Structure and Function of the Blood Flashcards
what is the function of blood
Carriage of oxygen
Part of immune system
Transport of substances
Maintenance of pH and temperature
what is blood
Specialist connective tissue
what percentage of extracellular fluid does plasma make up
20%
what is plasma made up of
90% water
10% solutes
what percentage of blood is plasma
55%
what is the function of plasma
- solvent
- lubricant
- cushion
- heat dissipator
what is is in the water in plasma
- glucose
- salts
- dissolved chemicals -
- makes up 2% of the 90%
what are the proteins in plasma
Albumin (60%) (transport and oncotic pressure)
Globulin (36%) (immune)
Fibrinogen (4%) (blood haemostasis - acts as a coagulant )
- makes up 8% of plasma
what are the plasma ions
- inorganic ions such as potassium, sodium, calcium, chloride, bicarbonate and phosphate
- dissolve carbon dioxide as carbonic acid , hydrogen and bicarbonate ions or bound to amino groups of proteins such as haemoglobin - this is important in maintaining pH
what are the functions of plasma ions
- involved in electrolyte balance to maintain blood pressure and support heart and muscle contraction
How does blood act as a buffer
H+ + HCO3- H2CO3 CO2 + H2O
- pH depends on the ratio of carbon dioxide and bicarbonate
- metabolic processes produce excess hydrogen ions which are buffered by excess bicarbonate and carbon dioxide
- prevent acisodiss
- histidine residues in haemoglobin bind to free hydrogen ions
what are the function of plasma proteins and name examples
Inflammatory response
- Complement proteins (permeability, opsonisation, chemotaxis, lysis)
- Cytokines e.g. interferons (released from lymphocytes to interfere with viral replication)
Protection from infection
- antibodies (γ-globulins)
Clot formation – enzymes stimulated in a cascade
- Fibrinogen leading to fibrin clot
Intravascular osmotic effect- albumin
what is the process of making blood cells called
Haematopoiesis
how many haematopoietic stem cells are there
11,000-22,000 per person
how many bone marrow cells are there to 1 stem cell
1 stem cell : 2x108 bone marrow cells
what are the two cells that a bone marrow stem cell can divide into
- Myeloid stem cell
- lymphoid stem cell
What do myeloid stem cells divide into
- erythrocytes
- megakartocytes these form platelets
- Myeloblast which leads to eosinophils, neutrophils and basophils
what do lymphoid stem cells divide to form
lymphoblast which forms a B and T lymphocyte and natural killer cells
what is the main control of red blood cell production
erythropoietin
how many red blood cells are produced a second
2 million
what is the lifespan of the red blood cells
120 day lifespan
What is haemoglobin structure
- tetramer
- 4 globin chains
- 2 alpha and 2 beta chains
- each has an iron containing heme group
- the oxygen binds to the heme group chaining the alpha and beta conformation
What are the molecules that promote oxygen release in tissues
- hydrogen ions
- carbon dioxide
- 2,3- DPG
What is oxygen release in tissues called
Bohr effect
what is anaemia
- this is when you have a lower haemoglobin concentration therefore you have a lower amount of oxygen that is transported around the body
How does the body respond to haemoglobin
- anaemia causes a reduction to the oxygen supply of the kidney this increases erythropoietin (hormone) this increases red blood cell production by bone marrow
anaemia is not a ..
