5: Water Flashcards
Structure and Properties of Water
- Water is a polar molecule
- slightly positive (δ+), slightly negative (δ–) charges of H and O atoms
- polar molecules are attracted to water = hydrophilic
- Nonpolar molecules are not attracted to water = hydrophobic
Hydrophilic
- Polar molecules that are attracted to and dissolve easily in water
- water loving
Hydrophobic
- not polar and not attracted to water
- water hating
Water content of human body
- Human body is 60–70% water by weight
- 2/3 of water found within cells = intracellular water
- 1/3 of water found outside of cells = extracellular water
Ex: blood, spaces between cells
Cytoplasm
- gel-like substance that is 80% water
- water in cytoplasm accounts for majority of the body’s water
Extracellular water
extracellular water content is constantly being used for the body’s needs and must be regularly replenished
Where can extracellular water be found?
- Most extracellular water is found within blood
- around joints, in the lungs, lining certain tissues and in the lymph
- extracellular space around cells
Movement of Water:
Osmosis
drives water to move across semi-permeable membranes, like blood capillaries, evening out concentration differences
Movement of Water:
Blood pressure
provides a force that pushes water out of blood and into the extracellular space
Functions of Water:
Structure
Helps structures maintain their form
Ex: Gives cells three dimensional shape necessary for cellular organelle to function, Water within synovial fluid sacs promote joint structure
Functions of Water:
Solvent
- water within cells also allows certain material to move around the cell
- water is always in motion, substances within water are in motion
- compatible reactants are dissolved in water, increased chance of colliding and undergoing a chemical reaction
Functions of Water:
Hydrolysis
Use water to split larger molecules into smaller ones
Given an example of a hydrolysis reaction
Breakdown of the double sugar maltose into two molecules of single sugar glucose
Functions of Water:
Defence from infections
- provides an environment for immune cells to fight off infections
- Main component of mucus, helps remove infectious agents
Functions of Water:
Protection from injury
- reduce friction and damage from movement or trauma that can negatively affect our tissues
- synovial fluid helps protect bones from scrapping against each other
- mucus lines, various structures, and protects them from physical injuries
- Water around brain and spinal cord helps protect from various forces
Functions of Water:
Temperature Regulation
Body temperature strictly maintained at around 37 ̊C to function properly
- Body uses water to regulate body temperature through two main mechanisms (sweating, blood shunt)
Functions of Water:
Temperature Regulation (Sweating)
release of watery sweat from our sweat glands
- When sweat evaporates, it cools down our skin and bodies
Functions of Water:
Temperature Regulation (Blood Shunting)
body tries to maintain its temperature by opening blood vessels close to the skin
- blood shunt some of the heat from the body’s core to the skin’s surface
Water Balance:
Sources of water
Every day, we lose water through urine, feces and evaporation
- Water is gained during certain metabolic processes
- plants/animals we eat are made of cells = break down their cells and release water from their cytoplasm
- water is a by product of cellular respiration
Water Balance:
Maintaining water balance
Water homeostasis is one of the body’s main priorities
- preserve body water levels through two main mechanisms (Thirst response, Kidneys)
When blood volume decreases, how does body try to maintain water balance?
- Thirst increases due to several body sensors that indicate brain that the concentration of dissolved particles in the blood is high, meaning that the concentration of water is low
- Kidneys decide what stays in the blood and what is excreted in urine
How do kidneys and water effect blood volume?
- Blood volume high, excess water is excreted at kidneys. A lot of waste products for the kidneys to remove, contributes to water loss, water is needed to aid materials pass outward
- blood volume/pressure is low, the kidneys decrease production of urine
Individuals that are deficient in water will notice what in their urine
urine is more darkly coloured, as it contains less water to dilute waste products
Water Balance:
Dehydration
- either due to insufficient consumption or excessive loss
What can causes dehydration?
excessive loss of water, potentially due to sweating, diarrhea or vomiting
Symptoms of dehydration
increased thirst, dry mouth, headaches, fatigue, dizziness, irritability and dark urine
Chronic dehydration can lead to what
more severe complications, including kidney damage, seizures and hypovolemic shock
Dehydration: Kidney disease
Dehydration puts extra stress on the kidneys, as they do not have enough water to help secrete waste products
- increases the risk of urinary tract infections, kidney stones, and in extreme cases lead to chronic kidney disease and even death
Dehydration: Seizures
Excessive sweating not only promotes water loss, but important electrolytes can also be lost in this process
- Electrolyte imbalance can compromise the body’s electrical activity, potentially promoting seizures
Dehydration: Hypovolemic shock
When the body loses a lot of blood or extracellular fluid
- Excessively low blood volume can promote significant drop in BP
- Low blood volume and pressure can compromise oxygen and nutrient delivery to the tissues
Water Balance:
Water Intoxication (Water Poisoning)
potentially fatal where content of water in body is too high with respect to the level of electrolytes
Why does water intoxication occur?
