Chapter 16: Blood Flashcards
Blood
Specialized kind of connective tissue in which formed elements- living cells - are suspended in a non-living fluid matrix (plasma).
Blood route
Heart-arteries-capillaries-body tissues (blood releases O2 & nutrients; picks up CO2 and wastes)-Veins-Heart-lungs-heart- body
Centrifuged blood splits into top to bottom
- Plasma
- Buffy-coat WBC & platelets
- Red blood cells
Functions of blood
- Distribution
- Regulation
- Protection
Distribution of blood
- Deliver oxygen & nutrients to all body cells
2 . Takes waste (CO2 & metabolic wastes) from cells to areas if elimination (eg. Lungs, kidneys) - Transports hormones from endocrine organs to target areas.
regulation
- maintains body temp; absorbs and distributes heat throughout the body and to skin surface to encourage heat loss.
- helps maintain normal pH; proteins and other solutes in the blood act as buffers to serious changes in pH that could be detrimental and blood holds a reserve of bicarbonate atoms
- helps maintain adequate fluid volume for circulatory system; Salts and blood proteins act to prevent excessive blood loss from bloodstream into tissues
protection
- preventing blood loss; platelets and plasma initiate clotting
- preventing infection; antibodies, complement proteins and WBC defend the body against bacteria and viruses.
% water in blood
90%
blood plasma composition is maintained by …
liver, respiratory system and kidneys
3 types of blood cells/ formed elements
- white blood cells - leukocyte -only true cell
- red blood cell- erythrocyte
- thrombocyte-platelets
3 structural characteristics for RBC’s function of gas transport
- small size and biconcave shape- allows for large surface area to volume
- over 97% hemoglobin (discounting water content)- hemoglobin binds to a transports respiratory gases
- lack of mitochondria and generation of ATP by anaerobic mechanisms-
more RBCs in blood , visocity is
higher, slower the blood
- fewer RBC -lower viscosity- faster the blood
function of RBC
-transporting respiratory gases
Hemoglobin
-protein makes RBC’s red, this binds easily & reversibly with oxygen
hemoglobin structure
- major: globin protein with 2 alpha and beta chains - 4 chains, each attached to a heme pigment - each has IRON FE2 core
each iron molecule can attach to one O2 molecule, so how many O2 can each hemoglobin molecule transport?
4 oxygen molecules
hemoglobin function in lungs
- in lungs: O2 diffuses from the air sacs of the lung into the lungs into the blood and goes to bind to the iron in hemoglobin, it changes its shape and forms oxyhemoglobin, blood is then bright red.
- less oxygen- blood is dark red
hemoglobin function in tissues
- in tissues: hemoglobin releases O2 and resumes its normal shape becoming deoxyhemoglobin
- CO2 then binds to the amino acids of hemoglobin, forming carbaminohemoglobin to be carried back to the lungs for elimination.
production of erythrocyte
- HEMATOPOIESIS- blood cell formation; occurs in red bone marrow . about an ounce of blood with 100 billion new cells are produced every day
- HEMOCYTOBLAST AKA hematpoietic stem cell-cell that are precursors to your blood cells of all types-reside on red bone marrow
- ERYTHROPOIESIS- hemocytoblast- myeloid stem cell- proerythroblast - early (basophilic) erythroblasts ( synthesize ribosomes) -late erythroblasts (starting to accumulate hemoglobin)- reticulocyte (start to lose nucleus)- erythrocyte
reticulocyte
-rough idea of rate of RBC formation
requirements for regulation of RBC
- too few RBC- not enough O2
- too many- blood that is too thick
erythropoietin EPO
- direct hormonal stimulus for creating RBC production
- EPO is produced by the kidneys & liver; so when kidney cells become low on O2 (hypoxic), the signaling molecule HYPOXIA-INDUCIBLE FACTOR. HIF is no longer broken down.
- accumulation of HIF speeds up the production/release of erythropoietin
drop in O2 that triggers EPO release results from:
- lower number of RBC due to hemorrage (bleeding out) or excessive RBC destruction
- Don’t have enough hemoglobin per RBC
- iron deficiency - low oxygen-at high altitude of during pneumonia
epo stimulates red marrow cells commited to becoming erythrocytes to….
mature more rapidly
synthetic EPO
-increases RBC production, could be used as athlete enhancement steroid
testosterone
- other chemicals can stimulate RBC production
Dietary reqs for RBC
- IRON is essential for erythropoiesis to form hemoglobin(contains 65% of body’s iron stores)
- free iron is toxic , so extra iron is stored as a protein iron complex in the stored in liver, spleen or bone marrow
- vitamins needed for DNA synthesis incl. Vit B12 and Folic Acid
RBC life span
100-120 days
why? They don’t have nucleus or organelles , thus can’t make new proteins for repair, when things break down cell dies.
why is spleen AKA RBC graveyard?
- fragmented dying RBC tend to get trapped in small circulatory channels commonly found in spleen
When macropages engulf dying RBC, how is it broken down?
- HEME is split from GLOBIN and IRON is stored for reuse
- the rest of the HEME is degraded to BILIRUBIN, which is picked up by the liver, transported in bile to the intestine and ultimately released as a brown pigment in feces
- the GLOBIN part is metabolized or reused
erythrocyte disorders-Anemias
blood has abnormally low capacity to carry O2 , you get pale , short of breath (lungs try to compensate for lack of O2)
Common causes for anemia
- insufficient # of RBCs
- Low hemoglobin
- Abnormal hemoglobin
hemorrhagic anemia
- blood loss-rapid(ex. stab wound)
- or gradual overtime (bleeding ulcer)-loss of more blood overtime
hemolytic anemia
- RBC lyse prematurely, takes on too much water, or mismatched blood transfusion, hemoglobin abnormality, or certain bacterial or parasitic infections that cause cells to break down
aplastic anemia
- destruction of red bone marrow
- by chemicals, rediation, viruses, side effect of chemo(bone marrow cancer)
iron deficiency anemia
- not enough iron in diet, loose all your blood
- RBCs produced called MICROCYTES are small and pale
pernicious anemia
- vitamin B12 deficiency , could be mutation of factor to breakdown B12 , can’t process
- developing RBCs grow but don’t divide, resulting in large pale cells called MACROCYTES
thalassemias
- you have a missing or faulty globin chain
- you would need blood transfusions