Circulatory System

Learning Outcomes On completion of this chapter students should be able to: OB13 describe the function and composition of blood, and know that blood contains white blood cells, red blood cells and platelets in a liquid called plasma OB14 understand the structure and function of the heart, identify the four chambers of the heart, and explain the difference between the left and right ventricles OB15 describe the passage of blood through the heart and lungs via arteries and veins, identify the pulmonary artery and vein, aorta and vena cava, and distinguish between arteries, veins and capillaries

Learning Outcomes contd.. OB16 demonstrate the effect of exercise and rest on pulse rate and understand that a balance of each promotes good health OB17 recall that the average pulse rate for an adult at rest is 70 beats per minute, and explain why exercise results in increased pulse and breathing rates

Lesson 1 Composition of Blood

What is the circulatory system? The Circulatory System is responsible for transporting materials to and from different places in the body. It is made up of: Blood Blood vessels The heart Students are asked for their own definition of the circulatory system and what it is responsible for. They are then asked what the circulatory system is made up of (hands up basis). It is then revealed and each of the three components are explained.

Blood consists of: Red Blood Cells White Blood Cells Platlets Plasma Students are asked if they know what makes up blood. Each component is revealed slowly and students are asked what they know (if anything) about each. Plasma

Red Blood Cells Most numerous cell in the body Small doughnut shape Contain haemoglobin which transports oxygen around the body Red blood cells are studied more thoroughly- this includes a physical description and an explaination of their function. Students are asked to identify the colour of blood. It is explained that red blood cells give blood its colour. The shape of red blood cells is identified and a simple diagram is drawn on the blackdoard for clarity. Students are asked if they are familiar with the term microscopic. If not it is explained and indicated that red blood cells are microscopic. The term haemoglobin is explained briefly and students are told that it is responsible for carrying oxygen around the body.

White Blood Cells Larger than red blood cells but also much fewer in number Fights infection by destroying bacteria and viruses that have invaded the body White blood cells are described in more detail. It is indicated that they are much bigger than red blood cells but there are less numerous (reference is made to the diagram for this) Their shape is explained, diagram drawn on the board for clarity. Their function is described. (it is explained to students how they work, ie produce antibodies and engulf bacteria. Reference is made to an infected wound-white cells often gather and produce puss. White Blood Cell

Platelets Tiny fragments of cells Cause blood to clot by producing tiny fibrinogen fibres These stretch across a cut to stop bleeding Students are instructed to look at the diagrams above for clarity. The term fibrinogen is explained. Comparisons are made to netting or spider webs. Students are asked if platelets didn’t exist what would happen if we got a nose bleed or cut our fingers?

Plasma It also contains useful things like: glucose carbon dioxide glucose amino acids proteins minerals vitamins hormones waste materials A straw-coloured liquid that carries the cells and the platelets which help blood clot. Reference is made to water to describe plasma-it is the reason blood is a liquid and not a solid. if it wasn’t liquid what would happen? It wouldn’t be able to flow around the body. The contents of plasma are explained- students are asked to come up with answers. They are prompted where necessary-i.e what are the nutrients that may be found in the plasma? Does it carry anything that we don’t need? Where does it pick up carbon dioxide?

Functions of Blood To transport food, oxygen and wastes To transport heat to the skin to keep the body temperature at 37°C. To fight infection The functions of blood are outlined. Based on the material covered during this class, students are asked to outline answers. Prompting takes place if necessary. e.g. whats the function of red blood cells, white blood cells, platelets? What is body temperature? Is the blood involved in keeping body temperature constant?

Lesson 2 Blood Vessels

There are 3 types of blood vessels found in our body: Veins Arteries Capillaries Students are asked if they know what a blood vessel is…if not it is explained. Students are asked to give an example of a blood vessel in the human body. If they fail to respond, prompts are given e.g. what can we see through the skin on our hands and our wrists?

Veins Veins carry blood towards the heart They have thin walls and a wide inner cavity which allows blood flow to the heart easily They also contain valves which stops the blood flowing backwards Veins are described thoroughly using the above diagram. The terms valves and lumen are explained. Students are asked if the veins carry blood from the toes to the heart what will stop the blood from flowing backwards? Students are asked if they have ever heard of varicose veins? They form when the valves fail to work effectively. Wide inner cavity (lumen) veins with valves

Arteries Arteries carry blood away from the heart They have thick elastic walls which allows them to stretch and recoil at each heartbeat These muscles contract to push the blood along If veins carry blood towards the heart then what direction do you think arteries carry blood? It is explained why the walls of the arteries need to be thicker and stronger than veins-i.e.the pressure from the heart. Students are asked if they are familiar with the term contract, if not it is explained. Why do you think arteries don’t need valves? It is explained that the force of the heartbeat and the contractions of the muscles will prevent the blood flowing backwards. Narrow inner cavity (lumen) Thick muscular walls No valves present

Capillaries Capillaries link arteries and veins Have very thin walls-just one cell thick Materials can be exchanged from the blood to other body cells and vice versa via capillaries Capillaries are responsible for connecting arteries and veins. If their walls are so thin, do you think they will be able to contract and push blood along like arteries? No. It is explained that capillaries have thin walls to allow materials to be exchanged .e.g. oxygen and carbon dioxide. Where in the body is oxygen and carbon dioxide exchanged. Wall just one cell thick

