Homeostasis and Transport Processes PDF

Review Bart Simpson is on holiday in the North Pole, and gets very, very cold. Explain how Barts integumentary system works to maintain his body temperature. Back home Bart goes out skateboarding and gets VERY hot from all his exercising. Explain how the integumentary system works to...

Review Bart Simpson is on holiday in the North Pole, and gets very, very cold. Explain how Barts integumentary system works to maintain his body temperature. Back home Bart goes out skateboarding and gets VERY hot from all his exercising. Explain how the integumentary system works to return Barts body temperature to normal. Module 3 Environment of the Human Body Homeostasis Homeostasis Is the ability of the human body to maintain relatively stable internal conditions in spite of changes in the environment Control Systems The Nervous System Communicates via electrical impulses The Endocrine System Communicates via chemical messengers Components of a Control System a stimulus produces a change & stimulates the control system a receptor that detects the stimulus a control centre that determines the response an effector that produces a change to influence that stimulus  Consider a trip to the airport You forget to take your cell phone out of your pocket as you go through the security gate. Next minute the alarm goes off and a customs agent comes over to investigate. Identify the receptor, the control centre and the effector in this example. What was the stimulus? Components of a Control System Pg. 9 A bimetallic strip is composed of iron and aluminum. The different metals will expand and contract at different rates due to their different molecular properties. Thus, when held above a Bunsen burner the strip will bend accordingly. Bimetallic strips are used in heaters, fire alarms, toasters, irons and other electrical equipment that needs to be turned on and off. Example (p10) Control Mechanisms Negative feedback Positive feedback mechanisms mechanisms response is in the response is in the same opposite direction to direction as the original the original change change i.e. negative feedback i.e. positive feedback works to slow the works to enhance the original stimulus original stimulus e.g. control of body e.g. blood clotting temperature Negative Feedback Mechanism Pg. 633 green, and 621 brown Jack Dog or Hog? Positive Feedback Mechanism Pg. 11  Labour When a contraction occurs, the hormone oxytocin causes a nerve stimulus, causing the hypothalamus to produce more oxytocin, which increases uterine contractions. This results in contractions increasing in size and frequency. These contractions stop, when the baby is out of the mothers body. Homeostatic Imbalance When the normal homeostatic balance of the body is not able to be maintained, the result may be disease Marge Simpson decides to go on a dairy free diet. Thus, her intake of Calcium is low. Explain how Marge’s body works to maintain her blood calcium levels. When normal homeostatic balance is not maintained, disease may result. Describe what disease or condition Marge might suffer from in the long term.  Acids and Bases - a quick overview. You need to follow this up by completing the online session. Fluids and Fluid Transport Processes In your nursing career, there will be times when things do NOT go according to plan. In nursing we are dealing with people – staff, patients, visitors with many demands. Situations will arise that stuff up even the best laid plans! For example, lets say you need to administer 1000ml of an intravenous solution to a patient over 10 hours. What sorts of things Blockages or kinks in the tubes Poor communication during change-overs could go wrong? Inadequate supervision Forgetting to set the drip factor correctly Needle in the wrong place Infection sets in once the skin is punctured A hole in the bag or in the tubes  Wouldn’t it be really, really tempting, when you realise that the IV wasn’t working and that half the correct quantity had to be administered over the next two hours, just to open the controls and let all the solutions flow out as fast as possible? What does the solution contain? What effects will the solutions have on the body and the patients health? Could such an action such as this cause too rapid a change, and the body wont be able to handle it? What if we overload the patient with fluid, with negative results? Lets look at the effects of fluids and their movements in and around cells – then judge for yourself! http://www.youtube.com/watch?v=XclGRjnilsk&feature=fvsr  Solutions Solution: mixture of 2 or more substances (solutes) Solute: substance dissolved in a solution Solvent: what the solutes are being dissolved in (i.e. usually H2O) Saturated Solution: solvent can dissolve all solutes at certain temperatures I.e. before the solution reaches the required