individual consumes excessive amounts of water in a short period of time and does not excrete it through urination
- significant amount of water is lost due to excessive sweating, diarrhea or vomiting = losses are replaced by only drinking water, it dilutes the electrolytes in the body
T/F: Extreme cases of dehydration can lead to malfunction of the central nervous system
True, causing increased risk for seizures, brain damage, coma and even death
Water Intoxication: Hyponatremia
- Low sodium in the blood
- Water levels, decrease concentration of dissolved particles in the blood
Why are most symptoms of water intoxication neurological based?
brain is susceptible to hyponatremia, can lead to an increase in intracranial pressure causing symptoms of headache, confusion, personality changes, irritability, and drowsiness
Diuretics
substances that promote water losses through urination
- Certain medications act as diuretics, as do certain psychoactive drugs like caffeine and alcohol
Diuretic pills (water pills)
prescribed for conditions such as high blood pressure, kidney stones and tissue swelling
- promote sodium excretion at the kidney, also promotes water excretion
T/F: Diuretic pills are generally safe
True, should only be consumed under recommendation of doctor, as they can increase risk for electrolyte imbalances, headache, dizziness and kidney failure
Diuretics: Caffeine
- psychoactive drug found in certain foods and beverages
- compound found naturally in seeds, nuts and leaves
- consumed for its effects on the central nervous system, as it can promote alertness, while reducing fatigue and drowsiness
Pros and cons of caffeine
Pro: promotes alertness, reduces tiredness, antioxidant, anti-inflammatory properties
Con: may promote kidney problems, increase risk of miscarriage, kidney stones
Diuretics: Alcohol
- psychoactive drug found in certain foods and beverages
- can affect hydration levels of over consumed
- provides energy to body; 7 kcal/g
Pros and cons of Alcohol
Pro: light to moderate drinkers (1–2 servings of alcohol per day) have a lower risk of cardiovascular disease compared to non-drinkers
Con: risk for cancers, liver cirrhosis, confusion, dementia, nutrition, mortality
What factors affect level of intoxication
Amount consumed, how quickly absorbed, size of individual, gender, genetics, type of alcohol, menstruation
Alcohol metabolism
- 90% of alcohol is metabolized and eliminated at the liver
- Alcohol dehydrogenase aldehyde dehydrogenase are the enzymes responsible for metabolizing alcohol
- Genetic changes can negatively impact the activity of these enzymes
How do genetics affect alcohol metabolism?
genetic variation of the enzyme aldehyde dehydrogenase leads to slower metabolism and lower risk for dependence. Resulting in facial redness, nausea, sweating, dizziness and a racing heartrate due to the buildup of acetaldehyde
Alcohol: Hangovers
- Typically occur 6+ hours after drinking
- May be due to direct effect of alcohol, acetaldehyde buildup, or congeners
- best way to avoid hangovers is to moderate or abstain from alcohol consumption
Alcohol Hangover:
Congeners
substances added during the fermentation process of alcohol
- suspected factor that produces hangover symptoms
Symptoms of hangovers
vomiting, tiredness, decreased attention, decreased concentration, stomach pain and disturbed sleep
Water recommendations
- amount of water an individual requires daily depends on various factors (sex, activity level and how much they sweat)
- AI for water is 2.7 L/day for women and 3.7 L/day for men
- When excessive water is lost due to sweating, vomiting or diarrhea, replenish both lost water and electrolytes
T/F: Water is an inorganic macronutrient
True, cannot live without a continuous supply of water to the body.
- provides no energy, but has key structural and functional roles
T/F: Alcohol and caffeine are food
False, they are diuretics that promote water loss.
- they are drugs and exert their main effects on the brain
T/F: If there is an area with more dissolved polar substances, water will move towards these
True
T/F: When blood pressure is higher, there is a greater chance the water will move from blood vessels to the extracellular space
True
In order for sweating to effectively cool the body, the sweat must _______________
Evaporate
________ can occur when the body loses a lot of blood or extracellular fluid. It is evidenced by a drop in blood pressure and compromised oxygen and nutrient delivery
hypovolemic shock