The Structure of the Heart Lesson 3 The Structure of the Heart

The Heart The heart is a muscular pump that transports blood around the body It consists of 4 chambers: Right atrium Left atrium Right ventricle Left ventricle The heart is introduced. Each student is asked to clench their fist, the size of their fist is roughly the size of their heart. It is explained that the heart is a pump that pumps blood all around the body. It is divided into 4 compartments- 2 at the top called atria and 2 at the bottom called ventricles. Blood vessels enter through the atria and leave through the ventricles. YouTube video

The Heart Atria Ventricles The lower chambers The upper chambers Receives blood from the atria Pumps blood out through arteries Left ventricle has thick walls (more strength required to pump blood around the body) Atria The upper chambers Receives blood from veins Pumps blood into ventricles Have thin walls The above points are outlined. It is explained why the wall around the left ventricles is thicker-more power is required to transport blood to every corner of the body, unlike the right ventricle which just needs to sent blood to the lungs (which is a relatively short distance)

Structure of the Heart Aorta Pulmonary artery Pulmonary vein Vena Cava Right Atrium Left Atrium Each chamber of the heart is pointed out using the above diagram. It is then pointed out what blood vessels are associated with each chamber. From what I have told them previously during the class, students are asked to identify what blood vessels are leaving the heart and what blood vessels are entering. Right Ventricle Left Ventricle

How does the heart work? Deoxygenated blood enters right atrium via vena cava Blood is pumped to right ventricle and then to the lungs via the pulmonary artery 3. Oxygenated blood enters left atrium via pulmonary vein 4. Blood is pumped to left ventricle where it leaves via the aorta The terms oxygenated and deoxygenated are explained. Students are asked which blood vessels carry oxygenated blood and which carry deoxygenated? The pathway of blood through the heart is explained thoroughly and slowly. Students are asked random questions throughout this process to test their understanding.

Pulmonary artery Aorta Vena cava Pulmonary Vein On a broader scale this diagram shows where the blood flows throughout the body. Students are asked to identify the relevant veins and arteries on the diagram. Prompting is given where necessary e.g. into what chamber is it flowing….so does that mean it is an artery or vein? What is the name of that particular artery/vein? etc.

Tips for remembering VEAL Veins Enter, Arteries Leave LORD Left=Oxygenated, Right=Deoxygenated Pulmonary = related to lungs e.g. Pulmonary vein enters from lungs These terms are explained i.e. the first letter of the above words represents a useful sequence relating to the circulatory system.

The Pulse & How to demonstrate the effect of exercise on the pulse Lesson 4 The Pulse & How to demonstrate the effect of exercise on the pulse

The Pulse Every time the heart contracts, the blood surges forward in the arteries. By placing your fingers over an artery, you can feel this pulse The term pulse is explained ie. What it is and where it can be found. Each student is given time to find their own pulse. Directions are given as to where to find it.

The Pulse Lets find out…... For an adult the average pulse rate is 70 beats per minute (b.p.m.). Children have faster heartbeats than adults. What happens to our pulse rate when we exercise? What do we mean by the term pulse rate? Students are asked to come up with explainations. It is explained why the pulse rate is greater in children and why fitness level effects the pulse (heartbeat) Students are asked to suggest what might happen to it when we exercise, but an answer is not revealed. Lets find out…...

Mandatory Practical Title: to demonstrate the effect of exercise on the pulse rate Beats per minute at rest vs. Beats per minute after exercise Students are asked to carry out this experiment, they are divided into pairs and each one is instructed to take each others pulse for one minute. (one students takes pulse, the other takes time). Repeat this procedure 2 times (after 3 minutes and again after 6 minutes) Title and method is written into experiment copies.

Results Beats per minute Person 1 Person 2 At rest Immediately after exercise 3 minutes after exercise 6 minutes after exercise Students copy down the above table into their experiment copies and fill in the blanks accordingly. Pulse rates are recorded immediately after the exercise, again after 3 minutes and again after 6 minutes. These results are inserted into the table above. Results are discussed. What do you notice about the pulse rate after 6 minutes? Can you suggest a reason for this?

Exercise increases the pulse rate. Conclusions When a person exercises, the muscles need more oxygen to get more energy from food. A faster heartbeat delivers oxygen to the muscles quicker. Exercise increases the pulse rate. Students are asked for conclusions to their experiment. (each pair are asked for their personal conclusion before the text is revealed on the above slide). It is also explained to students that too much exercise is not healthy. The body also needs rest. Students write conclusions into their experiment copies.

Why we need exercise To prevent heart disease we should: Exercising the heart makes it stronger and reduces the likelihood of heart disease. To prevent heart disease we should: Take regular exercise Never smoke Eat only small amounts of saturated (animal) fats Why do we need to exercise? If we don’t exercise what effect could this have on our heart? The benefits of exercise are discussed in a class discussion. The damaging effects of smoking and eating fatty foods are also discussed.

Assessment The circulatory system is made up of blood, blood vessels and the _____. Arteries _____ the heart and ______ enter the heart. The capillaries ______ arteries and veins. Blood is made up of red blood cells which carry _____, white blood cells which fight _______, platelets which causes blood to _____ and ______ which is the liquid part of blood. The heart is made up of _____ chambers, 2 atria and 2 ventricles. Students are given 10 minutes to copy down the above passage into their copies and fill in the blanks.

Solutions The circulatory system is made up of blood, blood vessels and the heart. Veins enter the heart; arteries leave the heart and The capillaries link arteries and veins. Blood is made up of red blood cells which carry oxygen, white blood cells which fight infection, platelets which causes blood to clot and plasma which is the liquid part of blood. The heart is made up of four chambers, 2 atria and 2 ventricles. Students are asked individually for the answers before being revealed and they are asked to correct any mistakes.

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