View
215
Download
1
Category
Tags:
Preview:
Citation preview
Water
H2O OH H105o
bent molecule
non-bonding electron pairs
polar character OH H
-
+
-
++
electrical dipole
Hydrogen bonding
-
+
-
+
-
+
-
+-
+
0 oC 3.6 / H2O
H bonds - much weaker than covalent bonds !
bond energy of H-bonds in liquid water: about 19 kJ/mol
( covalent H – O bond in water: 460 kJ/mol )
water is most dense at 3.98 °C !!! (when freezing, ice will form first on the surface)
attractions between water molecules
HIGH melting point
boiling point
specific heat
heat of vaporization
surface tension
Attraction between water dipoles and ions
"hydrated ions"
WATER - very good solvent !
Dispersing "amphipathic" molecules
"micelles"
"Amphipathic" molecules – contain both highly hydrophobic
and highly polar groups
palmitic acid
non-polar chain = hydrophobic polar group = hydrophilic
(water-loving)(water-fearing)
Phospholipids
phosphatidylcholine
(lecithin)
polar groups
Biological membranes
- separate the cells separate the spaces (compartments) of the cell
nucleus
endoplasmic reticulum lysosome
mitochondria
cell membrane
Phospholipid BILAYER
hydrophobic
hydrophilic
hydrophilic
Water in human body
~ 60 % of the body weight
intracellular ~ 40 %
extracellular ~ 20 % PLASMA 5 %
interstitial fluid 15 %
- a very complex solution of inorganic & organic components
K+ Na+ Mg2+
Phosphates
Proteins
Na+ K+ Ca2+ Mg2+
Cl- HCO3- Phosphates
Na+/K+ pump ( = Na+/K+ -ATPase )
Na+
K+
Water balance
Intake: ~ 1.5 - 2.0 l / day
metabolic water (produced in human body by oxidation of food) 0.3 – 0.5 l /day
Resorption: stomach, small intestine, LARGE INTESTINE
Secretion: Saliva 1 500 ml / dayStomach 2 500Bile 500 8 200 ml /dayPancreas 700Small intestine 3 000
Excretion: Urine 60 %Skin 20 % (perspiration)Lungs 15 %Faeces 5 %
mmol/l
Na+ 132 – 145
K+ 3.8 - 5.2
Ca* 2.1 – 2.6
Mg2+ 0.8 – 1.1
Cl- 97 – 108
HCO3- 22 – 26
Phosphates
HPO42- + H2PO4
- 0.6 – 1.6
Human blood plasma
pH = 7.36 – 7.44 * Ca "total Ca" Ca2+ "ionized" is about ½ of "total" ~ 1.2 mmol/l
Blood plasma( extracellular fluid )
Cell fluid (cytosol)( intracellular fluid )
phospholipids
cholesterol
PROTEINS - enzymes
- receptors
- transport systemsSELECTIVE permeability
(membrane = barrier)
The flow of molecules and ions between the cell and environment is
precisely regulated by SPECIFIC TRANSPORT SYSTEMS
They regulate cell volume, ionic composition, pH
They concentrate metabolic fuels and building blocks from the environment
The extrude toxic substances
They generate IONIC GRADIENTS essential for the excitability
Transport across membrane
1) Passive transport - does not involve energy
- diffusion from high to low concentration
2) Active transport - uses energy (ATP)
- can transport against the concentration gradient
- one direction, high specificity
3) Secondary active transport - no direct need of energy
- gradient created by active transport is used !
ATP
"pumps"
"channels"
Passive transport
1 2 3
1) Simple diffusion small molecule, NO charge, solubility in lipids !
O2 CO2
2) Ion channels - pore-forming proteins
- can be "GATED"
3) Facilitated diffusion ("carrier proteins") - selective !
