The circulatory system:Blood

Chapter 18

BSC 1086C

Fall 2007

Functions of Circulatory System• _____________

– O2, CO2, nutrients, wastes, hormones, and heat

• _____________– WBCs, antibodies, (immune system to fight

infection) and platelets (blood clotting to prevent blood loss)

• _____________ – fluid regulation (water distribution) and buffering

(pH levels of body fluids)

Blood• Adults have 4-6 L of blood (~1.5 gallons)

– ___________: a clear extracellular fluid– ___________: blood cells and platelets

• Centrifuge blood to separate components

18.118.2

Plasma and Plasma Proteins• Plasma – non-living fluid matrix

– consists of water (92%), ions (electrolytes) and proteins

• 3 major categories of plasma proteins– _____________ - most abundant.

• solute transport and pH buffering– _____________ (antibodies)

• solute transport and immunity• alpha, beta, and gamma globulins

– _____________ • precursor of fibrin threads that help form blood clots

• Plasma proteins formed by ___________ – except globulins (produced by plasma cells)

Nonprotein Components of Plasma• ________________

– amino acids (from diet and tissue breakdown)– nitrogenous wastes (urea)

• toxic end products of catabolism• normally removed by the kidneys

• ________________ – glucose, vitamins, fats, minerals, etc

• ________ and ___________

• ________________– Na+ makes up 90% of plasma cations

Formed elements in blood• __________________

– Most abundant formed element– 200 billion made per day– no cell nucleus (and few other

organelles)– blood type determined by surface

glycoprotein and glycolipids

• Function– 1)– 2)

• Biconcave shape. Why??

RBCs and Gas Transport

• RBCs are packed full of ______________ (280 million/cell)

• O2 binds to non-protein ____________(Fe2+ an ionic form

of iron)

• each heme group binds to 1 O2, therefore 1 RBC can carry approximately 1 billion molecules of O2!

18.5

RBCs and Gas Transport

• RBCs also contain the enzyme carbonic anhydrase

• This enzyme catalyzes the reaction of CO2 with H2O

This serves 2 functions:

Erythrocytes and Hemoglobin

• RBC count and hemoglobin concentration indicate amount of O2 blood can carry– hematocrit (packed cell volume) - __________________

• men 42- 52% cells; women 37- 48% cells

– hemoglobin concentration of whole blood• men 13-18g/dL; women 12-16g/dL

– RBC count • men 4.6-6.2 million/L; women 4-2-5.4 million/L

• Values are lower in women…..why?– 1)– 2)

RBC production: Erythropoiesis

Stem cells that formALL formed elements

in bloodLocation:

EPO:________________A hormone that stimulatesECFU to transform into an erythroblast

Erythroblasts multiply and synthesize hemoglobin

Leave bonemarrow andenter bloodstream

Fig 18.6

RBC production rate ~ 2.5 million / second

Erythrocyte Homeostasis• Negative feedback control

– drop in RBC count causes _______________________

– EPO production stimulates bone marrow

– RBC count in 3 - 4 days

• Stimulus for erythropoiesis– low levels O2

– increase in exercise– loss of lung tissue in emphysema

18.7

Erythrocytes Recycle/Disposal• RBCs lyse in narrow

channels in ____________• Macrophages in _________

– digest membrane bits– separate heme from globin

• Globins converted to AAs

• iron removed from heme and recycled

Bile pigments

18.9

Blood typing: Antigens and Antibodies

• ___________– unique molecules on cell surface

• used to distinguish self from foreign• foreign antigens generate immune response

• ___________– secreted by plasma cells

• as part of immune response to foreign matter

• ___________ – antibody molecule binding to antigens– causes clumping

Blood Types• RBC antigens

– agglutinogens; A and B– on RBC surface

• Your ABO blood type is determined by presence or absence of antigens (agglutinogens) on RBCs– type A person has ____ antigens– type B person has ____ antigens– type AB has ________ antigens– type O has __________ antigen

• most common - type O

• rarest - type AB

18.12

Plasma antibodies• Antibodies (agglutinins); anti-A and -B• Appear 2-8 months after birth; at maximum

concentration at 10 yr.– Anti -A and/or -B (both or none) are in plasma

• you do not form antibodies against your antigens

• Therefore:– type A blood has _____________ antibodies– type B blood has _____________ antibodies– type O blood has _____________ antibodies– type AB blood has _____________antibodies

• Transfusion with wrong blood type = agglutination

Rh Group

• Rh (D) agglutinogens discovered in rhesus monkey in 1940– Rh+ blood type has D agglutinogens on RBCs– Rh frequencies vary among ethnic groups

• Anti-D agglutinins not normally present

Leukocytes (WBCs)

• 5,000 to 10,000 WBCs/L

• Conspicuous nucleus

• Travel in blood before migrating to connective tissue

• Function:_____________________

Granulocytes

- in bacterial infections

-phagocytosis of bacteria

-release antimicrobial chemicals

in parasitic infections-phagocytosis of antigen- antibody complexes, allergens and inflammatorychemicals

-release enzymes to destroy parasites

in chicken pox, sinusitis, diabetes

-secrete histamine (vasodilator)-secrete heparin(anticoagulant)

Agranulocytes

in diverse infections and immune responses

-destroy cells (cancer, foreign, and virally infected cells)-“present” antigens to activate other immune cells-coordinate actions of other immune cells-secrete antibodies and provide immune memory

in viral infections and inflammation

-differentiate into macrophages-phagocytize pathogens and debris-“present” antigens to activate other immune cells

Platelets• Small fragments of _____________ cytoplasm

– 2-4 m diameter; contain “granules”

– amoeboid movement and phagocytosis

• Normal Count - 130,000 to 400,000 platelets/L• Functions

– 1

– 2

– 3

– 4

18.20

Hemostasis: preventing blood loss

1) Vascular spasm

18.21

• Causes– 1– 2– 3

• Effects– prompt constriction of a

broken vessel• pain receptors - short

duration (minutes)• smooth muscle injury

- longer duration– provides time for other

two clotting pathways

Hemostasis: preventing blood loss

2) Platelet plug formation

18.21

• broken vessel exposes _____________

• platelet pseudopods stick to damaged vessel and other platelets - draw walls of vessel together forming a __________– Release 5-HT

(vasoconstictor), ADP, and thromboxane A2

• positive feedback cycle is active until break in vessel is sealed

Hemostasis: preventing blood loss

• Clotting - most effective defense against bleeding– conversion of plasma protein __________ into insoluble

_________ threads to form framework of clot– Extrinsic and intrinsic pathways converge on common

reaction cascade to produce fibrin

3) Coagulation18.21