P1B - Organisation 2

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Tissue

Group of cells w similar structure and function

Organ

Group of tissues working together for a specific function.

• e.g stomach has muscle and glandular tissue, releasing enzymes.

Organ system

Groups of organs which work together to form organisms.

Main food nutrients + the type of molecule they are

All are large molecules. Too large to be absorbed into blood. Must be digested.

• carbohydrates (starch)

• protein

• lipids (fats)

Digestion

• Large food molecules broken down into small molecules by enzymes.

• Small molecules can then be absorbed into blood.

• These digestion products are used by the body to build new carbohydrates, lipids and proteins.

• Some glucose produced is used in respiration.

1st: Mouth function

• food is chewed.

• saliva enzymes begin digesting starch into smaller sugar molecules.

2nd: Oesophagus function

• food passes through oesophagus into stomach

3rd: Stomach function

• enzymes begin digestion of proteins

• has hydrochloric acid, helping the enzymes

• food spend several hours inside

• churning action of muscles turns food to fluid, increasing SA for enzymes to digest

4th: small intestine function

• when fluid’s inside, pancreas releases enzymes that continue starch and protein digestion, and begin lipid digestion.

• liver releases bile, speeding up lipid digestion. bile neutralises acid released from stomach

• small intestine walls release enzymes to continue lipid and protein digestion

• small food molecules produced are absorbed into blood by diffusion or AT

5th: large intestine function

• water from fluid is absorbed into blood

• faeces

V1 digestive system

Enzyme

• catalyse chemical reactions

• large protein molecules and have groove on surface (active site)

• active site is where substrate attaches

enzyme process and conditions

• active site and substrate MUST fit perfectly, attaching

• enzyme breaks down substrate into products

• not a perfect substrate fit = enzyme can’t break it down

• enzymes are specific (lock and key theory)

protein enzyme and where its located

proteases

• stomach

• pancreatic fluid

• small intestine

protein structure and digestion steps

long chains of chemicals called amino acids:

• when digesting proteins, protease convert them back to individual amino acids, which are then absorbed into the blood.

• when absorbed by body cells, they join in a diff order to make human proteins

Carbohydrate enzymes, and specific e.g location

carbohydrases

• amylase in saliva and pancreatic fluid

starch (carbohydrate) structure and digestion steps

Chain of glucose molecules:

• broken down by amylase (carbohydrase)

• when carbs like it are digested, produce simple sugars

lipid structure and digestion steps

Molecule of glycerol attached to 3 molecules of fatty acids.

• digested by the enzyme lipase

• produces glycerol and fatty acids

lipids enzyme and location

• lipase

• in pancreatic fluid and small intestine

bile’s purpose + creation and storage place

• made in liver, stored in gall bladder

• speeds up digestion of lipids but NOT an enzyme

• converts large lipid droplets into smaller droplets

• bile emulsifies the lipid = increasing lipid droplet SA = increased lipid breakdown rate by lipase

bile’s pH and purpose for pH

• alkaline, neutralising the stomach acid = alkaline conditions in small intestine

• this increases rate of lipid digestion by lipase

V2 digestive enzymes

temp effect on enzyme

1. increase temp = enzyme activity increases

   • because enzyme and substrate are moving faster, so more collisions/sec happen between them

2. Optimum temp = at a certain temp, enzymes work at fastest possible rate

   • max frequency of successful collisions between both

   • temp is usually 37C - body temp

3. Temp past optimum = activity rapidly decreases to zero

   • at high temp, enzyme molecule vibrates and active site changes

   • no longer perfect fit = active site has denatured = can’t catalyse

pH effect on enzyme

1. enzyme has an optimum pH = activity is maximum

   • each one has a specific optimum pH (protease better in acidic, lipase in alkaline)

2. if made more acidic/alkaline = activity is zero

3. active site denatures if conditions are too acidic/alkaline

V3 - effect of temp and ph on enzyme activity

RP5: effect of pH on amylase

1. One drop of iodine solution into each well of a spotting tile.

2. 1st test tube - 2cm³ starch solution, 2nd - 2cm³ amylase solution, 3rd- 2cm³ pH 5 buffer solution (controls the pH)

3. Place all into water bath at 30C. Leave for 10 mins to reach correct temperature

4. Combine all 3 into one test tube, mix w stirring rod, return immediately to water bath and start stopwatch.

5. After 30 secs, transfer 1 drop of solution to a well using a stirring rod

   • iodine should turn blue-black, showing that starch is present

6. Take a sample every 30 seconds, stop when iodine remains orange

   • starch is no longer present (reaction is completed)

