[B2] Organisation

What is a tissue?

A group of similar cells that work together to perform a specific function

What is an organ?

A group of tissues performing specific functions

What is an organ system?

A group of organs working together to form an organism

How does bile emulsify fats? (3)

It breaks fats into tiny droplets

This gives fats a bigger surface area for the enzyme lipase to work on

This makes its digestion faster

Give examples of tissues

muscle tissue, nervous tissue

Give examples of organs

heart, stomach, brain

Give examples of organ systems

digestive system, nervous system

What does the digestive system do?

Breaks down and absorbs food

What are enzymes?

They are large molecules (proteins) which make chemical reactions faster in living organisms

Why can enzymes be described as biological catalysts?

they increase the rate of chemical reactions in living organisms

Why do enzymes usually only catalyse one reaction?

the shape of their active site is specific to one reaction

What is the role of the stomach and small intestine in the digestive system? (2)

They both digest food

The small intestine absorbs soluble food molecules

What is the role of the large intestine in the digestive system?

Absorbs water from undigested food (leaving faeces)

The substance that an enzyme acts on is called the...

Substrate

Enzymes have an optimum ___ and ___, which is often ___.

Temperature, pH, Neutral

What is meant by an enzyme being "denatured"? Describe how this happens and what leads up to it. (4)

An increase in temperature will increase the rate of reaction until the enzyme reaches its optimum temperature

At a certain temperature, bonds in an enzyme are broken

This changes the shape of the active site

The substrate doesn't fit anymore

Amylase activity practical (12)

Put a drop of iodine solution into every well of a spotting tile

Place a bunsen burner on a heatproof mat and a tripod and gauze over the bunsen burner

Put a beaker of water on top of the gauze and heat it until it reacher 35°C (measure using a thermometer)

Try to keep the water temperature constant throughout the experiment

Put a boiling tube in the beaker

Use a syringe to add 1cm3 of amylase solution and 1cm3 of a buffer solution (pH 5) to the boiling tube

Use a different syringe to add 5cm3 of a starch solution to the boiling tube.

Immediately mix the contents and start a stopwatch

Use continuous sampling to record how long it takes for the amylase to break down all of the starch.

Do this by using a pipette to take a sample from the boiling tube every 30 seconds and putting a drop into different wells of the spotting tile. W

Then the iodine solution remains browny-orange, starch is no longer present

Repeat the experiment with buffer solutions of different pH values to see how pH affects the time taken for the starch to be broken down.

The enzymes used in digestion are produced by ___ and then released into the ___ to mix with food.

specialised cells in glands and in the gut lining, gut.

What do enzymes do to starch, proteins and fats, and why? (3)

They are molecules too big to pass through the walls of the digestive system

So they can't be absorbed into the bloodstream

Enzymes break them down into smaller, soluble molecules

Give 4 examples of smaller molecules that result from enzymes breaking down starches, proteins and fats.

Sugars (e.g. glucose and maltose)

amino acids

glycerol

fatty acids

Starch is a....

Carbohydrate

In what three places is amylase made?

Salivary glands

Pancreas

Small intestine

What is amylase and what does it do? (2)

It is a carbohydrase

It catalyses the breakdown of starch into maltose and other sugars like dextrins

What do proteases do?

Convert proteins into amino acids

In what three places are proteases made?

The stomach (it's called pepsin there - pepsin is one type of protease)

The pancreas

The small intestine

What do lipases do?

Convert lipids into glycerol and fatty acids

In what two places are lipases made?

Pancreas

Small intestine

What does the body do with the products of digestion? (2)

Make them into new carbohydrates, proteins and lipids

Some glucose is used in respiration

Where is bile produced?

In the liver

Where is bile stored before it's released into the small intestine?

The gall bladder

Why and how does bile neutralise stomach acid? (4)

Hydrochloric acid in the stomach makes the pH too acidic

This means enzymes in the small intestine don’t work properly

It is alkaline so it neutralises the acid and makes conditions alkaline

This is best for enzymes in the small intestine

An enzyme controlled reaction was carried out at pH 4. After 60 seconds, 33cm3 of product had been released. Calculate the rate of reaction in cm3 s-1.

33/60 = 0.55cm3 s-1

What is the formula used to calculate the rate of reaction for a certain pH? (2)

Amount of product formed = change/time(s)

units: cm3 s-1 or cm3/s

What enzyme do the salivary glands produce?

Amylase

What digestive enzyme does the stomach produce? What other substance is produced by the stomach and why? (2)

Pepsin (a type of protease)

Hydrochloric acid, to kill bacteria, and to give the right pH (2) for pepsin to function

What is the function of the stomach? (3)

Pummels food with its muscular walls

Produces pepsin

Produces HCl - to kill bacteria, and to give the right pH (2) for pepsin to function

What is the function of the liver?

To produce bile

What is the function of the pancreas?

Produces the enzymes protease, amylase and lipase and releases these into the small intestine

What is the function of the small intestine? (2)

Produces the enzymes protease, amylase and lipase to complete digestion

Here, nutrients from digested food are absorbed into the blood

What is the function of the rectum?

