B2- ORGANISATION Flashcards
What is a tissue?
A tissue is a group of cells with a similar structure and function
What is the order of organisation in the body?
Cells, tissue, organs, organ system
What is an organ?
- Organs are aggregations of tissue performing specific functions.
- Organs are organised into organ systems, which work together to form organisms
What is the digestive system an example of?
An organ system (in which several organs work together to digest and absorb food)
What are enzymes?
Enzymes are biological catalysts, which speed up chemical reactions in living organisms
What are the properties of enzymes?
- They are all large proteins
- There is a space within the protein molecule called the active site
- Each enzyme catalyses a specific reaction
- They work best at a specific temperature and pH called the optimum
What model is used to explain how enzymes work?
The lock and key theory
What is the lock and key theory?
The chemical that reacts is called the substrate (key) and it fits into the enzyme’s active site (lock)
What is denaturing?
When high temperatures and extremes of pH make enzymes change shape.
What happens when an enzyme becomes denatured?
The enzymes cannot work once it has been denatured, as the substrate cannot fit into the active site - the lock and key no longer fit together
What are the digestive enzymes?
Protease, lipase and carbohydrase
Where is amylase produced and what does it do?
- produced in the salivary gland and the pancreas
- is a carbohydrase that breaks down starch into sugar (maltose)
Starch ———> maltose
Where is lipase produced and what does it do?
- produced in the pancreas and small intestine
- breaks down lipids (fats) into fatty acids and glycerol
Fats ———> fatty acids + glycerol
Where is protease produced and what does it do?
- produced in the stomach, pancreas and small intestine
- breaks down proteins into amino acids
Protein ————-> peptides or amino acids
What are the products of digestion used for?
These products of digestion can be used to build new carbohydrates lipids and proteins. Some glucose is used in respiration
What is bile?
Bile is a liquid made in the liver and stored in the gall bladder
Is bile acid or alkaline? Why?
It is an alkaline to neutralise hydrochloric acid from the stomach
What does bile do?
Bile neutralises the hydrochloric acid from the stomach and emulsifies fat to form small droplets which increases the surface area for enzymes to act on
What does the alkaline conditions do in bile?
The alkaline conditions and large surface area increase the rate at which fat is broken down by lipase
What do digestive enzymes do?
Digestive enzymes convert food into small soluble molecules that can be absorbed into the bloodstream.
What do carbohydrase do?
Carbohydrases break down carbohydrates to simple sugars.
What is blood?
Blood is a tissue, made of a liquid called plasma, which has three different components suspended in it
- red blood cells
- white blood cells
- platelets
What do plasmas do?
Plasma transports various chemical substances around the body, such as the products of digestion, hormones, antibodies, urea and carbon dioxide
Properties of red blood cells
- contain haemoglobin, which binds to oxygen to transport it from the lungs to the tissues and cells, which need it for respiration
- do not contain a nucleus, so there is more room for haemoglobin
- are very small, so they can fit through the tiny capillaries
- shaped like biconcave discs, giving them a large surface area that oxygen can quickly diffuse across
Properties of white blood cells
- help to protect the body against infection
- can change shape, so they can squeeze out of the blood vessels into tissues or surround and engulf microorganisms
What are platelets?
Platelets are fragments of cells, which collect at wounds and trigger blood clotting
How does blood pass around the body?
Blood passes around the body in blood vessels
What are the different types of blood vessels?
Arteries, veins and capillaries
Properties of an Artery
- Take blood from your heart to your organs
- Thick walls made from muscle and elastic fibres
Properties of a vein
- Take blood from your organs to your heart
- Thinner walls and valves to prevent backflow
Properties of capillaries
- Allow substances needed by the cells to pass out of the blood
- Allow substances produced by the cells to pass into the blood
- Narrow, thin- walled blood vessels
How does the heart pump blood around the body?
The heart pumps blood around the body in a double circulatory system
What are the four chambers of the heart?
- the left and right atrium, which receive blood from veins
- the left and right ventricles, which pump the blood out into arteries
Where does blood enter the heart from?
The atria
What is the difference between the pulmonary artery and the pulmonary vein?
