Circulatory System Overview

The Circulatory System

• The circulatory system is responsible for regulating body temperature.
• Transports nutrients from the digestive system to body cells.
• Delivers oxygen and removes carbon dioxide from the respiratory system, as well as carrying other waste products for disposal.
• Carries disease-fighting white blood cells to fight invading viruses or bacteria.

Components of the Circulatory System

• The human circulatory system consists of three main parts: the heart, blood vessels (arteries, veins, capillaries), and blood.

Human Heart

• The heart is made of three types of tissues: cardiac muscle tissue, nerve tissue, and connective tissue.

• Cardiac muscle tissue is exclusively found in the heart.

• All cardiac muscle tissues contract simultaneously.

• Heart contractions propel blood throughout the body.

• The heart pumps with a regular beat; the frequency depends on factors like physical activity, stress, age, and health.

• A smooth layer of epithelial tissue covers the heart muscles and nerves, reducing friction and protecting the heart from damage during lung expansion and contraction.

• The inner surface of the heart is lined with smooth epithelial tissue, allowing blood to flow freely.

Anatomy of the Human Heart

• The heart has two pumps: a pulmonary circuit and systemic circuit, that work simultaneously to circulate blood.
• The pulmonary pump sends blood to the lungs.
• The systemic pump sends blood to the body.
• Each pump has two chambers: atrium and ventricle.
• The atrium is a thin-walled chamber that receives blood from veins.
• The ventricle is a thick-walled chamber that pumps blood to arteries at high pressure.
• The two sides are divided by a septum.

The Flow of Blood Through the Body

• The right ventricle pumps oxygen-poor blood to the lungs.
• These arteries are the only ones in the body transporting oxygen poor blood.
• Oxygen-poor blood travels to the right atrium from the body by two large veins.
• In the lungs, blood picks up oxygen and releases carbon dioxide.
• Oxygen-rich blood returns to the left atrium by veins.
• The heart pumps oxygen-rich blood to the body through arteries.
• This oxygen-rich blood travels through the capillaries to deliver oxygen, nutrients, and water to the body's cells.
• Waste products (carbon dioxide) are carried away from the cells during this process.
• Blood then returns to the heart.

Blood Vessels

• There are three types of blood vessels: arteries, veins, and capillaries.
• Arteries carry blood away from the heart.
• Most arteries carry oxygenated blood.
• Arteries have a thick layer of smooth muscle and elastic tissue to withstand high pressure.
• Veins carry blood toward the heart.
• Most veins carry deoxygenated blood.
• Veins have relatively thin walls compared to arteries because blood pressure is lower in veins.
• Veins have valves to prevent backflow.
• Capillaries connect arteries to veins and are extremely thin-walled, only one cell thick, allowing for efficient exchange of materials between blood and body cells.

Blood

• Blood is a specialized bodily fluid.
• Blood contains blood cells that deliver necessary substances like nutrients and Oxygen.
• Carries waste products such as carbon dioxide away from the body's cells.
• Blood is also involved in heat exchange and regulating body temperature.
• Humans have around 5 litres of blood (females (~4.5 liters) and males (~5.6 liters)).
• There are four main blood types: A, B, AB, O.

Components of Blood

• Plasma is the liquid part of blood (54% by volume). It is a rich liquid containing proteins and carrying blood cells.
• Red blood cells (RBCs), also known as erythrocytes, make up 45% of blood volume. They contain hemoglobin enabling oxygen transport, and do not contain a nucleus.
• White blood cells (WBCs or leukocytes), less than 1% of total blood volume, are infection-fighting cells of the immune system. They recognize and destroy invaders like bacteria and viruses, and are the only blood cells with a nucleus.
• Platelets help with blood clotting, less than 1% of total volume.

Centrifuged Blood

• Centrifuging separates blood into components based on density.
• Plasma (low density) rises to the top.
• Denser particles (like red blood cells) go to the bottom.

Where Do Blood Cells Come From?

• Blood cells are produced in the bone marrow, a soft, spongy material in bone.

Diseases and Disorders of the Circulatory System

• Coronary artery disease is a common problem leading to heart attacks. Plaque build-up in arteries is a major cause (fat, cholesterol, calcium and other substances in the blood).
• Arteriosclerosis, a general term for several conditions where artery walls thicken and lose elasticity, often involves plaque buildup.
• Heart attacks occur when coronary arteries become completely blocked, preventing oxygen and nutrient delivery to heart muscle cells; medical attention is urgent.

Arteriosclerosis

Symptoms may include chest pain, shortness of breath, blood clots, and heart failure.

Heart Attack

• Symptoms may include chest pain, shortness of breath, nausea, anxiety, upper body pain, abdominal or stomach pain, sweating, dizziness, and unusual fatigue.

Prevention of Arteriosclerosis and Heart Attack

Healthy lifestyle choices can reduce the risk, including exercise, not smoking, a healthy diet low in unhealthy fats (trans fat), and high in vegetables and fruit.

Homework

• Read pages 83-87 in textbook, and answer questions 1–3 and 8 on page 87.

Answers

• The circulatory system transports substances throughout the body.

• Four substances are: blood, oxygen, nutrients and carbon dioxide.

• The circulatory system obtains nutrient from the small intestine, and transports nutrients throughout the body.

• Cardiac muscle contracts rhythmically without nerve input.