Ch. 19 - Blood Flashcards
What kind of tissue is blood?
connective tissue
What are the components of blood?
55% blood plasma (suspended solutes and platelets)
45% RBC
- coat of WBC and platelets
What is hematopoiesis and where does it occur?
blood cell formation; in red bone marrow of spongy bone
What kind of cells are blood cells formed from?
pluripotent hematopoietic stem cells (HSCs)
What are precursor cells?
differentiate into specific blood cells
What are hematopoietic growth factors?
HGFs are hormones that regulate differentiation and proliferation of blood stem cells
What is erythropoietin?
EPO is a hormone produced by kidneys; increases production RBC precursors
What is thrombopoietin?
TPO is a hormone from liver; stimulate platelet formation
What are specific cytokines and the 2 families?
local hormones that regulate leukocyte development and function; colony-stimulating factors & interleukins
What are functions of specific cytokines?
- stimulate proliferation of progenitor cells in red bone marrow
- regulate cell activities (i.e. immune responses)
How does an RBC’s form relate to its function?
biconcave disk allows increases SA/V ratio; flexible shape for narrow passages
How does an RBC generate ATP?
anaerobically; doesn’t use O2 it transports
What does each hemoglobin molecule consist of?
- globin (prot composed of 4 polyp chains)
- 1 heme pigment (containing Fe2+ that combines w O2) attached to each polyp chain
What does each Hb molecule transport?
- can carry 4 O2 molec from lungs to tissue cells
- 23% of total CO2 waste from tissue cells to lungs
- nitric oxide which helps regulate BP/vasolidation
What is hematocrit?
percentage of blood occupied by RBCs
What is the difference between anemia and polycythemia?
A - not enough RBCs or Hb
P - too many RBCs (over 55%); can cause high blood viscosity
How are worn out cells removed?
by resident macrophages in spleen and liver; breakdown products are recycled
Why do RBCs have such a short life cycle? (~ 120 days)
- no repair due to lack of organelles
- wear out from bending to fit through capillaries
What is hypoxia?
insufficient O2; main stimulus for erythropoiesis
What are some causes of tissue hypoxia?
- high altitude
- anemia (iron/prot deficiency)
- RBC prod rate < RBC destruction rate
How do kidneys respond to hypoxia?
releases EPO which enhanes development of proerythroblasts into reticulocytes
What does a proerythroblast produce? What does it form into?
Hb; forms into reticulocyte when nucleus is ejected
Blood is characterized into different blood groups based on the presence/absence of what?
glycoprotein and glycolipid antigens on RBC surface
What antigens and antibodies does type A blood have?
A antigen; anti-B antibody
What antigens and antibodies does type B blood have?
B antigen; anti-A antibody
What antigens and antibodies does type AB blood have?
A&B antigens; neither antibody
What antigens and antibodies does type O blood have?
neither antigen; both anti-A and anti-B antibodies
Which blood type is considered universal donor? Universal recipient?
type O; type AB
What is agglutination?
clumping of blood cells, typically due to an antigen-antibody rxn
In terms of Rh antigens, what does normal plasma contain?
no anti-Rh antibodies
What does it mean to be Rh+?
have Rh antigen on RBC surface
What will happen is an Rh- person receives blood from Rh+ donor?
anti-Rh antibodies will be formed; dangerous upon 2nd exposure to antigen
What is hemolytic disease of the newborn?
small amount of fetal blood crosses placenta and enters maternal circulation; can cause baby to have anemia
What is RhoGAM?
anti-Rh antibodies; given to Rh- mothers
Describe the process of erythropoiesis
…
Where are WBCs found?
circulating in blood, lymphatic fluid, body tissues (ski, lymph nodes, spleen, lungs)
What are the 5 types of WBCs?
monocyte, eosinophil, basophil, lymphocyte, neutrophil
How do WBCs reach site of tissue injury/disease?
- leave blood via emigration
2. use chemotaxis (chem attraction) to migrate to site
What are the 2 groups of WBCs and which types belong to each group?
Granular - neutrophil, eosinophil, basophil
Agranular - lymphocyte, monocyte
What are the 2 WBC groups based on?
absence or presence of granule staining
What is hematoxylin and what does it bind to?
basic/+ (blue stain); binds to negatively charged (basophilic) substances e.g. nucleic acids
What is eosin and what does it bind to?
acidic/- (red/pink stain); binds to positively charged (acidophilic) substances
What are some properties of neutrophils and what do they respond to?
- most abundant type of WBC; recruited first in inflammation
- respond to bacteria
How do neutrophils respond to bacteria?
- phagocytize
- release lysozymes that destroy/digest bact
- release defensin proteins
- release strong oxidants
What are some properties of eosinophils and what do they respond to?
release histaminase (catalyzes breakdown of histamine); slows down inflammation caused by basophils; attacks parasites
What are some properties of basophils and what do they respond to?
release granules (containing histamine, heparin, serotonin) at infection cites and enhance inflammatory response; respond to allergic rxns
What are mast cells?
pro-inflammatory CT cells that release histamine, heparin, proteases
What are some properties of lymphocytes and what do they respond to?
move bt tissues, lymph, and blood; only WBC that returns to circulation after fighting infection; respond to viral infection
What are the 3 types of lymphocytes?
B cells, T cells, Natural killer cells
What is the function of B cells?
destroy bacteria and toxins; turns into plasma cells that produce antibodies
What is the function of T cells?
attack viruses, fungi, cancer cells, transplanted organs, some bact
What is the function of Natural killer cells?
attack microbes and some tumor cells; directly kill foreign invaders
What are some properties of monocytes and what do they respond to?
become macrophages; similar to neutrophils (phagocytize) take longer to arrive at infection site; respond to fungal/viral infections
What does thrombopoietin stimulate?
myeloid stem cells to produce platelets
How are dead platelets removed?
by resident macrophages in spleen and liver; life span of 5-9 days
How does a myeloid stem cell produce platelets?
MSC –> megakaryoblast –> megakaryocyte that fragment –> each fragment is a platelet
What is hemostasis?
sequence of responses that stops bleeding during BV damage; prevents hemorrhage
What are the steps of hemostasis?
- vascular spasm
- platelet plug formation
- blood clotting
What occurs during a vascular spasm?
- BV damage stimulates reflex contraction (narrowing lumen)
- reduces blood flow
- only for small BV/arterioles
What occurs during platelet plug formation?
a. platelet adhesion
b. platelet activation
c. platelet aggregation
Describe platelet adhesion
platelets stick to exposed collagen fibres from underlying CT of damaged vessel
Describe platelet activation
- platelets become activated and grow extensions to attach to one another
- platelets release substances that activate neighbouring platelets
- cause vasoconstriction
Describe platelet aggregation
- activated platelets stick together to form a platelet plug
- plug reinforced by fibrin threads formed later during clotting process
What occurs during coagulation? (blood clotting)
fibrinogen –> fibrin –> traps platelets/WBCs –> clot
*stops vessel leak until CT forms a permanent patch
What are the necessary factors for clotting?
Ca2+, enzymes synthesized by hepatic cells, substances released by platelets/damaged T
How is fibrin created?
- Prothombinase converts prothrombin into thrombin (active); Ca2+ necessary for activation
- Thrombin converts soluble fibrinogen into insoluble fibrin
What is the role of fibrin in blood clotting?
traps RBCs and platelets at damage site to form clot; reinforce platelet plug
If a clot forms too easily…
can lead to thrombosis
If a clot does not form…
will result in hemorrhage
