Transport in animals

Objectives Discuss the need for transport system in multi-cellular organisms. Describe the components of blood and their functions Differentiate among blood vessels Describe the structure & function of the heart.

Why do animals need a transport system? A transport system carries things to and from one place to the next. Smaller plants and animals have a larger surface are to volume ratio This means that from any point on their surface, materials can diffuse inwards and reach the destination quickly

The very small organisms such as the unicellular Amoeba don’t need a transport system. Different substances diffuse in and out of their bodies across surface membranes. In larger organisms the process of diffusion will occur only up to a few cells into the body from the surface. Also with skin, fur and feathers acting as barriers the process is slowed. It is inefficient as necessary substances will not reach to cells in required time.

Only organisms that are a few cells large are able to use diffusion as an efficient means of transport, after which a transportation system is necessary

*The larger an organism gets, the smaller the surface area to volume ratio is, so movement of materials by diffusion takes longer. Therefore the development of a transport system was essential for larger organisms This system functions to carry essential substances to each cell and carries away toxic substances from them in an effective and efficient manner.

The circulatory system

Circulatory System The circulatory system is the transport system found in mammals. Humans have a cardiovascular system in which two types of circulation occurs ( Systemic and Pulmonary) The circulatory system is composed of three main parts: The heart The blood The blood vessels.

Heart This organ pumps blood around the body at different speeds and at different pressures according to the body’s needs. The heart is made of CARDIAC MUSCLE. The cardiac muscles in the heart contracts and relaxes continuously.

Cardiac muscle This muscle has its own blood supply (coronary circulation). Blood reaches the muscle via the coronary arteries. These carry blood to capillaries that supply the heart muscle with oxygen & nutrients. This allows the heart muscle to keep on working. Blood returns to the atrium via coronary veins.

Structure of the Heart

Structure of the heart The heart has four chambers: The two upper chambers are the Right and Left Atrium The two lower chambers are the Right and Left Ventricles. It’s also divided into a right and left side by the SEPTUM; The left side of the heart circulates oxygenated blood. The right side of the heart circulates deoxygenated blood.

There are four valves separating each chamber. What is their function? As blood enters the atrium, its walls stretch to receive blood; then it contracts to push blood through onto the lower ventricles.

Valves Prevents backflow of blood to the previous chamber. The Tricuspid valve separates which two chambers? Mitral valve? Aortic Valve? Pulmonary Valve?

RULES Blood enters the heart through the atria. Blood leaves the heart when the ventricles contract. The right ventricle pumps blood only to the lungs The left ventricle pumps blood to all parts of the body. This requires much more pressure, which is why the wall of the left ventricle is much thicker than that of the right ventricle.

FLOW OF BLOOD THROUGH HEART Deoxygenated blood from body enters from Vena cava vein into RA Atria contracts and pushes blood from RA into RV Ventricles contract and blood is pushed into pulmonary artery which goes towards the lungs. Gaseous exchange occurs at alveoli and pulmonary vein brings back Oxygenated blood to LA.

When atria contract simultaneously again , the oxygenated blood is pushed into LV When ventricles contract the blood is pumped out to Aorta and to the rest of the body. Pulmonary artery and vein are the few blood vessels in which the roles of artery and vein are reversed. *Normally arteries carry oxygenated blood to organs and veins bring back deoxygenated blood from body to heart

Systole and Diastole The systole occurs when the chambers of the heart contracts. Pumps blood out of heart The diastole occurs when the heart’s chambers relax, allows new blood to enter heart This contraction and relaxation is what causes the “lub-dub” sound of the heartbeat.

Animation of heartbeat. http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_pumping.html

Double circulation in humans. This refers to a system that pumps blood to the heart twice. It has two main parts: Pulmonary circulation: blood is first circulated through the lungs where it is oxygenated. Systemic circulation: blood is then circulated throughout the body where it unloads its oxygen, and exchanged with deoxygenated blood.