   • record time for this in our results

7. Repeat entirely several times using diff pH buffers, 6,7,8.

RP5: pH effect on Amylase ISSUES

• only taking samples every 30 secs = only have approximate time for complete reaction

  • address by taking sample every 10 secs

• time for iodine not going blue-black is not always obvious - colour change is gradual, some wells may have a bit of blue-black mixed w orange, so hard to see when reaction has finished

  • ask several people to look and decide

V4 RP5: effect of pH on amylase

RP4: food tests setup

1. safety goggles must be worn due to harmful work chemicals

2. take food sample, grind with distilled water using mortar and pestle = paste

3. transfer to beaker, and add more distilled water. stir so chemicals in the food dissolve in water

4. filter to remove suspended food particles

RP4: starch test

1. 2cm³ of food solution into a test tube

2. few drops of iodine solution (orange)

3. present, iodine = blue-black, not = stays orange

RP4: sugars test

1. 2cm³ of food solution into a test tube

2. 10 drops Benedict’s solution (blue) in test tube

3. put test tube into beaker w half-filled water from kettle

4. leave for 5 min

5. present = benedict changes colour

   • colour gives idea of amount of sugar present but NOT exact

   • green = small amount

   • yellow = more sugar

   • brick-red = a lot of sugar

6. ONLY works w certain “reducing sugars” (glucose). Doesn’t work w “non-reducing” (sucrose).

RP4: protein test

1. 2cm³ of food solution into a test tube

2. add 2cm³ of biuret solution (blue)

3. present = biuret is purple/lilac

RP4: lipids test

1. during the setup DO NOT FILTER the solution

   • lipid molecules can stick to filter paper

2. 2cm³ of food solution into a test tube

3. few drops of distilled water and ethanol.

   • ethanol = highly flammable. no flames around.

4. gently shake - present = white cloudy emulsion

v5 - RP4: food tests

small intestine adaptations for rapid diffusion rate

• 5m = very large SA for absorption

• millions of villi cover inside = increase SA for absorption

  • microvilli on villi = increase SA even more

• villi have very good blood supply = bloodstream rapidly removes digestion products = increases conc gradient

• villi have thin membrane = short diffusion path + molecules that can’t be diffused are absorbed by AT

V6 - Absorption in the Small Intestine

Fish vs Human circulatory system

• fish - single: oxygenated from gills to organs, deoxygenated from organs to heart to gills.

• human - double: lungs to heart to organs = oxygenated, organs to heart to lungs = deoxygenated

Hearts chambers:

• right and left atrium

• right and left ventricle

• always shown as if your looking at the person

Main vessel in the heart and purpose:

1. vena cava = brings deoxygenated blood

2. blood goes through heart to lungs = pulmonary artery

3. oxygenated blood from lungs to heart = pulmonary vein

4. blood is pumped from heart to body = aorta

Process of blood flow in heart

1. blood enters the left and right atrium

2. atria now contract and blood is forced into ventricles

3. ventricles now contract and force blood out of the heart

4. valves stop the blood from flowing backwards into atria when ventricles contract

5. Left side of heart = thicker muscular wall since it pumps blood round body and needs to give a greater force, right ventricle only to lungs.

Coronary arteries location and purpose

• branch out of aorta and spread out onto heart

• provide oxygen to muscle cells of heart = respiration for contraction energy

Pacemaker:

• group of cells control resting heart rate in the right atrium

• stops working = artificial pacemaker

  • small electrical device that corrects irregularities in heart rate

V7 - Heart and Circulation

Arteries structure and purpose

• carry very high pressure blood from heart to organs

• thick muscular walls = withstand very high pressure of blood

• blood travels through them in surges w every heart beat = pulse

  • to cope, elastic fibres stretch when surge passes, and recoil between surges which keeps blood moving

Capillaries structure and purpose

• as blood passes through them, substances like glucose and oxygen diffuse from blood to cells

• carbon dioxide diffuses from cells back to the blood

• very thin walls = very short diffusion pathway = rapid substance diffusion between body and blood cells

Vein purpose and structure

• after blood passes organs, goes back to heart by veins

  • blood travels slowly at low pressure = stop or go backwards

• thin wall since blood pressures low

• many have valves = stop blood flowing backwards

  • valves open in correct direction, shut in wrong

V8 - Arteries, veins and capillaries

Blood plasma transports:

• the liquid part - transports dissolved substances around the body:

  • soluble digestion products (glucose) from small intestine to other organs

  • co2 (made by aerobic respiration) from organs to lungs to be breathed out

  • urea, the waste product from liver to the kidneys to be excreted in urine

Red blood cells transport:

