lecture 2 Flashcards
(18 cards)
asteriked elements on page 5
know them
ions
gaining or losing an electron
what are protons often called
H+(hydrogen)
electrons in physio
Electrons play four important roles in physiology
Chemical Bonds – Formation of molecules
Ions – Basis for electrical signaling in the body
High-energy Electrons – Involved in energy capture and transfer
Free Radicals – Unstable molecules thought to contribute to aging and the development of certain diseases
chemical bonds
Atoms are most stable when their outer (valence) shell is filled
The key to chemical reactivity is the octet rule. Except for shell 1, which is full when it has two electrons, atoms tend to interact in such a way that they have eight electrons in their valence shell.
A molecule forms when electrons of chemically reactive atoms interact to form chemical bonds
The number of bonds an atom can form is determined by the number of electrons in unfilled outer shells that participate in bonding. Examples:
Hydrogen has 1 outer electron so it can form 1 bond
Carbon has 4 outer electrons so it can form 4 bonds
3 major types of chemical bonds – covalent, ionic and hydrogen bonds
covalent bonds
Formed when atoms share outer (valence) electrons.
Strong bonds that require the input of energy to break them apart.
Nonpolar electrons are shared equally
Example: 2 Hydrogen atoms (H2)
Example: Carbon dioxide (CO2)
Polar electrons are not shared equally
Example: Water
V-shaped water (H2O) molecules have two poles of charge – a slightly more negative oxygen end (δ–) and a slightly more positive hydrogen end (δ+). oxygen has more protons than hydrogen so electrons go towards oxygen making the oxygen atom slightly more negative and hydrogen slightly more positive.
what is the octet rule
except for shell one which needs two, atoms tend to interact in a way that allows their valence (outermost) shell to have eight electrons
ionic bonds
Formed when one atom gives electrons to another so that both fill outer shells
Electron donor becomes positively charged. This atom is now a positively charged ion called a Cation.
Electron receiver becomes negatively charged. This atom is now a negatively charged ion called an Anion.
why are ions important in physio
they are charged and when they flow they make a current
know important ions of body
slide 14
water
Life as we know it is established on water-based, or aqueous, solutions.
The human body and all bodily fluids are 60% water.
Water is a polar molecule.
Water is a good solvent (most substances dissolve in it)
hydrophilic molecules dissovle easily in water. ex: nacl, glucose, other molecules that are polar or have ionic bonds.
hydrophobic molecueles cannot easily dissolve in water: fats, lipids, oils, other non polar molecuelswater
water and ions
Ionic compounds easily dissociate in water and ions form
Negative side of water is attracted to (+) cation, and positive side of water is attracted to (-) anion
hydrogen bonds
weak bonds formed betwen two polar molecules based on opposite charges atttracting, specifically between a hydrogen atom and a nearby oxygen, nitrogen or fluorine atom.
Found between water molecules
Between amino acids in a protein (critical for protein structure)
Holds the two DNA molecule strands together
acids, bases, and pH
Free hydrogen ions (H+) in solution play important physiological roles.
The concentration of free H+ in body fluids, or acidity, is measured in terms of pH.
In a Solution:
When H+ ions equal OH- ions neutral (pH=7)
When more H+ ions than OH- ions acid (pH below 7)
When more OH- ions than H+ ions base (pH above 7)
Buffers
Buffers neutralize H+ concentration in solutions
In blood, pH is stabilized by the:
bicarbonate (HCO3-) carbonic acid (H2CO3) system:
HCO3- + H+ ↔ H2CO3 ↔ H2O + CO2
If blood falls below pH 7.35, called acidosis
If blood rises above pH 7.45, called alkalosis
Organic/ biochemistry
Biomolecules – Molecules associated with living organisms.
Organic molecules are molecules that contain Carbon (C) and Hydrogen (H)
Carbon has 4 outer electrons so it forms 4 bonds
Carbon forms the backbone of all organisms on Earth
Can form chains and rings of carbons bonded to other atoms
Lipids-steroids
Structure includes four linked carbon rings
Cholesterol is the primary source of steroids in the human body and provides the core of four carbon rings
Include hormones such as testosterone, estrogen, and aldosterone
Carbohydrates
The most abundant biomolecule Organic molecules that contain carbon, hydrogen, and oxygen in a 1:2:1 ratio (CH2O)n Primary source of energy in the body Include sugars and starches Carbohydrates can be divided into three categories Monosaccharides Disaccharides Polysaccharides
