytes to interfere with viral replication)
Protection from infection
o antibodies (γ-globulins)
Clot formation – enzymes stimulated in a cascade
o Fibrinogen fibrin clot
Intravascular osmotic effect- albumin
How does plasma function as a carrier?
Free or bound to protein
Nutrients (glucose, amino acids, fats, vitamins)
Waste products (urea, uric acid, creatinine, bilirubin)
Hormones (cortisol, thyroxine)
Other chemicals (drugs, alcohol)
What ions are present in plasma and what are their functions?
Inorganic ions (potassium, sodium, calcium, chloride, bicarbonate, phosphate) o electrolyte balance to maintain blood pressure and support heart and muscle contraction o dissolved carbon dioxide as carbonic acid, hydrogen and bicarbonate ions or bound to amino groups of proteins – including haemoglobin (maintenance of pH)
What is the equation for the buffer function of blood? How does blood work as a buffer?
H+ + HCO3- H2CO3 CO2 + H2O
pH depends on the ratio of CO2 / HCO3-
Metabolic processes produce excess H+ ions, buffered by excess bicarbonate and carbon dioxide
o Prevents acidosis
o Histidine residues in haemoglobin bind free H+ ions
What are the components of bone, including marrow?
Cortical bone (outer) Spongy bone (inner) Marrow (within spongy bone)
How many haematopoietic stem cells are present in a person? How many bone marrow cells make 1 stem cell?
11,000-22,000 per person
1 stem cell : 2 x 10^8 bone marrow cells
What type of stem cell can go on to make erythrocytes, platelets, eosinophils, neutrophils and basophils?
Myeloid stem cell
What type of stem cell can go on to make B lymphocytes, T lymphocytes and natural killer cells?
Lymphoid stem cell
What are the characteristics of erythrocytes?
Oxygen from lung to tissues Full of haemoglobin No nucleus, biconcave 120 day lifespan 1010/hour= 2 million/second Erythropoietin main control
How do red cells carry oxygen?
Haemoglobin – tetramer o 4 globin chains o 2 α + 2 β chains o Each has an iron-containing heme group O2 binds to heme o Changes α and β conformation H+ , CO2 and 2,3 DPG promotes O2 release in tissues: Bohr effect
What are the symptoms of anaemia?
o Tiredness
o Faint
o Shortness of breath
o Worsening of heart related pain (angina)
o Rapid heart beat (experienced as palpitations)
What are the clinical signs of anaemia?
o Pale o Rapid heart beat (tachycardia) o Bounding pulse o Systolic flow murmur o Cardiac failure o Retinal haemorrhages
What are the three types of anaemia and their mean cell volumes?
Microcytic = MCV < 80 fL Normocytic = MCV 80-100 fL Macrocytic = MCV > 100 fL
What can each type of anaemia be caused by? (subdivided by MCV)
Microcytic = iron deficiency, thalassaemia Normocytic = acute blood loss, anaemia of chronic disease (e.g. infections, malignancy), renal failure, leukaemia, sickle cell anaemia Macrocytic = B12/folate deficiency (megaloblastic anaemia), alcohol, liver disease
What are the type of anaemia (subdivided by production), and what are they caused by?
Increased destruction/loss (high reticulocytes) = caused by bleeding or haemolysis Reduced production (low reticulocytes) = caused by haematinic deficiency, anaemia of chronic disease, medications, infiltration or aplasia
What are the features of iron deficiency anaemia? What is it usually caused by?
Iron key component of Hb Small (microcytic), hypochromic cells Diet is rare cause Causes include: o Menstrual loss (young females) o Infection (hookworm) o Growth spurt, pregnancy o Gastrointestinal loss: Bleeding ulcers, inflammatory bowel disease, CANCER Not the final diagnosis, what is the underlying cause?
What are platelets? What is their function?
Small circulating cells (2 - 3 micro l) without a nucleus
Fragments of megakaryocytes from bone marrow
1 million/second
10 day lifespan
Involved in coagulation
o Platelet plug
o Coagulation cascade
How are platelets and clotting proteins involved in haemostasis?
Platelets form an initial plug - primary haemostasis
Clotting proteins produce a firm thrombus - secondary haemostasis
Low platelet levels (thrombocytopenia) can cause bleeding and bruising
Low clotting factors e.g. haemophilia- no secondary haemostasis
What are the three main types of white blood cells (leukocytes)?
Granulocytes (against bacteria) o Neutrophils o Eosinophils o Basophils Monocytes Lymphocytes (against viruses) o T cells o B cells o Natural Killer Cells
What are the features of neutrophils?
About twice as big as red cell 2 -4 lobes, fine granules Normally the most common white cell - levels very dynamic Half-life 6-8 hours 1011/day=1 million/second
With which diseases do neutrophils increase (neutrophilia)? When do they decrease (neutropenia)?
Neutrophilia (increase) o Infection o Inflammation o Tissue damage o Haemorrhage Neutropenia (decrease) o Overwhelming sepsis (blood poisoning) o HIV o Bone marrow failure (no blood cells produced) – aplastic anaemia, leukaemia o Medications o B12/folate deficiency
What are the features of eosinophils? When do their numbers increase?
Bilobed nucleus Bright orange granules Increase in: o Parasitic (worm) diseases o Skin disorders o Asthma
What are the features of basophils? When do their numbers increase?
2 - 3 lobed nucleus
Large blue granules containing histamine
Variety of causes of increased levels
What are the features of monocytes? What can they differentiate into? When do their numbers increase?
Large with kidney shaped nucleus
They turn into macrophages and phagocytose pathogens
They also differentiate into Dendritic Cells and present foreign substance (antigen) to lymphocytes (trains them to recognise the antigens)
Increased in chronic infections and viral infections
What are the features of lymphocytes? What are the different types? When do their numbers increase?
Small and dense with little cytoplasm. Few granules
Part of the adaptive immune system- ie. the have memory
T cells: Coordinate immune responses and kill infected cells
B cells: produce antibody
NK cells: viral and tumour immunity (no memory)
Increased in viral infections
Lifespan: 1 week-100 years
What are the effects of bone marrow failure?
Anaemia, thrombocytopenia, leucopenia Fatigue, bleeding, infections, DEATH o Leukaemia and other haematological cancers o Aplastic anaemia o Chemotherapy, toxins, radiation o B12/folate deficiency
How do we detect haematological problems?
1st line tests - FBC - Blood Film - Bone marrow biopsy - Biochemistry tests - Scans 2nd line tests - Immunology tests - Chromosome analysis - Genetic analysis
What is involved in haematology? What diseases might be studied?
Pathology and diagnostics Anaemia Blood Transfusion Leukaemia, lymphoma, myeloma Stem cell transplant Sickle cell disease, thalassaemia Haemophilia Thrombosis and anticoagulation Paediatrics, pregnancy Anything else to do with blood….
What are the basic structural and functional features of blood?
- O2 Carriage. Immune system. Transport. pH Buffer
- What is blood made of? Cells and plasma
- What is plasma? Water, salt, proteins
- What are the blood cells? RBCs, WBCs, Plts
- How are they produced? Stem cells in bone marrow, RBC stimulated by erythropoietin.
- What is anaemia? Low Hb. micro/normo/macrocytic
- How do we detect haematological problems? Full Blood Count, Bone Marrow Biopsy, Haematologists
