The Cardiovascular System (Heart and blood) (2024)

Contents

Functions of the cardiovascular system
Blood
Blood vessels
The heart
The spleen
Roots, suffixes, and prefixes
Cancer Focus
Related Abbreviations and Acronyms
Further Resources

Functions of the cardiovascular system

Blood circulates through a network of vessels throughout the body to provide individual cells with oxygen and nutrients andhelps dispose of metabolic wastes. The heart pumps the blood around the blood vessels.

Functions of blood and circulation:

• Circulates OXYGEN and removes Carbon Dioxide.
• Provides cells with NUTRIENTS.
• Removes the waste products of metabolism to the excretory organs for disposal.
• Protects the body against disease and infection.
• Clotting stops bleeding after injury.
• Transports HORMONES to target cells and organs.
• Helps regulate body temperature.

Blood

Blood is made up of about 45% solids(cells) and 55% fluids (plasma). The plasma is largely water, containing proteins, nutrients, hormones, antibodies, anddissolved waste products.

General types of blood cells: (each has many different sub-types)

ERYTHROCYTES

(red cells) are small red disk shapedcells. They contain HAEMOGLOBIN, which combines with oxygen inthe lungs and is then transported to the body's cells. Thehaemoglobin then returns carbon dioxide waste to the lungs.Erythrocytes are formed in the bone marrow in the knobby ends ofbones.

LEUKOCYTES

(white cells) help the body fight bacteriaand infection. When a tissue is damaged or has an infection thenumber of leukocytes increases. Leukocytes are formed in thesmall ends of bones. Leukocytes can be classed as granular ornon granular. There are three types of granular leukocytes(eosinophils, neutrophils, and basophils), and three types ofnon-granular (monocytes, T-cell lymphocytes, and B-celllymphocytes). See also the lymphatic system.

THROMBOCYTES

(platelets) aid the formation of bloodCLOTS by releasing various protein substances. When the body isinjured thrombocytes disintegrate and cause a chemical reactionwith the proteins found in plasma, which eventually create athread like substance called FIBRIN. The fibrin then "catches"other blood cells which form the clot, preventing further lossof blood and forms the basis of healing.

Blood vessels

Simplified diagram of the circulatory system. Image Source: http://en.wikipedia.org/wiki/File:Circulatory_System_en.svg

ARTERIES

carry oxygenated blood away from the heart. Theyare thick hollow tubes which are highly ELASTIC which allowsthem to DILATE (widen) and constrict (narrow) as blood is forceddown them by the heart. Arteries branch and re-branch, becomingsmaller until they become small ARTERIOLES which are even moreelastic. Arterioles feed oxygenated blood to the capillaries.The AORTA is the largest artery in the body, taking blood fromthe heart, branching into other arteries that send oxygenatedblood to the rest of the body.

CAPILLARIES

distribute the nutrients and oxygen to thebody's tissues and remove deoxygenated blood and waste. They areextremely thin, the walls are only one cell thick and connectthe arterioles with the venules (very small veins).

VENULES

(very small veins) merge into VEINSwhich carry blood back to the heart. The vein walls aresimilar to arteries but thinner and less elastic. Veins carrydeoxygenated blood towards the lungs where oxygen is receivedvia the pulmonary capillaries. The PULMONARY Veins then carriesthis oxygenated blood back to the heart.

Image source: http://commons.wikimedia.org/wiki/File:Illu_capillary.jpg

The heart

The heart is a hollow muscular organ which beats over 100,000times a day to pump blood around the body's 60,000 miles ofblood vessels. The right side of the heart receives blood andsends it to the lungs to be oxygenated, while the left sidereceives oxygenated blood from the lungs and sends it out to thetissues of the body. The Heart has three layers; the ENDOCARDIUM(inner layer), the EPICARDIUM (middle layer), and MYOCARDIUM(outer layer). The heart is protected by the PERICARDIUM whichis the protective membrane surrounding it.