The pulmonary artery is unusual because unlike other arteries, it carries deoxygenated blood whereas the pulmonary vein carries oxygenated blood.
How does the blood go from the atria to the ventricles?
The atria contract and force blood into the ventricles
How does the heart pump blood?
- blood enters the heart through the atria
- the atria contract and force blood into the ventricles
- the ventricles then contract and force blood out of the heart
- valves make sure the blood flows in the correct direction
What is the natural resting heart rate controlled by?
Controlled by a group of cells located in the right atrium, which acts as a pacemaker
What do artificial pacemakers do?
Artificial pacemakers are electrical devices used to correct irregularities in the heart rate
Where is the pacemaker in the heart?
The Right Atrium
How does the heart send blood to the lungs?
Via the pulmonary artery
How does air retained by breathing reach the lungs?
Through the trachea
What does the trachea divide into?
The trachea divides into two tubes - the bronchi
What do the bronchi divide to form?
Bronchioles
What do bronchioles divide into?
The bronchioles divide until they end in tiny air sacks called alveoli
What are alveoli efficient at?
There are millions of alveoli that are adapted to be very efficient at exchanging oxygen and carbon dioxide.
Why are alveoli efficient at exchanging oxygen and carbon dioxide?
- They have a large, moist surface area
- They have a very rich blood supply
- They are very close to the blood capillaries, so the distance for gases to diffuse is small
How is the blood taken back to the heart?
Through the pulmonary vein
What is good health?
Being in a good state of physical and mental wellbeing
What is a disease caused by?
Caused by a part of the body not working properly
What are the 2 different types of disease?
Communicable diseases and non-communicable diseases
What is the difference between communicable diseases and non-communicable diseases?
Non-communicable diseases cannot be spread between organisms, but communicable diseases can
What does plasma do?
Plasma transports various chemical substances around the body, such as the products of digestion, hormones, antibodies, urea and carbon dioxide.
What do red blood cells contain?
Haemoglobin, which binds to oxygen to transport it from the lungs to the tissues and cells, which need it for respiration
Do red blood cells have a nucleus?
They do not contain a nucleus, so there is more room for haemoglobin
How much of Britains health budget is spent on people with diabetes?
10%
What can viruses infecting cells trigger?
They can be the trigger for cancers, such as cervical cancer
What can diseases of the immune system do?
It can mean that an individual is more likely to catch infectious diseases
What can immune reactions triggered by a pathogen do?
Immune reactions triggered by a pathogen can cause allergies, such as skin rashes and asthma
What increases the likelihood of developing certain diseases?
Poor diet, stress and difficult life situations
What are non-communicable diseases often caused by?
They are often caused by the interaction of a number of factors called risk factors. Examples of risk factors are a lack of exercise or smoking
How do scientists prove that a risk factor is involved in the chance of getting a disease?
Scientists need to look for a causal mechanism to prove that a risk factor is involved. A causal mechanism is a factor that makes a disease more likely to occur and the reason for this effect is known.
What are proven risk factors for cardiovascular disease?
Lack of exercise, smoking and high intake of saturated fat
What are proven risk factors for Type 2 diabetes?
Obesity
What are proven risk factors for liver and brain damage?
Excessive alcohol intake
What are proven risk factors for lung disease, including lung cancer?
Smoking
What are proven risk factors for skin cancer?
Ionising radiation
What are proven risk factors for low birth weight in babies?
Smoking during pregnancy
What are proven risk factors for brain damage in babies?
Excessive alcohol intake during pregnancy
What happens in coronary heart disease?
In coronary heart disease, layers of fatty material build up inside the coronary arteries and narrow them
What treatments are there for coronary heart disease?
1) A stent (which is a tube that is inserted into a blood vessel) is used to keep the coronary arteries open
2) A statin (which is a drug used to help lower cholesterol levels in blood) slows down the rate at which fatty materials build up.
What might happen to some people with coronary heart disease?
In some people, the heart valves may become faulty, developing a leak or preventing that valve from opening fully
What happens in the case of a faulty valve?
Faulty valves can be replaced using biological or mechanical valves
What happens in cases of heart failure?