diagnosis because there is always an underlying cause
what is the commonest blood disorder
- anaemia 25% wordwide
what are the levels that you need to be diagnosed with haemoglobin
Hb < 13 g/l (males) , <11.5 g/l (females)
what are the symptoms of anaemia
- Tiredness
- Faint
- Shortness of breath
- Worsening of heart related pain (angina)
- Rapid heart beat (experienced as palpitations)
what are the signs of anaemia
- Pale
- Rapid heart beat (tachycardia)
- Bounding pulse
- Systolic flow murmur
- Cardiac failure
- Retinal haemorrhages
what are the types of anaemia divided by
the mean cell volume (size of the red blood cell)
what are the types of anaemia
- microcytic - MCV <80 fL
- Normocytic MCV 80-100 fL
- macrocytic MCV >100 fL
what causes microcytic anaemia
Iron deficiency
Thalassaemia
what causes normocytic anaemia
Acute blood loss Anaemia of chronic disease (e.g. infections, malignancy) Renal failure Leukaemia Sickle cell anaemia
what can cause microcytic anaemia
B12/folate deficiency
(megaloblastic anaemia)
Alcohol
Liver disease
what are causes of anaemia
- small hypo chromic cells
- Diet is rare cause
- Menstrual loss (young females)
- Infection (hookworm)
- Growth spurt, pregnancy
- Gastrointestinal loss:
Bleeding ulcers, inflammatory bowel disease, CANCER
what are platelets
- how many are made a second
- what is there lifespan
what is there role
- Small circulating cells (2 - 3 l) without a nucleus - Fragments of megakaryocytes from bone marrow - 1 million/second - 10 day lifespan
Involved in coagulation
- Platelet plug
- Coagulation cascade
whats the difference between platelets and clotting proteins
- platelets form an initial plug
- clotting proteins produce a firm thrombus
What does low platelet lead to
- called thrombocytopenia which can cause bleeding and bruising
What does low clotting factors lead to
haemophilia
what are the granulocytes
Neutrophils
Eosinophils
Basophils
what are the lymphocytes
T cells
B cells
Natural Killer Cells
what are the types of white blood cells
- Granulocytes
- monocytes
- lymphocytes
describe neutrophils
- what is there structure
- what is there half life
- how many are produced per second
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
what diseases`can neutrophils cause
- Neutrophilia - this is an increase in the amount of neurtorphils
- Neutropenia - decrease in the amount of neutrophils
what does neutrophils cause
Infection
Inflammation
Tissue damage
Haemorrhage
what does neutropenia cause
Overwhelming sepsis (blood poisoning)
HIV
Bone marrow failure (no blood cells produced) – aplastic anaemia, leukaemia
B12/folate deficiency
describe the structure of eosinophils
-when do eosinophils increase in number
- Bilobed nucleus
- Bright orange granules
Increase in
- Parasitic (worm) diseases
- Skin disorders
- Asthma
describe the structure of basophils
-
- 2 - 3 lobed nucleus
- Large blue granules containing histamine
- Variety of causes of increased levels
describe the structure of monocytes
describe the function of monocytes
- Large with kidney shaped nucleus
- turn into macrophages
- important in immune system – presents foreign substance (antigen) to lymphocytes
- Increased in chronic infections and viral infections
describe the structure of lymphocytes
- describe the function of lymphocytes (T, B, NK cells)
- what is the life span
Small and dense with little cytoplasm. Few granules
T cells: Coordinate immune responses
B cells: produce antibody
NK cells: viral and tumour
immunity
Increased in viral infections
Lifespan: 1 week-100 years
What happens when the bone marrow fails
- anaemia, thombocytopenia, leucopenia Fatigue, bleeding, infections, DEATH - Leukaemia and other haematological cancers - Aplastic anaemia - Chemotherapy, toxins, radiation - B12/folate deficiency
How do we detect haematological problems
- full blood count
- bone marrow biopsy
- haematologists
How are red blood cells measured
full blood count
- Absolute numbers x 1012 /l
- Mean cell volume (MCV) – average size in fl
how do you measure haemoglobin
full blood count
- Amount in whole blood – in g/dl
- Mean cell haemoglobin (MCH) – average amount of Hb in a red cell – in pg
Reduced if cells are small
- Mean cell haemoglobin concentration (MCHC) – concentration of haemoglobin in a red cell – in %
- Reduced if haemoglobin in cell is low
How are plasma measured
- full blood count
- Haematocrit (Hct) or packed cell volume (PCV) – ratio or % packed cells
How are platelets measured
- full blood count
- Platelet count - absolute number x109/l
How are white cells measured
- full blood count
- White cell count (WCC or WBC) - absolute number x 109/l
- White cell differential (different types of cells seen)
- absolute number/l
- % of total white cells (neutrophils, lymphocytes, etc.)
How do you do a blood film
- Spread on glass
- Fixed with alcohol, stained with May-Grunwald Giemsa
- Used to examine morphology of cells
- Bone marrow biopsy may be considered
