Topic 2-Organisation Flashcards
What a tissue?
A tissue is a group of specialised cells with a similar structure and function. they can be made of more than one type of cell.
Examples include muscular tissue or epithelial tissue
What is an organ?
An organ is formed from a number of different tissues working together to produces a specific function.
An example would be the stomach, which has muscular tissue and epithelial tissue
What is an organ system?
An organ system is where organs are organised to work together to perform a certain function.
The stomach is part of the digestive system, along with organs such as the liver and small intestine
Which organs are involved in the human digestive system?
Glands (salivary glands and the pancreas)
Stomach
Small intestine
Liver
Large intestine
What do the pancreas and salivary glands do?
They produce digestive juices containing enzymes which break down food
What does the stomach do?
It produces hydrochloric acid to kill bacteria and to provide the optimum pH for the protease enzyme to work
What does the small intestine do?
It is where soluble molecules are absorbed into the blood
What does the liver do?
It is where bile is produced. This is then stored in the gall bladder and helps with the digestion of lipids
What does the large intestine do?
It absorbs water from undigested food to produce faeces. This passes out of your body through the rectum and anus
What is the role of enzymes in the digestive system?
They are biological catalysts
They are present in many reactions so that they can be controlled
How does the shape of an enzyme affect its function?
Enzymes have a specific active site which is complementary to their substrate
What is metobolism?
The sum of all the reactions in an organism
What types of metabolic reactions do enzymes catalyse?
-Building larger molecules from smaller molecules (glucose to starch)
-Changing one molecule to another
(eg glucose to fructose)
-Breaking down larger molecules into smaller molecules (eg carbohydrates to glucose)
What is the lock and key hypothesis of enzyme function?
The shape of the enzyme active site and the substrate are complementary, so can bind together to form an enzyme-substrate complex
Once bound, the reaction takes place and the products are released from the surface of the enzyme
How does temperature affect enzyme action?
Up to a certain point, increasing temperature increases enzyme action, as molecules have a higher kinetic energy
Above a certain temperature, the shape of the active site is altered because of broken bonds in the structure and the enzyme becomes denatures, so it can no longer catalyse the reaction.
The optimum temperature is around 37 degrees Celsius
What is the optimum pH for enzymes?
For most enzymes, it is 7 however some that are produced in acidic conditions, such as the stomach, have a low optimum pH
If the pH is too high or too low, the forces that hold the amino chains that make up the protein will be affected and this will change the shape of the active site, so the substrate can no longer fit in. The enzyme becomes denatured and can’t work anymore
Where are carbohydrases produced?
Amylase- salivary gland and pancreas
Maltese- small intestine
Where are proteases produced?
Pepsin- stomach
Others-pancreas and small intestine
Where are lipases produced?
Pancreas and small intestine
What is the role of carbohydrases in the digestive system?
They break down carbohydrates into monosaccharides and disaccharides. Amylase breaks down starch into maltose, and maltase breaks down maltose into glucose
What is the role of proteases in the digestive system?
Proteases break down proteins into amino acids
What is the role of lipases in the digestive system?
It breaks down lipids into fatty acids and glycerol
How are the products of digestion used?
They are used to build bigger molecules such as carbohydrates and proteins. Glucose is used as a substrate in respiration
What are the different food tests and what do they test for?
Benedict’s test for sugars (turns brick red)
Iodine test for starch (turns blue-black)
Biuret test for protein (turns purple)
Emulsion test for lipids (add ethanol which results in a cloudy layer if a lipid is present)
Sudan III test for lipids (red layer forms on top)
What is the role of bile?
It is alkaline to neutralise the hydrochloric acids which comes from the stomach-the enzymes in the small intestine have a higher (more alkaline) optimum pH than those in the stomach
It breaks down large drops of fat into smaller ones (emulsifies it). The larger surface area allows lipase to chemically break down the lipid into glycerol and fatty acids faster
What is the purpose of the circulatory system?
Carries oxygen and other useful substances to bodily tissues and removes waste substances
How does the double circulatory system work?
Deoxygenated blood flows into the right atrium and then into the right ventricle which pumps it to the lungs to undergo gaseous exchange
Oxygenated blood flows into the left atrium and then the left ventricle which pumps the oxygenated blood around the body tissues
Why is the double circulatory system important?
It makes the circulatory system more efficient-for example, oxygenated blood can be pumped around the body at a higher pressure by the left ventricle
How many chambers does the heart have and what are they called?
4-right atrium, right ventricle, left atrium and left ventricle
Why is the wall of the left ventricle thicker?
