Biology

definitions and causes

Health- a state of complete physical, mental and social well-being

Disease- a condition with a specific cause in which part or all of the body s made to function in a less efficient manner.

Pathogen- an organism that causes disease includes micro-organisms and larger ones

Pathogenic micro-organisms-includes bacteria, virus and fungus

Causes:

  1. pathogenic organisms - TB, cholera
  2. Lifestyle and working conditions - cancer, heart disease
  3. degeneratve disease- often due to old age
  4. genes- genetic diseases
  5. nutrient deficiency 
  6. social activities- smoking drugs
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Data and disease

Epidemology- study of the incidence of disease and pattern of a disease with a view to finding the means of preventing or controlling it. 

Morbidity- number of people currently living in the diseased state

Mortality- number of people who have died from a specific disease

Reliability- how trustworthy the data is.

CORRELATION DOES NOT PROVE CAUSATION - other factors

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Pathogens and toxins

Bacteria- larger than viruses, can replicate quickly, dont have a nucleu, not all harmful 

Viruses- smallest and simplest organisms, can't survive outside body cells, no nulcues, don't divide themselves, can't reproduce on own. 

Fungi- no stem, leaves or roots, no chlorophyll, consists of a mass of hollow and brancing tubes, can't make own food. 

Toxins- some pathogens damage cells, causes disease to develop, damage casued by releasing toxins.

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Lifestyle and risk factors

Lifestyle- the way a person lives. lifestyle can contain risk factors.

Risk factors:

  1. air pollution
  2. cigarette smoking
  3. excesssive exposure to radiation
  4. alcohol consumption
  5. overwirght/obese
  6. high saturated fat diet
  7. smoking
  8. drinking
  9. physical inactivity 
  10. stress
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Lung structure

Trachea- connects lungs with atmosphere- windpipe

            - held open by c-shaped rings of cartilage- allows air intake & prevent contraction

            - inner lining produces mucus to remove dust 

           - lower end splits into two bronchi 

Bronchi-links to each lung, two dividing from trachea

           - sub-divides mutiple times into very fine branches ( bronchioles) 

Bronchioles- linked to alveoli from bronchi

                  - walls of major ones are stiffened by cartilage to provide support & keep permantely open 

Alveoli- site of gas exchange between air and blood , tiny sacs 

           - millions coverng a very large surface area to take up more oxygen during breathing 

           - surrounded by blood capillaries 

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lung tissue

  • Cartilage- Connective tissue, composed of specialized cells

                         - prevents collapse of lungs when air pressure lowers

                        - allows movement of neck with out airways closing 

 

  • Smooth muscle-devired from embryonic germ cells

                                   - contractiting the lumen of the airways narrows

                                   - action is involuntary  

 

  • Ciliated epithelium- cilia project from cell surface

                                       - move in synchronised pattern, waft mucus up airways- bacteria swallowed there.

  • Goblet epithelium cells - mucus

                                                - traps particles from air- bacteria- reduce risk of infection 

  • Elastic fibres - bundle of protiens found in connective tissue and produced by fibroblasts and smooth muscle cells in arteries

                                - muscels can only contract- deform during progress

  • Aveoli- septal cells- produce alveolar fluid

                      - important to lung function- surfactant 

                     - mantains elasticity and prevents collapse 

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Inspiration and Expiration

Active process- uses energy 

  1. external intercostal muscles contract, internal intercostal muscles relax.
  2. Ribs are pulled upwards and outwards, increasing volume of thorax.
  3. Diaphragm muscles contract, causing it to flatten, also increases volume of thorax
  4. Increased volume of thorax results in reduction of pressure in lungs.
  5. atmospheric pressure is now larger than pulmonary pressure so air is forced into the lungs.

passve process

  1. internal intercostal muscles contract, external intercostal muscles relax.
  2. Ribs are pulled downwards and inwards, decreasing volume of thorax.
  3. Diaphragm muscles relax, causing it to move into upwardly position, also decreases volume of thorax
  4. decreased volume of thorax results in increase of pressure in lungs.
  5. atmospheric pressure is now smalller than pulmonary pressure so air is forced out of the lungs.
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calculations (lungs)

 pulmonary ventilation- total volume of air that is moved into the kungs during a minute 

Pulmonary ventilation = tidal volume * ventilation rate 

Tidal volume- volume of air taken in at each breath at rest 

ventilation rate- number of breathes taken in one minute 

Vital capacity- max volume of air that can be inhaled and exhaled

ventilation rate = tidal volume * breathing rate 

Dead space- air in the bronchi, bronchioles and trachea, no exchange between blood and air.

