Cymraeg

Body Systems
Session 2 - The Respiratory System and the Circulatory System in a Farm Animal

This resource is suitable to support Level 2 Agriculture courses.

Respiration

Respiration occurs as a physical and a chemical process:

  • Physical inhalation to move gases from the air to the bloodstream and expiration to remove waste gases and water.
  • Cell respiration when a chemical reaction takes place to release energy.
Image of lungs

Cell Respiration

Cell respiration is the process that allows plants and animals to release energy for their own use.

  • Energy in chemicals such as glucose is released when oxygen reacts with them to produce smaller molecules.
  • The process is similar to the release of energy by burning fuel such as petrol.
  • Food + Oxygen -> Carbon dioxide + Water + Energy
    • C6H12O6 + 6 O2 → 6 CO2 + 6 H2O +36 ATP Energy

Where Does Respiration Take Place?

Food + Oxygen -> Carbon dioxide + Water + Energy

  • This reaction occurs inside the cells, but the respiratory process must also move oxygen to the cells and remove the waste products. If an animal is unable to move oxygen to the vital organs, it will rapidly die.
    • graphic of mitochondria

    Functions of the Circulatory System

    The circulatory system has several functions:

  • To take oxygen to muscles and other tissues.
  • To remove waste products e.g. carbon dioxide.
  • To take the products of digestion to the tissues that need them.
  • To carry chemical messages in the form of hormones.
  • To transport blood cells and antibodies to fight disease.
  • To help with temperature regulation.
    • Image of heart

    Structure

    Gases are exchanged in the lungs.

  • As an animal shortens the muscles in the rib cage and contracts the diaphragm the volume in the chest increases.
  • This draws air into the lungs (the animal breathes in).

    • Diagram of inhalation and exhalation - Breathing in and out

    Diagram showing inhalation (left) and exhalation (right). Inhalation diagram on the left shows diagram of lungs with text 'air containing oxygen in', 'ribs push out', 'diaphragm pushes down'. Diagram on right shows lungs with text 'air containing carbon dioxide and water out', 'ribs push in', 'diaphragm pushes upwards'

    Exchange of gasses in the lungs

    The air in the sacks called alveoli in the lungs contains more oxygen than in the blood in the tissues.

  • Therefore oxygen dissolves and passes into the bloodstream from the alveoli.
  • This is a process called diffusion.
  • The oxygen is carried by red blood cells.

    • The Circulatory System

    The circulatory system moves oxygenated blood from the lungs to the tissues, and deoxygenated blood back to the lungs.

    The heart pumps the blood through a series of blood vessels (pipes) to the tissues.

    Components of the Circulatory Systems

  • Arteries
  • Veins
  • Capillaries

    • Arteries

    Arteries carry blood away from the heart.

    • Usually the blood is under high pressure and contains a lot of oxygen.

    Veins

    Veins carry blood to the heart.

  • Usually the blood is low in oxygen, but contains the carbon dioxide to be removed by the lungs.

    • Capillaries

    These occur where the arteries become very narrow to allow the blood to bathe the tissues so that food and oxygen can go into the cells and waste products can be removed.

    • Capillaries connect the arteries and the veins. The capillaries are the narrowest blood vessels and are semi-permaeble allowing the exchange of food nutrients, gases and waste e.g. urea through diffusion.
    Image of capillaries

    Red Blood Cells

    Red blood cells contain an iron based protein called haemoglobin which binds with oxygen and transports it in the blood.

    • Red cells are made in the red bone marrow of long bones such as the femur and ribs.
    Image of red blood cells

    White Blood Cells

    White blood cells are needed to protect animals from disease.

  • Phagocytes are large cells which can attack and engulf bacteria.
  • Lymphocytes produce antibodies to fight specific diseases.
    • Image of white blood cells

    Platelets

    These are required for blood clotting.

    Image of platelets
    Image of platelets

    Respiration Rate and Heart Rates

    In healthy resting animals the approximate rate of respiration and heart rate are shown in Table 1:

    Table adapted from Black’s Veterinary Dictionary. Table shows 3 rows ‘Animal’, ‘Respiration rate (breaths / minute)’ and ‘Pulse rate (beats / minute). Under these rows, 3 columns are as follows: ‘Cattle, 12-16, 45-50’, ‘Sheep, 12-20, 70-80’, and ‘Pigs, 10-16, 70-80’.

    Problems Associated with the Respiratory System

    Pneumonia.

  • This is an infection of the lungs.
  • This can be caused by bacterias, viruses, fungi and other environmental conditions such as dust, fumes or stale air.
  • This may be a particular problem if livestock are kept in poorly ventilated housing.
    • Image of bacteria on lungs

    Problems Associated with the Respiratory System

    Asphyxiation.

  • This would occur if an animal was not getting enough oxygen e.g. if large quantities of gases are released from under ground slurry store into livestock housing.

    • Problems associated with the Circulatory System

    Anaemia.

  • This is a shortage of haemoglobin which is the chemical in red blood cells that carries oxygen. This often arises if the animal is deficient in iron.
  • It may be seen in young piglets whose diet is low in iron, and in ewes which have a heavy worm burden or liver fluke.
    • Image of piglets suckling

    Problems associated with the Circulatory System

    The animal is not getting enough magnesium into the bloodstream which in turn causes cardiac failure.

    Cardiac failure:

  • The heart stops pumping the blood around the body.
  • This can occur in a case of grass staggers.
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