The Circulatory System

Define a ‘cell’

The basic structural and functional unit of an organism

Define a ‘tissue’

A group of cells with similar structure working together to perform a function

Define an ‘organ’

A group of tissues working together to perform a specific function

Define a ‘organ system’

A group of organs with related functions working together to perform body functions

State the 6 main organ system

• Skeletal System

• Muscular System

• Circulatory System

• Digestive system

• Nervous system

• Respiratory System

What are the tissues and organs that make up the circulatory system?

The heart, blood vessels and blood

How does the human circulatory System differ from that of a fish?

→ Human:

• The human heart has two circuits (The body to the heart = systemic) and (The heart to lungs = pulmonary) this allows for the seperation of oxygenated and deoxygenated blood and also allows for the management of blood pressure to avoid bursting capillaries

• 4 chambers (2x ventricle and atrium on both sides)

• Order of organs: heart: Heart → Lungs → Heart → organs of body → Heart

→ Fish:

• 1 circuit = deoxygenated blood from body flows through heart and into gills to be oxygenated and sent back to body

• 2 chambers (1 ventricle and 1 atrium)

• Order of organs: heart → Gills → Body/organs → Heart

(both have a one-directional flow of blood)

What are the advantages for having a double-circuit circulatory system?

• Deoxygenated and oxygenated blood kept separate

• Blood can be passed at different pressures depending on the requirements (protects some capillaries from bursting) and allows heart to force out blood into body at a higher pressure

• Animals can be taller

• Blood flow through capillaries can be slower so that blood can be efficiently and fully oxygenated

How does pressure change throughout the circulatory system?

1) Heart to lungs = Somewhat high (4kPa) so that it has enough pressure to travel through the lungs and maintain high concentration gradeints to allow for the diffusion of oxygen

2) Lungs to heart = low to avoid bursting capillary walls

3) heart to body = Highest (16kPa) so the blood has enough force to be circuited around the body

4) Body to heart = lowest (3kPa) so that body capillaries don’t burst and due to friction against blood vessel walls

Label the diagram of the heart

1. Superior Vena cava (brings blood into heart from body)

2. Pulmonary Artery (takes blood away into lungs)

3. Right Atrium

4. Right atrioventricular valve (Atrium to ventricle)

5. Inferioir Vena Cava (body to heart)

6. Right Ventricle

7. Septum (seperates right and left sides = oxygenated and deoxygenated)

8. Left ventricle

9. Left atrioventricular valve

10. Left atrium

11. Pulmonary vein

12. Pulmonary artery

13. Pulmonary vein

14. Aorta

15. Semilunar aortic valve

16. Semilunar pulmonary valve

What is the purpose of the ‘valves’?

To prevent the backflow of blood through the heart

Why are the muscular linings of the heart walls thicker around the left ventricle than the right ventricle?

The left ventricle needs to pumo blood at a much higher pressure in order to circulate it around the body and back to the heart

The right ventricle can’t pump blood at too high a pressure because it could be damaging to the capillaries in the lungs

Walk though the process of the cardiac cycle

1) Deoxygenated blood through the vena cava into the right atrium.

2) At the same time oxygenated blood leaves the heart through the aorta

3) The right and left atria are filled with blood

4) The atria contract to push blood into the ventricles through the atrioventricular valves which open due to the sudden increase in pressure

5) Blood flows into the ventricles

6) The walls of the ventricles contract to open the semilunar valves and push blood through

7) Blood flows into the aorta and pulmonary arterty which carry blood to the lungs or around the body

How can we measure heart rate?

→ Putting two fingers to the radial artery

→ heart rate monitor

→ Listening to the valves opening and closing through a stethoscope

→ Electrocardiogram

What is the purpose of veins?

→ veins are all blood vessels that carry blood in the direction of the heart

How are veins adapted for their function?

→ Thinner cell wall than arteries because they don’t usually have to withstand high blood pressure

→ Have valves to prevent backflow of blood and muscles contract to force the blood towards the heart (especially in legs where blood is acting against gravity) and when blood pressure becomes progressively lower due to friction

→ Wide lumen to allow as much blood flow as possible at low pressures

What is the purpose of arteries?