The heart has FOUR CHAMBERS, in the lower heart the right andleft Ventricles, and in the upper heart the right and leftAtria. In a normal heart beat the atria contract while theventricles relax, then the ventricles contract while the atriarelax. There are VALVES through which blood passes betweenventricle and atrium, these close in such a way that blood doesnot backwash during the pauses between ventricular contractions.The right and left ventricles are divided by a thick wall (theVENTRICULAR SEPTUM), babies born with "hole in the heart" have asmall gap here, which is a problem since oxygenated anddeoxygenated can blood mix. The walls of the left ventricle arethicker as it has to pump blood to all the tissues, compared tothe right ventricle which only pumps blood as far as the lungs.

Image source: http://commons.wikimedia.org/wiki/File:Diagram_of_the_human_heart_(cropped).svg" License: Creative Commons

The spleen

This is a large flat oval organ located below the diaphragm,it's main function is to STORE BLOOD. The size of the spleen canvary, for example it may enlarge when the body is fightinginfection also it's size tends to decrease with age. It is anon-vital organ and it is possible to survive after removal ofthe spleen.

Perinicious anaemia is a Vitamin B12 deficiencyresulting in a reduction in number of erythrocytes.

Aplastic anemia is a failure of the bone marrow toproduce the enough red blood cells.

Septicaemia - bacterial toxins in blood.

Roots, suffixes, and prefixes

Most medical terms are comprised of a root word plus a suffix (word ending) and/or a prefix (beginning of the word). Here are some examples related to the Integumentary System. For more details see Chapter 4: Understanding the Components of Medical Terminology

Cancer Focus

Overview of Haematological Malignancies

The most common haematological malignancy is leukaemia - cancer of the white blood cells. There are many types of leukaemia; Acute types progress rapidly, while Chronic types develop more slowly. Leukaemia is often accompanied by anaemia because the red oxygen carrying cells in the blood are crowded out by the cancerous white cells. There are a number of malignancies and disorders affecting other types of blood cells.

Internet Resources for Leukaemia

Acute Lymphoblastic Leukaemia (ALL)

Acute lymphoblastic leukaemia (also known as acute lymphocytic leukaemia or ALL) is a disease where too many immature lymphocytes (a type of white blood cell) are found in the blood and bone marrow. Symptoms can include persistent fever, weakness or tiredness, achiness in the bones or joints, or swollen lymph nodes. Adult ALL and its treatment is usually different to childhood ALL. Almost a third of adult patients have a specific chromosome translocation; "Philadelphia Positive" ALL.

Internet Resources for Acute Lymphoblastic Leukaemia

Acute Myeloid Leukaemia (AML)

Acute myeloid leukemia (AML) is a disease in which too many immature granulocytes (a type of white blood cell) are found in the blood and bone marrow. There are a number of subtypes of AML including acute myeloblastic leukemia, acute promyelocytic leukemia, acute monocytic leukemia, acute myelomonocytic leukemia, erythroleukemia, and acute megakaryoblastic leukemia.

Internet Resources for Acute Myeloid Leukaemia

Other Types of Leukaemia

Chronic Lymphocytic Leukaemia
Chronic Myelogenous Leukaemia
Hairy Cell Leukaemia

Internet Resources for Leukaemia

Childhood Leukaemia

Childhood leukaemias tend to have different characteristics and treatments compared to adult leukaemias. There is a "childhood peak" of Acute Lymphoblastic Leukaemia, there is a lower proportion of Acute Myeloid Leukaemias compared to adult patients. Clinical prognostic factors include age, White Blood Cell count (WBC) at presentation, and Central Nervous System (CNS) involvement. Infants less than 1 year and adolescents over 10 years of age, WBC greater than 50,000, or CNS involvement are associated with a less favourable prognosis.

Internet Resources for Childhood Leukaemia

See Also

Benefits of Physical Activity

Other Haematological Malignancies

- Lymphomas

These are covered in the chapter on the Lymphatic System

- Myelodysplastic Syndromes

Myelodysplastic syndromes, sometimes called "pre-leukaemia" are a group of diseases in which the bone marrow does not produce enough normal blood cells. Common symptoms are anaemia, bleeding, easy bruisability, and fatigue. These Myelodysplastic syndromes can occur in all age groups but are more common in people aged over 60. Myelodysplastic syndromes may develop spontaneously or be secondary to treatment with chemotherapy / radiotherapy. There is an association with Myelodysplastic syndromes and acute myeloid leukaemia.