• transport oxygen from lungs to body cells

• contain oxygen-carrying molecule haemoglobin

  • haemoglobin + oxygen —happens in lungs→ oxyhaemoglobin

  • oxyhaemoglobin —happens in organs→ haemoglobin + oxygen

• no nucleus = more haemoglobin room

• biconcave disc (centre dimples) = greater SA for rapid oxygen diffusion

White blood cells:

• form part of the immune system (e.g making antibodies)

• contain nucleus = DNA encodes instructions that they need to do their job

Platelets

• tiny fragments of cells - help blood to clot

Donated blood uses in medicine

1. replace blood lost during injury

2. some people are given platelets extracted = help clotting

3. proteins extracted from blood can also be useful (e.g antibodies)

Blood transfusion conditions

• donated blood is same as patients type = doesn’t reject and kill patient

• in UK blood is screened for infections = low risk of diseases transmitted via blood

v9 - Blood

Cardiovascular diseases

• diseases of heart and blood vessels

• non-communicable = not infectious, can’t be passed from person to person

Coronary heart disease - cardiovascular disease

• layers of fatty material build up inside the coronary arteries = they narrow

  • body wants to reduce blood flow through them = lack of oxygen for heart

  • extreme cases = heart attack (starved of oxygen)

Coronary heart disease treatments

• statins = drugs that reduce cholesterol blood levels = slows down rate that fatty materials build up in coronary arteries

• reduce the risk = effective

  • unwanted side-effects (e.g liver problems)

Coronary heart disease treatments 2

• stent = for almost total blockages

• a tube thats inserted to keep it open

  • blood can flow normally

  • but doesn’t prevent other regions from narrowing (doesn’t treat underlying causes)

Valve problems - cardiovascular disease

• heart valves don’t fully open so heart pumps extra hard to get blood through = heart englarges

• OR valves are leaky = weak and tired patient

Solutions of valve problems

• Replace with Mechanical Valve made of metal

  • can last a lifetime

  • but increase blood clot risk = need anticlotting drugs

• Animal valves (pig)

  • don’t last as long and need replacement

  • patients don’t need to take drugs

Heart failure problems and solutions

• Heart failure is when cardiovascular diseases mean that heart can’t pump enough blood around

• Donated heart or heart and lungs

  • not enough hearts available to treat every patient

  • patients need drugs to stop heart rejection by bodies immune system

• Artificial hearts = temporary solutions while waiting for heart transplant OR to allow damaged heart to rest

  • increase risk of blood clotting

  • not long term solution to heart failure

v10 - cardiovascular diseases

Gas exchange in the lungs

1. air passes into the lungs through a tube called the trachea

   • rings of cartilage prevent trachea from collapsing during inhalation

2. trachea splits into 2 smaller tubes called bronchi, 1 to each lung

3. bronchi subdivide into many smaller tubes called bronchioles

4. bronchioles end in tiny air sacs called alveoli (huge number, microscopic)

5. alveoli = where gases diffuse in and out of the bloodstream

Alveoli rapid gas exchange adaptations and process

Process: Oxygen in air diffuses into blood stream, co2 diffuses out back into air.

Rapidly done by:

• Millions of them = huge SA for lungs

• very thin walls = very short diffusion pathway

• very good blood supply = once o2 is diffused into blood, it’s rapidly removed = concentration gradient is as steep as possible

Breathing + gas exchange in the lungs

Breathing = rate of diffusion increases

• brings in fresh o2 to alveoli and takes away co2

• makes concentration gradients high for these gases

v11 - gas exchange in the lungs

Tumour creation

• Mitosis = tightly controlled. Genes in nucleus tell cells when to divide and not.

• Changes in these genes = uncontrolled growth and mitosis

Benign tumours

• growth of abnormal cells found in one area, usually contained within a membrane

• do not invade other parts of the body, stay in one place

Malignant tumours

• invade neighbouring tissues and move into the bloodstream = cancer

• once in the bloodstream, malignant cells spread to different body parts and form new tumours (secondary tumours)

Cancers linked to genetics

• certain breast types

• prostate

• large intestine

Cancers liked to lifestyle

• Smoking - lung cancer

• Ultraviolet light - skin cancer

• Alcohol - mouth and throat cancer

Substance in our environment that links to cancer

Radon:

• radioactive gas that increases risk of lung cancer

• releases ionising radiation which damages cell DNA

• causes uncontrolled cell division

v12 - cancer

Communicable (CD) and Non (ND) diseases

• CD - spread from person to person (e.g measles), spread by pathogens like bacteria or viruses

