Internal transport in the Cnidarian Aurelia. Open and Closed Circulatory Systems.
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Transcript of Internal transport in the Cnidarian Aurelia. Open and Closed Circulatory Systems.
The Heart
• Cardiac muscle
• Atria have thin walls
• Ventricles have thick and powerful walls
• Systole = ventricular contraction blood is pumped
• Diastole = ventricular 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
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
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
• 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.
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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).
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Figure 42.17
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. . ..