Maintaining a Balance Topic 8: Chemical Substances and How They are Transported Biology in Focus, HSC Course Glenda Childrawi, Margaret Robson and Stephanie Hollis

DOT POINT identify the form(s) in which each of the following is carried in mammalian blood: carbon dioxide oxygen water salts lipids nitrogenous waste other products of digestion

Introduction To maintain homeostasis, chemicals being transported in the blood must also be maintained at a particular concentration and carried in a specific form that will not affect the balance in the internal environment of the body. vascularbodybuildingmuscle.blogspot.com

Introduction If the normal balance of substances in the blood is altered, conditions such as ‘low blood sugar levels’ or ‘high blood pressure’ will arise. This brings on unpleasant and sometimes dangerous side effects. Its an indication that metabolic functioning has been compromised. Homeostasis relies on maintaining a balance of chemicals within the blood. cosmosmagazine.com

Hand Out DOT Point 2.1 Fill in the chart as we go through the rest of today’s presentation.

Blood Gases All living cells in the body require oxygen and produce carbon dioxide. Oxygen is required for the process of cellular respiration and carbon dioxide is produced as a waste product. These gases are carries in particular forms within the plasma or red blood cells of blood, so that the pH and fluid concentrations remain stable. bwlibys.blogspot.com

Oxygen Transport When oxygen diffuses (high concentration to low concentration) across the respiratory surface of the lung into the blood, most of it (98.5%) combines reversibly with haemoglobin inside red blood cells. The remaining 1.5% may travel dissolved in the plasma. hyperphysics.phy-astr.gsu.edu

Oxygen Transport Red blood cells are ideally adapted to carrying oxygen. They don’t have a nucleus which results in plenty of space for haemoglobin. Haemoglobin has an affinity for (its chemically attracted to) oxygen. Each red blood cell contains approximately 250 million molecules of haemoglobin, resulting in a very high oxygen carrying capacity. beltina.org

Oxygen Transport The slightly flattened biconcave shape of red blood cells gives them a larger surface area to volume ratio for easy diffusion of oxygen across the surface. exchange3d.com

Oxygen Transport When blood in the lungs comes into contact with oxygen that has entered the body by diffusion, haemoglobin in the red blood cells binds with this oxygen, forming a compound called oxyhaemoglobin. This compound gives a bright red colour to blood. gassama.myweb.uga.edu

Oxygen Transport Most arteries carry bright red oxygenated blood, whereas most venous blood is a dark red colour. Veins beneath the skin may appear blue, but this is a combination of the dark red deoxygenated blood within the white-yellow vessel wall. gurneyjourney.blogspot.com

Carbon Dioxide Transport When carbon dioxide enters the blood, most (70%) of it is transported in the form of hydrogen carbonate ions. This is formed in the red blood cells but is carried in the plasma. The remaining carbon dioxide is carried either dissolved in the plasma (7%) or is carried combined with haemoglobin (23%). rsc.org

Carbon Dioxide Transport Since carbon dioxide mixed with water forms carbonic acid, it is not ideal for all of the carbon dioxide to dissolve in the plasma, since this would affect the pH of blood. Instead, a large portion of the carbon dioxide enters the red blood cells. Once there one of two things happen. middleschoolchemistry.com

Carbon Dioxide Transport 1. Most of the carbon dioxide mixes with water in the cytoplasm within the blood cells and forms carbonic acid. This is rapidly converted to hydrogen carbonate ions (bicarbonate ions). These ions then move out of the red blood cells into the blood plasma and 70% of carbon dioxide is transported in this form. This can be summarised as: Carbon dioxide + water → carbonic acid → hydrogen carbonate + buffered hydrogen ions CO₂ + H₂O → HCO → H₂CO₃⁻ + H⁺ extraordinarylight.blogspot.com

Carbon Dioxide Transport 2. Some carbon dioxide binds to haemoglobin, forming carbaminohaemoglobin. Haemoglobin does not bind to carbon dioxide in the same way that it binds to oxygen. Oxygen binds to the iron atom of haemoglobin, whereas carbon dioxide binds to the amino group of the protein part-the globin molecule, forming carbaminohaemoglobin. bioc208.blogspot.com

Carbon Dioxide Transport As with oxygen, this is a reversible reaction and many carbon dioxide molecules can combine with a single haemoglobin molecule. Only 23% of carbon dioxide is carried in this form. chemistry.wustl.edu

Water and Salt Water is the medium of transport of all substances in the body. It forms the basis of the cytoplasm in all cells, the interstitial fluid (tissue fluids) surrounding the cells and blood and lymph. learner.org

Water and Salt About 90% of blood plasma is water. The other 10% is made up mostly of various kinds of protein molecules as well as other substances including hormones, vitamins, end products of digestion and salts. paduiblog.com

Water and Salt Salts are carried in blood as ions (charged particles) dissolved in the plasma. For example, the salt sodium chloride (NaCl) is carried as positively charged sodium ions (Na⁺) and negatively charged chloride ions (Cl⁻) in solution of the watery medium of the plasma. chem4kids.com

Water and Salt Substances (such as salts) that become ions in solution are often referred to as electrolytes, because their capacity to conduct electricity. The balance of the electrolytes in our bodies is essential for normal function of our cells and our organs. Common electrolytes include sodium, potassium, chloride and bicarbonate. health.howstuffworks.com

Lipids and Other Products of Digestion The aim of digestion is to break large molecules down to a size small enough for absorption through the intestine wall and into the bloodstream, so that they can be transported to cells in the body where they are required. kvhs.nbed.nb.ca

Lipids and Other Products of Digestion The digestion of large organic molecules to their smaller end products is summarised below: Carbohydrates → glucose (simple sugars) Proteins → amino acids Lipids (fats and oils) → fatty acids and glycerol Nucleic Acids → nucleotides extraordinarylight.blogspot.com

Lipids and Other Products of Digestion Glucose and amino acids are water soluble and so they are transported in the bloodstream dissolved in the plasma, along with other soluble substances such as nitrogen bases, vitamins and glycerol, absorbed from the digestive tract. middleschoolchemistry.com

Lipids and Other Products of Digestion Lipids pose a problem in terms of transport, since they are insoluble in water and therefore cannot be carried dissolved in plasma. They need to be packaged into small droplets (micelles), which pass into the lymphatic system and then into the bloodstream. chm.bris.ac.uk

Nitrogen Wastes Nitrogenous wastes are harmful substances produced in the body as a result of the breakdown of proteins. These substances need to be transported in a diluted form, from cells where they are produced to the excretory organs where they can be eliminated from the body. Such wastes in the form of ammonia, urea, uric acid and creatinine are all carried dissolved in blood plasma. baxter.com

Activity/Homework -NIL!! Enjoy!