Chapter 9 Grade 12 Biology PDF

9.1 - 9.3 - HOMEOSTASIS The maintenance of a constant internal environment despite changes in external environment Main homeostatic systems include blood pH, O2 / CO2, body temperature control, electrolytes / blood sugar, and blood pressure Homeostatic control systems have 3...

9.1 - 9.3 - HOMEOSTASIS The maintenance of a constant internal environment despite changes in external environment Main homeostatic systems include blood pH, O2 / CO2, body temperature control, electrolytes / blood sugar, and blood pressure Homeostatic control systems have 3 main components that detect stress or change and ACT to maintain equilibrium 1. Monitor system (receptors) -> sends signals thru sensory pathways 2. Coordinating center (brain) -> processes info and sends signals to motor pathways to address balance 3. Regulator system (muscles, glands…) -> carries out the actions with hormone levels, temperature adjustments, etc This all works thru feedback pathways - organs that communicate w each other to detect + respond to changes in the body and maintain stability NEGATIVE FEEDBACK The most common - reverses / counteracts change / opposes deviation Ex; if temp in body rises above normal, negative feedback is triggered Sweating to lower temp POSITIVE FEEDBACK Increases change and is less common Used for definitive outcomes, like childbirth Oxytocin is secreted to increase contractions until baby is delivered THERMOREGULATION A process where the body maintains stable internal temp Hypothalamus; gland in the brain that acts as a thermostat. It monitors body temp and triggered response if its too high / low It will activate effectors and hormones to communicate with organs and other systems Humans have a normal range of temp ; 36.2 - 37.2 degrees celsius  ABOVE; hyperthermia ~ due to infection (high fever) ~ can lead to heat stroke and organ damage BELOW; hypothermia ~ can lead to slow cellular processing, cell death, and organ failure… FATAL. HOW THE BODY REGULATES TEMP. IN HEAT STRESS 1. Detection of heat stress / MONITOR PHASE - Thermoreceptors in peripheral nervous system detect inc. in body temp - peripheral nervous system is outside the brain and spinal cord - Thermoreceptors send a signal to the brain via sensory neurons - Sensory neurons communicate w central nervous system (the brain and spinal cord) 2. Coordination of response / COORDINATION - Hypothalamus processes the info as its responsible for maintaining homeostasis - It sends signals thru motor neurons to activate cooling mechanisms 3. REGULATION - Sweating; hypothalamus signals for sweat glands to produce sweat - As sweat evaporates, it creates a cooling effect - taking heat away from the body - Vasodilation; blood vessels in skin dilate, which allows blood to flow near the skins surface and help release heat from blood - This cools it down before it returns to the bodys core - Cooling internal systems; as cooled blood returns to core, it helps cool down internal organs and keep them at a safe temp - Once the body is normal again, hypothalamus signals for the cooling mechanisms to stop - This process ensures that the body stays at a stable internal temp despite external heat. HOW THE BODY REGULATES TEMP. IN THE COLD 1. Detection of cold / MONITOR  - Thermoreceptors in skin detect a temp drop and send signals to hypothalamus using sensory neurons 2. Coordination of Response / coordination - Hypothalamus processes the info and turns the bodys’ warming systems on to send messages thru motor neurons and activate a response 3. REGULATION - Vasoconstriction; blood vessels constrict to reduce blood flow to skin and minimize heat loss to environment - shivering; muscle cells contract and cause heat to generate thru rapid muscle movement - goosebumps; smooth muscles around hair follicles cause the hair to stand up and give an insulating layer of air close to skin, however this is a vestigial feature A homeotherm is an Organism that maintains a relatively stable internal body temperature, regardless of external conditions A poikilotherm is an organism with a body temperature that varies significantly with environmental conditions. An endotherm is an Organism that generates heat internally through metabolic processes to maintain a constant body temperature. An ectotherm is an Organism that relies on external heat sources to regulate their body temperature 9.4 - WATER BALANCE Organisms must maintain constant volume, solute content, and temp OSMOSIS; water moving from low solute concentration to high solute concentration HYPOOSMOTIC; A solution is hypoosmotic when it has a lower concentration of solutes and a higher concentration of water ISOSMOTIC; A solution is isosmotic when it has the same concentration of solutes (and therefore the same osmotic pressure) as another solution.  HYPEROSMOTIC; A solution is hyperosmotic when it has a higher concentration of solutes and lower water concentration compared to another solution Osmolarity measures total solute in a concentration and applies to all solutes. Its measured in osmoles / L Tonicity measures the impact of a solution on cell volume. It only applies to non penetrating solutions and aims to predict movement in and out of the cell. Its descriptive (hypertonic / hypotonic) Osmotic pressure; pressure needed to stop flow of water through a membrane due to osmosis It occurs when water moves from an area with less solute (more water) to an area with more solute (less water). The more solute in a solution, the higher the osmotic pressure. Hydrostatic Pressure is the pressure exerted by a fluid (like water) due to its weight. It increases with the depth of the fluid and acts in all directions within the fluid. In plants; turgor pressure. In people; blood pressure NITROGENOUS WASTE - Fish and amphibians… -> waste is ammonia (NH3) and requires a LARGE amount of water to eliminate - Mammals -> waste is urea (NH2CONH2) and requires a moderate amt of water - Birds / insects / reptiles -> waste is uric acid (c5h4n4o3) and requires very little water - its not toxic so it can be excreted as paste 9.5 I - Functions of The Excretory