What valves are opening and closing at each point mark with a letter? [4 marks]

A = AV closes B = Semi-lunar opens C = Semi-lunar closes D = AV opens

Describe the structure of the heart. [10 marks]

Describe the structure of the heart. [10 marks] The heart is 4 cambered 2 atriums (at the top) 2 ventricles (at the base) The heart pumps blood around the heart. Blood flows in the atrium and is pumped to the ventricle. The right side of the heart pumps blood to the lungs. The left side of the heart pumps the rest of the body. The right side is thinner walled as it only pumps a short distance to the lungs. The left side is thicker walled to create a greater pressure to pump blood around the body. The inside of the heart is smooth to create less resistance to flow.

How does the brain cause an increase in heart rate? [7 marks]

The cardio-vascular centre (medulla) monitor monitors the blood. The medulla monitors the oxygen level, when it decreases, it starts the process of increasing the heart rate to get more oxygen pumping. The accelerator centre is stimulated. Impulses move down the SYMPATHETIC nerve To the SAN The SAN increase rate of pumping AND the strength of pumping

Describe how the circulatory system is involved in the respiration process. [10 marks]

Describe how the circulatory system is involved in the respiration process. [10 marks] Blood is the transport medium Blood carries oxygen and glucose The heart pumps the blood Air moves into the lungs Oxygen diffuses in Through the alveoli Red blood cells pick up the oxygen The oxygen attaches to the haemoglobin The oxygen is carried to respiring cells Carbon dioxide is released and carried back to the lungs and is removed.

Why does blood pressure decrease with increasing distance from heart? [2 marks]

Resistance to flow less Increased space for blood flow

Why does the blood pressure vary in the arterioles? [2 marks]

Contraction and relaxation of the ventricle Systole (contraction – high BP) and diastole (relaxation – low BP)