Transport In Animals

• Transport in animals

  • Large animals need transport systems so they can receive all the oxygen and nutrients necessary to survive.
  • They must also have a system for waste removal.
• There are 3 important features to consider in a transport system:

  • Body Size
  • Surface area : Volume ratio
  • Metabolic rate
• Body Size

  • There are several cell layers in a multicellular organism, so oxygen and nutrients diffusing into cells can only be done by outer cell layers, it is not an option for the others.
  • This is due to an increased distance from the nutrients and oxygen yet the cells still require them.
• Surface Area : Volume Ratio

  • Large multicellular organisms have a small surface area for their volume.
  • This smaller ratio means that through simple diffusion of the outer cell layers, there is just not enough nutrient and oxygen able to be distributed to the entirety of the cells.
• Metabolic Rate

  • Active animals will also require more oxygen for respiration.
  • (Most) Animals will also need to keep warm, which requires even more energy.
• A good transtransport system has:

  • A fluid or medium to transport substances around the body.
  • A pump to create pressure to push the fluid around.
  • Exchange surfaces to enable substances to enter or leave where they are needed.
  • Tubes or vessels to carry the fluid
  • 2 circuits - pick up (1) , then deliver (2) Substances.
• Mamalian Circulatory System Features

  • Double Circulatory system.
  • Blood travels through the heart twice per each circuit of the body.
  • Right Side of the heart pumps blood to the lungs.
  • Left side pumps blood to the rest of the body.
  • (Hence) High blood pressure and fast blood flow.
• Fish Circulatory System - Features

  • Single Circulatory System.
  • Blood travels through the heart once for each complete circulation of the body.
  • Blood travels first to the Gill capillaries to pick up oxygen.
  • Blood then goes onto the capillaries of the rest of the body.
  • (Hence) Lower Blood pressure, Slow blood flow.
• Double Circulatory System

  • The heart/pumping organ of the system will take blood to 2 main circuits per entire circuit, so blood passes through the heart per main circuit of the body.
• Single Circulatory System

  • The heart/pumping organ of the system will take blood to 1 main circuit per entire circuit, so blood passes through the heart once per main circuit of the body.
• Features of Closed Circulatory Systems

  • Blood flow is always confined within blood vessels.
  • Blood flow will be quick and under pressure.
  • Rate of Blood flow to different tissues can be adjusted.
  • Oxygen and nutrients are delivered quickly, and waste products are removed quickly.
• Features of Open Circulatory Systems

  • Found in insects and invertebrates.
  • Fluid called haemolymph (referred to as blood often ,but not the same), is not stored in blood vessels, but an open cavity, called the haemocoel.
  • Body muscles in the animal help to circulate blood- in insects there is a muscular pump that is similar to the heart but is a long tube lying under the dorsal surface called the dorsal vessel.
• Features of Open Circulatory Systems

  • Haemolymph circulates through the whole body cavity, so the animal's cells are bathed in haemolymph.
  • Haemolymph enters the dorsal vessel ("Heart") via the ostia.
  • The "Heart" then pumps blood towards the head via peristalsis.
  • At the forward end of the "heart", haemolymph pours out into the body cavity.
• Locust

  • Larger insects, like locust, have open-ended tubes attached to the dorsal vessel that direct haemolymph to the active parts of the body.
• Blood vessels - Arteries

  • Carries blood from the heart to the rest of the body.
  • The thick muscle layer in walls helps maintain a high pressure in the artery (due to large volume of blood)
  • Elastic tissue allows Arteries to stretch and recoil, as the heart beats, helping blood move along.
  • Folded endothelium allows the expansion of the Arteries with higher volumes of blood.
• Blood Vessels - Arterioles

  • Links the Arteries and capillaries.
  • There is more smooth muscle than in the Arteries, which is used in vasoconstriction to push blood into capillary beds.
  • There is less elastic tissue than in the Arteries, as they do not contain as much blood, so don't need to expand as much.
• Blood Vessels - Capilaries

  • Acts as a diffusion site, which delivers oxygen to cells and takes waste products from cells.
  • They are one cell thick
• Blood Vessels - Venules

  • Receives blood from capillaries and sends it to the veins.
  • It has very thin walls with a few muscle cells on the exterior.
  • This structure allows for diffusion across cells that still need Oxygen yet the stability increases as the volume of blood in the structure increases.
• Blood Vessels - Vein

