General Outcome A1 - Students will analyze how the human circulatory system facilitates interaction between blood cells and the external environment and investigate cardiovascular health.

Students will:
30–A1.1k describe the principal structures and associated blood vessels of the heart; i.e., ventricles, atria, septum, valves (specific names of valves not required), aorta, vena cavae, pulmonary arteries and veins, coronary arteries
30–A1.2k describe the rhythmic contraction of the heart and its function in the general circulation of blood through pulmonary and systemic pathways
30–A1.3k describe the structure and function of blood vessels and the flow of blood through arteries, arterioles, venules, veins and capillaries
30–A1.4k describe the main components of blood (i.e., plasma, red blood cells, white blood cells, platelets, blood proteins that include antibodies, hemoglobin and hormones) and their role in the transportation of substances (e.g., nutrients, wastes, gases, hormones), blood clotting, the defense against pathogens and the distribution of thermal energy.

General Outcome A2 - Students will analyze the defense mechanisms used by the human body to protect itself from pathogens found in the external environment.

Students will:
30–A2.1k describe how pathogens in the environment (e.g., mosquito-borne parasites, bacteria, viruses) enter the circulatory system and may have an adverse affect on health
30–A2.2k describe, in general terms, the function of various body mechanisms, including the skin and body secretions (i.e., tears and stomach acid), in preventing pathogens from entering body tissues
30–A2.3k describe, in general terms, how immunity to pathogens develops, how the immune system responds to a foreign antigen and the roles of macrophages, B cells, helper T cells, killer T cells, suppressor T cells, memory cells and antibodies
30–A2.4k explain the interrelationship of autoimmune diseases and the human immune system; e.g., multiple sclerosis, arthritis, lupus
30–A2.5k analyze how vaccines defend against disease-causing bacteria and viruses.

1.1 The Heart

The human circulatory system performs four key functions. It:

• transports and delivers oxygen and nutrients (e.g., minerals, vitamins, and glucose) to the body’s cells in exchange for carbon dioxide and wastes
• transports and delivers chemical messengers—such as hormones—throughout the body
• distributes body heat for heating and cooling
• defends against disease

The cardio vascular system refers to:

• cardio - refers to the heart
• vascular - refers to the blood and blood vessels

When looking at diagrams of the human body think of you looking at another person facing you. Their right side is on your left and their left side is on your right.

Blood Flow from the heart to the lungs
Body → vena cava vein → right atrium → atrioventricular valve (tricuspid) → right ventricle → semilunar valve → pulmonary artery to lungs

Blood Flow from the heart to the
Pulmonary veins → left atrium → atrioventricular valve (bicuspid) → left ventricle → semilunar valve → aorta artery → body

All blood is red. It is the structure of the veins that is blue not the blood.
Oxygenated blood in arteries is a slighter brighter red than the deoxygenated blood in veins. Veins are near the surface and when cut will bleed.
Arteries are deeper in the body and spurt when cut.
The human heart is composed of four chambers.
The top two chambers are known as atria(singular-atrium) and the bottom two chambers are ventricles.
The heart can be thought of as a double pump. When the left atrium contracts and the left ventricle relaxes, the right atrium contracts and the right ventricle relaxes at the same time.

Most adult’s heart rate is between 60 and 100 beats per minute with an average around 72 bpm.

Higher than 100 bpm is a concern because your heart is working hard and can lead to future health and/or heart problems.

Lower than 60 bpm is a concern because unless you are athletic, not enough blood will be circulating in your system.
In comparison to the normal 72 beats/min, resting heart rates of 35 beats/min have been recorded in athletes.

Factors Affecting Heart Rate

• Age – as we get older our hearts slow.
• Weight – as you put on weight you get more blood vessels and your heart pushes blood further.
• Diet – saturated fats build up as plaque in blood vessels restricting blood flow making the heart work harder.
• Exercise – the heart is a muscle, it gets stronger as you exercise.
• Genetics – Some people are predestined to heart problems (early heart attacks).
• Diseases – some diseases will directly affect the heart.
• Smoking (vaping) – some chemicals in smoking negatively affect the heart.

1.2 Blood Vessels

Blood Vesels

There are three types of blood vessels:

• Aterties
  Arteries come straight from the heart so they carry high pressure fast moving blood. You can feel your pulse through the pressure surges in arteries.
• Veins
  Veins carry slow moving low pressure blood. Therefore they need valves to stop blood pooling in your extremities (hands, feet)
• Capillaries
  You body is full of capillaries. Capillaries are very small (1 red blood cell wide) and porous. Oxygen, carbon dioxide, sugars, hormones, etc.. Flow from the capillaries into and out of cells. 80% of your blood vessels are capillaries and could cover a distance of 80 000 km if placed end to end.

