composition of mammalian fluids

• Plasma is 90% water. It Transports products of digestion, ions, carbon dioxide, urea, heat, prothrombin, fibrinogen and clotting factors
• Monocytes / macrophages

   Actively phagocytic, ingesting bacteria and other large particles

   A macrophage is a mature monocyte
• monoctye matures into a macropage
• monocytes have a kidney shaped nucleus.

  They are able to move out of capillaries to sight of infection where they engulf and digest
• lymphocytes have little cytoplasm and a big nucleus
• Lymphocytes

   Respond to foreign substances, antigens which may be on the surface of pathogenic microbes

   T-cells are concerned with directly attacking and destroying foreign cells (cellular immunity)

   B cells are concerned with making antibodies

   These antibodies attach to antigen on foreign cells inactivating, clumping or destroying them
• Polymorphs (microphages)

   Lobed nucleus and grainy cytoplasm

   Actively phagocytic engulfing and digesting disease causing bacteria

   Bacteria digested inside vesicles by lysozymes contained lysosomes
• microphages are a consequence of a blood clot at sight of infection
• Red Cells (erythrocytes)

  The main function of these cells is the transport of respiratory gases, the main one being oxygen.
• red blood cell adaptions

  • small size-all the haemoglobin molecules the cells contain are close to surface- allows oxygen to be picked up and readily released.
  • Red blood cells are BICONCAVE discs. This is a compromise between having a large surface area and a large volume.
  • no mitochondria or nuclei which allows more haemoglobin and hence oxygen to be transported.
  • Haemoglobin: This is the oxygen transporting pigment.
• Steps of blood clotting

  1. Platelets initiate blood clotting when they rupture in a damaged blood vessel and are exposure to air.
  2. Thromboplastin is released by platelets to set off a sequence of events
  3. Conversion of prothrombin to thrombin in the presence of calcium and Vit K
  4. Conversion of fibrinogen to fibrin by thrombin which forms the clot
  5. Clot prevents further blood loss and entry of pathogenic micro organisms
• prothrombin and fibrogen are plasma proteins
• Haemoglobin: the protein part consists of 4 polypeptide chains called globin molecules.

  Each globin molecule has a non-protein prosthetic group called haem attached.

  Each haem consists of iron enclosed in a ring structure.
• graphs of haemoglobin show Hb is well saturated with O2 at high partial pressures such as those found in the lungs.

  In contrast, Hb has a lower saturation at lower partial pressures of O2 such as those found in working muscles. This means that haemoglobin unloads oxygen.

  The lower partial pressures of O2 in working muscles is because it is being used in respiration.
• Partial pressure is the proportion of the total air pressure that is contributed by the oxygen in the mixture
• The haem molecule can bind with oxygen molecules. There is an enhancement of subsequent binding of oxygen ensures a rapid saturation of haemoglobin as illustrated by a sigmoidal curve.
• An 02 dissociation curve for haemoglin never reaches 100%.

  This is due to the low affinity of 02, so it prefers to release it.
• An oxygen dissociation curve showing the binding of O2 molecules shows full saturation occurs when haemoglobin is carrying 4 molecules of O2
• The Bohr Shift is vital because it means that the haemoglobin dissociates more at higher partial pressures of oxygen.
• Increased co2, temperature and decreased pH reduce the affinity of

  haemoglobin for oxygen – Bohr effect
• In terms of the Bohr effect, Working muscles produce greater conc of carbon dioxide, which reduces affinity of haem for oxygen which means that it gives it up more readily therefore delaying the onset of anaerobic respiration
• myoglobin is a oxygen transporting pigment found in red muscle – NOT BLOOD
• The oxygen dissociation curve for myoglobin is displaced to the left of that for haemoglobin. Consequently myoglobin has a higher affinity for oxygen than haemoglobin causing myoglobin to stay saturated at lower partial pressures of oxygen than haemoglobin would
• This adaptation of myoglobin having a higher affinity for oxygen is to help ensure that muscle metabolism can remain aerobic at lower partial pressures of oxygen.

  This delays anaerobic respiration, which doesn't give as much ATP for movement as aerobic respiration. Anaerobic respiration also builds lactic acid. (toxic waste)

  This means MYOGLOBIN ACTS STORE OF OXYGEN. IT ONLY

  GIVES ITS OXYGEN AWAY WHEN PARTIAL PRESSURE OF THE GAS IN

  TISSUES BECOMES VERY LOW. THIS MEANS IT ENABLES AEROBIC

  RESPIRATION TO CONTINUE FOR LONGER AND DELAYS THE ONSET OF

  ANEROBIC.
• describe the effect of altitude on oxygen transport by haemoglobin?

  • Partial pressure of oxygen in air is low at high altitude
  • People who live at high altitude have more red blood cells. This allows for more efficient delivery of oxygen
  • The haemoglobin of people who live at high altitudes is saturated more readily with oxygen than those of lower altitude
• At a high altitude, the dissociation curve shifts to the left. This means the affinity for oxygen is higher. This means it will be more effective to bind oxygen at lower partial pressures.
• What are some altitude adaptions?

  1. More red blood cells- more haemoglobin
  2. Haemoglobin has a greater affinity for oxygen
  3. Deeper breathing
  4. Faster heart rate
  5. More mitochrondria
  6. More myoglobin
• Tissue fluid is the liquid that leaves capillaries to bathe body cells to supply them with nutrients (glucose, amino acids etc) and oxygen and helps remove waste products such as CO2 and urea.
• urea comes from the breakdown of protein
• Tissue fluid is similar in composition to plasma except that it lacks red blood cells and

  has little if any proteins.
• Tissue fluid is hence formed at the arteriole end of capillaries and returns back into the bloodstream by osmosis, at the venule end of the capillaries.

  Any tissue fluid, which does not return by this means, passes into the open-ended lymphatic capillaries, and becomes known as lymph.
• Two factors govern whether or not tissue fluid enters or leaves capillaries. These are

  HYDROSTATIC PRESSURE and OSMOTIC PRESSURE.
• Hydrostatic pressure is due to the pressure of the blood generated by the contraction of the left ventricle. It tends to force tissue fluid out of the arteriole end of the capillary.
• Osmotic pressure is due to the presence of solutes in the plasma, particularly plasma proteins. These make the plasma a concentrated which will draw tissue fluid into the capillary.
• At the arteriole end of the capillary, the outward pressure due to hydrostatic pressure is greater than the inward pressure; hence tissue fluid is forced out of the capillary into the tissue bed.

  Making hydrostatic pressure to fall so that at the venular end, the osmotic pressure drawing tissue fluid in is more than hydrostatic pressure forcing it out. Hence the net movement of tissue fluid is

  back into the capillary.