Biology - MrBrown UNIT1

ANALYSING AND INTERPRETING DATA ON DISEASE.

Epidemiology is the study of incidence (no. Of cases.) and pattern of disease.

Look for patterns and relationships between diseases and various factors.

A CORRELATION occurs when 1 or 2 variables reflected by change in other variable.

There maybe a correlation BUT it does NOT PROVE that it may cause that factor (eg. Drinking alcohol and breast cancer.) may suggest but not evidence to prove it. Needs to be a CLEAR CASUAL CONNECTION. Also EXPERIMENTAL EVIDENCE would also need to be shown.                                                                                         LOOKING AT DATA CRITICALLY. (Must ask these questions)

1) has right factor been measured, correct questions asked?

2) how was data gathered, methods reliable, right apparatus used?

3) collected data have a vest interest in outcome of research?

4) study been repeated? Same results? Same conclusions?

RISK? - a measure of the probability that damage to health will occurs as a result of a given hazard.
Concept of risk has 2 points.
1) probability hazardous even will occur
2) consequences of hazardous risk.

MEASUREMENT OF RISK - as a value ranges from 0% to 100%
HEALTH RISKS NEED TIMESCALE
RISK IS OFTEN RELATIVE - measured in the likelihood of harm occurring in those exposed to the hazard and those not exposed to it.
When risk is quantified still many factors to consider that it is difficult to understand the risk.

Able to understand risk need to consider...
1) over what time period does it occurs
2) does the factor effect the figure? Eg. No of cigarettes smoked a day effect figure?
3) occupation, health, lifestyle, gender, pollution or other factors have a influence?
4) there location. Different figures in different countries or continents?

MISLEADING STATISTICS
reports in media may be misleading as they focus on a single figure.
Impression given applied to everyone.

RISK FACTORS AND CANCER - not a single disease so it does not have a single cause. Some casual factors beyond individual control. Some lifestyle factors within under visuals power to change.

Gland in human digestive system, produce enzymes that break down large molecules into smaller ones for absorption.  MAJOR PARTS OF DIGESTIVE SYSTUM
.OESOPHAGUS carries food mouth > stomach. Adapted for transportation/digestion/absorption. Made up of thick muscular walls.
.STOMACH inner layer produces enzymes. Store + digest food (especially proteins) glands produce digestive enzyme
.SMALL INTESTINE long muscular tube, food is further digested by enzymes that are produced by walls in glands. Inner walls are folded into villi = larger surface area. Surface area increased by tiny projections of MICROVILLI.
.SALIVARY GLANDS situated near the mouth. Enzyme AMYLASE breaks down STARCH into MALTOSE.
.PANCREAS secreate protease to digest PROTEINS, LIPIDS and AMALYSE to DIGEST STARCH.                    CHEMICAL DIGESTION. - breaks down larger insoluble molecules into soluble smaller ones. (CARRIED OUT BY ENZYMES)
-digestive enzymes function by HYDROLYSIS. Splitting up molecules adding water to chemical bonds that hold them together. Enzyme- HYDROLASES.
-enzyme specific. Different digestive enzymes....

CARBOHYDRASES- break down carbohydrates ultimately to MONOSACCHARIDES.
LIPASES- break down lipids (fats and oils) into GLYCEROL and FATTY ACIDS
PROTEASES-break down proteins, ultimately to AMINO ACIDS.

Once large food molecules been hydrolysed into monosaccharides, glycerol and fatty acids are absorbed. From small intestine into blood.

Carbon atoms readily form bonds with other carbons. Carbon contains molecules known as organic molecules
Individual molecules make up chains even general name - MONOMERS
repeating monomer units called POLYMERS
Biological molecules (eg. Carbohydrates + proteins) often POLYMERS
-In carbohydrates, single monomer is called MONOSACCHARIDES
-PAIR of monosaccharides combined to form DISACCHARIDES
-Monsaccharides can be also combined in much larger no. = POLYSACCHARIDES

MONOSACCHARIDES, soluble substances general formula CH2On (n = any number from 3 to 7)
Eg. GLUCOSE.     (See diagram structure of glucose) <--- need to learn this!             TESTING FOR REDUCING SUGARS - all monosaccardies and some dissaccardies (eg. maltose) are REDUCING SUGARS         Reduction is a chemical reaction involving GAIN of ELECTRONS.  reucing sugar is a sugar that can donate electrons to another chemcial. BENEDICTS REAGENT.  

Benedicts reagent is an alkanine solution. When reducing sugars are heated with benedicts insoluble RED precicpitate is formed.

