Circulatory System Flashcards
function of blood
transport:
- move respiratory gases (O2 to tissues, CO2 waste to lungs), nutrients, wastes, hormones, stem cells
protection:
- contains WBCs that destroy microorganisms and cancer cells, and produce antibodies that help fight infections
- platelets clot the blood if vessels have been injured to minimize blood loss.
regulation:
- capillaries help to stabilize fluid distribution in the body
- the blood contributes to optimal pH by buffering acids and bases
- shifts in blood flow regulate body temperature.
plasma
a complex clear, extracellular fluid of water, proteins, nutrients, electrolytes, hormones, and gases
- serum is what remains when solids are removed
- mostly water (92% by weight)
- proteins (most abundant plasma solute): albumin, globulins, and fibrinogen
- nutrients: glucose, amino acids, lactic acid, lipids, and others
- electrolytes: salts of Na, K, Mg, Ca, Cl, and others
- nitrogenous wastes: urea and others
- hormones
- gases: oxygen, carbon dioxide, and nitrogen
proteins in plasma
- albumin: most abundant and acts to transport solutes, buffer pH, and contributes to viscosity and osmolarity
- globulins play roles in transport, clotting, and immunity
- fibrinogen: (precursor of fibrin, a clotting protein) the liver produces all of the major blood proteins except gamma globulins, antibodies which come from plasma cells (descendants of B lymphocytes).
contents of blood
- plasma (55%): clear extracellular fluid (matrix)
- formed elements (45%): liquid connective tissue; cells and cell fragments ; they include erythrocytes (RBCs), platelets (fragments of bone barrow cells), and five kinds of leukocytes (WBCs).
erythrocytes
Function:
- hemoglobin (component of the RBC cytoplasm): transports nearly all of the O2 and some of the CO2 in the blood
Shape:
- discoid cells with a sunken center
- no nucleus, mitochondria, or organelles, but they do have a cytoskeleton of spectrin and actin that reinforces the plasma membrane
7 major formed elements
- erythrocytes: RBCs (transport gases)
- leukocytes (monocytes, lymphocytes, neutrohils, basophils, eosinophils): WBCs (immune responses)
- thrombocytes: platelets (initiates clotting)
formed elements: erythrocytes
- discoid cells with sunken center & no nucleus
- function mainly to transport O2 and CO2
- most abundant formed element
formed elements: monocytes
- 3-8%; nucleus ovoid/kidney shaped
- sparse nonspecific granules
- function to phagocytize
- differentiate into macrophages
- present antigens
WBC
formed elements: lymphocytes
- 25-33%; nucleus ovoid/round
- may be small or large
- function to destroy cancer cells, foreign, viral cells
- initiate an immune response
- secrete antibodies
WBC
formed elements: neutrophils
- 60-70% nucleus usually with 3-5 lobes
- red/violet granules
- function to phagocytize bacteria
- secrete antimicrobials
WBC
formed elements: eosinophils
- 2-4%; nucleus with 2 large lobes, connected by thin strand
- orange/pink granules
- function to phagocytize antigen-antibody complexes, allergens, and inflammatory chemicals, secrete enzymes to weaken & destroy parasites
WBC
formed elements: basophils
- <0.5%; nucleus large & irregular
- coarse, dark granules
- function to secrete histamine and heparin
WBC
formed elements: platelets
- fragments of bone marrow cells
- second most abundant formed element
- no nucleus, but do have other organelles
- function to form clots, dissolve clots, vasoconstrict, attract WBCs, destroy bacteria
hemostasis
“cessation of bleeding”
steps:
1. when a blood vessel is injured, platelets release serotonin, which triggers vasoconstrictor to minimize blood loss
2. the platelets then adhere to the vessel wall and each other, forming a platelet plug
3. the platelets release clotting factors that convert the protein fibrinogen to fibrin. together, the fibrin, platelets, and blood cells form a clot that seals the breach
4. once the leak is sealed, platelets secrete a growth factor that stimulates fibroblasts and smooth muscle to replace the damaged tissue
5. finally, platelets secrete factor XII that leads to the formation of plasmin, a fibrin-digesting enzyme that dissolves the old clot
thrombocytosis
condition in which there are too many platelets, resulting in abnormal clotting; abnormal clotting of an unbroken blood vessel (thrombosis)
B cells
- type of WBC created in the bone marrow for immune protection
- differentiate into plasma cells- secrete antibodies to fight infection
- some may become memory cells (like T cells) to confer long-lasting immunity
