Physiology - Cardiovascular System

The branches of science that will help you understand the body parts and functions are anatomy and physiology. Anatomy deals with the study of the human body (the component parts, structure and position) and physiology the study of how the body functions.

Body Systems

Select the appropriate body system link, in the table below, to view the available information.

Cardiovascular System

The cardiovascular system comprises of the heart, blood, blood vessels and lymphatic system.

Heart

The function of the heart is to pump blood around the body. The heart is a hollow, muscular organ divided by a vertical wall called the septum. These two chambers are further divided into the thin walled atrium above, and a thick walled ventricle below, making four chambers. Between each pair of chambers are valves preventing any back flow of blood. Blood vessels leaving the heart generally carry oxygenated blood through vessels known as arteries. These are large, hollow elastic tubes with thick muscular walls that are designed to withstand the high pressure with the blood leaving the heart. Their size gradually diminishes as they spread throughout the body, ultimately reaching fine, hair-like vessels known as capillaries. Blood vessels that return blood to the heart are known as veins which generally carry de-oxygenated blood to the heart. They are elastic tubes containing valves to help prevent back flow of blood. Blood is forced through arteries by the pressure from the heart whereas venous flow is aided by muscular contraction.

The only two exceptions to the above are the pulmonary artery, which carries de-oxygenated blood from the heart to the lungs, and the pulmonary vein, which carries oxygenated blood from the lungs to the heart. The circulation is divided into two principle systems known as the general or systemic circulation, that is the circulation around the body, and the pulmonary circulation to and from the lungs.

Blood

The fluid that surrounds tissue cells throughout the body is called interstitial fluid and is serviced by blood transporting oxygen and nutrients to it whilst lymph removes toxins and waste products. Blood forms about 709% of the body weight consisting of Plasma, Corpuscles and Platelets. Erythrocyte (red blood cells) transport oxygen and carbon dioxide, leucocytes (white blood cells), produced in red bone marrow (myeloid tissue), and lymphocytes fight infection and thrombocyte (platelet) are essential to blood clotting at the site of an injury. Plasma is a clear slightly alkaline yellow fluid in which the following are dissolved - blood, proteins, salts, waste materials, gases, enzymes, hormones and vitamins. The blood has three main functions, transport, regulation, and protection.

Transports

• oxygen from the lungs to the cells
• carbon dioxide from the cells to the lungs
• nutrients from the intestines to the cells
• waste material from the cells
• hormones from the endocrine glands to the cells
• heat from various cells

Regulates

• pH (concentration of hydrogen ions)
• body temperature
• salts
• water content in the cells

Protection

• Blood prevents loss by clotting and combats toxins

Lymphatic

As blood is the main transport system to the body, so it may also bring bacteria to the tissues. The lymphatic system is the protective system that picks up materials, cleanses them of waste products and toxins, and returns them to the blood. Although it is described as a separate system, it is really part of the vascular system, being intertwined with the blood circulation.

Effect of exercise on the cardiovascular system

The effects of regular exercise on the vascular system:

• The supply of blood vessels to the heart will increase thereby lowering blood pressure and improving the functioning of the heart
• Lowers the cholesterol levels in the blood helping to reduce the risk of arteries "furring up" and possible heart disease
• The period needed for the heart rate to return to normal after exercise is reduced
• The network of capillaries in a muscle will increase thereby increasing the supply of blood, oxygen and nutrients to the working muscle

Associated Pages

The following Sports Coach pages should be read in conjunction with this page:

• Articles on Physiology
• Blood Pressure
• Body Fat
• Body Type
• Energy Pathways
• Ideal Weight
• Lactic Acid
• Maximum Heart Rate
• Movement Analysis
• Muscle Types
• Protein
• Range of Movement
• Vitamins
• VO2 max

• Training Books
• Training Products

Associated Books

The following books provide more information related to this topic:

• Principles of Anatomy and Physiology, G.J. Tortora et al., ISBN 0 06 046704 5
• Strength Training Anatomy, F. Delavier, ISBN 0 7360 4185 0
• Atlas of Skeletal Muscles, R.J. Stone et al., ISBN 0 697 13790 2
• The Muscle Book, P. Blakey, ISBN 1 873017 00 6
• Advanced Studies in Physical Education and Sport, P Beashel et al., ISBN 0 17 4482345
• Physical Education and the Study of Sport, B. Davis et al., ISBN 0 7234 31752
• Essentials of Exercise Physiology, W.D. McArdle et al., ISBN 0 683 30507 7
• Physical Education and Sport Studies, D. Roscoe et al., ISBN 1 901424 20 0
• The World of Sport Examined, P. Beashel et al., ISBN 0 17 438719 9
• Advanced PE for Edexcel, F. Galligan et al., ISBN 0 435 50643 9
• Examining Physical Education, K. Bizley, ISBN 0 435 50660 9
• Sport and PE, K Wesson et al., ISBN 0 340 683821
• PE for you, J. Honeybourne, ISBN 0 7487 3277 2