- Myeloproliferative Disorders

Myeloproliferative disorders are diseases in which too many blood cells are made by the bone marrow, there are 4 main types of myeloproliferative disorders: chronic myelogenous leukaemia, polycythemia vera, agnogenic myeloid metaplasia, and essential thrombocythemia. Chronic myelogenous leukaemia is where an excess of granulocytes (immature white blood cells) are found in the blood and bone marrow. Polycythemia vera is where red blood cells become too numerous often resulting in a swelling of the spleen. Agnogenic myeloid metaplasia is a condition in which certain blood cells do not mature properly, this may result in a swelling of the spleen and anaemia. Essential thrombocythemia is a disease in which the body produces excessive numbers of platelets (cells in the blood that make it clot) which impedes the normal circulation of blood.

- Aplastic Anaemia

Anaplastic Anemia is not a cancer. AA is a rare disease in which the bone marrow is unable to produce adequate blood cells; leading to pancytopenia (deficiency of all types of blood cells). AA may occur at any age, but there is a peak in adolescence / early adulthood, and again in old age. Slightly more males than females are diagnosed with AA, also the disease is more common in the Far East. Patients successfully treated for aplastic anemia have a higher risk of developing other diseases later in life, including cancer.

- Fanconi Anaemia

Fanconi Anaemia is not a cancer, it is a rare disorder found in children that involves the blood and bone marrow. The symptoms include severe aplastic anemia, hypoplasia of the bone marrow, and patchy discoloration of the skin. Recent research has shown an association between Fanconi anaemia and leukaemia.

- Waldenstrom's Macroglobulinemia

This is a rare malignant condition, involving an excess of beta-lymphocytes (a type of cell in the immune system) which secrete immunoglobulins (a type of antibody). WM usually occurs in people over sixty, but has been detected in younger adults.

Internet Resources for Haematological Malignancies

French-American-British (FAB) Classification Scheme

Leukaemia can be classified using the French-American-British (FAB) criteria. for cell morphology:
L1 - ALL: small lymphoid cells, regular nuclei
L2 - ALL: large lymphoid cells, irregualr nuclei
L3 - ALL: large hom*ogeneous cells with prominent nucleolus
M1 - Myeloblastic leukemia without maturation
M2 - Myeloblastic leukemia with maturation
M3 - Promyelocytic leukemia
M4 - Myelomonocytic leukemia
M5 - Monocytic leukemia
M6 - Erythroleukemia
M7 - Megakaryoblastic leukemia
M0 - AML with minimal differentiation

CNS Prophylaxis

Leukaemia can sometimes spread to the spinal cord and brain (Central Nervous System). Intrathecal chemotherapy (injection into the fluid around the spine) may be given to combat or prevent CNS relapse.

Blood Counts

Blood counts are done to test the number of each of the different kinds of cells in the blood. This may be an aid to diagnosis or done to monitor toxicity after each course of chemotherapy. The next course of chemotherapy may be delayed until white cells, neutrophils, and platelets have recovered to a safe level.

Cardiotoxicity

Cardiotoxicity (damage to the heart) is associated with certain anti cancer drugs, especially Adriamycin. As such the total dose of these drugs may be limited to reduce the risk of cardiotoxicity.

Echocardiagram

An Echocardiogramis where an image of the heart is formed when high frequency sound waves are reflected from the muscles of the heart. An echocardiogram may be done before treatment starts to establish a baseline from which to compare future tests.

Metastases through the cardivascular system

The network of blood vessels reach all parts of the body and may provide one of the routes for cancer cells to spread to secondary sites.

Related Abbreviations and Acronyms

Further Resources (4 links)

Cardiovascular System

SEER, National Cancer Institute
Part of a SEER training module for cancer registry staff.

Cardiovascular System - Self Test questions

WebAnatomy, University of Minnesota
Test your anatomy knowledge with these interactive questions. Includes different question types and answers.

Human Anatomy - Heart circulatory system


eDewcate.com

The Circulatory System


Paul Andersen
Paul Andersen surveys the circulatory system in humans. He begins with a short discussion of open and closed circulatory systems and 2,3, and 4-chambered hearts. He describes the movement of blood through the human heart and the blood vessels. He discusses the major components of blood and the cause of a heart attack.

This guide by Simon Cotterill

First created 4th March 1996
Last modified: 1st February 2014