Water Balance and Homeostasis in Plants and Humans

Water Balance

Equilibrium between water uptake and loss in plants.

Vascular Plants

Plants with specialized tissues for water transport.

Water Potential

Indicator of water movement direction between soil and roots.

Root Hairs

Epidermal cell outgrowths for water absorption.

Transpiration

Water vapor loss from leaves through stomata.

Stomata

Leaf openings regulating gas and water exchange.

Guard Cells

Cells controlling stomatal opening and closing.

Turgid Guard Cells

Open stomata, allowing water loss.

Flaccid Guard Cells

Closed stomata, preventing water loss.

Osmotic Adjustment

Regulation of water potential in plants.

Homeostasis

Maintenance of stable internal conditions in organisms.

Negative Feedback

Mechanism returning a variable to its set range.

Stimulus-Response Loop

Process detecting and responding to environmental changes.

Receptor

Sensor detecting changes in physiological variables.

Control Centre

Evaluates signals and determines necessary responses.

Effector

Carries out responses to counteract stimuli.

Positive Feedback

Amplifies a stimulus, moving away from set point.

Core Body Temperature

Regulated temperature range in mammals.

Hypothalamus

Brain region regulating body temperature and homeostasis.

Vasoconstriction

Narrowing of blood vessels to reduce heat loss.

Vasodilation

Widening of blood vessels to increase heat loss.

Thermoreceptors

Sensors detecting changes in body temperature.

Thyroid Hormones

T3 and T4 regulate metabolism and body temperature.

Sweating

Evaporative cooling mechanism to lower body temperature.

Heat Conservation

Mechanisms to reduce heat loss in cold conditions.

Acute Hypothermia

Rapid onset of low body temperature from extreme cold.

Exhaustion Hypothermia

Hypothermia due to exhaustion and inadequate food.

Shivering

Muscle contractions to generate heat in cold.

Vasoconstriction

Narrowing of blood vessels to conserve heat.

Convection

Heat loss due to moving colder air or water.

Conduction

Heat loss through direct contact with cooler substances.

Non-fever Hyperthermia

Heat increase without set point change, can cause heat stroke.

Fever Hyperthermia

Increased body temperature due to reset set point.

Radiation

Heat loss as infrared radiation without contact.

Evaporation

Heat loss through liquid to vapor conversion.

Alpha Cells

Pancreatic cells that produce glucagon hormone.

Beta Cells

Pancreatic cells that produce insulin hormone.

Islets of Langerhans

Endocrine structures in pancreas producing hormones.

Physiological Responses

Automatic body responses like sweating or shivering.

Behavioural Responses

Conscious actions like removing clothing for temperature control.

Piloerection

Hair standing response for insulation in cold.

Brown Adipose Tissue (BAT)

Specialized fat tissue for heat production.

Hypothalamus

Brain region regulating body temperature responses.

Motor Neurons

Nerve cells transmitting signals for muscle contractions.

Shivering

Increases metabolic rate, producing heat fivefold.

Basal Metabolic Rate

Minimum heat generated by metabolic processes.

Brown Adipose Tissue (BAT)

Breaks down fatty acids, releasing heat without ATP.

Hypothalamus

Regulates metabolic rate and temperature responses.

Thyrotropin-Releasing Hormone (TRH)

Stimulates release of thyroid-stimulating hormone (TSH).

Thyroid-Stimulating Hormone (TSH)

Activates thyroid gland to release T3 and T4.

T3 and T4

Hormones that increase metabolic rate and heat production.

ATP

Energy currency driving biological reactions in cells.

Gluconeogenesis

Production of glucose from non-carbohydrate precursors.

Insulin

Hormone that lowers blood glucose by enhancing uptake.

Glucagon

Hormone that raises blood glucose by stimulating glycogen breakdown.

Hyperglycemia

Condition of excessively high blood glucose levels.

Hypoglycemia

Condition of excessively low blood glucose levels.

Glycogen

Stored form of glucose in liver and muscle cells.

Fatty Acids

Alternative energy source for many body cells.

Sweat Evaporation

Cooling mechanism requiring heat energy from blood.

Energy Stores

Reserves of energy in muscle tissue for metabolism.

Capillary Beds

Networks of tiny blood vessels for heat exchange.

Metabolic Demand

Increased need for energy and heat production.

Blood Glucose Regulation

Homeostatic control of glucose levels by hormones.

Evaporation of sweat

Cooling mechanism using heat from blood vessels.

Water's role in the body

Essential for life; major body component.

Water loss channels

Mainly occurs through the kidneys.

Water gain sources

From food, drink, or metabolic processes.

Homeostatic regulation

Maintains water levels and solute concentrations.

Osmoreceptors

Detect changes in water balance.

Hypothalamus function

Regulates thirst and ADH release.

Antidiuretic hormone (ADH)

Increases water reabsorption in kidneys.

Thirst centers activation

Triggered by low water levels.

Type 1 diabetes

Autoimmune disease affecting insulin production.

Hyperglycemia

Elevated blood glucose levels.

Insulin treatment

Administered to reduce blood glucose levels.

Hypoglycemia

Low blood glucose levels, often from excess insulin.

Hyperthyroidism

Overactive thyroid increases metabolic rate.

Thyroid hormones

T3 and T4 produced by the thyroid.

Glucagon function

Increases blood glucose by liver stimulation.

Negative feedback mechanism

Maintains glucose levels between 4.0-6.0 mmol/L.

Post-meal glucose response

Glucose rises, insulin released, levels normalize.

Fasting glucose response

Glucose falls, glucagon released, levels normalize.

Water balance equation

Water intake + metabolic water - water loss = 0.

Causes of low water levels

Excessive loss, inadequate intake, abnormal fluid loss.

Effects of water imbalance

Can disrupt muscle, nerve function, and cause confusion.

Over-hydration

Excess water intake causing cellular swelling.

Water intoxication

Condition resulting from severe over-hydration.

Cerebral edema

Swelling of the brain due to excess water.

Osmoregulation

Process controlling body water and solute concentration.

Osmolality

Concentration of dissolved solutes in body fluids.

Sodium

Major solute in extracellular fluids affecting water balance.

Osmoreceptors

Cells detecting changes in blood osmolality.

Thirst response

Physiological urge to drink fluids when dehydrated.

Antidiuretic hormone (ADH)

Hormone regulating kidney water reabsorption.

Hypothalamus

Brain region controlling thirst and ADH release.

Posterior pituitary gland

Releases ADH into the bloodstream.

Collecting ducts

Kidney structures where water reabsorption occurs.

Dilute urine

Urine with low solute concentration, produced when hydrated.

Concentrated urine

Urine with high solute concentration, produced when dehydrated.