1. Circulation
for GCSE Biology

2. Objectives:
* Describe one way flow of blood around the body.
** Describe the structure and function of a heart
*** Describe the cardiac cycle
Starter:
1.What components make up the circulatory system?
2. What are the substances carried by this system ? Name the route of each substance.
1.Blood, heart and blood vessels.
2. Oxygen from lungs to cells digested food from small intestine to cells CO2 from cells to lungs waste materials from cells to kidneys.

3. Double circulation Like all mammals, humans have a double circulation
The right side of the heart sends blood to the lungs (pulmonary circulation)
Blood returns from the lungs to the left side of the heart which pumps it into the systemic circulation supplying the rest of the body.
Blood passes twice through the heart.

4. Double circulation
What is the advantage of a double circulation?

5. Double circulation
A double circulation has the advantage of providing all body organs with oxygenated blood at high pressure and at low pressure to the lungs as they are spongy tissue.
In the single circulation of a fish, blood is pumped
Heart
Organs
Gills
Most of the pressure generated by the heart is lost in the gills, and the organs receive low pressure oxygenated blood.

6. Double circulation
Double circulation is made possible by the complete division of the heart into separate left and right sides
Pulmonary circulation
Lungs
The left side receives oxygenated blood(red) from the lungs, and pumps it to the systemic circulation; the right side receives deoxygenated blood (dark red) from the body, and pumps it to the lungs.
Heart
Systemic circulation
Body

7. Blood circulation
The heart pumps blood to the blood vessels. Arteries take blood away from the heart to different organs and veins bring them back to the heart. The smallest blood vessels that connect arteries to veins are capillaries. The circulatory system allows one way blood flow. The capillaries has very thin walls so to reduce the pressure of blood flow small muscular blood vessels called arterioles receive the blood to reduce the pressure before blood enters capillaries.
Most arteries contain oxygenated blood and most vein deoxygenated blood but not all.

8. You can get instructions for a heart dissection here

9. Structure of the heart
The diagram shows the heart at diastole – relaxed, between contractions.
Remember your rt is the body’s left
Semilunar valves( has 3 pockets and half moon shaped)
Pulmonary artery
Pulmonary veins
Superior vena cava
Aorta
Right atrium
Left atrium
Right atrio-ventricular valve (tricuspid valve)
Left atrio-ventricular valve (bicuspid valve)
Inferior vena cava
Right ventricle
Septum
Left ventricle
Tendon
Papillary muscle

10. Papillary muscles adjust tension in valve tendons
The cardiac cycle
At ventricular systole (0.3 s):
the ventricles contract;
ventricular pressure rises above atrial, closing the atrioventicular valves;
ventricular pressure rises above arterial, opening the semilunar valves;
blood is forced from ventricles into the pulmonary artery and aorta.
At atrial systole (0.1 s):
the atria contract;
the vein openings are constricted, preventing backflow into the veins
blood is forced from atria into ventricles through the open atrioventicular valves;
the semilunar valves remain closed, because arterial pressure is still higher than ventricular pressure.
At diastole (0.4 s):
the heart muscle is relaxed;
the atrioventicular valves are open, and blood flows passively from atria into ventricles;
the semilunar valves are closed, because arterial pressure is higher than ventricular pressure.
Papillary muscles adjust tension in valve tendons

11. Animation of the cardiac cycle
Try to identify the three stages of the cardiac cycle in this animation.
Note which valves are open and closed at each stage.

12. The cardiac cycle
Heart muscle relaxed; ________ valves open, allowing blood flow from ________ to ________. Semilunar valves ________ to prevent backflow from ________ to ________.
________ contract, opening ________ valves and forcing blood from ________ into ________ .
________ contract, closing ________ valves and opening ________ valves: blood pumped from ________ into ________ .

13. The Heart
1. Deoxygenated blood (i.e. blood without oxygen) enters through the vena cava into the right atrium
4. Oxygenated blood from the lungs enters through the pulmonary vein into the left atrium
2. It’s then pumped through the tricuspid valve into the right ventricle
5. It’s then pumped through the bicuspid valve into the left ventricle
3. It’s then pumped through the semi-lunar valve up to the lungs through the pulmonary artery
6. It’s then pumped out of the aorta to the rest of the body
20/04/2017

14. Blood Vessels
Objectives: *Name blood vessels and describe their structure ** Explain how structures are related to their functions *** Explain the role of valves in heart and blood vessels

15. Lesson 2: starter questionsB
Identify the stage of the cardiac cycle shown in the diagram. Give two reasons for your answer.
(3 marks)
Identify the blood vessels labelled A, B and C.
Explain the difference in thickness of the muscular wall at X and Y.
(2 marks) C X Y

16. The Circulatory system
The circulatory system is responsible for pumping ______ around the body. We need blood to be taken around the body because blood contains ________ and _______. These are needed so that all the ____ in our bodies can produce _____ through _________.
The main organs in the circulatory system are the _____, the lungs and the kidneys.
Words – energy, heart, blood, glucose, respiration, oxygen, cells
20/04/2017

17. Blood vessels
Arteries carry blood from the heart towards capillary beds, veins carry blood from capillary beds towards the heart
Arteries do not always carry oxygenated blood, nor veins deoxygenated: the pulmonary and umbilical arteries carry deoxygenated blood, the pulmonary and umbilical veins oxygenated blood

