3.2.1 Organisational Complexity of the Human Circulation System

Two types of Circulation System Heart pumps blood into vessels that are open ended ……eg in Insects Blood remains in a continuous system of blood vessels…..eg in Humans Open Circulation SystemsClosed Circulation Systems

Advantages of a Closed Circulation System 1.Blood can be pumped faster 2.Blood flow rate to different organs can be changed Therefore nutrients can be delivered faster to cells allowing the organism to be more active For example blood flow can be increased to the leg mucles when running

Main parts of Human Circulation System 1.Heart 2Blood Vessels Arteries 3.Blood Veins Capillaries Arterioles Venules

Main Blood Vessels Arteries Veins Carry blood away from the heart Carry blood under high pressure Thick elastic wall Narrow lumen Carry blood towards the heart Carry blood under low pressure Have valves to prevent backflow Thin wall Wide lumen

Smaller Blood vessels Arterioles Venules Arterioles connect arteries and capillaries venules connect capillaries to the veins Capillaries The thin wall allows easy exchange of materials with cells Tiny blood vessels linking arterioles and venules

Blood vessels under the microscope Thick Wall Arteries Veins Narrow lumen Thin Wall Wide lumen Have valves to prevent backflow

Cross section of blood vessel Collagen Muscle and Elastic fibres Endothelium Lumen

Learning check 1Give three differences between arteries and veins 2What is the function of valves in veins 3Name the blood vessels that connect capillaries and veins 4Give one advantage of a closed circulation system

Role of muscle and elastic fibres Muscle expand to allow increased blood flow through the vessel Elastic fibres bring the blood vessel back to shape Valves prevent backflow

The Heart LocationBetween the lungs, slightly to the left side of the thorax, above the diaphragm Function To pump blood around the body Structure A hollow structure made of cardiac muscle, surrounded by a double membrane

Role of Heart Muscle 1.The heart wall is made of Cardiac Muscle 2.Contraction of the cardiac muscle drives blood around the body 3.Cardiac Muscle does not fatigue

Human Two-Circuit Circulation Pulmonary Circuit Systemic Circuit Pumps to the head, trunk and limbs and back to the heart Pumps to the lungs and back to the heart

Advantages of a Double Circulation System 1.Separation of oxygen rich and oxygen poor blood 2.Blood pressure can be kept high

Pathway of blood Around Body

Portal systems Hepatic Portal System A blood pathway that begins and ends in capillaries Connects the stomach and intestines with the liver

Learning check 1Name the blood vessel that connects the digestive system with the liver 2Distinguish between the systemic the pulmonary blood circuits 3Give one advantage of a double circulation system

Vena Cava Right Atrium Tricuspid Valve Right ventricle Left Ventricle Left Atrium Pulmonary Vein Aorta Pulmonary Artery Bicuspid Valve Septum Cardiac muscle Semi Lunar Valves

Blood pathway through heart Right Atrium Tricuspid valve Right ventricle Left atrium Bicuspid valve Left ventricle Vena Cava Pulmonary arteryAorta Pulmonary vein

Role of Valves Semi Lunar valves Tricuspid valve Bicuspid Valve Prevent backflow into heart Prevents backflow into left atrium Prevents backflow into right atrium

Blood supply to the heart wall Coronary arteries Cardiac muscle is supplied with blood by the coronary arteries. These branch from the aorta just above the semi lunar valves ot the aorta Coronary veins Drain blood from heart wall into the right atrium

Learning check 1Where does blood go immediately after leaving the right ventricle ? 2Name the blood vessel that enters the right atrium 3What is the function of the coronary arteries ? 4State the exact location of the opening into the coronary arteries 2Name the valve between the left atrium and left ventricle

Heartbeat and its control ( Higher level material on heartbeat control in section ) The heart beat consists of alternate contraction and relaxation of the cardiac muscle The heart beat is controlled by the pacemaker in the right atrium. This sends an electrical signal to the cardiac muscle The heart beat sound is caused by the closing of the heart valves

Pulse A wave of expansion passes down the walls of arteries following a contraction of the left ventricle. The elastic fibres in the artery walls then bring about a contraction of the artery wall. Average pulse rate is 72 beats per minute The alternate expansion and contraction of arteries is called a pulse

Blood Pressure As blood passes from arteries to veins pressure drops Blood pressure is measured with an instrument that records the pressure it takes to stop the blood flow in an artery of the upper arm Pressure in the due the to contraction of the ventricles which forces blood into the arteries

Effect of smoking on the circulation system 2.CO 2 reduces the amount of O 2 carried by the blood 1.Nicotine increases the heart rate and blood pressure These puts a bigger workload on the heart This reduces energy levels 3.Other chemicals in tobacco Increase the chance of clots

Effect of Diet on the circulation system High salt intake High intake of fat causes a build up of cholesterol Cholesterol may block arterioles and lead to stroke or heart attack Raises blood pressure which can cause heart attack

Effect of Exercise on the circulation system Exercise increases our ability to transport oxygen Exersise strengthens the heart This improves circulation This gives increased energy levels

Learning check 1What causes the blood to be under pressure in the arteries ? 2Explain the term Pulse 3What controls the rate of heartbeat 4Give two harmful effects of cigarette smoke on the circulation system 5Explain why salt can have a negative effect on the circulation system

Lymphatic System A secondary transport system consisting of one way system of vessels that collects and returns excess tissue fluid to blood system 1.Lymph vessels 2.Lymph Nodes 3.Lymph Structure

Lymph vessels & blood vessels

Lymphatic System Functions 1.Collect tissue fluid and return it to the blood system 2.Fight Infection by 3.Transport digested fat away from intestine (a) Filtering out microorganisms in the lymph nodes (b) Destroying microorganisms by antibody production (c) Mature and store lymphocytes

Composition of Blood Plasma Liquid part of the blood Red Blood Cells White Blood Cells Platelets

Role of of Blood Parts Composed of mainly water which acts as a transport medium for the cells and dissolved substances Plasma Red Blood Cells White Blood Cells Platelets Carry Oxygen Fight Infection Clotting Higher level material in sec 3.2.3

Role of Plasma Composed of mainly water which as a transport medium for the cells and dissolved substances Digestion products ….Glucose, amno acids, Fatty acids, glycerol, minerals and vitamins Waste….Carbon dioxide, urea Hormones….eg Insulin Antibodies

4 Blood Groups It is essential to know a persons blood group for safe blood transfusions A B AB O Group

Rhesus Factor Another blood grouping system Involvs antigen called factor D on the red cells If you have factor D you are Rhesus positive or Rh+ If you haven’t you are Rhesus negative or Rh- Rhesus factor is important in pregnancy as problems may arise in second and further preganncies if the mother is Rh - and the baby is Rh +

Learning check 1Name the three main parts of the Lymphatic System 2Name three substances dissolved in plasma 3Name a blood grouping system other than the ABO System 4What is the function of white blood cells 5Give two functions of the Lymphatic System

END