- large molecules, insoluble in lipids
"gate" is open"gate" is closed
concentration and
electrochemical
GRADIENT
toward equilibrium
Ion transport antibiotics
Gramicidin - peptide: 15 amino acids
HELIX - hydrophilic groups inside
"wet channel"
- lipophilic groups outside
"wide wet pore"
increase of the permeability of bacterial cell wall
inorganic ions can travel through
equilibration of concentrations = NO GRADIENT
Valinomycin
hydrophillic groups INSIDE = "WET cave"
equilibration of K+ concentration = NO GRADIENT
hydrophobic (lipophillic) groups OUTSIDE
( = soluble in lipids of membrane)
K+highly selective carrier for K+
( Na+ with water coating is too big)
K+
K+
Valinomycin
hydrophillic groups
hydrophobic (lipophillic) groups
Active transport = "PUMPS"
ATP ADP + Pi
Transport against
GRADIENT
ENERGY !
3 Na+
2 K+
ATPNa+/K+ ATPase
(sodium potassium pump)
INHIBITION:
cardiotonic steroids
Na+/K+ ATPase
in cell membrane of EVERY human cell !
electrogenic = transfers 3 Na+ out and ONLY 2 K+ into the cell
inner side of the membrane - outer side of the membrane
+
inhibitors of this pump: cardiotonic steroids = cardiac glykosides
(oubain, digoxin)
treatment of heart failure, cardiac arrhytmia
Digitalis purpurea
(foxglove)
H+/K+ ATPase
stomach gastric acid HCl
* carboanhydrase Zn2+
CO2 CO2 + H2O
HCO3- HCO3
- + H+
H2CO3K+ H+
ATP
Cl-
Cl-
*
parietal cell blood pH = 7.4 lumen of the stomach
pH = 1 - 2
106 increase of H+ concentration !
Secondary active transport "COTRANSPORT"
Na+ dependent transport of glucose, aminoacids, Ca2+
"energy" = Na+ gradient generated by Na+/K+ ATPase
SYMPORT
ANTIPORT
Na+
glucose
Na+
Ca2+
Na+ - glucose symport
Na+
K+
glucose glucose
Na+
ATP
proximal tubulus of each nephron in the kidneys resorption of glucose
intestines resorption of glucose from GI tract
Na+/Ca2+ antiport = sodium–calcium EXCHANGER
Na+
K+
Ca2+ Ca2+
Na+
ATP
Ca2+ ATPase
Na+/Ca2+ exchanger very low concentration of Ca2+ in cytosol
Endocytosis
Large (polar) molecules – cannot pass through the hydrophobic membrane
phagocytosis - cell ingests large object such as bacteria
pinocytosis - uptake of solutes and molecules such as proteins
receptor-mediated endocytosis – specific ! LDL receptor
chylomicron remnant receptorreceptors that mediates endocytosis of
blood plasma lipoproteins
cell absorbs material by engulfing it with its own membrane
Exocytosis
= the opposite of endocytosis
Exocytosis is needed for:
- secretion of large molecules from cells: glands peptide hormones
B cells antibodies
- neuronal chemical synapses: realease of the neurotransmitter
vesicles with neurotransmitter synaptic cleft
receptor
Water transport across membranes
high osmolalityH2O
low osmolality
Water moves by "simple diffusion" through membranes ?
Additional mechanism for water transport:
AQUAPORINS "water channels"
Water transport - due to osmotic differences (osmotic gradient)
OSMOSIS
The bioelements (summary)
1) Principal bioelements: O, C, N, H, P, S
( biomolecules: proteins, nucleic acids, lipids, saccharides )
2) Water and ions ( H2O ) Na+, K+, Mg2+, Ca2+, Cl-, ( HCO3- , phosphates)
3) Mineral constituents of bones and teeth Ca
PO43-
4) Microelements (trace elements) Fe, Cu, Co, Zn, I, F, Se, ...
--------------------------------------------------------
5) Contamination (intoxication): Hg, Al, ...
Elements of group I
I A I B
H Hydrogenium Cu Cuprum
Li Lithium Ag Argentum
Na Natrium Au Aurum
K Kalium
Rb
Cs
Fr
Alkali metals
Alkali metals - very reactive
- react with air O2 and H2O
- must be stored under oil
Hydrogen H
biogenic element - it is present in almost all organic compounds !