18. Arteries Arteries characteristically have:
a narrow lumen, maintaining high pressure
a thick wall to withstand high pressure
a corrugated inner lining (endothelium), allowing stretching during systole
extensive elastic tissue, which absorbs some of the energy given to the blood at systole and then returns it by recoiling during diastole
muscle fibres, allowing the artery to be constricted or dilated to control the amount of blood flowing through it (NB this muscle does not propel the blood)

19. Veins Veins characteristically have:
a wide lumen, giving minimum resistance to low pressure flow
a smooth endothelium, again giving minimum resistance
little elastic or muscular tissue
valves to prevent backflow of low pressure blood

20. Arteries, veins and capillaries
Arteries carry high pressure blood away from the heart. They have smaller lumen and no valves.
Capillaries have thin walls (one cell thick) to allow glucose and oxygen to pass through. Also used to connect arteries to veins.
“Lumen”
Veins carry low pressure blood back to the heart. They have thinner, less elastic walls and have valves to prevent backflow of blood.
20/04/2017

21. Animation of the cardiac cycle
Try to identify the three stages of the cardiac cycle in this animation.
Note which valves are open and closed at each stage.

22. Action of valves in veins

23. Looking at valves in veins
Try this simple experiment to show valves in the veins of your hand.
 Hold your arm down by your side. This helps to fill the veins in your hand with blood and make them easier to see.
Find the vein shown in the picture that runs down the middle of the back of your hand.
With your other hand, gently press your index finger onto the top of the vein and push it downwards, towards your knuckles. This forces the blood in the vein against the direction it normally flows.
Notice that the vein does not fill up with blood from higher in your arm. This is because the vein contains a valve by your wrist. This valve prevents blood from the section of vein higher up in your arm from flowing back down and refilling the section of the vein in your hand.
When you stop pressing with your finger the vein refills with blood flowing from your fingers.

24. Arteries, capillaries and veins
As arteries branch and become smaller, their muscle and elastic layers are reduced.
Arterioles still have muscle and a nerve supply, and control the blood supply to capillary beds
Capillaries have no muscle or nerve supply, only a single cell layer (the endothelium)
As capillaries rejoin they form venules, which reunite to form veins

25. Capillary structure
The capillary wall is a single layer of very flat cells.
It is highly permeable, with gaps between cells and holes through cells: capillary beds are where exchange occurs between blood and tissues.
The lumen of a capillary is about 5 mm in diameter: red blood cells (diameter 7 mm) pass through in single file, squashed against the capillary wall.
Nucleus of squamous epithelial cell
Capillary lumen
Red blood cell
Basement membrane of squamous epithelial cell – allows small molecules through, keeps plasma proteins in

26. Name the most important arteries and veins
Vessel
O R G A
N S
Heart
Lungs
Liver
Kidneys
Bringing blood to organ
Taking blood away from organ
Vena cava to rt atrium pulmonary vein to lt atrium
Hepatic artery, hepatic portal vein
pulmonary artery
Renal artery
Hepatic vein
From rt ventricle to pulmonary artery from lt ventricle to aorta
pulmonary vein
Renal vein

27. Coronary Heart Disease(CHD)
Objectives:
* State and explain the effect of physical activity on pulse rate
**Describe the nature of coronary heart disease
***Describe the possible causes and preventative measures of CHD

28. Practice questions
The micrograph shows a blood vessel in transverse section
Identify the type of blood vessel shown and give two reasons for your answer.
(3 marks)
Name two kinds of tissue you would expect to find in the layer labelled X, and state one function for each.
(2 marks) X

29. Investigating pulse rate( the number of pulse beat /min=heart rate)
Sit still and get you partner to measure you pulse rate
Try doing step ups for 1 min (light exercise)and sit down and count the pulse rate again.
Wait till your pulse rate comes to the resting rate
Do step ups for 3 mins (heavy exercise) and sit down and count the pulse rate again.
You can repeat and calculate an average but wait for 5 mins before each repeat.
Ensure the same person is doing the exercise.
Explain your results in terms of supplying substances to your muscles and removing the wastes.
During exercise your muscle needs more energy from respiration to contract. Do heart beats faster and arteries supplying muscles dilate. These increase the blood flow to muscles resulting in:
1.An increase in supply of oxygen and glucose
2.An increase in removal of carbondioxide

30. Coronary circulation
Aorta
The muscular wall atria and ventricles of the heart is provided with high-pressure oxygenated blood by the coronary arteries, arising from the base of the aorta just above the semilunar valves.

31. Slow Flow
Healthy arteries has smooth lining letting the blood flow easily. However c………… which is made in the liver can stick to the wall making it n……….. Which will slow down the flow. This condition is known as atherosclerosis. The artery walls can become rough which can cause the blood to c……… and block the vessel. The blockage is called thrombosis.
These conditions can cause chest pains especially when the heart is working hard. This condition is called angina when enough o………… does not get to the heart muscle. Angina or thrombosis can lead to a heart attack. Parts of the heart can be damaged or it may stop beating altogether causing cardiac arrest.

32. Risk fcators Factors that can be avoided:
1. Diet with too much saturated (animal)fat increases concentration of cholesterol in the blood.
2. Overweight
3.Smoking
4.Taking little or no exercise
5. Stress
Factors cannot be avoided:
Genes that control the metabolism of fat and cholesterol
Age increases with age
Sex men are more likely than women

33. Taking care
1.Diet – Eat more poultry and fish fresh fruit and vegetables. Cut down on fried foods, red meat.
2.Take regular exercise
3.Do not smoke