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CR1 > Structure and Function of Blood > Flashcards

Structure and Function of Blood Flashcards

1
Q

What are the constituents of blood? What order do they centrifuge?

A

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

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2
Q

What percentage of extracellular fluid does plasma comprise? What is plasma made of?

A

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%)

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3
Q

What are the functions of plasma proteins?

A

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

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4
Q

How does plasma function as a carrier?

A

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)

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5
Q

What ions are present in plasma and what are their functions?

A 
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)
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6
Q

What is the equation for the buffer function of blood? How does blood work as a buffer?

A

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

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7
Q

What are the components of bone, including marrow?

A 
Cortical bone (outer)
Spongy bone (inner)
Marrow (within spongy bone)
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8
Q

How many haematopoietic stem cells are present in a person? How many bone marrow cells make 1 stem cell?

A

11,000-22,000 per person

1 stem cell : 2 x 10^8 bone marrow cells

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9
Q

What type of stem cell can go on to make erythrocytes, platelets, eosinophils, neutrophils and basophils?

A

Myeloid stem cell

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10
Q

What type of stem cell can go on to make B lymphocytes, T lymphocytes and natural killer cells?

A

Lymphoid stem cell

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11
Q

What are the characteristics of erythrocytes?

A 
Oxygen from lung to tissues 
Full of haemoglobin
No nucleus, biconcave
120 day lifespan
1010/hour= 2 million/second
Erythropoietin main control
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12
Q

How do red cells carry oxygen?

A 
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
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13
Q

What are the symptoms of anaemia?

A

o Tiredness
o Faint
o Shortness of breath
o Worsening of heart related pain (angina)
o Rapid heart beat (experienced as palpitations)

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14
Q

What are the clinical signs of anaemia?

A 
o	Pale
o	Rapid heart beat (tachycardia)
o	Bounding pulse
o	Systolic flow murmur
o	Cardiac failure
o	Retinal haemorrhages
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15
Q

What are the three types of anaemia and their mean cell volumes?

A 
Microcytic = MCV < 80 fL
Normocytic = MCV 80-100 fL
Macrocytic = MCV > 100 fL
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16
Q

What can each type of anaemia be caused by? (subdivided by MCV)

A 
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
17
Q

What are the type of anaemia (subdivided by production), and what are they caused by?

A 
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
18
Q

What are the features of iron deficiency anaemia? What is it usually caused by?

A 
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?
19
Q

What are platelets? What is their function?

A

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

20
Q

How are platelets and clotting proteins involved in haemostasis?

A

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

21
Q

What are the three main types of white blood cells (leukocytes)?

A 
Granulocytes (against bacteria)
o	Neutrophils
o	Eosinophils
o	Basophils
Monocytes
Lymphocytes (against viruses)
o	T cells
o	B cells
o	Natural Killer Cells
22
Q

What are the features of neutrophils?

A 
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
23
Q

With which diseases do neutrophils increase (neutrophilia)? When do they decrease (neutropenia)?

A 
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
24
Q

What are the features of eosinophils? When do their numbers increase?

A 
Bilobed nucleus
Bright orange granules
Increase in:
o	Parasitic (worm) diseases
o	Skin disorders
o	Asthma
25
Q

What are the features of basophils? When do their numbers increase?

A

2 - 3 lobed nucleus
Large blue granules containing histamine
Variety of causes of increased levels

26
Q

What are the features of monocytes? What can they differentiate into? When do their numbers increase?

A

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

27
Q

What are the features of lymphocytes? What are the different types? When do their numbers increase?

A

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

28
Q

What are the effects of bone marrow failure?

A 
Anaemia, thrombocytopenia, leucopenia
Fatigue, bleeding, infections, DEATH
o	Leukaemia and other haematological cancers
o	Aplastic anaemia
o	Chemotherapy, toxins, radiation
o	B12/folate deficiency
29
Q

How do we detect haematological problems?

A 
1st line tests
- FBC
- Blood Film
- Bone marrow biopsy
- Biochemistry tests
- Scans
2nd line tests
- Immunology tests
- Chromosome analysis
- Genetic analysis
30
Q

What is involved in haematology? What diseases might be studied?

A 
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….
31
Q

What are the basic structural and functional features of blood?

A
  • 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

CR1 (23 decks)

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