Differences in colour of the solution and the precipitate formed durng test mean that the test it SEMI-QUANTITIVE  = can be used to estimate approx. amount of reducing sugar in sample. 

REMEMBER: monosaccarides combined in large numbers to form polysaccardies.

DISACCARIDES:

Combined in pairs, monosaccarides = disaccardie. eg;

• GLUCOSE --- GLUCOSE = MALTOSE
• GLUCOSE --- FRUCTOSE =SUCROSE
• GLUCOSE --- GALACTOSE = LACTOSE

when monosaccaride join, molecule of water is removed = CONDENSATION REACTION     The bond is a GLCOSIDIC BOND. 

When water is added to a disaccardie (in right conditions) breaks the glycosidic bond realeasing monosaccardies = HYDROLYSIS REACTION ( +H2O = breakdown of bond)

CONDENSATION REACTION WITH 2 GLUCOSE MOLECULES

not a biological reaction .... but you get where im going with this...

Some dissaccardies (e.g MALTOSE) are reducing sugars. to dectect this use benedicts test (see card no. 6-7) other disaccarides (e.g. Sucrose)  are NON-REDUCING SUGARS they DO NOT CHANGE COLOUR of the benedicts test when heated. 

Must 1st be brokecen downnn into its monosaccarides by HYDROLYSIS.                         The Process:

• add sample to benedicts reagent
• place in boiling water 5 mins. make sure there is no colout change. = reducuing sugar not present
• add more sample then some dilute hydrochloric acid. Leave for 5 mins. acisd will hydrolyse any disaccaride present into monosaccardies.
• add sodium hydrocarbonate to neutralise solutions. benedicts will not work in acidic conditons.
• Re-test.

POLYSACCHARIDES:

are polymer, formed by many monosaccarides. joing be glycosidic bonds that from CONDENSATION REACTION. Are very LARGE molecules = insoluble. When hydrolysed

makes them suitable for storage. When hydrolysed, they break down into disaccarides + mono. not used for storage but to give plants cells support. 

STARCH:

dectected by ability to change colour of iodine solution from YELLOW to BLACK-BLUE 

STARCH DIGESTION:

Enzyme = AMYLASE. produced in mouth and pancreas. it HYDROLYSES  the alternate GLYCOSIDIC BONDS of starch ---------> dissacaride MALTOSE.  this can then by hydrolysed further into a glucose mono. by another enzyme. 

DISSACCARIDE DIGESTION:

two otther common disaccarides that need to be broken down. 

SUCROSE usually contained within cells must be physically broken down by teeth to release it. sucrose passes through lining of the stomach and into the small intestine, epithelial cells produce enzyme sucrase this hydrolyses bong to produce 2 mono. (glucose + fructose) 

LACTOSE sugar found in milk and in its products. Digested in the small intestine edpithelial lining produce lactase.   breaks it down into glucose and galactose. 

Moderen storage and distrubution of products mean that sults now consume milk in larger quantities. people pruce insifficent amount of lactase enzyme to break down the lactose sugar. Undigested lactos ereaches large intestine microorganisms break it down  = LOTA OF GAS. 

= bloating, nausea, diarrhoea or cramps. Some people cannot consume milk products at all. 

not life threatening but can be managed by regulating diet. main diffeiculty is not taking in enough calcium in the absence of milk. resolved by taking in food rich in calcium or by adding enzymes lactase to milk before drinking it. 

STRUCTURE OF AN AMINO ACID

basic monomer units which combine to make a polymer called a polypeptide, which can be further combined to form protieins. every amino acid has a centeral carbon atom to which are attached 4 groups. 1)  amino group (-NH3) badic group amino part of the name.... 2) carboxyl group (-COOH) - an acidic group    3) hydrogen atom and a R group - which is varous forms of different chemical groups 

              Formation of peptide bond

the sequence of amino acids in a polypeptide chain forms the PRIMARY STRUCTURE of protein. 

the protein structure that determinds the ultimate shape and hence its function. a in a single amino acid  can lead to change in shape and structure  and will stop protwin carrying out its original function . Proteins shape is specific to its function

SECONDARY STRUCTURE is linked amino acids the make up the polypeptide chain teh two groups on wither side of the peptide bond form redily weak bonds called HYDROGEN BONDS.  this causes the chain to be twisted in a 3D  helix.

after the helix it can be folded even more. and be twisted to form a complex 3D structure of each protein. This is maintained by different bonds 

• DISULFIDE BONDS =  fairly strong, not eaily broken down
• IONIC BONDS =  formed between carboxyl and amino group NOT INVOLVED IN FORMING PEPTIDE BONDS.  weaker than disulfide bridges and are eaily broken by changes in pH
• HYDROGEN BONDS = numerous, but eaily broken. 