→ Carry blood away from heart to the rest of the organs

How are arteries adapted for their process?

→ Thick cell wall to withstand high pressures

→ Narrow lumen to ensure high blood pressure can carry blood through body

→ Crinkled lumen lining in order to adapt to changes in blood pressure

→ Covered in elastic tissue so that it can stretch and recoil

What is the purpose of capillaries?

→ Sites of gaseous exchange (alveoli in lungs) and nutrient delivery (absorption of nutrients)

How are capillaries designed?

→ Single cell layer (fast diffusion of gases and nutrients)

→ Very narrow lumen to slow blood flow down

→ carries blood from artery to vein

How does blood pressure decrease between blood vessels through body

Highest:

Aorta

Elastic Artery

Muscular arteries

Arterioles

Capillaries

Venules

Medium Veins

Vena cava

Lowest:

Which veins and arteries belong to different bodily organs?

1) Heart → Lung → heart = Pulmonary arteries and veins

2) heart → Liver → heart = hepatic vein and artery

3) Stomach → Liver = hepatic portal vein

4) heart → Kidney → heart = renal artery and veins

Why is blood so important for our organs?

→ The oxygen carried in the haemoglobin of red blood cells allow the cells in our body to respire otherwise they will die

→ Deliver nutrients around our body through absorption

→ Responsible for getting rid of cellular waste

Why are the coronary arterties important for our heart?

→ They supply the muscular linings of our heart with oxygenated blood that allows the cells to respire and ensures that the heart can keep pumping oxygenated blood to the rest of our organs

How can our arteries get blocked?

→ LDL cholestrol and saturated fats can build up in the linings of our coronary arteries and form plaque that makes the lining narrower and restricts the movement of blood through the coronary artery and into the muscular lining of our heart

Why is it a problem if our coronary arteries get blocked?

If there is too much plaque restricting the flow of oxygenated blood the cells in our heart lining won’t be able to respire and will start to die. This slows the pumping of the heart down so that the rest of the organs in our body don’t get the oxygen they need, resulting in the death of other vital organs and potential death

How can CHD be prevented?

1) Diet : Eating foods low in saturated fats and LDL cholestrol/ having a high fibre diet to lower choletstrol

2) exercising regularly to improve blood circulation

3) Not smoking (damage blood vessel elasticity = narrower and restrict blood flow)

What are the three components that make up our blood?

1) Plasma

2) White blood cells + platelets

3) Red blood cells

What is plasma?

→ A yellow liquid that contains: water/salts/CO2/soluble products of digestion/hormones/ureas

→ It is the main medium of transportation for waste products/platelets (blood clotting)/nutrients and regulats the temperature of our body

Why are red blood cells important? + adapted characteristics

→ They contain haemoblogin that picks up the oxygen from the alveoli of lungs and releases it into respiring tissues of our organs

→ They do not have a nucleus to leave room for haemoglobin

→ Bi-concave to increase surface area for diffusion of oxygen and to squeeze through narrow capillaries

How are white blood cells important?

→ White blood cells are essential for our immunity defense

1) Phagocytes (irregular nucleus): engulf the bacteria and destroy it with digestive enzymes, leaving behind a harmless remanents

2) Lymphocytes (regular nucleus) : recognise bacteria as foreign particles and alert phagocytes to their destination + produce antibodies with complimentary shape to the antigens on the bacteria that neutralise their toxins

How are platelets important?

→ Transported by the plasma and used in blood clotting

(Blood clotting)

1) When a blood vessel is damaged, there is a risk of excess oxygenated blood being lost

2) release blood-clotting soluble enzymes that cause fibrinogen (soluble) to turn into insoluble fibrin

3) The fibrin acts as an impermeable mesh (drying to form a scab) that prevents oxygenated blood from escaping while the tissue around the blood vessel repairs (prevent pathogens from entering)