System Excretion is a process where your body gets rid of waste products it doesnt need Your body must eliminate waste to remain healthy The digestive , respiratory , skin, and urinary system work together as your excretory system It removes extra water, urea, carbon dioxide… from blood and helps regulate water level in your body KIDNEYS; filter out water and urea  LUNGS; filter out CO2 from blood SKIN; excretes sweat, which contains urea The Liver Breaks down toxins (alcohol) for kidneys to excrete When proteins are metabolized, they produce ammonia, which is toxic! The liver converts it to urea, which is less toxic and can be safely removed Waste is processed in the liver, prior to kidneys, then it's sent to bloodstream Detoxifies the blood - without it, harmful substances would accumulate Nitrogenous waste Proteins and amino acids are broken down and contain ammonia - HIGHLY TOXIC Liver converts it to urea When dna / rna (nucleic acids) are broken down, it produces uric acid, which is also broken in liver and excreted in the kidney Urea is the main waste product tho Urinary System Removes urea and waste from blood Waste was produced by cells in metabolism Kidneys regulate blood volume by removing water and salt and keep the fluid / salt balance in check Without it, toxic substances would build up in blood and there would be a salt / water imbalance Kidneys Filter waste from blood, clean blood, and produce urine Ureters Tubes that carry urine from kidney to the urinary bladder There is one ureter for each kidney Urinary bladder Stores urine until its ready to be excreted Stretchy sac that can hold a lot of urine Urethra Small tube that carries urine from bladder to outside body Last part of urinary system Regulation of Fluid levels Hypothalamus constantly keeps track of how much water is in your blood hormone called Antidiuretic hormone (adh) is released and signals kidneys to retain / release water Too little water in your body; Adh is released and signals kidneys to RETAIN / send back water to blood stream (DARK YELLOW PEE) Too much water in your body; less adh is released, kidneys excrete more water as urine (LIGHT YELLOW PEE) Overview of the system… 1. Blood enters kidneys thru renal artery, carrying dirty blood 2. Blood enters the nephrons and start the cleaning process 3. Blood enters the bowman's capsule, water, sugar, salt are filtered thru 4. Capillaries reabsorb water, sugar, salt into blood stream 5. Renal vein carries purified blood back into the body to be recirculated 6. Urine is left over and drained into funnel area of kidney 7. Goes from ureters -> urinary bladder -> urethra -> done! The nephron is in the kidney, it's around one million tiny filtering systems in the kidney 9.5 II - Functions of The Excretory System SIX PARTS OF THE NEPHRON 1. Bowman's capsule; surrounds glomerulus and collects filtered substances from the blood 2. Glomerulus; dense network of capillaries inside bowman's capsule. It filtered blood and allows water and waste to pass thru the nephron 3. Proximal Convoluted tubule; first twisty tube, reabsorbs filtrate water back into blood 4. Loop of Henle; reabsorbs water and salt 5. Distal Convoluted tubule; second twisty tube, secretes ions and reabsorbs salt / water 6. Cortical collecting duct; final site for water absorption and urine concentration FORMATION OF URINE OVERVIEW - Nephric filtrate (leftover of blood; water, salt urea) enters the bowman's capsule, then - PCT; glucose, amino acids and water are reabsorbed - Loop of Henle; water and salt are reabsorbed - DCT; more reabsorbing and secretion of waste (ions) - Collecting Duct; ADH is released - Renal Pelvis; -> ureters -> out!! 1. FILTRATION - Blood pressure pushes water, urea, salt etc from the glomerulus into the lumen of the bowman's capsule - Plasma proteins, blood cells, and platelets do not enter as they are too large for the capillary walls 2. REABSORPTION - Essential materials from the filtrate are returned to blood - Ex; glucose, amino acids, salt and water - Mainly the PCT, loop of Henle, DCT - Peritubular capillaries in nephron do the reabsorbing - Very important bc it allows the body to conserve water and nutrients and eliminate waste - Without it, we’d have to consume a litre of water every 10 mins to maintain homeostasis - The filtrate is 4x more concentrated with urea and waste by the end bc its NOT ABSORBED - DESCENDING LOOP OF HENLE; passive transport - filtrate is more concentrated with salt because water is removed. Also increase in osmotic pressure - ASCENDING LOOP OF HENLE; active transport, sodium and chlorine is reabsorbed. The filtrate is less concentrated w salt because it's pumped out. 3. SECRETION - Nitrogenous waste , H+, K+ are moved from the blood to nephron  - Helps balance out pH of blood - Mainly the PCT and DCT - A very selective process using active transport 4. EXCRETION - Filtrate reaches collecting ducts and fill with urea - Was not absorbed, but water and essential solutes were - When urine reaches the bottom of ducts, it goes to renal pelvis - Then to urinary bladder until it's ready to be excreted HOW ARE KIDNEY STONES DIAGNOSED? Urinalysis; a common test used to diagnose kidney stones Test a urine sample for high protein, blood in urine, high glucose, and pH Diabetes mellitus; chronic condition where body has issues regulating blood sugar due to issues w insulin, a hormone that regulates blood sugar Type 1 diabetes; body doesnt make insulin Type 2 diabetes; body doesnt respond well to insulin With time, high blood sugar can damage blood vessels, leading to diabetic nephropathy (damage to nephrons) Leads to kidneys not filtering waste properly = protein leakage and fluid retention Leads to kidney failure - requiring kidney transplant / dialysis Kidney stones; hard deposits of minerals / salts that form in the kidney Vary in size / shape = pain when blocking urinary passages Block urine flow and swell the kidneys (HYDRONEPHROSIS) Damage the renal tubules, infection and kidney failure The kidneys filter minerals, waste and fluid When calcium, oxalate, and uric acid are too concentrated, it can form stones