Science Focus Topic 7 Notes: Body Systems and Your Health | Print |
Muscles require more oxygen and nutrients as activity increases, making the heart work faster pumping blood (which supplies what is needed).

Blood ? The Body?s Transportation System

The blood vessels of the circulatory system form a complex network linking the outside environment with the internal environment of the body.  The blood supplies all the living cells in the body with the nutrients they need to carry out their functions. 
About 8% of an adult?s body weight is blood, made up of:
(Table 2.2, page 155)


% of blood (by volume)

Main Function



carries nutrients, waste products, hormones, and blood cells

red blood cells


carries oxygen (because they have hemoglobin ? an iron- rich chemical, which attracts oxygen)

white blood cell

less than 1%

defends the body against infection and disease


less than 1%

causes the blood to clot (thicken) at site of wounds to prevent blood loss

The circulatory system must work closely with the respiratory system (which supplies the oxygen) and the digestive system (which supplies the nutrients)

Disorders, which can hospitalize Canadians include: circulatory system (15%), digestive system (11%) and respiratory system (10%).

A Healthy Circulatory System

The heart circulates the blood throughout the body by pumping it to where it can supply nutrients and remove wastes.

Disorders of the circulatory system include: high blood pressure (hypertension), heart attacks (damage to heart muscle) and strokes (brain damage).

Blood Pressure

The device used to measure blood pressure is called a sphygmomanometer (an inflatable cuff wrapped around the arm, with a pump attached ? which is used to inflate it).  The blood flow is slowed and then listened to by a doctor, with a stethoscope.

Blood pressure indicates:
·        The volume of blood
·        Heart rate
·        Artery size
·        Artery elasticity
·        Blood viscosity

Disorders of the Circulatory System

Certain conditions place people at greater risk of contracting a circulatory system disorder:

·        Smoking (nicotine causes blood vessels to constrict, increasing the heart rate and raising blood pressure ? carbon monoxide competes with oxygen in the lungs, reducing the blood?s ability to carry oxygen)

·        Poor diet (may produce a high cholesterol level ? building fat in the arteries and restricting blood flow)

·        Little exercise (makes fatty deposits increase, because the nutrients are not used

A Healthy Digestive System

Food provides nutrients in the form of carbohydrates, fats, proteins, vitamins, minerals and water ? which provide energy and materials used for growth, development and repair.

Some foods cause poor health and promote disease (like refined sugar and low fibre foods) if consumed in large quantities over long periods of time.

Nutrients in Food

Starch and sugars are carbohydrates and provide the body with its main source of energy.  Fats are also essential in our diet, providing us with energy and cushioning the internal organs from shock.  Proteins are essential for growth and repair of body tissues.  Minerals and vitamins are also needed for good health.

Disorders of the Digestive System

High fibre diet is important because fibre is used by the colon to process waste materials (low-fibre can irritate the colon wall and lead to colon cancer).

Long-term stress, smoking, excessive use of alcohol or aspirin can lead to a peptic ulcer.

A Healthy Respiratory System

Smoking, air pollution and industrial by-products (coal dust) can lead to disorders of the respiratory system.

Disorders of the Respiratory System

Cilia (small hair-like projections in your lungs) beat continuously to remove airborne particles.

Poisons in cigarette smoke and pollutants irritate the lining of the lungs, causing certain cells to produce more mucus.  If this lining becomes inflamed, it can lead to bronchitis, which can lead to emphysema.

Lung cancer is caused by the tar and smoke in cigarettes, which cause the lung cells to grow out of control and overcome healthy cells.

You and Your Body

Proper care means maintaining healthy organs and organ systems.  This can be accomplished with clean air and water, nutritious foods, exercise and sleep.  This is a healthy lifestyle, which makes you feels better and helps your body resist disease.  Your immune system will work best when you are well fed and rested.

Topic 7 Review p. 162

WRAP-UP  p. 163
>>>>  A good review of Topics 6 ? 7  in this Unit  <<<<

Unit Review  p. 168-171
>>>>  A review of all of the Topics in this Unit  <<<<