Circulation and Gas Exchange

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8

Slide 49

Fluid exchange between capillaries and the interstitial fluid

Body tissue

Capillary

INTERSTITIAL FLUID

Net fluid

movement out

Direction of

blood flow

Net fluid

movement in

Blood pressure = hydrostatic pressure

Inward flow

Outward flow

Osmotic pressure

Arterial end of capillary

Venous end

Pressure

Slide 50

Fluid Return by the Lymphatic System

The lymphatic system - returns fluid that leaks out in the capillary beds … restoring filtered fluid to blood maintains homeostasis.

This system aids in body defense.

Fluid, called lymph, reenters the circulation directly at the venous end of the capillary bed and indirectly through the lymphatic system.

The lymphatic system drains into neck veins.

Slide 51

Lymph nodes are organs that produce phagocytic white blood cells and filter lymph - an important role in the body’s defense.

Edema is swelling caused by disruptions in the flow of lymph.

Slide 52

Blood Composition and Function

Blood consists of several kinds of blood cells suspended in a liquid matrix called plasma.

The cellular elements: red blood cells, white blood cells, and platelets occupy about 45% of the volume of blood.

Slide 53

Composition of mammalian blood

Plasma 55%

Constituent

Major functions

Water

Solvent for

carrying other

substances

Ions (blood electrolytes)

Osmotic balance,

pH buffering, and

regulation of

membrane

permeability

Sodium

Potassium

Calcium

Magnesium

Chloride

Bicarbonate

Osmotic balance

pH buffering

Clotting

Defense

Plasma proteins

Albumin

Fibrinogen

Immunoglobulins

(antibodies)

Substances transported by blood

Nutrients (such as glucose, fatty acids, vitamins)

Waste products of metabolism

Respiratory gases (O2 and CO2)

Hormones

Separated

blood

elements

Cellular elements 45%

Cell type

Functions

Number

per µL (mm3) of blood

Erythrocytes

(red blood cells)

5–6 million

Transport oxygen

and help transport

carbon dioxide

Leukocytes

(white blood cells)

5,000–10,000

Defense and

immunity

Basophil

Neutrophil

Eosinophil

Lymphocyte

Monocyte

Platelets

Blood clotting

250,000–

400,000

Slide 54

Plasma

Blood plasma is about 90% water.