Blood Physiology Flashcards
Functions of blood
- Transport of:
- gases, nutrients, waste products
- processed molecules
- regulatory molecules
- regulation or pH and osmosis
- maintenance of body temperature
- proctor took against foreign substances
- clot formation
What is the composition of blood?
Plasma - 55%
** made up of 7% proteins, 91% water, 2% other solutes**
Buffy coat - platelets and WBCs
RBCs - 45%
List the plasma proteins and state what they do
ALBUMINS: viscosity, osmotic pressure, buffer, transports fatty acids, free bilirubin, thyroid hormones
GLOBULINS: transports lipids, carbohydrates, hormones, ions, antibodies, and complement
FIBRINOGEN: Blood clotting
Components of plasma
Ions: osmosis, membrane potentials and acid base balance
Nutrients: glucose, amino acids, triacyglycerol, cholesterol, vitamins
Waste products:
- urea, Urica acid, creatinine, ammonia salts, breakdown products of protein metabolism
- lactic acid. End product of anaerobic respiration
- bilirubin. Breakdown product of RBCs
Gases: oxygen, carbon dioxide, and inert nitrogen
Regulatory substances: hormones, enzymes
What are the formed elements?
- RBCs - biconxave discs, anucleate, contain hempglobin; transports oxygen and carbon dioxide
- WBCs
- granulocytes
- agranulocytes - Platelets (thrombocytes) - cell fragments. Form platelet plugs, release chemicals necessary for blood clotting.
What is haematopoiesis
The process of blood cell production
what are the cells formed from haematopoiesis?
Proerythroblasts: Develop into red blood cells
Myeloblasts: Develop into basophils, neutrophils, eosinophils
Lymphoblasts: Develop into lymphocytes
Monoblasts: Develop into monocytes
Megakaryoblasts: Develop into platelets
what is the anatomy of RBCs
biconcave discs
lack a nucleus and other organelles
cannot reproduce
essentially consist of a plasma membrane, cytosol, and haemoglobin
each contains about 280 million haemoglobin molecules
lack mitochondria
what is the function of RBCs (erythrocytes)?
TRANSPORT
carries oxygen from lungs to tissue: 98.5%
transports Carbon dioxide from tissue to lungs
describe the composition of hemoglobin
- four globin molecules (polypeptide chains): transport carbon dioxide and nitric oxide.
- Four haem molecules, eahc containing one iron atom; transport oxygen
- Iron required for oxygen transport.
what is erythropoietin?
is a hormone produced by the kidney that promotes the formation of red blood cells by the bone marrow, in response to low blood O2 levels.
decribe the production of red blood cells
Stem cells → proerythroblasts → early erythroblasts → intermediate erythroblasts → late erythroblasts → reticulocytes
function of leukocytes
Protect body against microorganisms and remove dead cells and debris
describe the movements of Leukocytes
Ameboid: pseudopods
Diapedesis: cells become thin, elongate and move either between or through endothelial cells of capillaries
Chemotaxis: attraction to and movement toward foreign materials or damaged cells. Accumulation of dead white cells and bacteria is pus
describe erythrocytosis
an increase in RBCs relative to the volume of blood. Polycythemiais an increase in both RBC concentration and hemoglobin, the protein in red blood cells that carries oxygen to the body’s tissues.
describe the movement of neutrophils
after leaving bone marrow, stay in circulation 10-12 hours then move into other tissues. Become motile, phagocytoze bacteria, antigen-antibody complexes and other foreign matter. Secrete lysozyme. Last 1-2 days.
describe the movement of Eosinophils
. Leave circulation and enter tissues during inflammatory response. Prevalent in allergic reactions. Destroy inflammatory chemicals like histamine. Release chemicals that help destroy tapeworms, flukes, pinworms, and hookworms.
what is the movement of basophils
least common. Leave circulation and migrate through tissues, play a role in both inflammatory response and allergic reactions. Produce histamine and heparin.
movement of lymphocytes
produced in red bone marrow but then migrate to lymphatic tissues and proliferate. Responsible for antibody production. Studied extensively with the immune system.
movement of monocytes
remain in circulation for 3 days, leave circulation and become macrophages. Phagocytic cells. Can break down antigens and present them to lymphocytes for recognition
list some blood disorders
Erythrocytosis: Increased circulating RBC number
Polycythemia: Increased RBC concentration
Anemia: Low oxygen-carrying capacity due to a deficiency of functional hemoglobin
Iron-deficiency
Pernicious
Hemorrhagic
Hemolytic
Sickle-cell
define haemostasis
‘Arrest of bleeding’
the stop of blood flow
define the three stages of haemostasis
3 events occur in rapid sequence to prevent excessive blood loss
- Vascular spasm: Vasoconstriction of damaged blood vessels. Can occlude small vessels. Caused by thromboxanes from platelets and endothelin from damaged endothelial cells.