H2O
H+ = proton ( H3O+ )
pH = - log [H+]
The pH scale
0 7 14 acidic solutions alkaline (basic) sol.
neutral
water is weakly ionized: H2O H+ + OH-
KW = [H+] x [OH-] = 10-14 mol2 / l2 ionic product of water
pH + pOH = 14
pure water: [H+] = [OH-] = 10-7 mol/l pH = pOH = 7
-----------------------------------------------------------------------
Strong acids - fully ionised: monobasic acid: HCl H+ + Cl-
dibasic acid: H2SO4 2 H+ + SO42-
Weak acids – do not disociate completely: CH3COOH H+ + CH3COO-
Strong bases: NaOH, KOH, Ca(OH)2
Weak base: NH4OH
human blood plasma: pH = 7.40 0.04
gastric juice: pH = 1 – 2
pancreatic juice: pH = ~ 8
-----------------------------------------------------
H+ very low concentration in blood plasma !!!
pH = 7.40 H+ = 0.000 040 mmol/l (40 nmol/l)
(Na+ 142 mmol/l K+ 4.5 mmol/l)
extreme influence of H+ on biological systems !!!
ionisation of functional groups in PROTEINS
Ionisation of amino acids
+-
Lithium Li
compounds: LiCl Li2CO3 crimson (red) colour of flame
Therapy of manic-depressive psychosis (bipolar affective disorder)
= alternating periods of mania (euphoria) and depression
The manic phase - increased activity, decresased need for sleep
- persistent elevated mood
- impaired normal functioning !
The depressive phase - lack of energy
- pessimistic
- self-destructive behavior (risk of suicide !)
Li+ changes of ion transport in CNS
- still in use "mood stabilizing agent"
Lithium mineral water – therapy of GOUT (type of arthritis)
(Li-urate more soluble than uric acid)
Uric acid - in humans - the end product of purine catabolism
- poorly soluble in water
- lithium urate – more soluble !
N
N
NH
N
OH
OH
OH
Sodium Na (Natrium)
Na+ the main EXTRAcellular cation (132 – 145 mmol/l)
Na+ strongly binds water
ionic diameter: Na+
K+
!!! in hydrated form: Na+ larger in diameter than K+
Na+ ( together with Cl- ) large fraction of osmotic pressure (osmolality)
of body fluids
Water and Na balance are closely interdependent !
NaCl daily intake: 5 – 15 g food (common salt)
Elimination: urine (95 %)
sweat (perspiration)
stool
Kidney
BLOOD Glomerular filtrate (180 l H2O / day)
Glomerular filtration
URINE
2 l H2O 5 – 15g NaCl
[ 1.5 kg NaCl ]
Tubular resorption
dependent on hormones (aldosteron, ADH)
Hormones regulating tubular resorption
Aldosteron - steroid hormone (mineralocorticoid)- produced in the adrenal gland (adrenal cortex)- acting in the distal tubule of the kidney nephron:
reabsorption of Na+ into bloodsecretion of K+ into urine
Vasopressin = antidiuretic hormone (ADH) - peptide hormone- synthesized in the hypothalamus, released into
blood in the pituitary gland (posterior part)
- ADH increases the permeability of the collecting duct to water
allows water reabsorption small volume of concentrated urine
deficiency of ADH: DIABETES INSIPIDUS - polyuria
- excretion of large amounts of diluted urine ( 10 – 20 l /day !)
Potassium K (Kalium)
K+ the main INTRAcellular cation (cytosol > 100 mmol/l)
- human blood plasma: only 3.8 - 5.2 mmol/l
- daily intake: ~ 4g of KCl excretion: URINE
- proper concentrations of K+ and Na+ functions of membranes
„membrane potential“
most cells – membrane potential relatively stable
neurons, muscle cells – use changes of membrane potential for function !
(nervous system – communication between neurons)
action potential
3Na+
cell membrane
2K+
2K+
ATP !
Na+
K+
EXTRAcellular fluid
INTRAcellular fluid
Na+/K+ ATPase Ion channels
ACTION POTENTIAL falling phase = repolarisation
rising phase = depolarisation
resting potential
In cells K+ is bound to GLYCOGEN !
