CVS Flashcards
How much of the blood is the cellular component?
45%
What is haemocrit and what is the normal haemocrit in a human?
The volume of read blood cells, normally 0.45
What is haemopoiesis?
The process of the production of blood cells and platelets which continues throughout life
Where does haemopoiesis?
In adults- Bone marrow
In embryonic life and infancy- Other sites
What is the lifetime of an erythrocyte and how many are produces per second?
120 Days
2 million produced per second
What is the lifetime of a platelet?
7-10 Days
Where are the precursor cells of red blood cells located and what is a young red blood cell known as?
In adults- The axial skeleton
In children- All bones
In Utero- The yolk sac, the liver, the spleen
If they are found in the blood, it is a sign of leukaemia
Young red blood cells are known as reticulocytes
Describe the hormonal growth factors that stimulate the precursor stem cells to proliferate?
Erythropoietin (made in the kidney)- Stimulates erythrocytes
G-CSF (granulocyte colony stimulating factor)- White Blood Cells
Tpo- Platelets
What causes the oxygen disassociation curve to shift?
Shifts right when pH is decreased or temperature increases
What does a red blood cell consist of?
Membrane to enclose haemoglobin, Enzymes of glycolysis, and haemoglobin
Describe Haemoglobin
Carries oxygen from lungs to tissues where it transfers oxygen to myoglobin in muscles. Haemoglobin is formed of 2 alpha and 2 beta chains and 4 haem groups.
How do the various blood types work?
There is a gene that results in the synthesis of A antigens on red blood cells, and a gene that results in the synthesis of the B antigen. Having neither= Type O (Most common) Having AB (Most rare) Having Just A (More common than B) Having just B
What are the antibodies/antigens in the blood of each blood type?
Type A= has anti-B antibodies in plasma, A antigen is co-dominant
Type B= Has anti-A antibodies in plasma, B antigen is co-dominant
Type AB= neither antibodies, has A and B antigens on surface of RBC
Type O= has both antibodies in plasma and no antigens. O antigen is recessive
What blood type is universal recipient and universal donor?
Universal recipient= Type AB
Universal donor= Type O
What are the type of antibodies used in blood types?
Anti-erythrocyte antibodies known as natural antibodies
Explain rhesus blood types
C,D,E antigens. Rhesus positive means the D antigen is present, rhesus negative means D antigen is not present
What is the bounds for normal haemoglobin?
12.5-15.5 G/dl
What is polycthaemia?
Higher than normal haemoglobin, caused by smoking, lung diseases, inefficient lungs meaning less O2 is exchanged so more haemoglobin is required
What are the symptoms and signs of anaemia?
Symptoms- Tiredness, lethargy, malaise, reduced exercise tolerance, shortness of breath on exertion and angina
Signs- Palor, Pale mucus membranes and palmar creases, glossitis, angular stomatitis, kylonychia
Describe iron deficiency anaemia
Iron is needed for haemoglobin production, lack of iron results in reduced production of small red cells
Low haemoglobin and MCV<80 fl
Causes- Occult gastrointestinal bleeding, menorrhagia, dietry
Describe macrocytic anaemia
Large red blood cells. Macrocytosis can occur without anaemia (caused by liver disease, alcohol and hypothyroidism). In macrocytic anaemia, macrocytosis is a sign of it
Describe B12 and Folate deficiency anaemia
Vitamin B23 and foalte are needed for DNA synthesis, thus with a B12 and folate deficiency red blood cells cannot be made in the bone marrow and thus less are released. This deficiency will effect all dividing cells but bone marrow is most active so it is affected first. Can be caused by damage to the stomach if intrinsic factor is not being produced by parietal cells, or by pernicious anaemia. Folate deficiency can be caused by malabsorbtion, dietary or an increased need.
Describe haemolytic anaemia
Normal cell production but decreased lifespan
What can cause congenital anaemia?
Membrane issues e.g. spherocytosis
Enzyme issues e.g. pyruvate kinase deficiency
Haemoglobin issues e.g. Sickle cell anaemia/ thalassaemia
What can cause acquired anaemia?
