A LEVEL BIOLOGY 8 TOPICS 12 REQUIRED PRACTICALS 3 EXAMS

Lesson Aims How is the structure of the heart related to its function? How much blood does the human body contain? 5.6 litres

The Heart Where is it? Between the two lungs Enclosed by the PERICARDIUM Pericardial fluid is secreted between them to aid movement The pericardium protects the heart from over expansion Where is it?

Internal Features Semi-lunar valves (bicuspid valve) Septum Pericardial membranes

How far does your blood travel in one day? Watch this Video Blood flow through the heart How far does your blood travel in one day? nearly 12,000 miles

Blood flow through the heart Blood comes into the heart from the body It then has to pass to the lungs to collect oxygen This is called a double circulatory system After it returns to the heart it leave again to be transported to the body. Task: Draw a flow diagram to show the flow of blood through the heart. You should start and finish with the body.

Atrium- receives blood from veins Ventricle- pumps blood into arteries Body Left Vena cava Oxygenated blood Deoxygenated blood atrium Right atrium Bicuspid valve Tricuspid valve Pulmonary vein Left ventricle Right ventricle aorta Pulmonary artery body lungs

Drag the labels to the right place to complete the Activity Drag the labels to the right place to complete the diagram and the key A drag and drop activity

External Features

Your sheep’s heart What external features can you identify? A B C D How much blood does the heart pump in a lifetime? a million barrels of blood E F

External Features FRONT BACK Apex

The Circulatory System

The Cardiac Cycle Cardiac muscle contracts without nervous or hormonal stimulation these are MYOGENIC contractions. The muscle cells work together to produce the heartbeat (cardiac cycle)

Semi-lunar valves closed Systole (contraction) Atrial systole Atria contract Semi-lunar valves closed Blood forced from the atria into the ventricle Ventricular systole Ventricle contracts Blood is forced into arteries Bicuspid and tricuspid valves closed

Diastole (relaxation) Heart relaxes and fills with blood from the veins. Semi-lunar valves closed to blood entering through arteries. Cardiac Cycle Tutorial Task: Order the diagrams of the cardiac cycle and annotate.

HEARTRATE What effects heart rate??

Control of the heart beat Although the heart has its own rhythm it is also regulated by the nervous and hormonal systems. Sensory receptors in the walls of heart and blood vessels are sensitive to changes in blood pressure These send impulses to the CARDIORESPIRATORY CENTRE in the medulla oblongata A vagus nerve branch leads to the SA node. The vagus nerve is part of the Parasympathetic Nervous System and so is an inhibitory nerve, impulses slow the heart rate.