Diabetic coma ( glucose in blood )
Glycogen synthesis
Binding of K+ in cells
Plasma K+ depletion HEART failure !!!
insulin
Copper Cu (Cuprum)
microelement (in human body 100 - 150 mg) dietary intake: ~ 2 mg / day
Cu2+ - cofactor of some enzymes: cytochrom c oxidase (metalloenzymes) superoxide dismutase
- cofactor of HEME biosynthesis
CERULOPLASMIN - transport of Cu2+ in blood plasma ( 8 Cu2+ / mol. )
- 2 globulin synthesized in the liver - enzymatic activity: Fe2+ Fe3+
WILSON‘s DISEASE - accumulation of copper in tissues(hepatolenticular degeneration) - low ceruloplasmin levels
- hereditary disease - neurological symptoms, liver disease
CuSO4 . 5 H2O copper (II) sulphate pentahydrate
= „blue vitriol“
- in Fehling‘s solution (detection of glucose in urine)
copper salts - poisonous !
-------------------------------------------
Hemocyanins - Cu2+ containing proteins
- O2 transport - MOLLUSCA (snail, clam, mussel, ...)
- ARTHROPODA (crabs)
Silver Ag (Argentum)
precious metal ( + H2S Ag2S black ! )
AgBr - photosensitive photography
------------------------------------------------------------------
Ag - useful in dental alloys for fittings and fillings
( Ag + Hg amalgam )
AgNO3 - caustic effect treatment of warts
Bartholin’s gland abscess in women
(removal: silver nitrate stick insertion)
- diluted solution: antiseptic properties it was dropped into newborn‘s eyes
to prevent gonococcal conjuntivitis !
(Gonorrhoea is a venereal disease caused by the bacteria Neisseria gonorrhoeae)
Gold Au (Aurum)
precious metal chemically and biologically resistent, inert
in nature – almost exclusively in the native state
pure gold – soft ! in jewellery: alloys (+ Cu, + Ag) harder
The gold content of gold alloys
in carats or in thousandths
pure gold: 24 carats = 1000/1000
The standard for high quality jewellery: 18 carats = 750 / 1000
What is the gold content (g) of a 100 g piece marked 18 carats?
1824
x 100g = 75 g
Elements of group II
II A II B
Be Beryllium Zn Zincum
Mg Magnesium Cd Cadmium
Ca Calcium Hg Hydrargyrum
Ba Barium
Sr Strontium
Ra
Alkaline earth
metals
Magnesium Mg
PLANTS: Mg2+ - central atom of green pigment CHLOROPHYLL
(photosynthesis)
in human body: ~ 20 g Mg > ½ in bones ( Ca-Mg phosphates ) intracellular cation
Mg2+ activates number of enzymes !!! ENZYMES using ATP"kinases"
glucose glucose–6–phosphate
(Enzymes of ATP-dependent reactions require Mg2+ as cofactor)
hexokinase
ATP ADP
other effects of Mg2+: anti-convulsive effect
(MgSO4 - prevention of eclamptic convulsions)
influence on neuromuscular excitability
can help to prevent kidney and gall stones
"duodenal reflex" - MgSO4 delivered into the region of the sphincter of Oddi
relaxation of the sphincter + contraction of the gallbladder
expulsion of bile to intestine
( the bile release from the gallbladder is stimulated by Mg2+ )
Magnesium mineral water (Karlovy Vary) purgative effect
Calcium Ca
CaO + H2O Ca(OH)2
"slaking"
slaked lime
"burning"CaCO3
limestone, chalk
quicklime
CaO + CO2
Ca(OH)2 + CO2 CaCO3 + H2O
Hardening of mortar:
Calcium Ca
in human body ~ 1 kg (99% in bones, teeth)
dietary intake: 800 - 1200 mg / day
human blood plasma: "total Ca" 2.5 mmol/l
(extracellular !) ionized Ca2+ 1.2 mmol/l
resorption: ileum – specific protein carrier
~ 200 mg / day
excretion: urine
liver bile feces
Mineral constituents of bones and teeth
enamel
dentin