Ficks Law:

rate of diffusion = (surface area * difference in concentration) / thickness of exchange rate 

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Pulmonary tuberculosis ( TB)

An infectious disease that can affect any part of the body although is usually found in the lungs.

Spread by droplet infection- droplets that reach the alveoli result in following:

  1. Bacteria are engulfed by macrophages but not destroyed. Bacteria multiply rapidly inside macrophange and cause it to burst releasing bacteria.
  2. Around 21 days later T lymphocytes activate the macrophage so they can destroy bacteria. 
  3. If bacteria is not eliminated by immune response, tubercules start to form containg bacteria. 
  4. tubercules cetre alters and bacteria present inside start to mutiply, tubercule grows invading bronchi or arteries. 
  5. Rapid repro of bacteria results in cavities, called consumption, in lungs. 

Symptoms- 

  • fever 
  • night time sweating 
  • loss of weight 
  • persistent cough 
  • constant tiredness
  • loss of appetitie 
  • coughing up blood 
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Asthma

Symptoms: difficulty breathing, wheezing sound, tight feeling in chest, coughing 

affects on lungs: white blood cells invade bronchioles- release histamines causing inflammation 

                            bronchioles more sensitive to asthma attacks 

                            smooth muscles of bronchioles contract narrowing lumen 

                            cells lining bronchioles secret excess mucus 

                            restruction of airflow- reduced gas exchange- difficulty breathing 

Treatment: no cure, reduced by inhaler, relievers- relax smooth muscle, Preventers- reduce underlaying inflammation of bronchioles 

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Emphysema

Symptoms: shortness of breath, chronic cough, bluish skin colouration, hyperventilation 

How it affects lungs: toxins in cigarettes smoke provoke inflammatory response- alveoli wall break down

                                 phagocytotic white blood cells release enzyme elastase- breakes down elastin in conective tissues.

                                 elastin ensures exhaled air is released by allowing elastic recoil of streached alveoli after inhalation.  

                                 walls between alveoli are damaged- lose shape and become floppy 

                                gas exchange affected due to damage meaning fewer alveoli

                                don't empty clearly, CO2 builds up in lungs 

Treatment:

no treatment as irreversible

advised to stop smoking 

avoid high levels of atmospheric pollutants

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pulmonary fibrosis

symptoms: breathlessness, persistent cough, fatigue, weight loss

how it affects lungs: tissue between bronchioles and alveoli scar due to substance 

                                 macrophages engulf bacteria and foreign particles entering connective tissue in alveoli; remove unwanted particles in lymph. 

                                 excess dust- macrophages remain in CT resukting in fibrous tissue forming hard lumps

                                 Breathlessness and poor gas exchange due to scar tissue twisting alveoli and bronchi compressing and reducing tissue elasticity 

treatment: no treatment 

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Blood vessels

Blood goes through>>>

Pulmonary Vein- connected to left atrium, oxygenated blood in from lungs >>>>

Aorta- connected to left ventricle, carries oxygenated blood to all parts of body but NOT lungs >>>>>

Vena Cava- connected to right atrium, deoxygenated blood back from body tissues >>>>>>

Pulmonary artery- connected to right ventricle, deoxygenated blood to lungs >>>>>

Into lungs. 

