Ch. 2. Physiological chemistry and processes Flashcards
Control mechanisms
Nearly all are controlled by negative feedback mechanisms Some use positive feedback mechanism - control of uterine contractions during childbirth and blood clotting
Movement of substances within body fluids
In liquids or gases, molecules distribute from an area of high concentration to one of low (if there is no barrier) until the molecules are evenly spread throughout (equilibrium is reached). No energy is required (passive)
two main fluid compartments of the body
Most body water is intracellular (70%), the remaining 30% is extracellular (mostly in the interstitial fluid bathing the tissues, with the remainder found in plasma)
Diffusion
Movement of molecules from area of high concentration to area of low concentration and occurs mostly in gases, liquids, and solutions
Nucleic acids
largest molecules in the body, built from nucleotides, include deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)
Homeostasis
fairy constant state, tightly controlled internal environment (unchanging)
Strong acids and bases
dissociate more extensively than weak acids. Same goes for bases.
Catabolic reaction
involve breakdown of substrate into smaller products (digestion)
The pH scale
Scale from 0 to 14, with 7 as midpoint (neutral)
Enzyme action
If conditions are unsuitable, enzyme action is reduced or stopped (temperature, pH)
pH most body fluids
Most of bodily fluids (except gastric juices) are close to neutral
Rings around nucleus
electrons orbit them, they represent different energy levels of atom’s electron
Body’s reactions release energy
breakdown of sugars in presence of O2
When atoms are joined together…
they form a chemical bond, generally one of two types: covalent or ionic
Enzymes in mitochondria …
capture the released energy, using it to make ATP from adenosine diphosphate (ADP)
Cation
with positive charge Na+
Osmotic pressure
Force with which osmosis occurs
Element
contains only one atom (carbon, hydrogen) There are 92 elements
Steroids
including important hormones produced by gonads (ovaries and testes) and adrenal glands.
Peptide bond
when two amino acids join up to form a bond, the reaction expels a molecule of water
Plasma (osmosis) hypertonic
The other way, plasma water concentration falls so plasma becomes more concentrated then intracellular fluid within red blood cells (plasma becomes hypertonic), water passively moves by osmosis from blood cells into plasma and blood cells shrink
Electrons
negatively charged, super small
interstitial fluid or tissue fluid
Cells are bathed in fluid called interstitial fluid or tissue fluid – they absorb oxygen and nutrients from the surrounding interstitial fluid, which absorbed these from the circulation blood (opposite happens for excretion)
Carbohydrates
Sugars and starches Contain carbon, oxygen, and hydrogen, usually in ratio 1:1:2
Phospholipids
Integral to cell membrane structure Form a double layer, providing a water-repellent barrier separating cell contents form its environment
Extracellular fluid (ECF)
Mainly blood, plasma, lymph, cerebrospinal fluid, and fluid in the interstitial spaces of the body Other fluids mainly lubricate joint (synovial) fluid, pericardial fluid (around the heart), pleural fluid (around the lungs)
Functions of sugars:
Ready source of energy to fuel cell metabolism Form of energy storage (glycogen) Integral part of structure of DNA and RNA Acting as receptors on the cell surface, allowing cell to recognise other molecules and cells
Lipids
Substances with common property of inability to mix with water (hydrophobic) Made up mainly of carbon, hydrogen, and oxygen atoms (some also contain nitrogen or phosphorus)
When NaCl is dissolved in water…
the ionic bond breaks and two atoms separate. The atoms are charged (since they traded electrons) so are no longer called atoms, but ions
Hydrogen ions
disrupt these internal stabilizing forces and change the shape of protein, leaving it unable to function
Atomic number
number of protons in the nuclei of its atoms, each element has its own atomic number
Internal environment
water-based medium in which body cells exist
Carbon atoms
are usually arranged in a ring with the oxygen and hydrogen atoms linked to them
Total body water (men and women)
Lower in women than men due to higher amount of adipose tissue then muscle tissue (adipose tissue is 10% water, and muscle tissue is 75%)
Monosaccharide
can be linked together to form bigger sugars – disaccharides (2 sugar units) sucrose
Positive feedback mechanism (labour)
During labour – contractions are stimulated by hormone oxytocin, forcing baby’s head into the uterine cervix, stimulating stretch receptors there. In response, more oxytocin is released further strengthening the contractions and maintaining labour. After baby is born, the stimulus (stretching of cervix) is no longer present and so release of oxytocin stops
internal bonds between amino acids
protein chains are stabilised by them Function of the protein will depend on the 3D shape into which it has been twisted
Atomic weight
of an element, sum of the protons and neutrons in the atomic nucleus, average atomic weight using all its atoms
Exert osmotic pressure
keeping body fluids in their own compartments
Anabolic reaction
when enzyme catalyses the combination of two or more substrates into a larger product
Substrate
the molecule(s) entering the reaction, binds to specific site on enzyme (the active site) and the reaction proceeds Once it is complete the product(s) of reaction breaks away from the enzyme
Lungs (buffers)
regulators of blood pH – excrete CO2 which increases H+ in bodily fluids (it combines with water to form carbonic acid which then dissociates into bicarbonate ion and hydrogen ion) Brain detects rising H+ in the blood and stimulated breathing, causing increased CO2 loss and fall in H+ (works the other way around)
Atoms
contain equal number of protons and electrons (no net charge)
Covalent bonds
when atoms share their electrons with each other, a strong and stable link (H20)
cofactor
Some enzymes require presence of cofactor (ion or small molecule) Can catalyse both synthetic and breakdown reactions
pH
measuring system to express the concentration of hydrogen ions H+ in a fluid, it is an indicator of its acidity or alkalinity