13 blood physiology m[1]

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Chapter 13

Blood


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Circulatory System


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Functions

Transportation:

02 and C02, nutrients, waste

Regulation:

hormones, body temperature

Protection:

blood clotting, immune system


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CIRCULATORY SYSTEM:

- Cardiovascular System (CV)

Heart:Pump.

Blood vessels:

Arteries, arterioles, capillaries, venules, veins.

- Lymphatic System:

Lymphatic vessels and lymph nodes.


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BLOOD


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COMPOSITION OF BLOOD

C i h Th M G Hill C i I P i i i d f d i di l


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Composition of Blood

Plasma- liquid part

Formed elements- cells and platelets

C i ht Th M G Hill C i I P i i i d f d ti di l


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Plasma:

- H20

- dissolved solutes.

Ions (Na+, etc.), nutrients, hormones.

- plasma proteins (7-9% of plasma)

albumin, a b and g globulins, fibrinogen

C i ht Th M G Hill C i I P i i i d f d ti di l


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Plasma proteins:

Albumin:Major-Accounts for 60-80% of plasma proteins.

Provides the osmotic pressure needed to draw H20 frominterstitial fluid into capillaries.

.: Maintains blood pressure.

Globulins:a globulins and b globulins:

Transport lipids and fat soluble vitamins.g globulins:

Antibodies.

Fibrinogen:clotting factor.

Copyright The McGraw Hill Companies Inc Permission required for reproduction or display


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Blood

Formed elements:

RBC

WBC

platelets

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Blood

Formed elements:

RBC

WBC= leukocytes, including:

- granulocytes

- agranulocytes, including:

lymphocytes

Platelets (not cells)

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Blood Cells and Platelets



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RBC

Red Blood Cells (RBC)= Erythrocytes

biconcave discs.

increased surface area through which gas can diffuse.

full of hemoglobin (and iron), to carry O2.

no nuclei, no mitochondria (anaerobic metabolism).

Life span of ~ 120 days.

Each RBC contains 280 million hemoglobin molecules.



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WBC

White blood cells (WBC)= leukocytes

Roll in blood, and can crawl.

Can squeeze through capillary walls= diapedesis

or extravasation.Granular leukocytes= granulocytes

Neutrophils (aka polymorphonuclear leukocytes), eosinophils(vs. parasites), basophils (heparin)

Life span of ~ under 3 daysAgranular leukocytes= agranulocytes

Lymphocytes = immune system

Monocytes (macrophages)

Life span of ~ 100-300 days



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Extravasation



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Extravasation



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py g p , q p p y

Platelets (thrombocytes)

Are fragments of megakaryocytes.lack nuclei.

amoeboid movement.

small

blood clotting

Survive 5-9 days.



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py g p , q p p y

FORMATION OF BLOOD CELLS



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py g p q p p y

Hematopoiesis

Hematopoiesis

Differentiation process which forms blood cells.

- much mitosis, differential gene expression.

Occurs in myeloid tissue (bone marrow of long bones).

2 types of hematopoiesis:

Erythropoiesis:Formation of RBCs.

Leukopoiesis:Formation of WBCs.

Also in lymphoid tissue.



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Erythropoiesis

Erythropoiesis:- formation of new RBC

- In myeloid tissue (bone marrow of long bones)

- takes about 3 days2.5 million RBCs are produced every second!

- stimulated by Erythropoietin- A hormone, secreted by kidneys (they sense need for more O2)

- EPO-GEN: recombinant erythropoietin- for chemotherapy, dialysis patients

Old RBCs are destroyed in spleen and liver.Iron recycled

- carried by transferrin in the blood

Need iron, vitamin B12 and folic acid for erythropoiesis.



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Illnesses

Anemia: lack of RBC or hemoglobin



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Leukopoiesis

Leukopoiesis

- development of WBCs

- In myeloid and lymphoid tissue

- stimulated by cytokines, including interleukins



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BLOOD TYPING



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Blood Typing

Genes -> proteins (antigens) on surface of RBC

A, B, AB, O.

Important for transfusions.

Some use in paternity, maternity determinations.

See lab!



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Rh Factor

Rh Factor:

Another group of antigens found on RBCs.

Erythroblastosis fetalis or hemolytic disease of thenewborn.

- RhoGAM

See lab!



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BLOOD CLOTTING



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Blood vessels

ENDOTHELIAL cells line the bloodvessels.

- simple squamous epithelium



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Blood Clotting

Intact endothelial cells repel platelets.

by prostacyclin which is a prostaglandin,

made by Cox2.Celebrex, Vioxx inhibit Cox2



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Blood Clotting

Hemostasis: blood clotting.

- Vasoconstriction

- Platelet plug- Fibrin



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Platelet plug

damage to the endothelium wall ->exposes collagen and Von Willebrands factor ->

platelets stick -> platelets secrete contents ->

platelet plug.

note: a positive feedback cascade!

Aspirin: inbits formation of platelet plug by inhibiting COX1

which is necessary for synthesis of a prostaglandin calledthromboxane A which increases stickyness of platelets toeach other once the first ones stick.



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Fibrin

Fibrinogen in blood + thrombin (enzyme) -> fibrin fibers in clot

Instrinsic pathway:

Collagen, test tube glass -> clotting factors -> prothrombin ->

thrombin -> fibrinogen -> fibrin

Extrinsic pathway:

thromboplastin from damaged cells, clotting factors, Ca++,phospholipids from platelets -> prothrombin -> thrombin ->

fibrinogen -> fibrin

Common pathway: prothrombin -> thrombin -> fibrinogen ->fibrin



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Blood Clotting



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Blood Clotting

Serum = plasma without fibrinogen



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Illnesses

Hereditary hemophilias (can bleed to death).



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DISSOLUTION OF CLOTS



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Dissolution of the clot

Kallikrein -> plasminogen -> plasmin

Plasmin is an enzyme that digests fibrin.



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Anticoagulants

Anticoagulant: prevents clots.

- sodium citrate, edta

- Heparin (mucoprotein, stops thrombin)- Coumarin drugs (dicumarol, warfarin)

- recombinant TPA(tissue plasminogenactivator)

13 blood physiology m[1]

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