4 Heart chambers: 

left atrium > left ventricle > right atrium > right ventricle 

Left ventricle has thicker wall than right > carries oxygenated blood, doesn't want it to diffuse

pulmonary vein> left atrium > left ventricle > aorta > vena cava > right atrium > right ventricle > pulmonary artery 

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Cardiac cycle

systole- period of ventricuar contraction

diastole- period of ventricular relaxation

diastole is normally longer than systole

Atrial systole:

  • heart full of blood, ventricles relax
  • atria contracts, blood passes to ventricles
  • atria-ventricular valaves ope due to blood pressure

ventricular systole:

  • atria relax
  • ventricle walls contract, forces blood out
  • blood pressure opens semi-lunr valves 
  • blood passes in aorta & pulmonary artery
  • blood flows from ventricles into arteries

Diastole:

  • Atria and ventricles relax
  • semilunar valves in aorta and PA shut, prevents backflow
  • left and right AV values open 
  • relaxation of ventricle draws blood from atria 
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control of cardiac cycle

Mycogenic- to generate impulses spontaneously contraccting without any external stimulus being applied SAN- produce a wave of eletrical activity that causes the atria to contract 

  • cardiac muscle is mycogenic
  • wave of eletrical activity from SAN spreads acroos both atria causing them to contract
  • layer of non-conductive tissue (AV Values) prevents wave crossing to ventricles 
  • AVN, after short delay, conveys wave between ventricles along specialised musce fibres called Bundle of HIS.
  • Bundle of HIS conducts wave through AV septum to base of ventricles where the bundle branches into smaller fibres.
  • wave of eletrical activity is released from fibres causing ventricles to contract quickly at same time from apex of heart upwards 
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ECG and cardiac output

An ECG trace shows the eletrical activity withina person's beating heart.

ECG can:

  • assess heart rhythm
  • diagnose pooor blood flow to heart
  • diagnose a heart attack
  • evaluate certain abnormalities of  the heart

Cardiac Output:

  • volume of blood pumped by one ventricle of the heart in one minute.
  • dm3min-1
  • cardiac outpu is dependent on heart rate per minute annd stoke volume 

Cardiac output = Heart Rate * Stoke Volume

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Atheroma, Thrombosis, Aneurysm and Angina

Atheroma:

  • a fatty deposit that forms within artery walls
  • fatty deposit bulges into the lumen of the artery 
  • causes lumen to narrow meaning blood flow is reduced

Thrombosis:

  • clotting of blood within a blood vessel 
  • if an atheroma breaks through the lining of the blood vessel it forms a rough surface.
  • results in the formation of a blood clot and prevents smooth flow of blood
  • throumbus blocks the blood vessel reducing/preventing supply of blood to tissues beyond.
  • region of tissue that is deprived of blood dies due to lack of oxygen.

Aneurysm:

  • Balloon like swellling of artery 
  • atheromas that lead to thrombus weaken the artery walls.
  • weakend points swell to form balloon-like, blood-filled structure called an aneurysm.
  • if it bursts leads to a haemorrhage and lacked of blood to the region that the artery serves.

Angina:

  • plaques narrow arteries so blood cant reach tissue proabably
  • if conary arteries are narrowed cand cause breathlessness and cramp pain
  • pain called angina
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Myocardial infarction

Known as a heart attack

refers to a reduced supply of oxygen to the muscle of the heart

results from a blockage in the conary artery, if occurs to close to junction of the artery and aorta the heart will stop beating as  blood suplly will be cut off. 

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risk factors for CHD

Diet:

  • high levels of salt- raise blood pressure
  • high levels of saturated fat- increase low-density lipoprotein levels and hence blood cholesterol concentration

High blood cholesterol level:

  • high dentsity lipoprotiens- remove cholesterol from tissues and transport to liver for excretion. help protect arteries against heart disease.
  • low density lipoprotiens- transport cholesterol from liver to tissues whcih infiltrate leading to development of atheroma and hence heart disease.

Smoking:

  • carbon monoxide- reduces oxygen-carrying capacity of the blood. heart must work harder. can lead to raised blood pressure increasing risk of CHD.
  • Nictone- increases heart rate and raises blood pressure. greater risk of CHD.

