9-Circulatory Systems in Animals Part 2

8/12/2019 9-Circulatory Systems in Animals Part 2

1/21

Lymphatic System


2/21

The exchange of substances between the blood

and the interstitial fluid that bathes the cells takes

place across the thin walls of the capillaries.


3/21

As blood proceeds along the capillary:1. Blood pressure drops

2. The capillary becomes hypertonic compared to thesurrounding tissue fluids

3. The resulting osmotic gradient pulls water into the capillary byosmosis near the venule end.


4/21

About 85% of the fluid that leaves the

blood at the arterial end of the capillary

bed re-enters from the interstitial fluid at

the venous end.

The remaining 15% is eventually returned

to the blood by the vessels of the

lymphatic system.


5/21


6/21

Fluid enters this system by diffusing into tiny lymphcapillaries intermingled among capillaries of thecardiovascular system.

Once inside the lymphatic system, the fluid is called

lymph, with a composition similar to the interstitial fluid. Eventually the lymphatic system drains into the

circulatory system near the subclavian veins.


7/21

Lymph vessels, like

veins, have valves thatprevent the backflow offluid toward thecapillaries.

Rhythmic contraction ofthe vessel walls helpdraw fluid into lymphaticcapillaries.

Also like veins, lymph

vessels depend mainly onthe movement of skeletalmuscle to squeeze fluidtoward the heart.


8/21

Along a lymph vessels are organs called lymph

nodes. Inside a lymph node is a honeycomb of

connective tissue with spaces filled withleukocytes (WBC) called lymphocytes and

macrophages Lymphocytes and macrophages are

specialized for attacking viruses and bacteria.

When the body is fighting an infection, thesecells multiply, and the lymph nodes becomeswollen.


9/21


10/21


11/21

In addition to

defending against

infection and

maintaining thevolume and protein

concentration of the

blood, the lymphatic

system transports fatsfrom the digestive

tract to the circulatory

system.


12/21

Blood


13/21

Figure 42.14 The composition of mammalian blood

99%


14/21

Figure 42.14x Blood smear

erythrocyte

platelet

leukocytes

Fi 42 1 Diff i i f bl d ll


15/21

Figure 42.15 Differentiation of blood cells

Macrophages


16/21

Erythrocytes

Biconcave in shape due to absence of

nucleus

Absence of nucleuslifespan of 120

days

Dead erythrocytes recycled by spleen and

liver into bilirubinbile


17/21

Erythrocytes

Hemoglobin is the protein

attached to the

erythrocyte

Hemoglobin has 4

polypeptide chains

(quaternary structure)

Each polypeptide chain

has a heme (iron) group

that binds O2

Therefore one erythrocyte

carries 8 oxygen atoms


18/21

Regulation of Erythrocytes

1) + Low blood O2

2) + erythropoietin

3) + erythrocytes

4) + High blood O2

5) - erythropoietin


19/21

Blood Clotting

Platelets initiate

clotting at site of tear

in blood vessel wall

Fibrin is produced toseal any leaks in the

blood clot

Platelets + Fibrin +

Pus = Scab

Fig re 42 16 Blood clot


20/21

Figure 42.16x Blood clot


21/21

Mechanism of Blood Clotting

9-Circulatory Systems in Animals Part 2

Documents

Transcript of 9-Circulatory Systems in Animals Part 2