The left ventricle has to pump blood at a higher pressure around the whole body rather than just to the lung like the right ventricle
What does the aorta (left) do?
It carries oxygenated blood from the heart to the body
What does the pulmonary vein (left) do?
It carries oxygenated blood from the lungs to the heart
What does the Vena Cava (right) do?
It carries deoxygenated blood from the body to the heart
What does the pulmonary artery (right) do?
It carries deoxygenated blood from the heart to the lungs
What is the purpose of valves in the heart?
To prevent the backflow of blood
What is the purpose of coronary arteries?
Coronary arteries supply the heart muscle with oxygenated blood
Describe the process of blood flow through the heart
Blood flows into the right atrium through the vena cava, and left atrium through the pulmonary vein
The atria contract, forcing the blood into the ventricles
The ventricles then contract, pushing the blood in the right ventricle into the pulmonary artery to be taken to the lungs, and blood in the left ventricle to the aorta to be taken around the body
As this happens, valves close to make sure the blood does not flow backwards
What is the approximate value of the natural resting heart rate?
70 bpm
How is heart rate controlled?
Heart rate is controlled by a group of cells found in the right atrium that act as a pacemaker
They provide stimulation through small electrical impulses which pass across the heart muscle, causing it to contract.
How can an abnormal heart rhythm be treated?
Irregular heart rhythms can be treated using an artificial pacemaker, which sends out electrical signals to correct the heart’s rhythm
What are the three types of blood vessel in the body?
Arteries
Veins
Capillaries
What are arteries and how are they adapted for their function?
Arteries carry blood away from the heart
- Layers of muscle in the walls make them strong
- Elastic fibres allow them to stretch
- This helps the vessels withstand the high pressure created by the pumping of the heart
What are veins and how are they adapted to their function?
- Veins carry blood towards the heart
- The lumen (the actual tube in which blood flows through) is wide to allow the low pressure blood to flow through
- They have valves to ensure the blood flows in the right direction
What are capillaries and how are they adapted to their function?
- They allow the blood to flow very close to cells to enable substances to move between them
- One cell thick walls create a short diffusion pathway
- Permeable walls so substances can move across them
Where are the lungs found in the body?
The lungs are located in the thorax (within the chest). They are protected by the ribcage and separated from the rest of the abdomen by the diaphragm
How would you calculate the rate of blood flow?
Volume of blood/number of minutes
What types of white blood cells are there?
- Those that produce antibodies (small proteins that clump them together) against microorganisms
- Those that engulf and digest pathogens
- Those that produce antitoxins to neutralise toxins (poisons) produced by microorganisms
What are stents?
They are metal mesh tubes inserted in arteries to keep them open to allow blood to flow through
What are the advantages and disadvantages of stents?
They are effective in lowering the risk of a heart attack
The recovery time from surgery is quick
The risk of a heart attack during the procedure, or that infection could occur following it
There is a chance that blood clots can form near the stent (called thrombosis)
What are statins?
They are drugs that decrease the levels of LDL (bad cholesterol) which could otherwise lead to coronary heart disease
What are the advantages and disadvantages of statins?
They reduce the risk of strokes, coronary heart disease and heart attacks
They increase the levels of HDL (good cholesterol)
They need to be taken continuously which may be an inconvenience
Can produce side effects
May not have an immediate effect as it only slows down the rate it is deposited
What is a faulty valve?
This is when a heart valve becomes stiff so it cannot open or it is damaged so it leaks.
Therefore, blood flows in the wrong direction which means that the heart does not work as efficiently as it should
What are the advantages and disadvantages of replacing a faulty valve with a biological valve?
- Works very well
- Less risks of blood clots forming
- No lifelong anticoagulant treatment is required
- Only lasts for 12-15 years
What are the advantages and disadvantages of replacing a faulty valve with a mechanical valve?
- Last for a long time
- Constant medication is needed to stop blood from blotting around the valve
What are the advantages and disadvantages of an artificial heart?
-Less likely to be rejected by the immune system since metal and plastic are not recognised as foreign
Surgery temporarily leaves the body exposed to infection
As it is mechanical, parts of it could wear out and the motor could fail
Blood clots could form, leading to strokes
To prevent the above, drugs are taken to thin the patients blood-this affects the individuals bleeding if they are hurt
What is a communicable disease?
These are infectious diseases as they are caused by pathogens (bacteria, viruses, fungi) and are passed on from one person to another. An example is the flu
What is a non-communicable disease?
These are not passed on from person to person. An example is heart disease
How can diet affect health?
Eating too little or too much food, not enough nutrients or the wrong type of food prevents you from having a good, balanced diet.