Autoimmune: immune system attacks own red blood cells
Mechanical: Fragmentation of red blood cells by mechanical heart valve or intravascular thrombosis in DIC
Explain Haemolytic disease of the foetus
Mother has rhesus negative blood and baby has rhesus positive blood. When mothers blood is exposed to babies blood, and mothers immune system recognises foreign rhesus positive blood and begins making antibodies against babies blood. First baby is unaffected since it takes time for antibodies to be produced, the mother is said to be sensitised. However if the second baby is RhD positive blood, then antibodies are produced immediately and begin destroying babies red cells.
Describe Neutrophils
Most numerous white cell- Lifespan is 10 hrs
Phagocytose and kill bacteria
Release chemotaxins and cytokines- important inflammatory response
Multi-lobed Nucleus and granular cytoplasm
Describe Eosinophils
Found in blood and in mucosal surfaces lining GI, Resp and urinary tract
Phagocytic response in parasitic infection. Neutralise histamine thereby restricting inflamatory response.
Bi or Tri lobed nucleus
Large red cytoplasmic granules and IgE receptors
Describe Basophils
Secrete heparin anticlotting factor and histamine in response to allergens.
Bi-Lobed nucleus and prominant dark-blue staining cytoplasmic granules. IgE receptors
Describe Monocytes
Monocytes are phagocytes that circulate in the blood and then migrate into tissues and organs to develop into macrophages. In the blood, monocytes play a major phagocytic role.
Reniform nucleus. Large so capable of engulfing bacteria and viruses
Describe lymphocytes
Lymphocytes are hard to distinguish as they all look the same.
B cells form plasma cells and secrete antibodies. Made in bone marrow and stored in secondary lymphoid organs.
T helper cells help B cells and activate macrophages. (CD4) Made in bone marrow and mature in thymus.
T cytotoxic cells kill previously marked target cells (CD8)
T suppressor cells suppress T-H cells
Natural killer cells kill virus infected cells.
Describe acute leukaemia
Proliferation of primative precursor cells usually found in bone marrow, proliferation without differentiation. These replace normal bone marrow cells resulting in anaemia, neutropenia infections and thrombocytopenia. The presence of primitive white precursor cells in the blood is a sign of acute leukemia.
Describe acute myeoblastic leukemia
Malignant proliferation of precursor myeloblasts in the bone marrow. Primarily affects adults
Describe acute lymphocytic leukemia
Malignant proliferation of the lymphoblast precursor cells in the bone marrow. Primarily affects children
Describe high grade lymphoma (hodgkins disease)
Disease of the lymph nodes that spreads to the liver, spleen, bone marrow and blood
Describe a platelet
Small cytoplasmic anucleate cell that blocks up holes in blood vessels
Made in bone marrow from cells called megakaryocytes. Lifespan of 5-10 days. . Circulate in an inactive state.
What is a reduced number of platelets?
Thrombocytopenia. Increased bleeding and spontaneous bleeding
What is an increased number of platelets?
Thrombocytosis. Can lead to arterial and venous thrombosis leading to increased risk of heart attack and stroke.
What coagulation factors is vitamin K essential for correct synthesis of?
II, VII, IX, X
What do the coagulation factors do?
Their function is to make a vlood clot. They convert soluble fibrinogen into insoluble fibrin polymer.
Where are the coagulation proteins produced and what is the key enzyme?
Produced in the liver, key enzyme is thrombin
Describe albumin
Most numerous protein in the plasma. Produced in the liver. Maintains oncotic pressure. Carries fatty acids, steroids and thyroid hormones.
What are the classes of immunoglobulins?
IgG ( Most important)
IgM (all start off as this)
IgA
IgE
How do platelets become activated?
When there is damage to a blood vessel, the sub-endothelium is exposed so platelets will bind directly to collagen or via large molecules such as Von Willebrand factor, which activates the platelets.
When does a platelet change shape and what does this mean?
Changes shape once activated from a smooth discoid to spiculated with extending pseudopodia. This increases surface area. This makes the platelets bind together.
What changes does activation cause to a platelet?