High Blood Pressure:

  • weakens coronary arteries
  • higher the blood pressure the greater the risk of CHD
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Nonspecific vs. specific defences

Non specific defences don't distinguish one infectious microbe from another

specific defences recognise and defend against invading microbes and cancer cells

Non specific:

  • physical barrier
  • phagocytosis
  • response immediate same for all pathogens

Specific:

  • response is slower and pathogen specific
  • humoral response- B lymphocytes
  • cell-mediated response- T lymphocytes
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T cells

T cells:

  • only respond to cells that have been invaded by non-self material
  • respond to transplant material
  • only respond to antigens attracted to body cells- cells mediated immunity
  • formed from stem cells found in bone marrow
  • mature in thymus
  • respond to own body cell invasion

Killer T cells:

  • identify an infected cell
  • produce proteins that make holes in the cell surface membrane
  • holes mean cells are freely permeable to all substances
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B-cells

Humoral response- relies on soluble antibodies in the blood and lymph

  1. B-cell is triggered when it encounters its matching antigen
  2. B-cell engulfs the antigen and digests it 
  3. displays antigen fragments bound to its unique MHC molecules
  4. combination of antigen and MHC attracts the help of a mature matching T-cell
  5. Cytokinnes secreted by T-cells help B-cell to multiply and mature into antibody producing plasma cells.
  6. Released into blood, antibodies lock onto matching antigens. Antigen-antibody complexes are cleared by complement cascade or by the liver and spleen. 
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immune response

Pathogen invades

Engulfed by macrophage

Macrophage presents antigen

Triggers response of T-cells



Divide by mitosis and clone:

  1. T-memory- circulates in blookd and tissue fluid ready to respond to future infection
  2. stimulate phagocytes 
  3. T-helper- attach to processed antigens on B-cells activating them, B-cell engulfs antigen and digests/clones, presents the antigen, reproduces, memory cells and plasma cells (secrete antibody to antigen) 
  4. T-killer- makes hole in cell-surface membrane, cell is permeable to all substances so dies.
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Antigenic variability

pathogens that cause disease are of a single type- quickly identified by memory cells when they eneter the body

other pathogens and influenza viruses have over 100 different strains- antigens these viruses are made of are constantly changing along with those they produce----Antigenic variability

Any subsequent infections are likley to be casued by different varieties of the patogen.

antigens won't correspond to antibodies or memory cells formed during previous infections.

only way to overcome the infection is primary response as no memory cells to simulate antibody production.

Primary response:

body reacts asif each infection is new meaning immune response if slower and symptoms develop in the mean time.

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Monoclonal Antibodies

  • Mouse is exposed to non-self antigen to which antibody is required
  • B-cells in the mouse produce antibodies that are then extracted from the spleen of the mouse
  • to enable B-cellls to divide outside body they are mixed with cells that readily divide outside body
  • detergent is used to break open cell membranes to enable them to fuse together
  • fused cells are then seperated and cultivated to form clones
  • all clones then found to be producing required antibody aare grown on a large scale
  • since antibody comes from cells cloned from a single B-cell they are monoclonal
  • antibodies in this way obtained then need to undergo humanisation.
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Vaccincations

Types of vaccine:

  • live-live pathogens
  • inactivted- killed pathogens
  • attenvated- weakened pathogens
  • toxins (made harmless
  • edible vaccines

Vaccination- a method of giving antige to stimulate the immune response through active immunization.

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Digestion of Carbohydrates (starch)

starch >>>>>>>>>> maltose >>>>>>>>>>>>>>glucose (small intestine) 

         amylase                           maltose                   ^

       salivary and then pancreatic                             blood

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-saccharides

Monosaccharides:

  • glucose - C6H12O- hexagon
  • fructose- pentagon
  • glucose and fructose have same chemical formula- arranged differently so are isomers.
  • Glucose in organisms comes in 2 forms- different structures and reactions.