  • Returns deoxygenated blood to the heart under a low pressure. (low pressure due to distance blood has already travelled in one pump)
  • A large lumen ensures despite lower pressure, the blood is still transported efficiently.
  • A thin elastin layer with muscle tissue allows veins ro expand to support a higher blood flow.
  • Valves stops backflow of blood due to the low pressure.
• Blood

  • A specialised transport medium, which is also considered a special type of connective tissue.
  • An average adult has 4-6 litres of blood.
  • Blood functions as: Transport, Defence, Thermoregulation, Maintaining pH of body fluids, Transport of hormones, Repair.
• Composition of

  • 55% Plasma (91% Water, 7% Proteins, 2% Other Solutes)
  • 45% Cells (Erythrocytes, Platelets, Leukocytes)
• Tissue Fluid

  • Surrounds cells in tissues, made from blood passing through capillary walls.
  • Contains the same things as blood aside from Erythrocytes and Proteins, this is due to them being too large to pass from the capillaries into the tissue.
• Formation of Tissue Fluid

  • Tissue Fluid moves out of the capillaries via pressure filtration.
• Lymph

  • Not all tissue fluid returns to the capilaries, the excess drains into the lymphatic system, where it forms lymph.
  • A colourless, sometimes pale yellow, fluid similar to tissue fluid but containing more lipids.
  • The lymphatic system drains into the circulatory system near the vena cavae via the thoracic duct.
• The Lymphatic System

  A secondary circulatory system and a major part of the immune system.

  It consists of:

  • Lymphatic Capilaries and Veins
  • Lymph Nodes
  • Lymphatic Tissue
• Lymphatic Capilaries and Veins

  • Lymph vessels that contain valves, they transport lymph fluid.
• Lymph Nodes

  • Sac-like organs that trap pathogens and foreign substances.
  • They contain large numbers of white blood cells.
• Lymphatic Tissue

  • In the spleen, thymus and tonsils, these also contain large amounts of leukocytes and are involved in their development.
• Blood - Molecules/Cells Present

  • Erythrocytes
  • Leukocytes
  • Platelets
  • Proteins
  • Water
  • Dissolved Solutes
• Tissue Fluid - Molecules/Cells Present

  • (Very Few) Leukocytes
  • (Very Few) Proteins
  • Water
  • Dissolved Solutes
• Lymph - Molecules/Cells Present

  • Leukocytes
  • Antibodies
  • Water
  • Dissolved Solutes
• The Heart

  • A muscular organ located between the lungs in the centre of the chest. (Thorax)
  • The heart is around the size of a fist (in humans).
  • It pumps blood around the body.
• The Heart Muscles

  • The Heart is mainly composed of cardiac muscle tissue, which, like smooth muscle, contracts involuntarily.
  • Cardiac muscle is made up of cells that are connected by cytoplasm bridges. This enables electrical impulses to pass through the tissue.
  • Unlike regular skeletal muscle, cardiac muscle does not fatigue or need to rest, it's supplied with oxygen via the coronary arteries.
• Inelastic Pericardial Membranes

  • Membranes that surround the heart.
  • Prevent it from bursting with too much blood.
• Mammalian Hearts

  • In some animals, the heart is no more than a simple muscle tube.
  • But for mammals, the heart is complex, consisting of four muscular chambers in an outer muscular "bag", in the chest enclosed by the ribs and sternum.
  • There are two main sides of the heart, one carrying oxygenated blood, the other carrying deoxygenated blood, the blood of these sides are never mixed.
• Heart - Right Side

  • Thin walls.
  • Carries deoxygenated blood.
  • Blood is carried only to the lungs from here.
• Heart - Left Side

  • Thick Walls.
  • Carries oxygenated blood.
  • Blood is carried to the entirety of the body.
• Valves in the heart

  • Atrioventricular Valves - Link the atria to the ventricles.
  • Seminar Valves - Link the ventricles to the Pulmonary Artery and Aorta.
  • Valves stop blood from flowing in the wrong direction.
• How Valves Work

  • Valves only open on way.
  • Whether they open or close is dependent on the pressures of the surrounding chambers.
  • If there is a higher pressure behind a valve, it's forced open.
  • But if pressure is higher in front of the valve, , it's forced shut.
  • This makes bloodflow unidirectional- it flows one way.
• The Cardiac Cycle

  Occurs in three stages.

  1. Atrial Systole
  2. Ventricular Systole
  3. Diastole