Large proteins often form complex molecules containing indervidual popeptide chains linked in various ways. the QUATERNARY STRUCTURE  is a combination of different polypeptide chains associated non-protein groups into large and complex molecule. 

Test:

the Biuret test which detects PEPTIDE links. using a samole of the solution and a equal volume of sodium hydroxide solution at room temperature. adding few drops a copper sulfate and mix.

PURPLE is positive. 

Protein shape and function :

2 basic type of proteins. 1) FIBROUS PROTIENS - eg. collagen have structural functions. they for, long chains linked by cross-bridges form very stable molecules. . the PRIMARY stucture is an unbranched polypeptide chain. SECONDARY structure the polypeptide chain is tightly wound. TERTIARY structure made up of 3 polypeptide chainsa wound together in the same way indervidual fibers in rope. Collagen found in tendons, muscle joins to bone.     

2) GLOBULAR PROTEINS - eg. enzymes + haemoglobin carry out metabollic functions. 

REMEBER: Enzymes are catalysts that lower activation engergy. 

The initial boost of energy needed to kick start a reaction is called the actication energy

ENZYME STRUCTURE:

Being GLOBULAR PROTEINS have a specific 3D shape result of seqence of amino acids. Only small region is functional ----> ACTIVE SITE. made up of small numbers of amino acids. Molecule which enzyme reacts with called SUBSTRATE.  fits neatly into a ENZYME-SUBSTRATE COMPLEX

LOCK AND KEY METHOD:

enzyme has a specific shape that will only fit into a specific substate to create the effect of a lock and key method. Supported by the observation that enzymes are specific in their reactions. RIDGID STRUCTRE. 

INDUCED FIT MOLECULE:

Suggested that the enzyme's shape was being altered by the binding site structure was flexible. 

 the enzyme has a certain shape but can alter it in the presence of a substrate. as it changes puts strain on the substrate which breaks the bonds and consiquently lowering the activation energy needed to break the bond.  is a better expalination as it explains:

• how other molecules can affect enzyme activity
• how activation energy is lowered.

To measure prgress of an enzyme-catalysed reaction - time it takes to run its course. two events measured. 1) formation of the products of the reaction. 2) disapperance of the substrate.                                                                                                       EFFECT OF TEMP OF ENZYME ACTION: ---- rise in temperature increases the KINETIC ENERGY of molecules. = more rapid and successful collisions. -----> rate of reaction increases. 

• Although higher body temps increase metabolic rate, advantages offset by additional energy needed to be maintain the higher teperature (more intake of food)
• Other proteins (apart from enzymes) denature
• even higher temps enzymes denature. 

EFFECT ON PH:  ph solution is the measure of hydrogen ion concentration . effects enzymes by ...

• alters charges on the amino acid makes up active site of enzyme ----> sunstrate can no longer bond = enzyme-substrate complex cannot be formed. 
• cause bonds in tertiary structure to break. enzyme denature.                       substrate concentration, more substrate more active stie is filled. addtion of substrate will have no overall effect of the rate of reaction. there is ecess, rate of reaction levels off.

      DIGRAM OF A BACTERIUM.

HOW IS CAUSES DIEASE:

Main symptoms: diarrhoea, constant dehydration.                                                             Transmitted by ingestion of water/food that has been contaminated with  faecial material containting the pathgen. Once ingested causes ...

• most killed by acidicty in the stomach. however some can survive.
• when they reach the small intestine use flagella to propelle them into the mucus lining of the small intestine. 
• prduce toxic protein, on parts binds to specific carbohydrate receptors on cell surface membrane.

EPITHELIAL CELL OF SMALL INTESTINE HAVE SPECIFIC REPTORS EXPLAINS WHY CHOLERA TOXIN ONLY AFFECTS CERTAIN REGION OF THE BODY.

• other part of toxin enters epithelial cell. cuases ION CHANNELS of the cell surface of the membrane to OPEN CHLORINE IONS  normally contained within the epithelial cell to FLOOD IN LUMEN of small intestine. 
• loss of cholrine ions = increase chlorine ions in lumen in intestine lowers its water potential ------> water flows from cells into the lumen. 

