The Circulatory System

Blood The human body contains 4-6 litres of blood (about 9% of body weight) Anatomy Liquid Plasma Solid Red Blood Cells White Blood Cells Platelets

Blood

Red Blood Cells About 5 000 000 per mm3 of blood About 25 trillion (25 000 000 000 000) in the entire organism Live 20-135 days (destroyed by phagocytosis, the liver and the spleen) Get their colour from HEMOGLOBIN (a red protein) Function: attach to molecules of oxygen and/or carbon dioxide to transport them

Red Blood Cells

White Blood Cells 5000-9000 per mm3 of blood Completely colourless Much larger than red blood cells Functions: Phagocytosis: engulf and digest old blood cells, microbes and other foreign particles Produce antibodies Help with coagulation of blood

Antibodies, Antibiotics, Immunity & Vaccines Microbes (bacteria and viruses) often enter the body If a microbe cannot be destroyed by phagocytosis, the white blood cells produce ANTIBODIES to destroy them Once antibodies have been produced to destroy a particular microbe, they can always destroy it in the future. This is called IMMUNITY

Antibodies, Antibiotics, Immunity & Vaccines When the production of antibodies is not effective enough, doctors sometimes prescribe ANTIBIOTICS (artificial antibodies) to kill off the microbe Antibiotics only work on bacteria and do not produce immunity VACCINES are microbes that have been weakened. When vaccines are injected, white blood cells produce antibodies. The person is then immune to the disease.

White Blood Cells

Platelets 300 000 – 350 000 per mm3 of blood Functions: Stick to microbes to slow down their progress Produce enzymes necessary for coagulation and for the formation of scar tissue

Platelets

Plasma A complex liquid that occupies about 55% of blood volume Composed of: 90% Water 10% Dissolved substances (digested food, hormones, enzymes, waste products…)

Plasma Functions Keeps blood fluid Transports nutrients, waste products, etc. Transports antibodies

Lymph A liquid derived from plasma (much higher percentage of water) Functions: Carries cellular needs out of the bloodstream to the cells Carries waste products from the cells back into the bloodstream

The Heart A pump responsible for circulating blood throughout the body The muscle of the heart, the myocardium, contracts regularly Has four cavities The right and left atrium (on top) The right and left ventricle (on the bottom)

The Heart

The Heart

The Heart

The Heart

The Blood Vessels Three groups of blood vessels Arteries Veins Capillaries

Arteries Blood vessels responsible for carrying OXYGENATED blood, under pressure, from the heart towards the body’s cells Divide into arterioles, that then connect with the capillaries

Veins Blood vessels responsible for carrying VICIATED blood (filled with carbon dioxide) from the body’s cells towards the heart Divide into venules that are connected to the capillaries

Blood Vessels Venules Arterioles Arteries Capillaries Veins

General (Systemic) Circulation Beginning in the LEFT ATRIUM, oxygenated blood is pumped into the LEFT VENTRICLE, then into the AORTA The aorta connects to all of the ARTERIES in the body The VEINS carry the blood back to the VENA CAVA on the right side of the heart

General (Systemic) Circulation

Pulmonary Circulation Viciated blood returning from the cells is pumped from the RIGHT ATRIUM into the RIGHT VENTRICLE The blood is then pumped into the PULMONARY ARTERIES to enter the lungs The PULMONARY VEINS bring the blood back to the left side of the heart

Pulmonary Circulation Pulmonary arteries Pulmonary arteries Pulmonary veins Pulmonary veins

All together…

Blood Pressure Blood pressure (the pressure exerted by blood on the walls of the arteries) is measured at two different moments in the cardiac cycle: Systole: when the heart is beating Diastole: when the heart is at rest

Blood Pressure Normal blood pressure Systolic pressure: 100-140 mm/Hg Diastolic pressure: 60-90 mm/Hg

Blood Pressure Hypertension (high blood pressure) Risk factors Pressure above 140 and/or 90 Risk factors Excess body weight Poor diet (high in fat and/or sodium) Stress Heredity Smoking

Blood Pressure Symptoms Possible complications Remedies and Treatments None!! (known as the silent killer) Possible complications Heart attack/failure (myocardial infarction) Stroke (cerebrovascular accident) Remedies and Treatments Lifestyle changes (healthy diet & exercise, stop smoking, stress management) Medication

Blood Pressure Hypotension (low blood pressure) Common Causes Symptoms Pressure below 100 and/or 60 Common Causes Weakness of the heart (lack of exercise and/or lack of food energy) Symptoms Fatigue Dizziness/Fainting Difficulty concentrating

Blood Pressure Treatment Lifestyle changes (healthy diet & exercise)

Blood Types To identify an individual’s blood type, the presence or absence of two antigens (specific proteins) is used: Antigen Blood Group A B A and B AB None O

Blood Types

Blood Types The different antigens determine the presence of certain antibodies: Group Antigens Antibodies A anti-B B anti-A AB A & B none O None anti-A & anti-B

Blood Types

Blood Types

Blood Types The presence or absence of a third antigen (Rh) determines the blood type Rh present = positive (+) Rh not present = negative (-) This gives us 8 blood types: A-, A+, B-, B+, AB-, AB+, O-, O+

Blood Types Blood Type Can donate to: Can receive from: A- A+ B- B+