Disaccharides:

  • digestive system breaks food into disaccharides and then monosacharides
  • sugars end in -ose
  • Glucose + Glucose = Maltose
  • Glucose + Fructose = Sucrose
  • Galactose + Glucose = Lactose + Water

Polysaccharides:

  • starch is a polysaccharide
  • large molecules such as starch are insoluble
  • polymers formed by combining many monosaccharide molecules
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carbohydrate identification

Glucose:

is a reducing sugar, solution containing glucose can be identified through using the Benedict's test (changes colour) 

Starch:

identified by using iodine (turns blue/black) 

Sucrose:

is a non-reducing sugar, identified through carrying out the Benedict's test as well as then using hydrochloric solution followed by sodium hydrogen carbonate (turns orange/brown) 

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Protein structure

Primary structure- two or more amino acids joined through condensation reaction- forms peptide bond. 

                           - Joining of amino acids- polypeptide

polypeptide becomes secondary structure

secondary structure- due to hydrogen bonds ordered structures made. 

                              - order of amino acids in primary causes reaction between hyrdogens- results in folding                                    into each other to form twist- Helix.

Teritary structure- covalent bonds and ionic bonds form in primary, bonds are very strong cause shape of                                  polypeptide to change.

                           - if protein heated- unravel and denature- both disulphide and ionic bonds break when                                       heated.

Quaternary structure- multiple polypeptides join.

                                - Non-peptide groups also joined with polypeptides- heme groups. 

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Biuret test

Biurtet test-test for peptide bonds

Take an egg white 

v       protein so contains peptide chains           

Add sodium hydroxide

v        denatures the peptide chain- turns stringy 

Add copper sulphate

v         binds to the peptide bonds

Solution turns lilac

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Oesophagus

  • A thick-walled, muscular long tube
  • leads from mouth to stomach 
  • function: convey food through neck and thorax region to stomach 
  • 3 main layers in gut wall: mucosa, submucosa and muscularis externa allows quick transport of food 

3 layers functions:

  • mucosa- increases surface area, allows expansion
  • submucosa- elastic, allows expansion
  • muscularis externa- provides protection, enables peristlasis

process of peristalsis:

process of which food is squeezed through the tube in the oesophagus and intestine.

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Stomach and small intestine (duodenum)

  • muscular bag with extendable walls 
  • three thick layers of muscularis externa
  • 3 fuctions: stroes food temp, some digestion, absorps substances that don't need digestion
  • stomach lined with gastric glands- secrete gastric juice
  • gastric juice contains: mucus, hyrochloric acid and pepsin 
  • rings of muscle around enterance and exit to stomach act like valves
  • contract- food movement stops
  • relax- food movement resumes
  • wave-like contractions: churns food and mixes with gastric juice- produce semi-liquid mixture

Small intestine:

  • two functions: finish digestion, absorption of food
  • seperated into duodenum and illeum 

duodenum:

  • concerned with digestion
  • recieves secretions from liver (bile) and pancreas (amylase)
  • produces alkaline secretions from the glands: to neutralise acid from stomach, to provide alkaline medium for enzymes.
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small intestine (ileum),large intestine & Colon, r

  • deals with digestion and absorption

Digestion:

  • gands in illeum walls secrete intestinal juice
  • intestinal juice contains several enzymes: to complete carbohydrate digestion, to finish breakdown of proteins into soluble amino acids.

Absorption:

made efficient becuase:

  • internal surface area of small intestine enlarger by: folded nature, villi and microvilli
  • rhythmic contractions of villi help to squeeze end product into the main lymph vessels

large intestine:

  • recieves residue after completion of digestion and absorption in SI
  • consitis of colon, rectum and ****
  • large population of bacteria lives there.

Colon function: reabsorption of water colon and rectum: secrete mucus for lubrication Rectum: stores faeces until forced out of **** by muscle contraction

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salivary glands and pancreas

salvia:

  • lubricates and binds food together into a bolus for swallowing 
  • secreted into mouth from 3 pairs of salivary glands 
  • contains starch digestive enzymes which catalysis the hydrolysis of starch into maltose sugar
  • Ph7 

Salivary amylase contributes little to digestion- as food remians in mouth for short time 

carry out digestion outisde cells 

Pancreas

between duodenum and stomach 

Amylase passes down pancreatic duct in duodenum 

pancreatic juice contains: 

  • sodium bicarbonate- nutralises stomach acid
  • amylase
  • lipases
  • endopeptidases 
  • exopeptidases
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Organelles

SER:

  • description-tubular system of memebranes without ribosomes, near nucleus
  • functions-synthesise, store and transport lipids and carbohydrates.

