CVR week 1: Flashcards
valves- name and location?
R atrium to R venticle- tricuspid valve
L atrium to L venrticle- mitral valve
L ventricle to aorta- aortic valve
R ventricle to pulmonary artery- pulmonary valve
describe constituents of plasma?
- plasma 55% of total blood :
- 90% water (solvent)
- 7-8% proteins e.g. albumin (blood volume), globulins (immune function), fibrinogen (blood clotting)
- electrolytes: sodium, potassium, calcium etc.
- nutrients: glucose, fatty acid, amino acid
- gases: oxygen and carbon dioxide)
describe functions of the blood plasma?
- transport nutrients
- carries hormones and other signalling molcules
- maintains blood pressure and volume
- functional proteins e.g. antibodies, complement and clotting factors
- temp and pH
what is normal oncotic pressure value?
30-50g/L
role of plasma in heat regulation?
plasma acts as a heat sink, circulating plasma removes excess heat from ‘hot’ organs and circulates heat to extremities, becomes the fluid for sweat
how does plasma act as a pH regualtor?
proteins act as H+ buffer through binding to amino acid side chain
role of plasma in inflammation and immunity?
- contains and circulates immune cells and proteins produced by these
- contains specialsied proteins that contribute to inflammatory response- complement system
How is complement activated?
3 different ways:
- classical: trigger by antibodies on pathogens
- alternative: activated directly by pathogens or damaged cells
- lectin pathway: initiated by specific sugars on microbe surfaces
Function of complement?
Opsonization/phagocytosis: complex bound to antigen antibody complex or on surface of pathogen activates phagocycotic cells.
Cell Lysis: Directly attacking and rupturing pathogen cell membranes through the formation of the membrane attack complex (MAC)
Inflammation: Complement proteins stimulate inflammation by attracting immune cells to the site of infection or injury
Aid production of antibodies: B cells have complement receptors and bind causing B cell to secrete more antibodies 9amplifies antibody production)
syntheis of plasma proteins- where does it occur?
produced in liver - liver disease levels of these are low leading to swelling, infection and bledding
Coagulation cascade - intrinsic pathway:
activated by damage to endothelial lining, slow and complex:
factor XII is activated by exposed collagen or other damage.
Activated Factor XIIa activates Factor XI
Factor XIa activates Factor IX, which, together with Factor VIIIa, activates Factor X in the common pathway.
Coagulation cascade - extrinsic pathway:
Triggered by external trauma that causes blood to escape from the vessel (e.g., tissue injury),
Faster than the intrinsic pathway
Key steps:
Tissue Factor (TF) is released from damaged tissue
TF combines with Factor VIIa, activating Factor X in the common pathway
Coagulation cascade: common pathway
Activated Factor X (Xa), with Factor Va, converts prothrombin (Factor II) to thrombin (Factor IIa)
Thrombin converts fibrinogen (Factor I) into fibrin, which forms a mesh that strengthens the platelet plug
Thrombin also activates Factor XIII, which cross-links fibrin to form a stable clot
How is the coagulation cascade regulated?
- antithrombin III (Inhibits thrombin and Factors IXa, Xa, XIa, and XIIa)
- Protein C and S (inactivate Va and VIIIa)
- Tissue Factor Pathway inhibitor (TFPI) (blocks tissue factor VIIa complex formation in extrinsic pathway)
Fibrinolysis:
purpose?
how it happens?
- breakdown of fibrin by proteolytic enzymes, example of use is given as a drug during stroke
- plasminogen converted to plasmin (by XIa, XIIa, Kallikrein and Tissue plasminogen activator) which breaks down fibrin
Platelets - what they are? role? lifespan? avg platelet count?
fragments of megakaryocytes found in bone marrow, aid blood clot and wound healing, lifespan of 7-10 days, ranges from 150,000 to 450,000 per microlitre of blood.
platelet function-
Function:
- adhere at site of injory to form plug
- release chmicals to attract more platelest and coagulation factors
- stabalize clot
- relase growth factors to repair tissue
- recruit leucocytes and release pro-inflammatory mediators
platelet activation? physical change that occurs after?
- activated by expose to collagen which they adhere to and release chemical signal to activate more platelts
- undergo shape change to stellate (spiky) to increase SA and form plug to stop bleeding
haemocrit- what is it? percentage of blood volume?
part of blood that’s erythrocytes- 45%
feature of erythrocyte
biconcave shape, lacks nucleus(more haemoglobin), flexible to move through capillaries, 10 micrometers
features of haemoglobin
- each molecule can carry 4 oxygen molecules
- 2 alpha, 2 beta subunits
- porphyrin ring with iron make up heme group (4 in 1 molecule)
what would cause a left shift in oxygen disocation curve? what about right?
Shift to left: (increased affinity)
- decrease temp, decrease 2,3-DPG, decrease H+, CO , feotal haemoglobin, myoglobin(very large shift left), lungs
Shift right (Bohr Shift): (decreased affinity)
- increased temperature, increase 2,3-DPG, increase H+, respiring tissues
What is 2,3-DPG? What does it do? How is it produced?
2,3-diphosphoglycerate:
- produced by erythrocytes during glycolysis by lumbering-rapoport pathway
- reduces affinity of haemoglobin for oxygen, promoting release of oxygen to tissues
- increased by factors associated with increase tissue oxygen demand e.g. hypoxia, anaemia, low pH
How is CO2 transported in the blood?
- CO2 binds to haemoglobin forming carbaminohaemoglobin
- CO2 converted to bicarbonate by enzyme carbonic anyhdrase in RBC
- small amount of CO2 dissolves directly in plasma