cementum
pulp
Enamel: - hardest substance of the body
water 1-3 % organic comp. 1% mineral > 95 % (bones ~ 60 %)
F -
fluoroapatite
Hydroxyapatite
Ca5 (PO4)3 OH
Hormones regulating Ca metabolism
Parathormone - peptide hormone ( 84 amino acids )
- secreted by parathyreoid glands
- activation of bone mineral degradation
Ca2+ release from bones
- stimulation of Ca2+ readsorption in kidney- stimulation of calcitriol formation (kidneys)- stimulation of Ca-resorption protein formation (ileum)
Ca2+ in blood
PTH
Calcitonin - peptide hormone ( 32 amino acids )
- produced by parafollicular cell of the thyreoid gland
- inhibition of bone mineral degradation (decrease of „osteoclasts“ activity)
- stimulation of Ca2+ excretion in kidney
Salmon calcitonin is used for the treatment of OSTEOPOROSIS
Ca2+ in blood
Calcitriol = 1,25-dihydroxycholecalciferol
- active form of D–vitamin
- stimulation of Ca-resorption protein formation
absorption of calcium from the gastrointestinal tract
Ca2+ increase PTH release inhibition
Ca – FOOD (protein-bound)
ILEUM
Ca-resorption protein
PLASMA
Ca 2.5 mmol/l
Ca2+ 1.2 mmol/l
URINEBONES
PTH
PTH
PTH
calcitonin
calcitonin
calcitriol
calcitriol
milkexcrements
Very low concentration of Ca2+ in cytoplasma 10-6 mol/l
MUSCLE - Ca2+ is stored in sarcoplasmic reticulum (SR)
CALSEQUESTRIN = calcium-binding protein of the SR
40 Ca2+ binding sites
Ca2+ in cytoplasma can cause the specific action of the cell:
MUSCLES contraction
Ca2+ = important SECOND MESSENGER
"SIGNAL"
release of Ca2+
EFFECT
endoplasmic reticulum
Clotting of BLOOD
Ca2+ is required for the proper function of the coagulation CASCADE
Xa
Fibrinogen Fibrin
Prothrombin Thrombin
Extrinsic pathway
(Tissue factor pathway)
Intrinsic pathway
(Contact activation pathway)
Removing of Ca2+ = NO clotting !
Anticoagulants - bind Ca2+ ions( "in vitro" = outside the body)
Oxalate
EDTA = ethylenediamine tetraacetic acid
COO -
COO -
COO
COO + Ca2+ Ca
Citric acid
Gypsum, plaster of Paris
CaSO4 . 2 H2O
CaSO4 . 2 H2O
CaSO4 . 1/2 H2O
+ H2O
hardening
heating
When the dry plaster powder is mixed with water, it re-forms into gypsum
bandage impregnated with plaster = support for broken bones
Strontium Sr
- similar to Ca2+ incorporation in BONES
(naturally present in bones in trace amounts)
- new treatment for osteoporosis: „Strontium ranelate“
(improves bone density and strenght)
excess: Strontium rickets
radioisotope Sr bone marrow irradiation LEUKEMIA
(important isotope regarding health impacts after the Chernobyl disaster)
radioisotope Sr - treatment of bone cancer
90
89
half life 28 years
half life 50 days
Barium Ba
toxic heavy metalwater-soluble compounds - strongly neurotoxic
[ Ba(NO3)2 BaCl2 ] - painful cramps, tremor
BaSO4 (barium sulphate)
- almost insoluble in water ! - radiocontrast agent for X-ray imaging
( "barium meal" )- imaging of the gastrointestinal tract
large intestine
Zinc Zn (Zincum)
microelement dietary intake: 12 -15 mg / day
cofactor of many ENZYMES:
carboxypeptidase - protein digestion
carbonic anhydrase H2O + CO2 H2CO3 H+ + HCO3-
alcohol dehydrogenase - oxidation of ethanol to acetaldehyde
CH3CH2OH CH3CHO
NAD+ NADH+H+
Insulin binds ZINC ! "Zn – insulin hexamers"
Metallothionein - protein synthesized in kidneys rich of -SH groups
- can bind metals ( Zn2+ Cd2+ .... )
- zinc transport, heavy metal detoxification (Hg2+) ?
