Blood. Intermediate 2 Biology Unit 3 : Animal Physiology

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1 Blood Intermediate 2 Biology Unit 3 : Animal Physiology

2 Composition of Blood Blood contains Red blood cells White blood cells platelets plasma

3 Plasma Watery, yellowish fluid Suspended in plasma Proteins e.g. Antibodies Transports water-soluble substances to within diffusion distance of living cells. Glucose Amino acids Carbon dioxide transported as bicarbonate ions (as CO 2 with water to form an acid which can cause problems)

4 Red Blood Cells Very small and numerous Flexible squeeze through tiny capillaries to deliver oxygen to cells Biconcave disc shape large surface area in relation to volume No nucleus Cytoplasm rich in haemoglobin

5 Haemoglobin Haemoglobin combines with oxygen to increase the oxygen-carrying capacity of blood. Association Haemoglobin combines with oxygen when the oxygen concentration is high Dissociation Haemoglobin rapidly releases oxygen when oxygen concentration is low

6 Association and dissociation Association (in lungs) haemoglobin + oxygen oxyhaemoglobin dissociation (in tissues)

7 Oxygen affinity Haemoglobin has a high affinity for oxygen when oxygen concentration in the environment is high Haemoglobin has a low affinity for oxygen when the oxygen concentration in the environment is low. Affinity Tendency to combine with oxygen

8 oxygen dissociation curve Partial pressure of oxygen (po 2) Measure of concentration of oxygen Measured in kpa The oxygen dissociation curve shows saturation of haemoglobin at different partial pressures of oxygen (po 2 ). High po 2 haemoglobin saturated with oxygen Low po 2 oxyhaemoglobin gives up its oxygen to respiring cells (dissociates)

9 oxygen dissociation curve

10 Respiring cells Actively respiring cells have a low oxygen tension (2.7kPa) Alveolar air has a high oxygen tension (13kPa) In lungs haemoglobin is loaded with oxygen It moves along a concentration gradient from the alveolar air (High oxygen concentration) to the blood (low oxygen concentration) In respiring tissues oxygen is unloaded Diffuses from a high concentration in the blood to a low concentration in the respiring cells.

11 White Blood Cells White blood cells Contain a nucleus Can change shape and squeeze through capillary walls Types of white blood cell include Monocytes Phagocytosis Lymphocytes Antibody production

12 Phagocytosis Bacteria are engulfed and destroys by phagocytic cells, e.g. monocytes or macrophages Stages of phagocytosis Bacteria releases a chemical and the phagocyte moves towards it The phagocyte adheres to the bacteria The cell membrane changes shape and engulfs the bacteria in a phagocytic vacuole Lysosomes fuse with the vacuole releasing powerful digestive enzymes Bacteria is digested Products of digestion are absorbed into the cytoplasm of the phagocyte

13 Phagocytosis Dead bacteria and phagocytes can accumulate at the site of infection forming pus. Macrophages can be found in liver, spleen and lymph

14 Immunity Immunity An organism s ability to resist infection Phagocytosis is an example of non-specific immunity Providing protection against a range of microorganisms Antibody production is an example of a specific immune response Each antibody is specific to a particular antigen Thee antibody and antigen are complementary

15 Antigens An antigen is a protein molecule that is recognised as foreign by the body s lymphocytes VIRUS antigens

16 Antibody Y-shaped molecule Produced by lymphocytes Receptor sites are specific to an antigen

17 When an antibody attaches to its complementary antigen, the antigen is rendered harmless

18 Immunological memory Primary response Infection by disease-causing organism Latent period when the lymphocytes respond and start to produce antibodies Often person suffers symptoms of the disease Secondary response Exposure to the same antigen Memory cells remain in blood from first infection and as a result antibodies Produced more rapidly Produced at a high concentration Remain in the bloodstream for a longer time

19 Primary and secondary response

20 Immunity Natural acquired immunity The person has been exposed to the diseasecausing organism Memory cells remain in bloodstream Artificially acquired immunity Vaccinations contain a small dose of the antigens Lymphocytes are stimulated to produce antibodys Memory cells remain in bloodstream