- a donor heart, or a heart and lungs, can be transplanted
- artificial hearts can be used to keep patients alive while waiting for a heart transplant or to allow the heart to recover
What is given to patients who are recovering?
Drugs such as blood-clotting enzymes or warfarin are sometimes used to treat recovering patients
What are given to patients who have lower cholesterol levels?
Statins
What type of disease is cancer?
Non-communicable disease
What are some lifestyle risk factors for some types of cancer?
Smoking, obesity, common viruses and UV exposure
What are some other risk factors for cancer that aren’t lifestyle based?
Genetic risk factors. Example: some genes make the carrier more susceptible to certain types of breast cancer
What is cancer caused by?
Cancer is caused by uncontrollable cell division, which can form masses of cells called tumours.
What are the two main types of tumours?
Benign tumours, which do not spread around the body
Malignant tumours which spread, in the blood, to different parts of the body where they form secondary tumours
Why is the narrowing of coronary arteries dangerous?
The narrowing of coronary arteries reduces the flow of blood, so not enough oxygen can reach the heart muscle, which can cause heart failure
What is the function of the epidermis?
Covers the outer surfaces of the plant for protection
What is the function for palisade mesophyll?
The main site of photosynthesis in the leaf
What is the function of the spongy mesophyll?
Air spaces between the cells allow gases to diffuse through the leaf
What is the function of xylem vessels?
Transports water and minerals through the plant, from root to leaves. Also supports the plant
What is the function of phloem cells?
Transports dissolved food materials through the plant
What is the function of meristem tissue?
Found mainly at the tips of the roots and shoots, where it can produce new cells for growth
What do plant tissues gathered together form?
Organs
What is the leaf?
A plant organ
In the structure of a leaf, what do the chloroplasts do?
Chloroplasts close to the top of the leaf to trap maximum sunlight
In the structure of a leaf, what does the air space do?
Lots of air space allows gases to diffuse
In the structure of a leaf, what does the stomata do?
The stomata allow the diffusion of gases in and out of the leaf and can be opened and closed by the guard cells
Describe the process of water transport
1) water enters the plant from the soil, through the root hair cells, by osmosis
2) root hair, xylem and phloem cells are specialised to transport water, minerals and sugars around the plant
3) the water contains dissolved minerals
4) water and minerals transported up the xylem vessels, from the roots to the stems and leaves
5) at leaves, most water will evaporate and diffuse out the stomata - the loss of water from the leaves is transpiration
What is transpiration?
Transpiration is the loss of water from the leaves
What factors can affect the rate of transpiration?
- an increase in temperature will increase the rate, as more energy is transferred to the water to allow it to evaporate
- faster air flow will increase the rate, as it will blow away water vapour allowing more to evaporate
- increased light intensity will increase rate, as it will cause stomata to open
-an increase in humidity will decrease rate, as the air contains more water vapour, so the concentration gradient for diffusion is lower
What is the role of guard cells?
The role of the guard cell is to open and close stomata
Why are the stomata closed at night?
As carbon dioxide is not needed for photosynthesis, so closing the stomata reduces water loss
What happens to guard cells and the stomata when they is a plentiful amount of water?
When water is plentiful, guard cells take up water and bend. This causes the stomata to open, so gases for photosynthesis are free to move in and out of the stomata along with water from transpiration.
What happens to the stomata when water is scarce?
When water is scarce, losing water makes the stomata change shape and close. This stops the plant from losing more water through transpiration
How can the rate of transpiration be measured from a cut shoot?
The rate can be estimated by measuring the rate at which the shoot takes up water. This is only an estimate because not all the water taken up the shoot is lost - a very small percentage is used in the leaf
Where is the stomata located and why?
In most plants, the stomata are found on the bottom surface of the leaf. This means that the sun does not shine directly on them which reduces water loss
Why can’t plants stop transpiration completely?
Because carbon dioxide is needed for photosynthesis, so water will always escape
What is translocation?
- phloem tissue transports dissolved sugars from the leaves to the rest of the plant
- this movement of food through phloem tissue is called translocation
- phloem cells are adapted for this function
What are risk factors?
Risk factors are factors that make developing a disease more likely