RER:

  • description- layered collection of flattened cavitites covered with ribosomes, near nucleus
  • functions- protein synthesis and glycoproteins and pathway for transport of materials.

Golgi apparatus:

  • description- stck membrane-bounded vesicles, near plasma membrane
  • function- recieves and assembles substances

Lysosome:

  • description- membrane-bound vesicle containing digestive enzymes
  • functions- responsible for reorganising cells involved in metamorphosis. destroys unwanted substances

Mitochondria:

  • description- rod-shaped organelles smooth outer membrnae and folded inner membrane with folds called cristae. 
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Microscopes

Magnification-how much an object is enlarged under a microscope

resolution- the smallest scale division of a particular measuring instrument 

transmission electron microscopy:

  1. shine a beam of electrons through prepared sample and onto photographic paper
  2. if beam hits something electron is absorbed
  3. if electron is absorbed when light photographic film, leaves dark patch

Issues: 

  • must be in a vaccum
  • sample must be really thin
  • staining process complex, cause artefacts to appear (not originally there)
  • only does b&w

Scanning electron microscopy:

  1. scan surface of object- fire electrons from above
  2. electrons bounce of surface
  3. from way the scatter- work out what image looks like

Issues:

  • same issues as TEM but electrons dont penetrate doesn't need to be thin
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testing for lipids/ emulsion

  1. take a test tube
  2. to 2cm3 of sample add 5cm3 of ethanol
  3. shake tube throughly to dissolve sample
  4. add 5cm3 of water and shake gently
  5. cloudy white colour presence of lipid
  6. repeat with other fats also with water (test sample)
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cell surface membrane

phospholipid bilayer:

great as allows:

  • lipid-soluble stuff to cross the membrane with ease
  • prevention of anything crossing that is water-soluble. membrane has special adaptitions to control how many get it. 
  • flexability- cells can easily change shape when squeezed or streched. 

Protiens:

  • help cells stick together
  • make overall structure stronger
  • act as receptons

Fluid-mosaic model:

  • Fluid: nothing is in a rigid position, stuff moves around, whole structure flexible 
  • Mosaic: lots of different sized bits that lock together 


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Diffusion

Two reasons:

  • empty spaces between molecules of all substances
  • all molecules in constant random movements- kinetic enrgy allows the to collide and intermingle.

passive process- no energy required

takes place in both gases and liquids

net movement of molecules from high conc to low con 

con grad- difference in con between regions before diffusion occurs

Simple diffusion: molecules move from areas of higher concentration to lower areas.

Facilitated diffusion: special carry protein with essential channel acts as selective corridor- helps molecules move acroos membrnae. this proteins bind only to a specific molecule. after protien helps or facilities diffusion process by changing shape and moving molecule down its concentration gradient.

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effects on diffusion

surface area:

  • all organisms exchange food, oxygen, waste and heat with environment--- diffusion
  • rate of diffusion affected by organism's surface area. materials have to be tansported to all partss of these surfaces
  • larger surface area = greater rate of diffusion
  • fast rate of fiffusion achieved by large SA, high conc grad & small distance

concentration difference:

  • rate of diffusion directly proportional to conc grad across cell membrane- net movement of diffusing substancce
  • rate of diffusion increases as conc grad increases
  • diffusion speed up by raising conc of diffusing substance
  • steep conc grad acroos the alveoli wall maintained by: oxygen diffuses from air to blood, carbon dioxide diffuses from blood to air

Thichness of the exchange surface:

  • unicellular organisms and small multicellular organisms exchange gases directly across cell membrane 
  • large multicellular organisms can't maintain gas exchange by diffusion- develop special respiratory
  • further particle must diffuse- longer it takes and slower the rate of diffusion 
  • alveoli in lungs are thin-walled so diffusion rapidly across shorter distance
  • gas exchange across thin membrane
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Osmosis and Water potential

