Animal Physiology Circulatory Systems Quiz

Circulation and Cardiovascular Systems

• Overview: The human cardiovascular system is a closed system, including the heart, blood vessels, and blood. It has two major circuits: pulmonary and systemic.

Transport in Invertebrates

• Simple Systems: Some small aquatic animals lack a circulatory system, relying on external water in a gastrovascular cavity or other means to transport substances to cells.
• Pseudocoelomates: Roundworms and other pseudocoelomates have a fluid-filled body cavity that acts as a simple circulatory system for transport.
• Invertebrates with Skeletons: Some invertebrates with skeletons use body fluids, like hemolymph, for locomotion.

Open vs. Closed Circulatory Systems

• Open System: In an open system, the heart pumps hemolymph through vessels that empty into body tissue spaces.
• Closed System: In a closed system, blood remains within blood vessels at all times. Blood, not hemolymph, is circulated throughout the system.

Transport in Vertebrates

• Closed System: All vertebrates have a closed circulatory system with a heart that pumps blood through blood vessels.
• Vertebrate Heart: These hearts have atrial chambers that receive blood from general circulation, and ventricular chambers that pump blood into vessels.
• Vertebrate Vessels: Specialized vessels (arteries, arterioles, capillaries, venules, veins) carry and transport blood, facilitating the exchange of needed materials with tissue fluids.

Transport in Humans

• Human Heart: The human heart is fist-sized, cone-shaped, and contains specialized cardiac muscle fibers. It sits within the pericardium.
• Gross Anatomy: The septum divides the heart into left and right halves, each with an atrium and a ventricle. The atria receive blood, while the ventricles pump blood.
• Atria: Upper chambers, thin-walled, receive blood from circulation.
• Ventricles: Lower chambers, thick-walled, pump blood away from the heart.
• External Anatomy: Includes the superior vena cava, inferior vena cava, aorta, pulmonary arteries, and veins.
• Internal Anatomy: Details the valves of the heart (tricuspid, bicuspid/mitral, pulmonary, and aortic), which control one-way blood flow. The heart has four chambers: the right/left atria, and the right/left ventricles.
• Blood Flow Through the Heart: The flow pattern from the pulmonary circuit and the systemic circuit.
• Valves: The valves in human heart control blood flow by opening and closing. Each valve prevents blood from flowing back.

Heartbeat

• Systole: Contraction of the heart chambers, which is the pumping portion of the heartbeat.
• Diastole: Relaxation, or filling, of heart chambers, which allows the chambers to fill again. This part is longer than systole.
• Pulse: A two-stage action of the heart, taking about one second. Blood collects in the atria, which contract to force blood into the ventricles, while the ventricles are resting. The resting phase of the heart is called diastole.

Cardiac Cycle

• Stages: The cardiac cycle has phases of systole and diastole, regulated by electrical signals.

Circulation System Components

• Blood: Made up of plasma (liquid) and formed elements (cells). The formed elements include red blood cells (transporting oxygen), white blood cells (defending against infection), and platelets (crucial for clotting).
• Blood Vessels: Arteries carry blood away from the heart, veins carry blood towards the heart, and capillaries facilitate the exchange of materials between blood and tissues.

Cardiovascular Disorders

• Hypertension: High blood pressure.
• Atherosclerosis: Plaque buildup in artery walls.
• Stroke: Blocked or burst blood vessel in the brain.
• Heart attack (myocardial infarction): Blockage of a coronary artery that impairs blood flow.
• Angina pectoris: Pain and squeezing sensation due to insufficient oxygen supply to the heart muscle.

Blood Types

• Blood types are determined by the presence or absence of surface antigens on red blood cells and antibodies within the plasma.
• Various blood types—A, B, AB, and O—result.

Blood Clotting

• Blood clotting is a complex process where platelets aggregate and form fibrin threads to stop bleeding.

Capillary Exchange

• Capillaries have thin walls to allow the exchange of gases, nutrients, and wastes between the blood and the tissues. Oxygen and nutrients are transferred to the tissues at the arterial end of the capillary. In contrast, carbon dioxide and waste molecules are diffused into the capillary at the venous end.

Vascular Pathways

• Pulmonary Circuit: Transports deoxygenated blood to the lungs for gas exchange, then oxygenated blood returns to the heart.
• Systemic Circuit: Distributes oxygenated blood to the rest of the body and returns deoxygenated blood to the heart.

Blood Pressure

• Systolic Pressure: Blood pressure in the arteries when the ventricles contract.
• Diastolic Pressure: Blood pressure in the arteries while the ventricles relax.

ECG (Electrocardiogram)

• ECG: An ECG is a recording of electrical activity in the heart. It shows the electrical impulses during each heartbeat. Electrical signals activate the heart, allowing the heart muscle to contract and relax rhythmically.