Anatomy & Physiology - Body Systems

The 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

The body comprises of a number of systems including the: Cardiovascular system, Digestive system, Endocrine system, Muscular system, Neurological system, Respiratory system and the Skeletal system.

The 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 79% 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

The Bohr Shift

This is a microbiological phenomenon first described in 1904 by the Danish physiologist Christian Bohr: a decrease in blood pH or an increase in blood CO2 concentration will result in haemoglobin proteins releasing oxygen and a decrease in carbon dioxide or increase in blood pH will result in haemoglobin picking up more oxygen.

Page Reference

The reference for this page is:

MACKENZIE, B. (2001) Physiology - Cardiovascular System [WWW] Available from: http://www.brianmac.co.uk/physiolc.htm [Accessed

Associated Pages

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