Cardiovascular System: Blood Flashcards
name the formed elements of blood
erythrocytes, leukocytes, platelets
briefly describe the role of each formed element in blood
- erythrocytes: oxygen transport
- leukocytes: immune defense
- platelets: blood clotting
describe arterial blood
blood leaving the heart
describe venous blood
blood returning to the heart
compare the appearance of arterial and venous blood
- venous blood is darker red due to less oxygen
- arterial blood is bright red bc of high oxyhemoglobin
*both don’t apply to blood to and from lungs
what are the main components of blood; % composition of each?
formed elements (cellular portion) and plasma (fluid portion); 45% and 55% respectively
describe blood plasma
- straw-coloured
- has water and dissolved solutes (mostly Na+, but also metabolites, hormones, enzymes, antibodies, other proteins)
what are the plasma protein types
albumins, globulins, fibrinogen
describe albumins
- water-soluble
- made in liver
- give osmotic pressure needed to draw water from the surrounding interstitial tissue fluid into capillaries;
what are the subtypes of globulins
alpha, beta, and gamma
describe alpha globulins
- produced by liver
- transport lipids and fat-soluble vitamins
describe beta globulins
- produced by liver
- transport lipids and fat-soluble vitamins
describe gamma globulins
- antibodies made by lymphocytes
- important for immunity
describe fibrinogen
- important clotting factor
- made by liver
describe what happens when the body faces water loss; how is this fixed?
- plasma concentration ↑
- osmoreceptors in hypothalamus go off
- feel thirsty
- ADH releases from post. pit.
- dehydration and ↓ blood volume are compensated for by ADH and ↑ fluid intake
describe erythrocytes
- lack nuclei, mitochondria, and organelles
- biconcave disc from spectrin making spectrin net
- get energy thru anaerobic metabolism
what is the importance of biconcave disc
↑ surface area to allow for gas diffusion
describe the life cycle of erythrocytes
- short (120 days) due to lacking nuclei, organelles, mitochondria
- made in red bone marrow (erythropoiesis)
- filtered thru phagocytic cells in liver, spleen, bone marrow
- mature RBCs don’t divide
describe the hemoglobin molecule in regard to O2 and CO2 transport
- significantly ↑ O2 transport
- also binds to CO2, CO, and H for carbonic anhydrase and CO2 rxns
describe hemoglobin composition
4 globin subunits (protein) each bound to one heme (red pigment w iron)
describe transferrin; how does it enter erythrocytes
- protein carrier for iron
- receptor-mediated endocytosis
outline the process of erythropoiesis
- starts in bone marrow
- hemocytoblast (hemopoietic stem cell) → myeloid stem cell → normoblast/erythroblast → lose nucleus to become reticulocytes → lose remaining organelles to become erythrocytes
where does fluid, nutrient, and waste exchange occur b/w blood and tissues
across walls of capillaries
define arteries; arterioles?
vessels that carry blood away from the heart - extensive branching to make a tree; smallest arteries
describe veins; venules; microscopic capillaries?
- vessels that carry blood to the heart
- microscopic veins
- thinnest and most numerous of blood vessels
describe lymphatic vessels
- located on connective tissues around blood vessels
- any fluid present inside called lymph
describe lymph nodes
cleaners of lymph before returning to venous blood
how can iron-deficiency anemia happen
- lack of enough iron to make normal amounts of hemoglobin
- heavy periods
- peptic ulcers
- bleeding in GI tract
- diseases preventing iron absorption
- demands from fetus in pregnancy
what is needed to produce erythrocytes
iron, folic acid, vitamin b12
what is the importance of folic acid for erythrocyte production
needed for DNA rep. and therefore cell proliferation
what is the importance of vitamin b12 for erythrocyte production
needed for DNA rep. and therefore cell proliferation
how can pernicious anemia happen
- lack of intrinsic factor molecule secreted by stomach epithelium
- prevents intestinal absorption of vitamin B12;
- autoimmune attack on gastric epithelium
- intestinal malabsorption of vit b12 in diet
- crohn’s disease
- inadequate dietary vit b12 intake
draw out the life cycle of erythrocytes
…
what are the leukocytes
neutrophils, basophils, eosinophils, monocytes, lymphocytes
describe the function of neutrophils
phagocytes foreign material (therefore ↑ # during infections)
describe the function of eosinophils
- defends against parasitic invaders due to granules with toxic molecules
- secretes enzymes that dissolves clots
- detoxifies foreign substances
describe the function of basophils
- can defend against big parasites thru toxic substance release
- contributes to allergic rxns (releases anticoagulant heparin and histamine which improves blood flow)
describe the function of monocytes
- completes phagocytosis
- turn into macrophages after circulating in blood for short time
what is the difference b/w wandering and fixed macrophages
- wandering: detect invaders by moving thru bloodstream and lymph nodes
- fixed: stay in areas like lungs or intestines that are more susceptible by pathogen invasion
what is leukocyte development controlled by
colony stimulating factors and interleukins
describe platelets
- disc shaped
- made when pieces of megakaryocyte bone marrow cells break off
- colourless
- have mitochondria, smooth ER, cytoplasmic granules
- move by amoeboid motion
- causes vasoconstriction
- aka thrombocytes
describe the mechanism to stop bleeding
hemostasis
- vascular spasm
- formation of platelet plug
- formation of blood clot (thrombus)
what chemical plays a role in blood clotting and how
- serotonin
- stimulates constriction of blood vessel to ↓ blood flow
what do platelets secrete, and what is their importance
- growth factors;
- maintain integrity of blood vessels
- may lead to development of atherosclerosis
describe vascular spasm
- ↑ in resistance to blood flow (vasoconstriction)
- the sympathetic nervous system activates → more vasoconstriction
- blood loss minimizes
describe platelet plug
- have stickiness to allows for plug around site of vessel damage
- ↓ blood loss
- necessary step to make blood clot
- many plasma proteins make plug but von wellebrand factor (vWf) most important
make a flowchart of hemostasis
blood vessel damage → subendothelium is exposed → vWf binds to collagen fibre → platelets bind to vWf due to stickiness, adherence, and anchors
outline the factors limiting clot formation
- anticoagulants
- tissue factor pathway inhibitor
- thrombomodulin
- plasmin dissolving clots
what are anticoagulants
proteins in plasma on the surface of endothelial cells
what are tissue factor pathway inhibitors
inhibitory molecules secreted by healthy endothelial cells; inhibit extrinsic pathway
what is thrombomodulin
binder to thrombin making a complex that activates protein C; secreted by healthy endothelial cells
what is protein C
anticoagulant that inhibits intrinsic & extrinsic pathways
how do clots dissolve
- plasminogen activations leads to increased conversion of plasminogen to plasmin (EX tissue plasminogen activator (TPA))
- clots are dissolved enzymatically by plasmin to break fibrin
describe hemophillia
genetic disorder caused by deficiency of gene for specific coagulation factor (VIII)
describe vWf disease
- ↓ of vWf
- ↓ platelet plug formation
what is the outcome of vitamin b12 deficiencies
↓ synthesis of clotting factors
how can aspirin be used as an anticoagulant
- low doses inhibits formation of TXA2 (thromboxane A2) leading to ↓ platelet aggregation and platelet plug formation
- high doses inhibits formation of PGI2 (prostacyclin) (which is supposed to prevent platelet plug spread) leading to ↑ likelihood of clot