- Platelet plug formation
- Coagulation or blood clotting
describe platelet plug formation of hameostasis
- platelet adhesion
- platelet release reaction.
- platelet aggregation
- expression of coagulation factor V and Phospholipids.
stages of coagulation
- Activation of prothrombinase
- Conversion of prothrombin to thrombin
- Conversion of fibrinogen to fibrin
types of clot formation
extrinsic and instrinsic
describe extrinsic clotting
Stage 1:
Damaged tissues release tissue factor (TF; factor III)
When Ca2+ is present, forms complex with factor VII, activating factor X
Prothrombinase is formed
Stage 2: prothrombinase converts prothrombin into thrombin
Stage 3:
Thrombin converts fibrinogen to fibrin
Thrombin activates factor XIII, which stabilizes clot
describe instrinsic clotting pathways
Stage 1
In damaged blood vessels, factor XII comes in contact with exposed collagen, activating factor XII
Stimulates factor XI, activates factor IX
Activated factor IX joins with factor VIII, platelet phospholipids and Ca2+ to activate factor X
Prothrombinase is formed
Stages 2 and 3 progress to clot formation
control of clot formation
anticoagulants: prevent coagulation factors from initiating clot formation.
coagulation : occurs when coagulation factor concentration exceeds a given threshold. At site of injury, threshold is exceeded.
Anticoagulants
Antithrombin: produced by liver, slowly inactivates thrombin
Heparin: produced by basophils and endothelial cells. Increases effectiveness of antithrombin
Prostacyclin: prostaglandin derivate from endothelial cells. Causes vasodilation and inhibits release of coagulating factors from platelets
define fibrinolysis in clot retraction
Clot retraction. Fibrin threads of clot attached to blood vessel walls. Platelets produce processes that attach to fibrin threads. Actin and myosin molecules within platelets contract, pulling edges of wound together and squeezing out serum.
Clot dissolved by activity of plasmin, an enzyme which hydrolyzes fibrin
define transfusion and infusion
Transfusion: transfer of blood or blood components from one individual to another
Infusion: introduction of fluid other than blood
how is blood grouped?
Determined by antigens (agglutinogens) on surface of RBCs
Antibodies (agglutinins) can bind to RBC antigens, resulting in agglutination (clumping) or haemolysis (rupture) of RBCs
Groups: ABO and Rh
describe the ABO blood groups
A and B antigens
Type A blood has A antigen only
Type B blood has B antigen only
Type AB blood has both A and B antigens
Type O blood has neither A nor B antigens
Four different blood types, caused by the presence or absence of two RBC antigens
describe a transfusion reaction
If transfused blood is not matched to the recipients blood it will cause a transfusion reaction
this measn that antibodies attack antigens, causing the RBC to clump together (agglutinate) and break the cells open killing them (lysis)
what is an agglutination test?
Before blood is transfused, agglutination tests are used to determine blood type
Take a blood sample and add anti-A and anti-B antibodies to it, to see if either antibody causes agglutination
E.g. Type A blood will form clumps if exposed to anti-A but not to anti-B antibody
What anions and cations make up electrolytes?
Positively charged cations:
Calcium
Sodium
Potassium
Negatively charged anions:
Phosphate
Sulfate
Bicarbonate
describe the regulation of clot formation and how clots are removed
when a person cuts themselves, eg their finger, some blood is spilt, and due to the walls of the blood vessels being open, the platelets are exposed to the collagenous fibres, binding, which then turns the platelets sticky, allowing them to clump together to form a barrier, blocking the open section.
fibrin then attached on top of the covering platelets and then binds the vessel back together.
the clot then dissolves after a few days
describe Rh
rhesus antigens, you may be Rh positive or Rh negative.
eg, O-, AB+
Rh positive can receive both antigens ( + and -)
Rh negative should just receive their negative antigens.
describe the Hemolytic disease of the Newborn (HDN)
when a mother is negative Rh but the child in womb is Rh positive.
it is okay for the first time, but after first birthing in this situation, the mother will develop Rh + antibodies which will fight in a secondary Rh positive pregnancy.