• ND - can’t be passed from person to person. Caused by risk factors (e.g coronary heart disease)

Health, disease interaction and causes

• Health - state of physical and mental well-being

• Ill health can be caused by CD/ND, poor diet, high stress and other life-situations (e.g working with harmful chemicals)

• different types of diseases can interact

Tuberculosis (TB)

• Communicable lung disease, fatal

• immune system fights TB, but defective immune system (HIV) is more likely to suffer from infectious diseases

• e.g one disease increasing risk of another

Human papilloma virus (HPV)

• extremely common, mostly harmless

• can cause cervical cancer (3000 women/yr in UK)

• infects cervix cells

• e.g one disease causing another disease

Allergies

• body is infected by pathogen, which immune system fights off but the person is then left with an allergy

• Asthma or dermatitis

• e.g disease triggered by the immune system

Arthiritis

• joint condition

• difficult to move and live a normal life = isolated and depressed

• e.g mental illness triggered by a physical illness

V13 - Communicable and Non diseases

Lung cancer studies, graph and history

• epidemiology meaning

Studying patterns of disease to determine risk factors = Epidemiology

• 1930s: lung cancer rates had a sharp increase

• Scientists looked at lifestyle habits to find links (correlation):

  • more common among smokers = positive correlation

• Correlation =! cause. Graph doesn’t prove that smoking causes lung cancer. It only suggests they might be linked.

  • if x-axis = numbers of years of smoking, you also get a positive correlation

Causal mechanism

• Scientists looked at how smoking could cause cancer

• Found that smoke has chemicals that damage DNA and increase cancer risk = Carcinogens

Sampling issues

• If investigating whether a disease is linked to diet, we want to look at every single person’s diet and then the chances of them developing the disease.

• It’s not possible to sample every single person.

  • Scientists sample a group of people and try to draw conclusions about whole population.

• Biased sample

Biased sample

• Sample from only one town may not represent the entire population, so we can’t use these for conclusions about whole country.

  • might exercise less than average OR

  • exposed to certain pollution only found in that town

Avoiding bias

• large sample

• random

• cannot draw conclusions from a small or non-random sample

v14 - correlating risk factors

ND examples

Not person to person or pathogens:

• cardiovascular diseases

• type 2 diabetes

• most cancers

Risk factors for cardiovascular diseases

• high fat, low veg diet increases certain types of cholesterol levels in the blood

  • this increases the rate that fatty materials build up in arteries

• high salt diet increases blood pressure

  • increasing the risk of developing this

• smoking increasing risk

• regular exercise decreases risk

Risk factors for lung disease and cancer

• smoke has chemicals that damage DNA and massively increase cancer risk = Carcinogens

• smoking also increases risk of other lung diseases; emphysema

• both lead to very poor quality of life

Smoking when pregnant

• increases miscarriage risk and premature death

• leads to birth with low body-mass

Drinking alcohol when pregnant

• fetal alcohol syndrome = learning difficulties and other mental/physical problems

Drinking alcohol on adults

• excessive = increase risk of liver cirrhosis/cancer

• brain - addiction and memory loss

Type 2 diabetes and how risk factors interact

• struggle to control their blood glucose levels

• can lead to blindness

• may need limb amputation

• obese = higher risk. Risk factors can interact; excess alcohol can lead to obesity

v16 - Lifestyle and disease

Leaf def and tissues

A plant organ that contains different tissues:

• upper and lower epidermis

• waxy cuticle

• stomata

• guard cells

• palisade mesophyll

• spongy mesophyll

• xylem

• phloem

Epidermal cells function and location

• top and bottom of the leaf are covered by a layer of very thin cells

• epidermis protects the leaf’s surface

• upper epidermis

  • transparent = light can pass through to the photosynthetic cells bellow

  • covered with waxy cuticle

• lower epidermis

  • has tiny pores called stomata

Waxy cuticle

• cover the upper epidermis with a thin layer of oily material

• reduces the evaporation of water from the surface = prevents from drying out

Stomata

• on the lower epidermis

• allow co2 to enter the leaf and oxygen to leave

• help control water vapour amount that passes out

• guard cells on either side

Palisade mesophyll

• palisade cells are packed full of chloroplasts (contain chlorophyll, absorbs light needed for photosynthesis) where photosynthesis takes place

• underneath there is spongy mesophyll

Spongy mesophyll

• full of air spaces which allow co2 to diffuse from stomata through it to the palisade cells

• other way round for o2 - palisade to spongy to stomata