Double Circulation

Types of blood vessels Small Lumen Large Lumen Muscle & elastic layer Outer wall with muscle fibres Small Lumen Large Lumen Muscle & elastic layer

Capillary-the linkage between artery and vein

Exchange of material at cell site At the cells, a capillary network is formed. Plasma from the blood capillaries ooze out under arteriole pressure and surrounds the cells This is known as TISSUE FLUID. This provides a moist medium for substances to diffuse across the cell and capillary membranes. Increases diffusion rate. On the Venous end of the capillary network the plasma is reabsorbed back into capillaries.

Blood The blood is the medium in which substances are transported throughout the body. It has many other functions besides transportation alone.

BLOOD COMPOSITION The composition of materials transported by blood are: Water Gases (Oxygen, Carbon dioxide) Salts Nutrients Nitrogenous waste products e.g. urea Hormones & antibodies Heat These substances that are transported are dissolved in the blood plasma

BLOOD COMPONENTS Blood is comprised of Plasma Red blood cells White Blood cells Platelets

Plasma This is the yellowish liquid part of blood,90% is water Transports dissolved substances : Dissolved food CO2 Hormones Mineral salts Nitrogenous waste

Red blood cells The red blood cells are responsible for the transport of oxygen It contains haemoglobin which combines reversibly with oxygen (oxyhaemoglobin) and is carried to cells. Oxygen is readily released from haem at tissues where O2 level is low.

At the cells the rbc encounters carbon dioxide Why? The carbon dioxide diffuses into blood (along conc. gradient) and travels as hydrogen carbonate ions in the plasma

Red Blood Cell RBC has no nucleus which increases amt of haem carried in it and hence can transport more O2 RBC die after 3-4 mths Rbc is produced in the bone marrow of long bones: femur, humerus, pelvis, ribs etc

White blood cells These are the bodyguards against pathogen infection They help fight against disease by surrounding and destroying foreign objects that are introduced into the system They are categorized according to their actions Phagocytes: lobed nucleus, surrounds and “eats” pathogen Lymphocytes: round nucleus, produce antibodies which stick to and deactivates pathogen.

Platelets Platelets are fragments of cells formed in bone marrow They have no nucleus Function to help clot blood preventing blood loss. What is the importance of clotting blood? Draw diagram of formation of blood clot.

Draw diagramto show blood clot process Draw diagramto show blood clot process. include Ca+ and vit K importance

BLOOD TRIVIA Human body has between 4.5 to 5.6 litres of blood Blood vessels in body laid end to end would stretch 60,000miles The normal heart pumps 5 liters of blood per minute

ABO BLOOD GROUPS There are 4 blood types: A, B , O ,AB These arise from the presence or absecence of antigens a and b on blood cell membranes Each blood type produces different and specific antigens which fight foreign objects Important to know blood group especially during a blood tranfusion The donor’s blood must match the recipient for transfusion to be successful. Important steps to take when having blood transfusions?

Diseases associated with circulatory system Hypertension This is persistent high pressure of blood on the inside walls of arteries. This high pressure can cause vessels as capillaries to burst. A stroke is where a blood vessel in brain burst, affecting portion of brain and damaging it because oxygen is not being delivered. Hypertension can cause vessels to burst in other organs e.g. kidney failure

Arteriosclerosis Hardening of artery walls Clotting of blood in arteries can lead to ateriothrombosis

Immunization Immunization is the ability to withstand or fight any illness or disease. When there are foreign bodies or antigens entering the body , the blood makes antibodies to fight and rid the body of the deleterious effects .

The first line of defense is the physical barrier of skin to germs. Other body orifices are also protected by some means or the other: nose, lungs, vagina, eyes, stomach The second defense is the presence of white blood cells that attack and eat the pathogens that may enter body. This is a non specific defense mechanism The third is the production of antibodies that are specific to antigens or germs that enter the body. It is produced by lymphocytes.

Antibodies perform 4 different type of functions: They surround and kill the antigen They neutralise the toxic effect of the antigen on the body. Immunity is obtained either naturally or artificially. Natural immunity is obtained when the body when infected, produces the antibodies to fight the infection

Immunization process When infection first occurs it takes time for the body to make the antibodies to fight the antigens. Afterwards the blood cells retains memory antibodies which are capable of producing the antibodies faster if it is infected with the same disease again.

Natural immunity This is the immunity gained when