This is where faeces is stored before it is excreted through the anus

Before doing a food test, how would you prepare a food sample? (3)

Break a piece of food up with a mortar and pestle

Transfer it to a beaker and stir in some distilled water

Filter out any solid bits of food

How would you test for reducing sugars?

Using the Benedict's test

How would you test for starch?

Using iodine solution

How would you test proteins?

Using the biuret test

How would you test for lipids?

Using the Sudan III test

What would be a positive result for the Benedict's test? (2)

Testing for reducing sugars

The solution starts off blue, then can change to green, to yellow and to brick-red, depending on the concentration of sugar

What would be a positive result for the iodine solution test? (2)

Testing for starch

The solution will change from browny-orange to blue-black

What would be a positive result for the Biuret test? (2)

Testing for proteins

The solution will change from blue to pink to purple

What would be a positive result for the Sudan III test? (2)

Testing for lipids

The mixture will separate into 2 layers, the top one (containing the lipids) will be bright red

What is the thorax? (2)

The part of your body between the neck and the abdomen

It is separated from the lower part by the diaphragm

What surrounds the lungs? (3)

Pleural membranes

Intercostal muscles

Protected by the ribcage

The air you breathe in travels through the __, which splits into 2 tubes called the __ (each one is a __), one going to each lung.Each of these splits into progressively smaller tubes called __, which finally end at small bags called __.

Trachea Bronchi Bronchus Bronchioles Alveoli

Where does gas exchange happen? (2)

The lungs contain millions of tiny air sacs, called alveoli, surrounded by a network of blood capillaries

Gas exchange happens between the alveoli and capillaries

Describe what happens during gas exchange. (4)

Blood passing through capillaries by the alveoli has just returned to the lungs from the body, so it contains lots of carbon dioxide and very little oxygen.

An alveolus contains air just breathed in, so it contains lots of oxygen and very little carbon dioxide

Oxygen diffuses out of the alveolus into the blood

carbon dioxide diffuses out of the blood into the alveolus, to be breathed out

Describe how gas is exchanged between body cells and capillaries. (3)

When blood reaches body cells, oxygen is released from red blood cells and diffuses into body cells

Carbon dioxide diffuses out of body cells and into the blood

The blood is then carried to the lungs

Through which vein does blood flow into the right atrium?

The vena cava

Which blood vessel carries blood to the heart muscles?

The coronary artery

Through which vein does blood flow into the left atrium?

The pulmonary vein

Through which artery does blood flow out of the right ventricle?

The pulmonary artery

Through which artery does blood flow out of the left ventricle?

The aorta

Why does the heart have valves?

To assure that blood flows in the right direction - to prevent it flowing backwards

Humans have a double circulatory system. Describe the flow of blood through each circuit and how they fit together. (4)

In the first circuit, the right ventricle pumps deoxygenated blood to the lungs, to take in oxygen

the blood then returns to the heart

In the second circuit, the left ventricle pumps oxygenated blood to all our organs

deoxygenated blood returns to the heart to be pumped out to the lungs again

Where in the heart is the natural pacemaker?

In the wall of the right atrium

How does the heart's natural pacemaker work? (2)

It is a group of cells which produce a small electric pulse which spreads to the surrounding muscle cells, causing them to contract

This causes the heart to beat regularly

Describe the structure of arteries and how this relates to their function (3)

Strong, thick and elastic walls to carry blood pumped out by the heart at high pressure

Thick muscular layer and elastic fibres

Small lumen to maintain the high pressures of blood

What happens when the atria in the heart relax?

The atria fill with blood

What happens when the atria in the heart contract?

Blood is forced into the ventricle

Describe the structure of veins and how this relates to their function. (4)

Walls thinner than arteries' as blood is at lower pressure

Elastic fibres

Big lumen to help the blood to flow despite the low pressure

Valves keep blood flowing in the right direction

Describe the structure of capillaries and how this relates to their function (2)

Thin and permeable (1 cell thick) walls allow the diffusion of substances at a high rate

Capillaries carry blood close to cells to allow food and gases to be exchanged

What are platelets and what is their function? (2)

They are small fragments of cells (no nucleus) which help blood to clot at wounds

This prevents excessive bleeding, bruising and infection

Plasma is the liquid that carries the contents of the blood. Name at least 3 substances carried by plasma (9)

Red blood cells

White blood cells

Platelets

Nutrients/soluble products of digestion - e.g. glucose. Carbon dioxide, oxygen

Urea

Hormones

Proteins

Antibodies

Antitoxins

What is coronary heart disease? (3)

Where the coronary arteries (which supply blood to the muscles of the heart) become blocked by buildup of fatty deposits

This narrows the arteries, restricting blood flow

There is a lack of oxygen to the heart muscle, risking a heart attack

Name treatments for coronary heart disease (5)

Stents

Statins

Artificial hearts (temporary)

Transplants

Artificial blood (for emergencies)

How do stents work? (2)

Stents are hollow tubes inserted inside arteries to push out the wall and keep it open, making sure blood can flow through it

This keeps the heart beating

Give 3 advantages of stents.

