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