cardiovascular system Flashcards
explain the basic function of the cardiovascular system and the 5 basic functions of blood
- transportation of dissolved substances, 2. regulation of pH and ions, 3. restrict fluid losses at injury sites, 4. defend against infection and toxins, 5. stabilisation of body temperature.
what are the main characteristics of blood?
highly viscous, slightly alkaline, hematocrits males have 5-6 litres, females 4-5l
what does haemltocrit mean? what does it tell us about someones body?
haematocrit is the total amount of RBCs present in a blood sample. it is normally expressed as a percentage. males normally have a range of anywhere between 40-54% and females slightly less at 38-46%
identify what the formed elements in our blood are
formed elements are developed by hemopoiesis in red bone marrow. they developed hemocytoblasts, which produce myeloid stem cells and lymphoid stem cells.
explain what the main functions / action of each of these elements are
myeloid stem cells, gives rise to RBC, platelets, eosinophils, basophils, neutrophils, monocytes.
lymphoid stem cells, gives rise to lymphocytes, and go to lymphatic system to complete maturation.
explain blood typing and what the possible blood types there are.
blood typing is, cell surface proteins that identify cells to immune system. foreign cells are attacked. are genetically determined by presence or absence of certain antigens. A, B, AB, O
how can we determine someones blood type?
determined through the Rhesus factor. 5 rhesus antigens, if Rh + absence of a particular antigen, if negative prescence.
explain how we know if someone is rhesus positive or negative
testing to conduct presence of the antigen, done through cross testing, where foreign cells are attacked. plasma antibody meets specific surface antigen, blood will then agglutinate and hemolyze if present indicating Rh negative. if no reaction, positive.
describe the 3 stages of homeostasis, i.e. how a blood clot is formed.
1., vascular phase, 2., platelet phase, 3., coagulation phase.
1. contraction of smooth muscles of damaged blood vessel wall carried out by, damage to smooth muscle and endothelial cells, activation of platelets and release of vasoconstrictors. reflexes initiated by pain receptors, start to form platelet plug.
2.Platelets contact and adhere to damaged tissue in blood vessel wall. Platelets become activated. Extend projections to attach to one another
Positive feedback loop of aggregation. Activated platelets release clotting compounds. Plug size restricted by inhibitory compounds, negative feedback and formation of blood clot (isolation)
3. Begins 30 seconds post injury. Clotting factors (liver enzymes, substances from platelets and damaged tissue) promote formation of prothrombinase. Convert prothrombin (enzyme produced by liver) intro thrombin. Thrombin converts soluble fibrinogen into fibrin. Fibrin forms threads which trap formed elements to form clot.
how is a wound healed?
Platelets pull on fibrin threads. Clot contracts drawing wound edges closer together. Fibroblasts form connective tissue and new endothelial cells repair vessel lining. Clot eventually dissolved through action of plasmin (plasma membrane)