temperature, the solutes will remain un- dissolved  Solutions Unsaturated Solution: solution that hasn’t reached its saturation point (the point at which the solute can be dissolved) Supersaturated Solutions: all solutes not able to be dissolved (it contains more solutes that a saturated solution) Solution contains more solutes (salts) than the solvent can dissolve, thus deposits are formed from the solution E.g. kidney stones: kidneys excrete excessive amounts of stone-forming substance (e.g. uric acid) These crystallise and form stones that can block urinary tract  Solutions Cont. Colloidal Solutions: solutes join to form large molecules (non-diffusible) E.g. cytosol, cerebrospinal fluid & blood These solutions appear cloudy, and cannot pass through plasma membranes because of their larger sizes. (think about the role of the kidney – the blood cells stay in the blood vessels)  Mole: molecular weight (MW) of a substance measured in grams (the number of particles in a solution) Molarity: a way to express the concentration of a solution e.g. moles per litre of solution Molar Solution: MW of a substance in 1L of solution E.g. a molar solution of sodium chloride contains 58.5g of sodium chloride in 1L of solution pH scale expressed in moles/L i.e. represents no° of H + ions in 1L of blood Think-Pair-Share 1 2 3 5 4 Plasma Membrane - Review The plasma membrane separates the cell and its contents from the surrounding extra-cellular (interstitial) fluid Composed of phospholipids, cholesterol & proteins It is a selectively (differentially) permeable membrane (it allows some substances into the cell and keeps others out)  Transport Processes in Cells Passive processes - no energy input from cells e.g. diffusion, facilitated diffusion, osmosis, filtration Active processes - cells provide energy e.g. sodium-potassium pump (Na+ / K+ Pump) Diffusion Simple diffusion - molecules move randomly from an area of high solute concentration to an area of low solute concentration. Down the concentration gradient ***animation*** The rate of diffusion depends on size of molecules, concentration, temperature, surface area, pressure and electrical gradients Because the plasma membrane is lipid-based, only lipid-soluble or very small molecules can diffuse through it Diffusion A patients blood is pumped through a dialysis machine. This has a semi- permeable membrane that separates the blood from the clean dialysis fluid. Urea and other small solutes diffuse into the dialysis fluid. Blood cells and other large molecules stay within the membrane. Facilitated Diffusion Allows passage of molecules that can’t pass by simple diffusion Channels: Allow lipid-insoluble substances to pass through the membrane may be selective – dependent of size of substances & on electrical charge of amino acids lining channel may be controlled – channels contain gates that open & close in relation to chemical or electrical changes Leakage Channels: Always open so allow constant flow of ions & water in accordance with concentration gradient Facilitated Diffusion Cont. Carriers: Transport molecules that are too large or that are not recognised by the channel across the membrane Proteins change shape to engulf waiting substance, carry through the channel then release on other side E.g. glucose and amino acids ***animation*** Substances move down their concentration gradient Simple & Facilitated Diffusion  Glucose needs a large enough channel to go through. Glucose only goes part of the way. The glucose binds to a receptor in the channel. The channel changes shape and then the glucose can get released. Then what? Share with your neighbour the remaining steps in Carbohydrate metabolism You should have used the following terms: facilitated diffusion, glucose-6-phosphate, complex series of reactions, mitochondria, oxygen, ATP, carbon dioxide, water  Osmosis The movement of a solvent (water) from an area of high water (low solute) concentration to an area of low water (high solute) concentration through a selectively permeable membrane down the concentration gradient i.e. water moves because solutes can’t In the human body, osmosis is very important in determining the movement of water in and out of cells Osmosis Cont. Occurs whenever the water concentration differs on either side of the membrane If the solute concentration differs on either side of the membrane, so does water conc. Solute conc. increases = water conc. decreases The extent to which water’s conc. decreases depends on the number of solutes in a solution Osmolarity: total conc. of all solute particles in a solution Osmosis Cont. When equal volumes of solutions are separated by a fully permeable membrane both water & solutes will move down their concentration gradients This will continue until the concentrations are the same on both sides of the membrane  Osmosis Cont. If the same solutions were separated by a membrane that is impermeable to solutes, only water can move by osmosis Osmosis will continue until its conc. is the same on either side of the membrane The volume of water on either side of the membrane will differ *** animation*** Osmosis Cont.  