Blood pressure

Blood pressureis made of two numbers.

• The higher number is the maximum arterial blood pressure as the heart muscles (ventricles) contracting.
• The lower number is the minimum arterial blood pressure as the heart muscles (ventricles) relax and blood flows from the atria to the ventricles.

What is normal blood pressure?
An optimal blood pressure level is a reading under 120/80 mmHg. Readings over 120/80mmHg and up to 139/89mmHg are in the normal to high range. Your doctor will advise what your ideal blood pressure should be based on your circumstances.

What is high blood pressure?
Blood pressure over 140/90mmHg is generally considered to be high. Often high blood pressure is an indication of blockages due to build up (plaque caused by excess fats) and restrict the flow of blood in blood vessels. The heart has to push the blood harder to get enough oxygen to different body parts increasing your blood pressure.

Concerns
The big concern is the arteries that supply oxygen to the heart. If they get completely blocked that part of the heart will not get oxygen and you will have a heart attack.

1.3 Blood

Blood is made of four main components:

• Red blood cells (erythrocytes)
  Biconcave shaped disks that are produced in your bone marrow. RBC have lots of hemoglobin, the molecule that carries oxygen or carbon dioxide. They pick up oxygen in the lungs where it has a high concentration and release it to cells in capillaries when the O2 concentration is low. They then pick up carbon dioxide in capillaries when the CO2 concentration is high and release it into the lungs.
• White blood cells (leukocytes)
  Approximately 1 WBC per 600 - 700 RBC These form the body’s immune system.
• Plasma
  A yellowish liquid that carries RBC, WBC, platelets, urea (waste from the liver), hormones, digested nutrients, proteins, CO2 and O2. Sometimes hospital patients are given plasma with no RBC or WBC to make up liquid volume in the blood vessels.
• Platelets
  These cells rupture when they encounter a rough surface and they trigger a complex series of chemical reactions. This causes dissolved fibrinogen protein to convert to its active form which traps RBC in a net of fibrin forming a blood clot. Once the skin under the scab heals, it dries and falls off. Blood clotting inside of blood vessels can cause life threatening blood vessel blockages. Lack of platelets leads to hemophilia where no clotting takes place and people can bleed to death from small cuts.

1.4 Cardiovascular Diseases and Disorders

Stroke
Strokes are brain damage caused by arterial blockages. If treated quickly blood thinning and anti-clotting medications can reduce the damage.
Strokes are caused by a build up of fatty tissues in blood vessels.

• Fats are long organic molecules made of a carbon chain surrounded by hydrogens.
• Saturated fats have no carbon double or triple bonds, singles only. These are linked with animal fats and coronary risks.
• Unsaturated fats have at least one carbon double or triple bond. These are linked with plant fats and decreased risk of coronary problems.

Aneurysm
When a blood vessel develops a bulge or weakness it is called an aneurysm. If the aneurysm ruptures the bleeding can cause damage and/or deprive body parts downstream of blood.
Aneurysms are often fatal when located in the brain.

Septal Defect
Mammalian hearts have 4 chambers with the left side pumping blood to the lungs and the right side pumping blood to the rest of the body.
Fetuses have a hole in the septum because the fetus in the womb doesn’t breath and gets oxygenated blood from their mother’s umbilical cord.
Sometimes the septum doesn’t seal properly leaving a hole between the ventricles. If this doesn’t close naturally it must be surgically closed.

Valvular Heart Disease
There are 4 valves in the heart. If they do not function properly it can cause problems with blood flow direction, or blood pressure.

1.5 The Immune System

Regularly washing your hands is one of the best ways to avoid getting sick. All you need is soap and water. Ideally, you should rub your hands together for at least 15 s and scrub all surfaces including your wrists, under your fingernails, between your fingers, and the backs of your hands.

Spreading Disease

Diseases are spread by different pathogens:

• Protozoans – single celled organisms that can live inside a human cell
• Fungi – live off the remains of dead or decaying organisms, they are killed by antifungals
• Bacteria – single celled organisms that can reproduce rapidly, they are killed by antibiotics
• Virus – extremely small proteins that infect a cell and make it a virus-making factory, they are killed by anti-virals (rarely used)

4 Blood types: O, A, B, AB

Chapter 1 Summary

Chapter 1 Review Questions