This can have a big effect on mental and physical health, causing issues such as type 2 diabetes or obesity
How can stress affect health?
Physical and mental stress places strain on our bodies. This can lead to problems such as heart disease, cancers and mental illnesses
What are some risk factors for cardiovascular disease?
- Diet containing lots of LDL cholesterol results in arteries becoming blocked, increasing blood pressure
- Smoking damaged the walls of arteries
- Exercise lowers blood pressure, reducing strain on the heart
What are some risk factors for type 2 diabetes?
-Obesity affects the body’s metabolism-fat molecules are released into the blood which can affect the cells uptake of sugar
What are some risk factors for reduced liver and brain function?
- Alcohol causes fatty liver, which can lead to liver failure
- Alcohol can damage nerve cells in the brain
What are some risk factors for lung disease and lung cancer?
-Smoking damages the cells in the lining of the lungs
What are some risk factors for cancer?
Carcinogens such as ionising radiation can lead to cancers
Smoking
Obesity
UV light
Viral infection
You can inherit certain genes which increase the likelihood of getting cancer
What is epidermal tissue and what does it do?
Epidermal tissue covers the entire plant. It has a waxy cuticle. This helps reduce water loss by evaporation, as the waxy cuticle prevents water from moving out
How is palisade mesophyll adapted for its function?
It is found underneath the epidermal tissue
It has lots of chloroplasts. Having many chloroplasts means photosynthesis can happen rapidly. They are positioned at the top of the leaf so they receive lots of light
How is spongy mesophyll adapted to its function?
It is found underneath palisade mesophyll and has lots of air spaces. This allows gases to diffuse in and out of cells
What is xylem and what does it do?
It is found in the roots, stems and leaves and is made up of dead cells joined together, creating a continuous tube
The tube allows the movements of water and mineral ions from the roots to the stem and leaves, where it evaporates and leaves the plant. This is called the transpiration stream
What is lignin and how does it help the xylem tube?
Xylem tubes are strengthened with a substance called lignin, but this has some holes in it along the tube called bordered pits
Lignin makes it strong and waterproof so water will not leave except at bordered pits, allowing minerals to go to specific places in the plants
What is meristematic tissue and how does it help the plant
It is found at the tips of shoots and roots and if able to differentiate into different types of plant cell
This allows the plant to grow
What is phloem and what does it do?
Phloem is elongated cells with holes in the cell walls
Many organelles from the cells are removed so cell sap can move through
Food substances can be moved in both directions from the leaves where they are made for use, or from storage (underground) to parts of the plant that need it.
What is translocation?
The movement of food substances made in the leaves up or down the phloem, for use immediately or storage
What is transpiration?
It is the loss of water or water vapour from the leaves and stems of the plant via evaporation
It is a consequence of gaseous exchange
How does transpiration work?
Water evaporates from the leaf surface via the stomata
Water molecules cohere together-more water is pulled up the xylem in an unbroken column
More water is taken up from the soil-creating a continuous transpiration stream
How does an increase in temperature affect the rate of transpiration?
- Molecules move faster
- Evaporation happens at a faster rate
- Rate of photosynthesis increases meaning more stomata are open for gaseous exchange
- More water evaporated and the rate of transpiration increases
How does an increase in relative humidity affect the rate of transpiration?
Reduced concentration gradient between the concentrations of water vapour inside and outside the leaf
This will result in a slower rate of diffusion. This will decrease the rate of transpiration
How does an increase in air movement affect the rate of transpiration?
The concentration of water vapour surrounding the leaf will be lower
Steeper concentration gradient resulting in diffusion happening faster
Increase the rate of transpiration
How does an increase in light intensity affect the rate of transpiration?
Leads to increased rate of photosynthesis so more stomata open to allow gaseous exchange to occur
More water can evaporate
Increased rate of transpiration
How are stomata adapted to their function?
More stomata on the base of the leaf
This minimises water loss as the side is cooler and shaded
Have guard cells which control their opening and closing
How do guard cells work?
They are kidney shaped
They have thin outer walls and thick inner walls
When lots of water is available to the plant, the cells fill and change shape, opening stomata (light sensitive)
This allows gases to be exchanged and more water to leave the plant via evaporation
Amylase is a polymer of smaller molecules
Name the type of smaller molecules
Amino acids
Explain how amylase breaks down starch
Answer in terms of the ‘lock and key theory’
Amylase is an enzyme which has an active site with a specific complementary shape to the substrate starch
These join to form an enzyme substrate complex
Products release from the amylase surface
Enzyme remains unchanged
