Homeostasis: Biology Notes PDF

CHAPTER 5 H O M E O S TA S I S  CORE TEMPERATURE Humans have a normal temperature of around 36.2 to 37.2 degrees Celsius Body temperature goes above normal temperature then likely suffering from an infection and your body had to raise its temperature to fight off...

CHAPTER 5 H O M E O S TA S I S  CORE TEMPERATURE Humans have a normal temperature of around 36.2 to 37.2 degrees Celsius Body temperature goes above normal temperature then likely suffering from an infection and your body had to raise its temperature to fight off the infection. If your body goes below this range it indicates hypothermia. Therefore if left untreated it could lead to cell damage and possibly death. Where Knowledge Is  WHAT IS HOMEOSTASIS? The body’s attempt to maintain “normal” levels within your body Homeostasis is often referred to as a dynamic equilibrium- which is a mechanism to ensure that all body systems function within an acceptable range to sustain life. Where Knowledge Is  KEY CONCEPT Homeostasis is the regulation and maintenance of the internal environment. Where Knowledge Is CONDITIONS WITHIN THE BODY MUST REMAIN WITHIN A NARROW RANGE. Homeostasis involves keeping the internal environment within set ranges. Where Knowledge Is  HOMEOSTATIC CONTROL SYSTEMS 3 components: – Monitor Monitor – Coordinating centre – Regulator Monitor sends a signal to the Change Coordinatin in coordinating centre that the normal balance g centre levels have changed. The coordinating centre then messages the regulator which helps restore normal balance. Normal Regulat balance or Where Knowledge Is  HOMEOSTASIS EXAMPLE: HOUSEHOLD THERMOSTAT Room temperature is set to 22 degrees Celsius. When the temperature falls below the “normal” temperature of 22 degrees, the thermostat recognizes change in “normal” temperature and switches on the furnace. When the thermometer detects a temperature above the “normal”, the thermostat switches off the furnace. http://gasfurnaceprices.co.cc/ Where Knowledge Is  HOMEOSTASIS EXAMPLE: HOUSEHOLD THERMOSTAT Monitor- Thermometer Detects decrease in temperature Coordinating centre- Furnace turns off Thermostat switches on furnace Thermostat detects Regulator- Furnace temperature increases over “normal” Whole control system is called a negative feedback system Where Knowledge Is  NEGATIVE FEEDBACK Process by which a mechanism is activated to restore conditions to their original state It ensures that small changes don’t become too large. Why is a thermostat a negative feedback system? Where Knowledge Is  pore Control systems help maintain homeostasis like... sweat A. Sensors = gather data glands senses B. Control Center= receives data, interprets info, sends messages out. hair follicle  brain muscle C. Communication System= delivers messages to target organs, tissues PNS (e.g. motor neurons) D. Targets = respond to change. goose muscles, glands (release bump hormones) Where Knowledge Is NEGATIVE FEEDBACK LOOPS ARE NECESSARY FOR HOMEOSTASIS. Feedback compares current conditions to the body’s comfort levels (=Set Ranges). Negative feedback counteracts change and brings the body back to homeostasis. Negative Holding breath, CO2 Feedback Loop levels rise, O2 / CO2 level returns to normal Control system forces exhale, inhale Where Knowledge Is  Positive feedback: increases change away from the set points. Needed for rapid change in the body. Ex. #1 = Torn blood vessels stimulates the release of clotting factors to stop blood flow. platelets blood vessel fibrin clot white blood cell red blood cell Ex. #2 = Delivery process and stimulation of mammary gland by oxytocin Where Knowledge Is Thermoregulation: The process of maintaining a steady body temperature under a variety of conditions. Systems Involved: 1. Muscular 2. Integument (skin) 3. Respiratory 4. Circulatory 5. Nervous (hypothalamus in brain) 6. Endocrine (hormones, feedback) Where Knowledge Is Where Knowledge Is Where Knowledge Is INSULIN & GLUCAGON - Purpose: Regulate blood glucose levels, ensuring energy supply and metabolic balance. - 2 major player, insulin and glucagon INSULIN Insulin - Source: Produced by beta cells in the pancreas. - Function - Decrease Blood Glucose Levels: Facilitates glucose uptake into cells, particularly muscle and fat cells. - Promote Glycogenesis: Stimulates liver and muscle cells to convert glucose into glycogen for storage. - Inhibit Glycogenolysis: Prevents the breakdown of glycogen into glucose. - Facilitate Lipogenesis: Encourages fat storage by converting excess glucose into fatty acids. - Regulation - Increased Insulin Secretion: Triggered by high blood glucose levels (e.g., after a meal). - Feedback: Lowers blood glucose levels, reducing the stimulus for insulin secretion. GLUCAGON - Source: Produced by alpha cells in the pancreas. - Function - Increase Blood Glucose Levels: Stimulates the release of glucose from stored glycogen in the liver. - Promote Glycogenolysis: Activates the breakdown of glycogen into glucose. - Facilitate Gluconeogenesis: Stimulates the production of glucose from non-carbohydrate sources in the liver. - Inhibit Glycolysis: Reduces glucose utilization by cells. - Regulation - Increased Glucagon Secretion: Triggered by low blood glucose levels (e.g., between meals or during fasting). - Feedback: Raises blood glucose levels, reducing the stimulus for glucagon secretion. INTERACTION - Postprandial State (After Eating) - Insulin: Released to lower blood glucose by promoting glucose uptake and storage. - Glucagon: Low levels as blood glucose is high. - Fasting State - Insulin: Reduced secretion as blood glucose levels drop. - Glucagon: Increased secretion to release glucose from storage and stimulate glucose production. Where Knowledge Is  Causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle, and stopping use of fat as an energy source. When insulin is absent (or low), glucose is not taken up by body cells, and the body begins to use fat as an energy source, for example, by transfer of lipids from adipose tissue to the liver for mobilization as an energy source. As its level is a central metabolic control mechanism, its status is also used as a control signal to other body systems (such as amino acid uptake by body cells). In addition, it has several other anabolic effects throughout the body. Where Knowledge Is WATER AND ELECTROLYTE BALANCE Water Balance - Water Intake - Sources: Drinking fluids, food, and metabolic processes. - Water Loss - Pathways: Urine, sweat, breathing, and feces. - Kidney Regulation - Concentrated urine during dehydration. - Diluted urine when excess water is present. Homeostasis in Action - Excess Water Intake - Reduced ADH secretion. - Production of more diluted urine. - Dehydration - Increased ADH secretion. - Production of concentrated urine.  Renin and Angiotensin Where Knowledge Is Renin and Angiotensin KIDNEYS AND BLOOD PRESSURE REGULATION THE “RENIN-ANGIOTENSIN SYSTEM” 1. Low blood volume (ingestion of salt or low water intake), decreases blood pressure. 2. Decrease in extracellular pressure near distal convoluted tubule cause juxtaglomerular cells (in renal) to release the hormone RENIN. 3. RENIN in blood stream converts the liver enzyme ANGIOTENSINOGEN into ANGIOTENSIN I. 4. ANGIOTENSIN CONVERTING ENZYME (in the lung) converts Angiotensin I into ANGIOTENSIN II. 5. Angiotensin II causes ADRENAL GLAND to secrete/release ALDOSTERONE. 6. Aldosterone is a vasoconstrictor (increasing blood pressure) and INCREASES COLLECTING DUCT PERMEABILITY. 7. Urine volume decreased, fluid retained, blood volume increases, blood pressure up. Where Knowledge Is