Lower the risk of cardiac arrest

Effective for a long time

Recovery time from surgery is relatively quick

Give 3 disadvantages of stents.

Risk of complications during operation, e.g. heart attack.

Risk of infection from surgery

Risk of thrombosis (patients developing a blood clot near the stent)

How can cholesterol lead to coronary heart disease? (2)

Cholesterol is an essential lipid that the body needs to function properly

Producing too much LDL cholesterol causes fatty deposits to form inside arteries

How do statins work? (2)

The body producing too much LDL cholesterol causes fatty deposits to form inside arteries

Statins are drugs which reduce the amount of LDL present in the bloodstream, slowing the rate of fatty deposits forming

Give 3 advantages of statins.

Reduce risk of strokes, coronary heart disease and heart attacks

As well as reducing LDL cholesterol, statins increase the amount of HDL cholesterol produced, a beneficial type that removes LDL cholesterol from the blood

Studies suggest statins may prevent some other diseases.

Give 3 disadvantages of statins.

There is a risk that someone forgets to take the drug

Can cause negative side effects, e.g. headaches, kidney failure, liver damage or memory loss

The effect of the drug is not instant

Give 3 disadvangages of heart transplants.

Donor organs aren't always available straight away

A donor heart may be rejected by the receiver's immune system

Transplant surgery can lead to bleeding and/or infection

Give 2 advantages of artificial hearts.

They can be sourced straight away (compared to donor organs) so keep people alive in emergencies

They're less likely to be rejected by someone's immune system than donor hearts

Give 3 disadvantages of artificial hearts (3)

Surgery can lead to bleeding and/or infection

They don't work as well as real hearts - parts could wear out, or the motor could fail

Blood doesn't flow smoothly through them, causing clots and leading to stroke (The patient has to take blood thinners to prevent this)

How can heart valves become damaged? (2)

Can be damaged/weakened by heart attacks, infection or age, which can cause stiffening of tissue, so that it won't open properly

A valve could become leaky, allowing blood to flow in both directions

How does artificial blood keep people alive in emergencies? (3)

When someone loses a lot of blood, their heart can still pump the remaining red blood cells to their organs, provided that they have a high enough volume of blood

Artificial blood is a saline solution which is used as a substitute for this lost volume

It keeps people alive, and may give someone enough time to produce new red blood cells (or they'll need a transfusion)

What is health?

The state of physical and mental wellbeing.

Give 4 examples of how different diseases can interact (4)

Defects of the immune system make people more vulnerable to communicable diseases

Viruses living in cells can trigger cancers

Immune reactions caused by pathogens can trigger allergic reactions or rashes, or worsen athsma symptoms

Severely ill physical health can trigger mental illnesses

Discuss the human cost of non-communicable (non infectious) diseases.

Death, Lower quality of life, Shorter lifespan, Affects loved ones around those suffering

Discuss the financial cost of non-communicable (non infectious) diseases (3)

Research and treatment is very expensive for health organisations

Families have to accomodate for someone with a disease (which is costly), e.g. moving house or adapting their home

If someone with a disease has to stop working or dies, their income stops, affecting their family and the economy

What are the 4 main types of risk factor for non-communicable diseases?

Lifestyle choices

Substance's in someone's body

Environment

Genetics

Give at least 3 (there are 6 in total) examples of causual mechanisms (things which are proven to directly cause) for non-communicable diseases (10)

Diet, smoking and exercise risk cardiovascular disease

Smoking risks lung disease and lung (and some other types of) cancer

Obesity risks Type 2 diabetes and cancer

Alcohol risks damaging liver and brain function

Smoking and alcohol affect the health of unborn babies

Carcinogens, including ionising radiation, are risk factors of cancer

UV exposure risks skin cancer

Certain viruses increase the chances of developing certain cancers

Many diseases are caused by the interaction of a number of factors

What is cancer?

Uncontrolled cell division leads to the formation of a tumour. But not all tumours are cancerous - only malignant ones.

What are the 2 types of tumour?

Benign, Malignant

What are benign tumours? (2)

Growths of abnormal cells which are contained in one area, usually within a membrane

They do not invade other parts of the body

What are malignant tumours? (2)

Cancerous growths of abnormal cells which invade neighbouring tissues

Malignant cells can break off and spread to different parts of the body, through the blood, where they form secondary tumours

Name 5 risk factors of cancer.

1) Smoking risks lung (and some other types of) cancer.2) Obesity/diet.3) Carcinogens (substances capable of causing cancer) e.g. ionising radiation, alcohol, UV exposure (causes skin cancer)4) Certain viruses increase the chances of developing certain cancers.5) There are genetic risk factors for some cancers.

Where is plant epidermal tissue found?

It covers the whole plant

Where are xylem and phloem tissues found?

Through the roots, stems and leaves of plants

Where is meristem tissue found? What is its function? (2)

Found at the growing tips of shoots and roots

It's able to differentiate into many different types of plant cell, allowing the plant to grow

Name the 4 types of tissue found in leaves.

Upper epidermis

Palisade mesophyll

Spongy mesophyll

Lower epidermis