Heart and Circulatory System Quiz

Heart, Circulatory System, and Blood

• The heart is a hollow muscular organ located in the thorax between the lungs.
• It has four chambers: two atria and two ventricles.
• The heart has four valves.
• The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs.
• The left side of the heart receives oxygenated blood from the lungs and pumps it to the body.
• The heart is surrounded by a membrane called the pericardium, a fibroserous sac.

The Pericardium

• The pericardium is a fibrous sac that encloses the heart and the roots of the great vessels.
• It lies within the middle mediastinum.
• Its function is to restrict excessive movements of the heart and serve as a lubricated container for the different parts of the heart to contract.

Heart Wall

• The heart wall has three layers: endocardium, myocardium, and pericardium.
• Endocardium is the deepest layer, a smooth lining to reduce friction of blood flow.
• Myocardium is the middle layer, it contains muscle fibers responsible for pumping.
• The pericardium itself consists of two layers: a visceral pericardium, adjacent to the heart, and a parietal pericardium, forming the outer layer of the sac.

Heart Chambers

• The heart has four chambers: two atria and two ventricles (right and left).
• The atria receive blood.
• The ventricles pump blood.

Heart Valves

• Heart valves ensure unidirectional blood flow through the heart.
• They are composed of endocardium with a connective tissue core.
• Major types are atrioventricular (AV) and semilunar valves.

Blood Vessels

• There are three types of blood vessels: arteries, veins, and capillaries.

Arteries

• Arteries carry blood away from the heart.
• They have thick muscular walls with elastic tissue, allowing for expansion and recoil during the heartbeat.
• They have a relatively small lumen reducing frictional loss and maintaining high pressure.
• Blood flows under high pressure and in pulses.
• They lack valves.

Veins

• Veins carry blood back to the heart.
• They have thin muscular walls with little elastic tissue; their walls do not need to withstand high pressure.
• They have a relatively large lumen, accommodating the slower flow rate of blood.
• Blood flows under low pressure and slowly; no pulse.
• They have valves to prevent backflow.

Capillaries

• Link arteries and veins in the tissues.
• They lack muscle.
• They have a wall made of one cell thick endothelium, allowing for efficient diffusion of substances across the capillary wall.
• Pressure falls as blood flows along capillaries.
• Blood flow slows.
• No pulse, no valves.
• Lumen is small enough for red blood cells to squeeze through.

Closed System

• Blood never leaves the network of blood vessels.
• Oxygen (O2), carbon dioxide (CO2), and nutrients are diffused from blood into tissues.

Human Circulatory System Functions

• Transport oxygen and carbon dioxide.
• Distribute nutrients and remove wastes.
• Maintain body temperature.
• Circulate hormones.
• Protect against blood loss from injury.

3 Main Circuits

• Pulmonary circulation
• Coronary circulation
• Systemic circulation

Coronary Circulation

• Oxygen-rich blood is pumped within the heart muscle to nourish the heart muscle tissue.

Pulmonary Circulation

• Oxygen-poor blood is pumped into the lungs for gas exchange.
• Oxygen-rich blood is carried back to the heart.

Systemic Circulation

• Oxygen-rich blood is carried to body tissues delivering oxygen and nutrients.
• Oxygen-poor blood is carried back to the heart.

Pulmonary and Systemic Systems

• Pulmonary circulation involves the heart and lungs, transporting blood for gas exchange.
• Systemic circulation transports oxygenated blood to the body to deliver oxygen and nutrients and return deoxygenated blood to the heart for re-oxygenation.

Cardiac Cycle

• The cardiac cycle has two phases: diastole and systole.
• Diastole: Atria receive blood from the body/lungs, ventricles relax, filling with blood passively.
• Systole: Ventricles contract, pumping blood to arteries, atrioventricular valves close, semilunar valves open.

Heart Rate

• An electrocardiogram (ECG) measures the heart's electrical activity.
• A normal resting heart rate is 70 beats per minute.
• Heart rate varies due to factors such as exercise, sleep, emotions, and drugs.

Blood Pressure

• A sphygmomanometer measures blood pressure.
• A normal reading is 120/80 (systolic/diastolic).
• High blood pressure can be dangerous, causing vessel damage and plaque buildup.

Role of the Kidney in Blood Pressure Regulation

• Healthy kidneys respond to aldosterone, a hormone produced by adrenal glands.
• Aldosterone helps regulate blood pressure by controlling sodium and water reabsorption.
• Kidney damage and high blood pressure create a negative feedback loop, harming kidneys.

Test your knowledge on the anatomy and functions of the heart and circulatory system. This quiz covers the heart's structure, the pericardium, and the layers of the heart wall. Perfect for biology students and those interested in human physiology.