Internal transport in the Cnidarian Aurelia

Open and Closed Circulatory Systems

The Mammalian Heart: A Closer Look

Generalized Circulatory Schemes of Vertebrates

The Mammalian Cardiovascular System: An Overview

The Heart

• Cardiac muscle

• Atria have thin walls

• Ventricles have thick and powerful walls

• Systole = ventricular contraction blood is pumped

• Diastole = ventricular filling

The Cardiac Cycle

•One completesequence of pumping and filling

•Lub dub = heart sounds opening and closing of the valves

–Lub = blood recoiling against the AV valves

–Dub = blood recoiling against SL valves

•Heart murmur = valve defect

The Control of Heart Rhythm

The Structure of Blood Vessels

Blood Pressure

• The force that blood exerts against vessel walls

• BP is greater in arteries than veins

• Pulse is measure of BP

• Exact BP is measured as systolic/diastolic pressures

• Constricted blood vessels have higher BP than dilated vessels

• In veins heart has little effect on BP

Measurement of Blood Pressure

The Interrelationship of Blood Flow Velocity, Cross-Sectional Area of Blood

Vessels, and Blood Pressure

Blood Flow in Capillary Beds

The thoroughfarechannels remain open whether or not the sphinctermuscles are contracted or relaxed

The Movement of Fluid Between Capillaries and the Interstitial Fluid

fluid moves out of capillary

fluid moves into capillary

Lymphatic System

• Lymphatic system returns lost fluid to circulatory system (about 4L per day or 15% of the fluid)

• Lymph nodes filter the lymph

and help fight infection

Differentiation of Blood Cells

5-6 million/mm3

Atherosclerosis: Normal Artery and Artery With Plaque

• A cascade of complex reactions converts prothrombin to thrombin and then fibrinogen to fibrin, forming a clot

Plateletplug

Collagen fibers

Platelet releases chemicalsthat make nearby platelets sticky

Clotting factors from:PlateletsDamaged cellsPlasma (factors include calcium, vitamin K)

Prothrombin Thrombin

Fibrinogen Fibrin5 µm

Fibrin clotRed blood cell

The clotting process begins when the endothelium of a vessel is damaged, exposing connective tissue in the vessel wall to blood. Plateletsadhere to collagen fibers in the connective tissue and release a substance thatmakes nearby platelets sticky.

1

The platelets form a plug that providesemergency protectionagainst blood loss.

2This seal is reinforced by a clot of fibrin when

vessel damage is severe. Fibrin is formed via amultistep process: Clotting factors released fromthe clumped platelets or damaged cells mix withclotting factors in the plasma, forming an activation cascade that converts a plasma proteincalled prothrombin to its active form, thrombin.Thrombin itself is an enzyme that catalyzes the final step of the clotting process, the conversion of fibrinogen to fibrin. The threads of fibrin become interwoven into a patch (see colorized SEM).

3

Figure 42.17

Blood Clot

In which type of blood vessel is the blood pressure the highest?

What type of blood vessel providesthe heart muscle with oxygen?

Name two factors which are under your control that affect

your heart and cardiovascular

health.

What do you think is an“ideal” blood pressure?

When is the blood blue?

After leaving the right ventricle blood flows to . .

The heart is enclosed in a protective sac of muscle calledthe ______________.

The “pacemaker” of the heart is. . ..

Of what three substances are the walls of arteries, capillaries, and veins composed?

Oxygen and carbon dioxide areexchanged in the lungs in vesselscalled _____________.

During inhalation air passes fromthe mouth through the pharynxand into the __________.