7. Unit 2A Blood

8/3/2019 7. Unit 2A Blood

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Unit 2A

Human Form & Function

Body systems

Blood



Study Guide

Read :

•

Text Chapter 9 Complete:

• RQ 1-12

• AYK 5&6



The circulatory system

Blood



Functions of blood

• Transport

•

Transports nutrients, oxygenand hormones to the tissues.

• Removes wastes such as

carbon dioxide and urea.



• Regulation

•

Helps to keep the body’s pHwithin its homeostatic range.

• Helps in regulating the body's

temperature.



• Protection

•

Prevents blood loss if bloodvessels are damaged.

• Protects the body against

pathogens and toxins.



Features of blood

• Temperature 380C

•

pH 7.35-7.45• Salinity 0.9%

• Total body weight 8%

• Volume Men 5-6 L,Women 4-5 L



Composition

~55%~40%

~4%

~1%



Blood plasma

• Plasma is a clear, pale yellow liquid

which comprises 46-63% of the whole

blood• Plasma consists of:

water (92%)

dissolved organic and inorganic solutes

(e.g. sodium & chloride ions, nutrients &wastes) (1%)

dissolved plasma proteins (7%)



Bloodcells

Number/mm3

Principal function

Red bloodcells (Erythro-cytes)

4-6 million Transport of O2 (&some CO2 transport)

White blood cells (Leukocytes)

Granularleukocytes

Neutophils 2 000-7 000 Phagocytes

Eosinophils 100-400 Phagocytes & anti-inflammatory response

Basophils 20-100 Inflammatory response

Agranularleukocytes

Monocytes 100-900 Phagocytes

Lymphocytes 1 500-3 000 Immune response

Platelets (Thrombo-

cytes)

200 000 -500 000

Blood clotting



Formed elements

Red bloodcells

White blood

cells

Bloodplatelets



Red blood cells

EM unit / Royal Free Medical School, Wellcome Images



White blood cells

Neutrophil Basophil

Eosinophil Monocyte



Clotting of blood

David Gregory& Debbie Marshall, Wellcome Images



Clotting of blood

• A blood clot is a jelly-like massthat forms at the site of a wound

to stop bleeding.

• A clot consists of a mesh of long,

stretchy protein fibres, andtrapped blood cells.



• When the clot solidifies it formsa scab.

• If a clot forms inside a blood

vessel it forms a thrombus.If a thrombus breaks loose itcan lodge in a vital blood vessel

in the heart or brain causing aheart attack or stroke.



The thrombin system

1.Following damage to a blood vessel,blood platelets and the injured cellsrelease thromboplastin.

2. Thromboplastin interacts with Ca ++and prothrombin (an inactive plasmaprotein) to form thrombin.

3.Thrombin converts finbrinogen (another inactive plasma protein) tolong, stretchy fibres of fibrin.





Serum is the clear yellow fluid

that oozes out of the clot – thisis plasma minus the fibrinogen.

After a couple of days an enzymein the clot activates fibrinolysis

- this starts the break-down of the clot



The thrombin system - summary

• Thromboplastin +prothrombin + Ca++= thrombin

• Thrombin + fibrinogen = fibrin

• Fibrin + blood cells = clot



The inflammatory response



• Inflammation is the body’sresponse to harmful substances,

injury, or irritants.

• Typically the affected area

becomes red, tender andswollen.




Stages in the inflammatory

response

• When the body is injured,

infected or exposed to irritants,radiation, or extremetemperatures, a complex

chemical response is initiated.



• This response involves severalcompounds being released in theaffected area. These substancesboth interact and have specificoutcomes (i.e. the inflammatoryresponse)e.g. histamine is released by mastcells, which causes local dilation of

the blood vessels and increasesmucus secretion – anti-histamine drugs reverse this effect.




The inflammatory response includes:

• Dilation of the blood vesselsin the affected area.

• Increased permeability of the capillaries, allowingplasma to leak into

surrounding tissue.

• Chemotaxis – phagocytes areattracted to the affected area.

Resulting inredness,swelling,heat & pain




1. Chemical response toinjury

A variety of chemicalsreleased in theaffected area

2. Inflammatory response

•Vasodilation of blood vessels

•Increased permeability ofblood vessels

•Chemotaxis

Site ofinjury

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7. Unit 2A Blood