  • passive process
  • no energy required
  • applies to water and permeable membranes that allow certain molecules to pass
  • net movement of water molecules from high water con. to lower water conc. 
  • water molecules diffuse until water potential is same on both sides of membrane
  • water potentiall gradients- difference in con. of water molecules between two regions

Water potential:

  • measures potential energy of water
  • measured in negative values
  • more water >> higher water potential = lower negative value
  • more solutes>> lower water potential = higher negative value
  • in osmosis, water moeules move from high to lower water potential 
  • factors that affect it: addition of solute: lowers water potential, increase in pressure: raises water potential 



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Active transport and carrier protiens

Active transport:

movement of molecules:

  • against conc grad
  • low conc >>> high conc

requires enerrgy from ATP

Carrier proteins:

  • nteggral membrane proteins that bind to specific molecules or ions and transport them through lipid bilayer of the membrane 
  • very specific for kinds of molecule or ions will be transported
  • binding sites for specific ions- make contact cause carrier proteins to change shape and move ions across membrane- relaeasing them.
  • sodium pump is a carrier protien in neuron membranes that move sodium ios out of cells
  • pumping process uses energy supplied by breakdown of ATP
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Absorption

Absorption of carbohydrate digestion products: 

  • absorption takes place over large surface area of folds, villi and microvilli- increases rate
  • end product (glucose) absorbed into blood capillaries through ileum wall
  • movement of absorbed food out of villi ito blood is assisted by rhythmic contractions of villi

Sodium ions:

  • glucose and amino acids absorbed into blood capillaries partly by facilitated diffusion an active transport
  • glucose carrier proteins and amino acid carrier proteins rely on help of sodium ions. 

In glucose absorption:

  • glucose and sodium ions bind to glucose carrier protein
  • by facilitated diffusion- glucose diffuses into blood capillaries throgh glucose channel protein
  • by active transport- sodium ions transported out of cell through pump

In amino acids absorption:

  • amino acids and sodium ions bind to amino acid carrier protein
  • by facilitated difusion- amino acids diffuse into blood capillaries through amino acid channel protein
  • by active transport- sodium ions are transported out of cell through pump
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cholera bacterium

cholera bacterium cell is prokaryotic:

  • doesn't contain nucleus
  • no membrane-bounded organelles
  • smaller than eukaryotic cell
  • DNA is circular

Flourishes in places with inadequate water treatment, poor sanitation, inadequate hygeine

survive in natural environment in brackish rivers and coastal waters

casues cholera- produces watery diarrhoea and vomiting

progess to dehydration- sometime death

predominatly transmitted through water

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structures of bacterias

present in all bacteria:

cell wall- maintain shape of cell, protects against bursting

Cell-surface membrane- seperates interior from outside enevironment, controls movement in and out

circular DNA- contains genetic information to make proteins- not associated with proteins

Not always present in all bacteria:

Flagellum- whip-like flagella lash from side to side- propel body along

capsule- outside cell wall, provides extra protection, stops cell drying out

plasmid- small circular loop of DNA in cytoplasm, carries extra genes for antibiotic resistance, not associated with proteins.

Eukaryotic- nuclues. nuclear membrane, linear DNA, organelles

prokaryotic- no nucleus, circular DNA, no organelles

 

 

 

 

 

 

 

 

 

 

 

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Oral rehydration solution

Mixture of salt and sugar

helps replce fluids lost in diarrhoea

When reaches small intestine, sugar removed from lumenn to the epithelium through villi

Sugar makes absorption more effectient

Salt promotes water absorption 

Water- rehydration

Sodium- increases activity of sodium- glucose channels

Glucose- gives cells additional energy

Potassium- replaces lost ions + increases appetite

Other electrolytes- brings everything back into balance

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phagocytosis

Microbe detected by phagocyte by chemicals it gives off

sticks microbe to its surface

engulfs microbe - wraps it in vesicle

phagosome formed- encloses microbe in membrane

fuses with lysosome - contains powerful enzymes

microbe broken down by enzymes 

indigestible material discharged from phagocyte cell 

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