9) Transport in animals (INCOMPLETE)

Define Circulatory system

A system of blood vessels with a pump and valves to ensure one-way blood flow.

Describe the circulatory system in a fish

Fish have a two-chambered heart, consisting of an atrium and a ventricle, and a single circulation, meaning for every one circuit of the body, the blood passes through the heart once.

Describe the circulatory system in mammals

Mammals have a four-chambered heart and a double circulation, meaning for every one circuit of the body, blood flows through the heart twice.

Pulmonary circulation

The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs

Systemic circulation

The left side of the heart receives oxygenated blood from the lungs and pumps it to the body, the systemic circulation.

Through what is blood pumped away from the heart and through what does blood return to the heart

Arteries - Pumped away from the heart
Veins - Returns to the heart

What are the advantages of double circulation

1) Oxygenated and deoxygenated blood do not mix as they are separated in the heart by the septum.

2) Blood travelling through the small capillaries in the lungs loses a lot of pressure given by the heart, meaning it cannot travel fast. This also prevents damage to capillaries in the lungs. By returning to the heart after flowing through the lungs, its pressure can be raised again before sending it to the body, so cells can be supplied with the oxygen and glucose needed for respiration faster and more frequently.

3) It allows more time for gas exchange.

What are the chambers of the heart

Right and left atrium

Right and left ventricle

Explain the relative thickness of the muscle walls of the atria compared to those of the ventricles

The ventricles have thicker muscle walls than the atria as they pump blood out of the heart, so they require higher pressure.

Explain the relative thickness of the muscle walls of the left and right ventricles

The left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body, whereas the right ventricle pumps at lower pressure to the lungs.

Describe the functioning of the heart

Deoxygenated blood (oxygen-poor) coming from the body flows into the right atrium of the heart via the vena cava. Once the right atrium is filled with blood, the heart beats and the blood is pushed through the tricuspid valve into the right ventricle. The walls of the ventricle contract, and the blood is pushed into the pulmonary artery through the semilunar valve, which prevents blood from flowing backwards into the heart. The blood travels to the lungs and moves through the capillaries at low pressure to avoid bursting the capillaries, and moves past the alveoli where gas exchange takes place. Oxygen rich blood returns to the left atrium via the pulmonary vein. It passes through the bicuspid valve into the left ventricle. The thicker muscle walls of the left ventricle contract to strongly push blood at high pressure into the aorta and to the rest of the body for systemic circulation. The semilunar valve in the aorta prevents the backflow of blood into the heart.

How can heart activity be measured:

1) An ECG

2) Measuring heart or pulse rate (bpm)

3) Listening to the sound of valves closing using a stethoscope.

What are the independent, dependent, and control variables when investigating effect of physical activity on heart rate

IV: Exercise length

DV: Pulse rate

Control: Age, Gender, Weight, Health conditions

Describe the investigation of the effect of physical activity on heart rate

1. Take resting pulse

2. Perform exercise A for 2 minutes and immediately take pulse rate

3. Rest for 3 minutes to return pulse to resting

4. Repeat steps 2 and 3 twice more and calculate average.

5. Carry out same steps for 4 other exercises

6. Calculate difference in pulse rate.

Why does heart rate increase during physical acitivty

Heart rate increases to increase blood flow to working muscles so they can provide them with glucose and oxygen for respiration, and to remove waste products (lactic acid and carbon dioxide) at a faster rate.

Why does the heart continue to beat fast after exercise

- To ensure all waste products are removed

- To deliver extra oxygen to muscle cells to pay off oxygen debt when oxygen levels are too low to support aerobic respiration.

What are coronary arteries

The heart is a muscle. Coronary arteries are the arteries that supply blood to the heart and cells to deliver oxygen and glucose to respire, and to remove waste products such as carbon dioxide.

How does coronary heart disease occur (CHD)

Coronary heart disease occurs because of a blockage in coronary arteries. The blockages are plaques made from cholesterol.

What are the risk factors of CHD

- Lack of exercise

- Diet

- Stress

- Smoking

- Genetic predisposition

- Age

- Sex

Reducing the risk of CHD

Diet: Reduce animal fats and eat more vegetables to reduce cholesterol levels in the blood and help weight loss.

Exercise regularly: This will help with weight loss, decrease blood pressure and cholestrerol levels, adn reduce stress.