Chapter 16 - Homeostasis Flashcards
Homeostasis
The body’s ability to maintain stable internal conditions.
Diabetes mellitus
Condition of uncontrolled blood glucose concentration.
Type I diabetes
Autoimmune destruction of insulin-producing beta cells.
Hyperglycaemia
Elevated blood glucose levels after eating.
Hypoglycaemia
Dangerously low blood glucose levels.
Insulin therapy
Treatment involving regular insulin injections.
Type II diabetes
Insulin resistance or insufficient insulin production.
Obesity
Excess body weight linked to Type II diabetes.
Colorimetry
Technique to measure glucose concentration in solutions.
Benedict’s reagent
Chemical used to test for glucose presence.
Calibration curve
Graph correlating absorbance with glucose concentration.
Serial dilution
Method to create solutions of decreasing concentration.
Glucose tolerance test
Test to assess body’s glucose handling ability.
Absorbance
Measurement of light absorbed by a solution.
Islets of Langerhans
Pancreatic cells that produce insulin.
Insulin receptors
Cell membrane proteins that bind insulin.
Dietary recommendations
Guidelines for healthy eating to prevent diabetes.
Glucose concentration
Normal level around 90 mg per 100 cm³ blood.
Health problems
Complications from uncontrolled diabetes, like kidney failure.
Exercise
Activity that lowers blood glucose levels post-meal.
Artificial sweeteners
Sugar substitutes potentially linked to weight gain.
NHS Change4Life
Campaign promoting healthier lifestyles to reduce diabetes.
Viral infection
Possible trigger for Type I diabetes onset.
Glucose-lowering medication
Drugs to help manage Type II diabetes.
Blood glucose monitoring
Regular checks to maintain glucose levels.
Dietary fiber
Component of whole grains aiding glucose control.
Nutritional labeling
Information on food packaging for healthier choices.
Junk food advertising
Promotion of unhealthy foods, especially to children.
Kidney failure
Severe complication of uncontrolled diabetes affecting kidneys.
Blood Glucose Concentration
Amount of glucose in the bloodstream.
Insulin
Hormone that lowers blood glucose levels.
Glucagon
Hormone that raises blood glucose levels.
Beta Cells
Pancreatic cells that secrete insulin.
Alpha Cells
Pancreatic cells that secrete glucagon.
Glycogenesis
Formation of glycogen from glucose.
Glycogenolysis
Breakdown of glycogen into glucose.
Gluconeogenesis
Formation of glucose from non-carbohydrates.
Hepatocytes
Liver cells that regulate glucose levels.
GLUT4
Glucose transporter in muscle cells.
Second Messenger
Intracellular signal activated by hormones.
Cyclic AMP (cAMP)
Second messenger activating protein kinase A.
Negative Feedback Mechanism
Process that maintains stable blood glucose levels.
Adrenaline
Hormone that increases blood glucose during stress.
Protein Kinase A
Enzyme activated by cAMP for glycogenolysis.
Enzyme Activity
Rate of biochemical reactions in cells.
Optimum Temperature
Temperature for maximum enzyme activity, ~37°C.
Optimum pH
pH for maximum enzyme activity, usually ~7.
Respiration
Process of converting glucose into energy.
Channel Proteins
Proteins that facilitate glucose transport across membranes.
Energy Source
Stored glycogen used for cellular energy.
Hormonal Response
Slower response than nervous impulses.
Blood pH
Acidity or alkalinity of blood affecting enzymes.
Water Potential
Likelihood of water molecules diffusing in/out.
Metabolic Reactions
Chemical processes maintaining life in cells.
Stress Response
Physiological changes triggered by stress.
Osmosis
Water movement across a semi-permeable membrane.
Homeostatic Systems
Involve receptors, communication, and effectors.
Receptors
Detect high or low levels in the body.
Effectors
Respond to restore normal levels.
Body Temperature Regulation
Maintained within 0.5 °C of 37 °C.
Multiple Negative Feedback Mechanisms
Provide greater control over internal changes.
Positive Feedback Mechanism
Amplifies changes away from normal levels.
Hypothermia
Low body temperature below 35 °C.
Ultrafiltration
Filtering substances from blood in kidneys.
Selective Reabsorption
Reabsorbing useful substances back into blood.
Nephrons
Functional units of the kidneys.
Proximal Convoluted Tubule (PCT)
Site for active transport of glucose.
Loop of Henle
Part of nephron involved in water reabsorption.
Distal Convoluted Tubule (DCT)
Final site for selective reabsorption.
Microvilli
Increase surface area for reabsorption in PCT.
Osmosis in Kidneys
Water moves from filtrate to blood.
Urine Composition
Contains water, urea, salts, hormones.
Renal Artery
Supplies blood to the kidneys.
Glomerular Filtrate
Fluid filtered from blood in kidneys.
Capillary Network
Surrounds nephron tubules for reabsorption.
Blood Clotting
Positive feedback mechanism for injury response.
Negative Feedback Example
Body temperature regulation during heat.
Positive Feedback Example
Amplification during blood clot formation.
Kidney Functions
Excrete waste and regulate water potential.
Urine Formation
Process of filtering and reabsorbing substances.
Efferent Arteriole
Carries blood away from glomerulus.
Afferent Arteriole
Brings blood into the glomerulus.
Arterioles
Small blood vessels branching from arteries.
Glomerulus
Capillary bundle within Bowman’s capsule.
Bowman’s capsule
Hollow structure surrounding the glomerulus.
Efferent arteriole
Carries filtered blood away from glomerulus.
High pressure
Caused by smaller diameter of efferent arteriole.
Glomerular filtrate
Liquid and small molecules entering Bowman’s capsule.
Nephron
Functional unit of the kidney.
Reabsorption
Process of reclaiming useful substances from filtrate.
Collecting duct
Final part of nephron where urine collects.
Osmoregulation
Regulation of water potential in blood.
Water potential
Measure of water concentration in blood.
Descending limb
Part of Loop of Henle permeable to water.
Ascending limb
Part of Loop of Henle impermeable to water.
Sodium ions
Ions actively transported to create osmotic gradient.
ADH
Hormone regulating water reabsorption in kidneys.
Osmoreceptors
Cells detecting blood water potential changes.
Hypothalamus
Brain region regulating thirst and ADH release.
Concentrated urine
Produced when more water is reabsorbed.
Dilute urine
Produced when less water is reabsorbed.
GFR
Glomerular filtration rate, typically 6300 cm³/hour.
Reabsorption rate
Calculated based on glucose concentration and GFR.
Basement membrane
Layer filtering larger molecules in kidneys.
Collecting duct permeability
Controlled by ADH to regulate water reabsorption.
Filtrate concentration
Increases as water is reabsorbed in nephron.
Medulla
Inner kidney layer where Loop of Henle is located.
Capillary network
Surrounds nephron for substance exchange.
