Settler Explain why large active animals need a

Settler Explain why large, active animals need a transport system. (3 marks)

Exam answer

Single Circulation – e. g. fish Blood pressure reduced as blood passes through the gill capillaries - slows down flow to the rest of the body Blood passes through heart ONCE per complete circuit Limits the rate of delivery of O 2 and nutrients to cells and removal of waste Efficient for the level of activity of fish but not mammals – also fish do not maintain their body temperature – need to respire relatively less compared to mammals Double Circulation – more efficient - e. g. mammals Heart is composed of two separate pumps – right side pumps blood to the lungs to pick up oxygen; the blood is returned to the left side; the left side pumps oxygenated blood rapidly and at high pressure to the body; the blood is returned to the right side Higher level of activity (energy) and need to maintain their body temperature at 370 C – through respiration Need to deliver and remove materials to and from cells rapidly – achieved by delivering blood at high pressure to tissues. Pulmonary – oxygenates blood & removes CO 2 Systemic – oxygenated blood from lungs pumped rapidly at an increased pressure by the heart Blood passes through heart TWICE per complete circuit

1 Size 1)If an animal has several layers of cells, any oxygen and nutrients will not reach the deeper cells within the body • Explain why large, active animals need a transport system (Grade C –B)

2 Surface Area to Volume Ratio • Larger animals have a small surface-areavolume-ratio. • Larger volume due to range of tissues. • Their surface area is not large enough to supply all the oxygen and nutrients needed by internal cells.

3 Level of Activity • If an animal is active it will require a good supply of oxygen and nutrients to supply the energy for movement. • Mammals also require more energy to keep themselves warm.

From the spec. . . • explain the need for transport systems in multicellular animals in terms of size, level of activity and surface area: volume ratio;

What is the difference between these two circulatory systems? What are the advantages of a double circulation?

Module 2 Exchange and transport 1. 2. 6 Structure of the mammalian heart

Closed circulatory systems

Advantages of Double over Single • Double circulatory system – blood travels through the heart twice for each complete circuit of the body • Efficient so deliver nutrients quickly • Can increase pressure of blood flow • Quicker supply oxygen • Can keep pressure to exchange surface low to avoid damage

Starter • Label the diagram of the heart – previous knowledge from KS 4 • Label the structures of the heart (Grade E - D)

Learning Objectives Success Criteria • Label the structures of the heart (Grade E - D) • To understand the structure of the mammalian • Describe with the aid of diagrams/photographs, the heart external and internal structure of the mammalian heart (Grade C –B) • Explain the difference in the thickness of the walls of the different chambers of the heart in terms of their functions (Grade B – A)

RIGHT LEFT (a) (c) Semi-lunar valve Pulmonary artery Deoxygenated blood from the body (d) Vena cava (main vein) (f) Right atrium (h) Tricuspid valve (j) Papillary muscle(l) Tendons (m) Right ventricle (b) Aorta (main artery) Oxygenated blood from the body (e) Pulmonary vein (g)Left atrium (i)Bicuspid valve (k)Left ventricle • Label the structures of the heart (Grade E - D)

The human heart The heart is a muscular organ located between the lungs in the centre of the chest (thorax), and is about the size of a fist. It pumps blood continuously around the body. An organism can lose conscious within just a few seconds if the brain is deprived of blood. In foetuses, the heart begins beating about 5– 6 weeks after conception. 15 of 24 © Boardworks Ltd 2008

Cardiac muscle The heart mainly consists of cardiac muscle tissue, which like smooth muscle (but not skeletal muscle), contracts involuntarily. Cardiac muscle is made up of cells that are connected by cytoplasmic bridges. This enables electrical impulses to pass through the tissue. It contains large numbers of mitochondria and myoglobin molecules. 16 of 24 © Boardworks Ltd 2008

Structure of the heart • Explain the difference in the thickness of the walls of the different chambers of the heart in terms of their functions (Grade B – A)

• Explain the difference in the thickness of the walls of the different chambers of the heart in terms of their functions (Grade B – A)

Task • Heart dissection – identify all the internal parts of the heart and external parts of the heart. • Label each part with its function Include – tendinous cords, septum, • Describe with the aid of diagrams/photographs, the external and internal structure of the mammalian heart (Grade C –B)

Can you identify the following without looking at your diagram? 1. The vessel which carries blood to the lungs. Pulmonary 2. The valve betweenartery the left atrium and ventricle. Bicuspid 3. The chamber which receives deoxygenated blood from the body. 4. The vessel which carries. Right bloodatrium pumped out of the left side of the heart. Aorta 5. The vessel which carries blood into the heart from the lungs. Pulmonary vein

Plenary • Heart drag and drop • Homework – worksheet on heart

From the spec. . . (b) explain the meaning of the terms single circulatory system and double circulatory system, with reference to the circulatory systems of fish and mammals; (c) explain the meaning of the terms open circulatory system and closed circulatory system, with reference to the circulatory systems of insects and fish; (d) describe, with the aid of diagrams and photographs, the external and internal structure of the mammalian heart; (e) explain, with the aid of diagrams, the differences in the thickness of the walls of the different chambers of the heart in terms of their functions;