Zinc is an essential nutrient for proper sperm production !
------------------------------------------------
compounds used in medicine: ZnO - a basis of powders, pastes, creams
( in DERMATOLOGY )
dental fillings (cements): Zn3(PO4)2 . 4 H2O "hopeit"
Cadmium Cdtoxic heavy metal
metallothionein – strongly binds Cd2+
Cd intoxication
kidney damage
"Itai itai disease" - mass Cd poisoning in Japan in 1950
- the name comes from painful screams
( "itai" in Japanese = PAIN )
- the bones become soft and weak severe pain, fractures
"Chemical castration" = destruction of seminiferous epithelium
of testicles ( Zn2+ antagonism )
Mercury Hg (Hydrargyrum)
Toxic effects
1) elemental Hg - very toxic when absorbed as a vapour through lungs
- poorly absorbed through the gastrointestinal tract !!!
(only purgative effect)
2) inorganic Hg compounds
HgCl2 - "sublimate" - soluble in water = toxic
- corrosive ulceration of GI tract
- renal failure
Hg2Cl2 – "calomel" - low solubility = less toxic
- it was used in medicine ! (diuretic and purgative
effect, ointments in dermatology)
- calomel electrod (reference electrod - measurement of pH)
2) organic Hg compounds
- often extremely toxic
- dimethylmercury Hg(CH3)2 damage of CNS (central nervous system)
- one of the strongest known neurotoxins !
"The Minamata Disease" - mass Hg poisoning in Japan in 1956
- Minamata Bay – waste industrial water with Hg2+
biomethylation by a variety of microorganism
bioaccumulation in FISH
dietary intake from fish diets
Poison grain disaster in Iraq (1971) - seed grain mercury-treated to prevent rot
was used as FOOD
Elements of group III
III A III B
B Borum Sc
Al Aluminium Y
Ga La
In Ac
Tl
Ra
Boron B (Borum)
PLANTS – micromineral
Boric acid H3BO3 - a very weak acid
- disinfectant (used in dermatology and ophtalmology)
- also toxic properties !
NH3 + glutamate glutamine
glutamine synthetase
H3BO3 = inhibitortoxic to BRAIN
Sodium tetraborate Na2B4O10 = borax (fusible glaze for pottery)
Aluminium Al
in human body – only traces – contamination ?
Al(OH)3 together with MgO or Mg(OH)2 oral antacid
(neutralization of acid in the stomach)
Al – also considered as toxic
ACID RAIN SOIL release of Al3+ !
Elements of group IV
IV A IV B
C Carboneum Ti
Si Silicium Zr
Ge Hf
Sn Stannum
Pb Plumbum
Carbon C (Carboneum)
the most important biogenic element
organic compounds (covalent bonds C-C, chains, rings)
biomolecules: proteins, nucleic acids, lipids, carbohydrates
combustion CO, CO2
respiration CO2
Toxic: CO competes with O2 for hemoglobin
HCN reaction with cytochromes inactivation of cell respiration
Silicon Si (Silicium)
abundant element in lithosfere, but not useful in human body
SiO2 (silica) Quartz - common mineral in the Earth‘s crust
- many varieties: amethyst (purple)
citrine (yellow)
morion (dark-brown)
rose quartz (pink)
- in many rocks (granit, sandstone), metallic ores
cutting, breaking, crushing, ...
inhalation of fine SiO2 dust SILICOSIS - lung disease
occupational disease (miners, ceramics workers)
progressive, signs of it will appear years after exposure !
Silicic acids: general formula n SiO2 . m H2O
H4SiO4 orthosilicic acid
Silicates - salts of silicic acids SiO44-
Si atom - tetrahedral coordination by 4 oxygens
complex structure - different degrees of "polymerization"
linear arrangement FIBERS (asbestos)
planar arrangement MICAS
Silicate minerals - largest class of rock-forming minerals
Recommended