Platelet shape change
Activation of further receptors on the surface of platelets
Intracellular signalling causing platelets to release their stored granular contents.
What are the stored granular contents of a platelet?
Dense granules contain ATP, Calcium etc. That help the platelet plug form by activating more platelets.
Alpha granules contain von Willebrand factor, fibrinogen etc. which enhance binding.
Briefly describe the coagulation cascade
A series of proteolytic enzymes that circulate in an inactive state are activated in a cascade in order to generate Thrombin which cleaves fibrinogen, creating fibrin (a blood clot). It is NOT an all or nothing response.
Describe haemophilia
Recessive X-Linked severe bleeding disorder. Bleeding into muscles and joints as not enough clotting factors in the blood= slow clotting time or long PTT.
What is haemophilia A?
Rare bleeding disorder. Deficiency in clotting factor VIII, treat with factor VIII
What is haemophilia B?
Very rare bleeding disorder. Deficiency in clotting factor IX. Treat with factor IX
What is Von Willebrands disease?
Autosomal dominant disease with a lack of Von Willebrands factor. Lack of VWF causes platelet dysfunction hence muco-cutaneous bleeding.
What happens in Vitamin K deficiency?
Vitamin K is a fat soluble vitamin, and deficiency is caused by malabsorption. Manifests as a prolonged PTT. Incorrect synthesis of coagulation factors II, VII, IX, X. Treat with IV vitamin K. Coagulation factors are still produced but they do not work
What drugs affect bleeding?
Asprin affects platelet function
Heparin and warfarin inhibit vitamin K, affecting the coagulation cascade.
Steroid makes tissues thin and causes bruising and bleeding
Describe disseminated intravascular coagulation
A rare life threatening condition caused by sepsis, obstetric issues, or malignancy. Causes a breakdown of haemostatic balance resulting in simultaneous bleeding and microvascular thrombosis. Treat underlying cause
What is the first response of a damaged blood vessel?
It will constrict due to neural control and release of endothelin-1. This temporarily slows the flow of blood in the affected area and presses opposed surfaces of the vessel together and this keeps them ‘glued’ together.
What breaks down a blood clot?
Plasminogen is converted by plasminogen activators into plasmin which then goes on to break fibrin down and thus the entire blood clot.
What is the appearance of cardiac muscle?
Striated due to regularly repeating sarcomeres composed of myosin-containing thick filaments interdigitating with thing filaments that contain actin (Troponin and tropomyosin are present in the actin thin filament)
Individual cells are relatively small with a single nucleus
Arranged in layers
Adjacent cells joined end to end with intercalating discs within which desmosomes that hold the cells and gap junctions are present
What are the polypeptide chains found in myosin?
2 Large heavy chains and 4 smaller light chains
Combine to find a molecule with two globular heads and a long tail formed from the intertwined heavy chains
What is the structure of actin?
A globular protein composed of a single polypeptide that polymerises with other actin monomers to form a polymer made up of two intertwined helical chains
Where is tropomyosin found?
It occupies the grooves between two actin strands and overlies the myosin binding sites
What happens when calcium ions bind to troponin?
The troponin changes shape which pushes the tropomyosin exposing the myosin binding sites on actin
What is the A-Band?
The region of the sarcomere occupied by thick and a few overlapping thin filaments
What is the I-Band?
The area occupied only by thin filaments that extend to the centre of the sarcomere from the Z lines
What are the Z lines?
Two successive Z lines define the limits of one sarcomere
What is the H zone?
The area occupied by only thick myosin filaments
What is the M line?
The centre of the H zone
Describe titin
Elastic protein filaments in sarcomeres that extend from the Z-Line to the M line, linked to both proteins.
What is the sarcoplasmic reticulum and what importance does it have during contraction?
It is a membrane network that surrounds the contractile proteins. It releases calcium ions when calcium ions binds it to ryanodine receptor
Why is the resting membrane potential -90mV?
The membrane is much more permeable to K+ which is leaving the cell as k+ channels are open. Pumps then move 3Na+ ions out for every 2 K+ ions pumped in, which means the inside is relatively more negative.