• loss of ions from epithelial cells = concentraition gradient. Ions move by diffusion into epithelial cells from the surrounding tissues including blood. ------> water potential gradient that causes water to move by osmosis from blood and other tissues into intestines. 
• loss of water from blood and tissues = symptoms of cholera. 

it is treated by restoring water and ions that have been lost using ORAL RHYDRATION. 

Transmission of Cholera by the ingestion of water or food that has been contaninated by faecial material. may arrise because:

1) drinking water not properly purified

2) untreated sewage leaks into water sources.

3) food dontaminated by people who prepare and serve it.

4) organisms have fed on untreated sewage release into rivers or sea. 

It is to treat diarrhoel diesases vital to rehydrate a patient. 

It contains: water - rehydrate tissues.   Sodium - replace lsot sodium ions fromthe epithelium of the intestineand to make optimum use of the alterantive sodium glucose carrier proteins.     Glucose - stimulate uptake of sodiumk ion = provide energy.    Potassium - replace lost potassium ions + stimulate appetite    Other electolyes - chloride and citrate ions to prevent electrolyte imbalance. 

HOW TO USE ORT

• Boil water - kills bacteria
• Clean glass ( prevent re-infection)
• getting right vol. of water
• can be used to prevent bowl movement
• good based ORT. (Bananas, Maze, Rice.. etc.) strach and glucose broken down gradurally, contain potassium. 

• ATRIUM - think walled and elastic, streches as it collects blood. only has to pump blood short distances = thin muscular walls.
• VENTRICLE - much thinker wall pump blood some distance (lungs or rest of body)
• RIGHT SIDE - pumps blood to lungs ----> less thicker than LEFT SIDE- pumps blood to the rest of the body.
• Both atria and ventricles contract together. 
• between atrium and ventricles are valves prevent back flow  of blood into artia and ventricles when they contract. 2 sets of valves. 

1) LEFT ATRIOVENTRICULAR (BICUSPID) VALVES - foremd of the two cup shaped flaps on the left side of the heart.

2) RIGHT ATRIOVENTRICULAR (TRICUSPID) VALVES -  fored of the three cup shaped flaps on the right side of the heart.

• ventricles pump blood away form the heart. Atria receieve blood from veins. 
• vessels connecting heart to lungs called pulmonary vessels

AORTA -  connected to the left ventricale and carried oxygenated blood to all parts of the body except lungs

VENA CAVA - connected to right atrium and brings deoxygenated blood back from body tissues.

PULMONARY ARTERY - connected to right ventricle and  deoxygenated blood to the lungs where it's oxygen is replenished and its co2 removed.  unusual artery that carries deoxygenated blood.

PULMONARY VEIN - connected to left atrium brings oxygenated blood from lungs. 

CORONARY ARTERIES - supplied by blood vessels to the heart to supply the heart with oxygen. Any blockage here can lead to a myocardinal infarction. (HEART ATTACK) because an area of the heart muscle is deprived of oxygen. 

RELAXATION OF THE HEART: (DIASTOLE)

• bllod returns from atria of heart through pulmonary vein (from lungs) and vena cava (from body) 
• Atria fills PRESSURE RISES. pushing OPEN AV VALVES. 
• muscle walls relax at this stage
• relaxtion of the ventricle wall reduces pressure within the ventricle.
• causes pressure to be lower that aorta and pulmonary artery ----> semi lunar valves in aorta and pulmonary artery CLOSE

CONTRACTION OF ARTRIA: (SYSTOLE)

• muscles of atria wall CONTRACT, forcing remaining blood that they contain into ventricles. 
• blood pushed short distance = atria walls thin.
• muscles of ventricle walls relaxed. 

CONTRACTION OF VENTRICLES ( VENTRICULAR SYSTOLE)

• after short delay ventricles fill with blood
• walls contract simultaneously 
• increasing blood pressure within them forcing shut AV valves + preventing backflow
• pressure rises opening semi-lunar valves pushing blood into pulmonary artery + aorta.
• walls of ventricles much thicker = pump blood further.

VALVES CONTROL BLOOD FLOW:

valves prevent the back flow of any blood. these include...

Atrioventcular valves - between left atrium and ventricle. prev. back flow of blood when ventricles contract means that when ventricle pressure > atrial pressure. closure of valves ensures that when ventricles contract, blood will moves towards aorta + pulmonary artery.

Semi-lunar valves - in aorta and pulmonary artery. prevent back flow of blood into the ventricles when the recoil action fo the elastic walls of htese vessels create BIGGER pressure in vessels > ventricles. 

