Quiz 5: components of blood (23)

Question 1

role of blood

Answer 1

• distribution of nutrients, oxygen, and chemical messengers
• removes metabolic waste products like urea, carbon dioxide, and nonmetabolites
• maintains body’s temp, defends against infection, hydrates tissues, and forms clots to stop loss of fluids.

Question 2

properties of blood

Answer 2

• semi-viscous fluid made of both fluid and cellular components. Approx 5 liters in a human
• normal blood pH is 7.2–7.4
• normal temp. ranges 36.5–37.2
• salinity is maintained by controlling fluid balance
• blood viscosity is fairly high which is essential to normal flow. viscosity based on vol. of formed elements and protein concentration

Question 3

components of blood

Answer 3

• plasma–fluid component, approx. 55% of total blood vol.
• erythrocytes–(RBCs)–most common cell components. amount varies by sex, environmental conditions, and age. Adult hematocrit is approx. 45%
• leukocytes–(WBCs)–represent less than 1% of circulating blood vol. but can rapidly increase in number.
• Platelets–smallest cellular component of blood. Actually fragments of larger blood cells called megakaryocytes

Question 4

blood plasma

Answer 4

• water makes up about 90% of the plasma
• salts– (electrolytes, ions) make up about .9% and Na dominates
• proteins– make up about 9% of the total plasma; albumin, is the most abundant and acts as a buffer, transport protein, and the blood colloid osmotic pressure. Globulin acts as antibodies against anything foreign. Clotting factors allow the blood to form a clot.
• nutrients and waste–blood contains vitamins, minerals, glucose, and amino acids as nutrients. Urea, uric acid, and creatinine as waste.

Question 5

Erythrocyte form and function

Answer 5

• RBCs = ave of 45% of total blood vol.
• 4.2–5.4 million RBC/mm3 in females (4.6–6.1 in males). New borns tend to have more (7.2 million) and elderly tend to have less.
• RBCs are anuclear–cannot reproduce–no mitosis. Die after about 120 days. Replaced by hemopoietic tissue in the red bone marrow. most in sternum and ilium of adults.
• principal component of RBCs is hemoglobin–red colored, iron-containing protein complex
• reduced Hb can combine O2 to produce oxyhemoglobin, which increases bloody )2 20-fold. Hb can also bind to CO2 and form carbaminohemoglobin, which transports CO2 in the veins back to lungs.
• hemopoietic stem cell–>CPU colony forming unit–> erythroblast–>reticulocyte–> erythrocyte mature cell

Question 6

erythrocyte production

Answer 6

• erythrocyte production takes about 3-5 days. Quantity of cells can be increased but not rate. Main factor in stimulating erythrocyte production is erythropoietin (EPO)
• EPO is produced in the kidney and liver in response to lowered RBC count in the blood or increased oxygen demand.
• hemoglobin synthesis also influences RBC production. This requires sufficient B12 and iron in the diet. Hb is synthesized in the immature erythrocytes.

Question 7

erythrocyte destruction

Answer 7

• aging red blood cells become progressively more fragile. The spleen is a mass of small channels through which these cells must pass, causing the older ones to rupture (hemolysis)
• cell fragments are picked up by phagocytes (macrophages) lining these channels and digested.
• Hb is also broken down but the iron is released into the blood where some of it is bound to transferrin (transport protein) and carried to the liver for storage.
• the remaining heme is converted into biliverdin, which is converted into bilirubin. This is released into the blood, moves to the liver and is stored as bile salt.

Question 8

Leukocytes

Answer 8

• 2 groups and 5 types
• 1) agranulocytes: no granules in their cytoplasm and nuclei are fairly normal in shape
  
  1. Monocytes (largest)
  2. Lymphocytes (smallest, mostly just nucleus)
• 2) granulocytes: granules in cytoplasm, defined by colors of how granules stain. Nuclei are polymorphic—weird shaped.
  
  1. Eosinophils—red granules
  2. Basophils— blue granules
  3. Neutrophils— unstained granules

Question 9

Neutrophil

Answer 9

• granulocyte
• 60-70% of all WBCs. Part of myeloid series
• increase in number in response to bacterial infection

-function is to destroy and engulf bacteria…major component of pus
capable of diapedesis and positive chemotaxis in response to histamine.

Question 10

Eosinophil

Answer 10

-granulocyte
-2-4% of WBCs. Part of myeloid series
cell count increases with allergies, parasitic infections, and menstrual cycle
Sequestered in mucous membranes of repertory, digestive, and lower urinary tract
Act against the chem antigens of large parasites and surface allergens

Question 11

Basophil

Answer 11

• granulocyte
• less than 1% of WBCs. Part of myeloid series
• never found in large numbers.
• secrete histamine and heparin (anti clotting agent)
• histamine attracts other leukocytes and heparin prevents clot formation so that the leukocytes can gain access to the wound site.

Question 12

monocyte

Answer 12

• agranulocyte
• 3-8% of total circulating WBCs
• increase in number in response to inflammation and viral infection
• convert selves into macrophages, leave the blood stream and follow histamine signals to wound site
• they destroy and foreign organisms that they can engulf

Question 13

lymphocyte

Answer 13

• agranulocyte
• 25-35% of WBCs
• lymphocytes look alike but play many different roles in the immune response
• divided into B cells (plasma cells) and T cells (cytotoxic cells)
• both will increase in number in response to an acute infection

Question 14

Thrombocytes (platelets)

Answer 14

• average count is from 130,000–400,000/mm3
• extremely small (1/10 of vol of a RBC)
• not truly cells but cell fragments of a megakaryocyte
• secrete several chemical factors that can influence blood clotting, vasoconstriction, and inflammatory agents in response to injury.
• they can engulf and digest bacteria, produce agents to begin clot destruction, and several growth factors to stimulate cell prolilferation