Salt sucks Hydrostatic & Osmotic Pressure Hydrostatic Pressure: pressure produced by fluid against a wall e.g pushing fluid out of a capillary Osmotic Pressure: cell’s resistance to further water entry – this is the pressure need to STOP more fluid flowing inwards Osmosis occurs until both HP and OP are equal Osmotic imbalances cause animal cells to shrink or swell depending on water loss or gain Cells are closed containers. Adding volume will increase the pressure. Volume and pressure of cells remains constant (homeostasis) because the fluid on the outside of the cells, is the same on the inside of the cells (isotonic – is the same pressure)  Mannitol An intravenous solution used in clinical settings is an alcohol. As the mannitol enters the blood it has MORE solutes so it increases the osmolarity of the fluid outside the cells. Where will the water go? Water moves out of the cells and into the fluid outside the cells. This is very useful in cases like cerebral odema. Not good for someone with congestive heart failure because the extra fluid will cause blood pressure to rise, and put extra strain on the heart.  Filtration Process that forces water and solutes through a membrane caused by fluid (hydrostatic) pressure Relies on a pressure gradient Filtrate moves from an area of high pressure to an area of low pressure E.g. hydrostatic pressure exerted by the blood forces fluid out of capillaries e.g. lymph and nephrons Non-selective, passive process Tonicity Tonicity describes the ability of a solution to change the shape or tone of a cell An isotonic solution contains the same number of solutes as in the cells = no change in cell shape A hypertonic solution contains more solutes than in the cells = cells will shrink A hypotonic solution contains less solutes than in cells = cells will swell  Tonicity Hypotonic – cell will swell Isotonic – no shape Hypertonic – cell will shrink Increase in volume as water change moves into the cell. The cell Shape is maintained as Lose volume and shrink as swells and may burst. there is constant volume volume and pressure decrease as and pressure. The osmotic water moves out. The spikes are pressure inside and outside microtubules of the cytoskeleton What might the consequences of the cell are the same. that become visible as the cell this be? deflates. Hypertonic dehydration Body water is lost much faster than electrolytes e.g. Diarrhoea This causes cells to become HYPERTONIC The blood thickens, blood pressure decreases, circulation is sluggish. This can lead to heart failure and death. Isotonic dehydration Sometimes when there is excessive haemorrhaging or fluid loss from burns can mean the loss of not only electrolytes but also fluid. Because both are lost, this kind of dehydration is not always noticeable. The body usually restores itself by homeostasis. If not blood pressure will drop and death can occur. Hypotonic dehydration Vomiting and diarrhoea causes loss of electrolytes (gastric juice in the stomach is made of hydrogen and choride ions). Water will move into cells as the osmolarity decreases in the fluid outside of the cells. This will cause water to move into the cells and the cells will swell. This is a problem in the brain where space is limited by the cranium.  At the beginning of the session…. You were asked to consider the effects of fluids and their movements. Hopefully you can now see the overwhelming importance of body fluids, as the welfare and life of your patients depends on you understanding these processes.  Active Transport  Active Transport Requires energy (ATP) to drive a pump to move solutes against a concentration gradient Solutes move from an area of low solute concentration to an area of high solute concentration E.g. Na+/ K+ pump http://www.youtube.com/watch?v=_bmp2_T0c7k Na+ / K+ Pump Pg. 76 Muscle cells pump all the calcium ions out of the cell. This is important or the muscle cell cannot function. Muscle fibres can’t work unless the calcium concentration is LOW when they are resting. Thus, the muscle cells actively pump the calcium out of the cell into the surrounding space. The muscle will contract as the calcium ions flow back in. This pump is essential for all cell survival. By transporting sodium out, and potassium in, means that the sodium concentration is LOWER on the inside. This maintains the electrochemical gradient that cells need. Other types of active transport are phagocytosis, and endocytosis – this is where the membrane pinches off to trap proteins etc. Exocytosis occurs to release products e.g. endocrine glands release hormones.