Pocket valves - in veins occure through the venous systum. when veisn squezzed, blood flows back to heart rather than away from it. 

CARDIAC OUTPUT

(volume of blood pupmed by ONE ventricle of the heart in ONE minute. 

measured in ... dm^3 min -1

depends upon 2 factors

1) the heart rate

2) the stroke volume 

    cardiac output = heart rate x stroke volume

• Cardiac muscle is myogenic (contraction initiated from within the muscle itself, rather than nervous impulses0 
• in wall of right atrium, distinct group of cells - sinoatrial node (SAN) From there the initial stimulus for contraction starts.
• has basic rythum for the stimulation of the heart beat. 
• often refered to the 'pacemaker'

The Seqence Of Events:

1) wave electrical energy spreads from SAN across both atria = CONTRACT

2) layer of non-conductive tissure (atrioventricular septum) prevents wave flowing through ventricles

3) Wave allowed to pass through a 2nd group of cells called the atrioventricular node (AVN) lies between atria.

4) AVN after short delay, convays wave of electrical activity between ventricles along a series of specialised muscle fibres called the bundle of his. 

5) bundle of his conducts the wave through thte atroventricular septum to base of ventricles, where the bundle of his branch into smaller fibres. 

6) the wabe of electrical activity is released fromt hese fibres, causing ventricles to CONTRACT quickly at the same time form the apex of the heart upwards. 

Coronary Heart Disease (CHD) - affects pair of blood vessles, (coronary arteries) which supply oxygen and glucose to the heart muscle.

May be imapired due to the build up of fatty deposits known as atheroma. 

If blood flow to the heart is interupted may lead to a mycardial infarction.

ATHEROMA:   ~ BUILD UP OF FATTY DEPOSITS IN THE WALL ON AN ARTERY.

• begins as fatty streaks that are accumilations of white blood cells that have taken up low-density lipoproteins (LDLs). 
• These streaks form an irregualr patch or atheromatous plaque. - commonly occure in larger arteries, made up of deposits of choleserol, fibres and dead muscle cells. 
• Buldge in the lumen of the artery = narrowing blood flow.
• Increasing the risk of THROMBOSIS and ANEURYSM.

• ATHEROMA BREAKS through the lining (endothelium) of the bloodvessel ----> rough surface that interrupts the smooth flow of blood.
• result in the formation of a blood clot eg. THROMBUS  in a condition known as a thrombosis.
• may block vessel or prevent blood to tissue, which can die due to the lack of oxygen and glucose adn other nutrients. 
• Can be carreid from place to palce and lodges in, and blocks, anotehr artery.

• Atheromas that lead to the formation of a thrombus also weaken the artery walls, 
• these swell to form a balloon like blood filled structure called a ANEURYSM. 
• can frequently burst leading to a haemorrhage and loss of blood from that region of the body served by that artery. 
• A brain aneursym is known as a cerebrovascular accident (CVA) / STROKE.

• commonly known as a heart attack. 
• reduced supply of oxygen to the muscle of the heart.
• it reults in a blockage in the coronary arteries.
• if this occures to the junction of the coronary artery, symptoms milder.(only small area of heart muscle will suffer.

RISK FACTORS

1) SMOKING ~ 2 main ingedients in tabacco smoke increase heart disease. CARBON MONOXIDE, combines easily with the haemoglobin in blood to form oxyhaemoglobin. reduces the amount of oxygen-carrying capacipity of the blood cells. RAISE BLOOD PRESSURE and REDUCE OXGEN TO HEART MUSCLE during exercise. NICOTINE ~ stimulates productiuon of the hormaone adrenaline, which increases heart rate and raises blood pressure. 

2) HIGH BLOOD PRESSURE ~ prolonged stress and lack of exercise increase rate of blood pressure. if high blood pressure in arteries make heart work faster more prone to failing. high pressure in arteries = more likely to develope aneurysm and burst = haemorrage. resist high blood pressure, walls of arteries thicken and may harden = resitricting blood flow. 

3) BLOOD CHOLESTEROL~   cholesterol essentail component in membranes 2 types of cholesterol. high density lipoprotiens (HDLs) - remove cholestrol from tissures transport it to liver for secreation. PROTECT against heart disease. low-density cholestrol - transport cholesterol form lover to tissure, including artery walls which they infiltrate = development of atheroma = heart disease.

4) DIET ~

high levels of salt increase blood pressure

high levels of saturated fat increase low-density lipoproteins levels.

foods that act as antioxcidents (VITIMIN C) reduce risk of heart disease