B2 Flashcards
What is a cell?
The basic building block of a living organism
What is a tissue?
A group of cells with a similar structure and function working together
What is an organ?
A collection of tissues working together to perform a specific function
What is an organ system?
A group of organs working together to perform specific functions.
What is the main function of the digestive system?
To digest and absorb the nutrients obtained form digestion
What is role of the pancreas and the salivary gland in the digestive system?
The pancreas and the salivary gland are glands which produce digestive juices containing enzymes
What is the role of the stomach in the digestive system?
Produces hydrochloric acid - which kills any bacteria present and provides the optimum acidic pH for the protease enzyme to function
What is the role of the small intestine in the digestive system?
The small intestine is the site where soluble food molecules are absorbed into the bloodstream
What is the role of the liver in the digestive system?
Produces bile (stored in the gallbladder) which emulsifies lipids and allows the lipase enzyme to work more efficiently
What is the role of the large intestine in the digestive system?
Absorbs water form undigested food, producing faeces
What is the role of enzymes in the digestive system?
Enzymes act as biological catalysts which speed up the rate of biological reactions without being used up
How does the shape of an enzyme affect its function?
Enzymes have a specific active site which is complementary to their substrate
What is metabolism?
The sum of all the reaction in a cell or an organism
Wat types of metabolic reactions do enzymes catalyse?
- Building larger molecules from smaller molecules
- Changing one molecule to another
- Breaking down larger molecules into smaller molecules
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
How does temperature affect enzyme action?
Increasing temperature increases enzyme action as the molecules have a higher kinetic energy. Above a certain temperature the enzyme becomes denatured.
How does pH affect enzyme function?
The optimum pH for most enzymes is 7 (apart from proteases in the stomach). If the pH is too extreme the enzyme will denature
Where are carbohydrases produced in the body?
- Amylase: salivary gland and pancreases
- Maltase: small intestine
Where are proteases produced in the body?
- Pepsin: stomach
- Others: pancreas and small intestine
Where are lipases produced in the body?
Pancreas and small intestine
What is the role of carbohydrases in the digestive system?
Carbohydrases 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 breaks down proteins into amino acids
What is the role of lipases in the digestive system?
Lipases break down lipids into fatty acids and glycerol
How are products of digestion used?
They are used to build bigger molecules such as carbohydrates and proteins. Glucose is used as a substrate in respiration
Where is bile stored in the body
Bile is made by the liver and stored in the gallbladder
What is the role of bile in the digestive system?
-Bile is an alkaline substance which neutralises the hydrochloric acid secreted by the stomach
- Bile emulsifies lipids to form droplets, this increases the surface area for the lipase enzyme to work on
What is the heart?
An organ that pumps blood around the body
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?
- One pathway carries blood from the heart to the lungs, where the gaseous exchange of oxygen and carbon dioxide takes place.
- One pathway carries blood from the heart to the tissues
Where does blood pumped by the right ventricle go?
The lungs
Where does blood pumped by the left ventricle go?
Body tissues
Why is the double circulatory system important?
It makes the circulatory system more efficient
How many chamber of the heart are there and what are they called?
4 - right atrium, right ventricle, left atrium, 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
What are the four main blood vessels associated with the heart?
Aorta (left) - carries oxygenated blood form the heart to the body.
Pulmonary vein (left) - carries oxygenated blood from the lungs to the heart.
Vena cava (right) - carries deoxygenated blood from the body to the heart.
Pulmonary artery (right) - carries deoxygenated blood from the heart to the lungs.
What is the purpose of valves in the heart?
Prevent the back flow 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 enters the right atrium via the vena cava, and the left atrium via the pulmonary vein
- The atria contract, forcing blood into the ventricles and causing valves to shut
- After the ventricles contract, blood in the ventricle enters the pulmonary artery (to the lungs) and blood in the left ventricle enters the aorta (to the body)
What is the approximate value of the natural resting heart rate?
70 bpm
How is the heart rate controlled?
Heart rate is controlled by a group of cells in the right atrium which act as a pacemaker. They release waves of electrical activity which cause the heart muscle 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
How are arteries adapted for their function?
Function: carry blood away from the heart
Thick muscle layer - adds strength to resist high pressure
Thick elastic layer - allows arteries to stretch and recoil - in order to withstand high pressure
How are veins adapted for their function?
Function: carry blood towards the heart
Wide lumen - enables low pressure
Valves - prevent backflow of blood
How are capillaries adapted for their function?
Function: enable transfer of substances between the blood and tissues
Walls are one cell thick - short diffusion path
Permeable walls - substances can diffuse across
Narrow lumen - blood moves slowly - more time for diffusion
How could you calculate the rate of flow?
Volume of blood/ number of minutes
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
What tissues and organs make up the gas exchange system?
Trachea
Intercostal muscles
Bronchi
Bronchioles
Alveoli
Diaphragm
Explain how the lungs are ventilated by the action of intercostal muscles?
Intercostal muscles contract
Rib cage moves upwards and outwards
Diaphragm flattens and volume of the chest increases
Increased volume results in decreased pressure
Air is drawn into lungs down pressure gradient
Describe how gas exchange occurs at the alveoli?
Oxygen diffuses form the alveoli into the capillary blood stream down is concentration gradient
Carbon dioxide diffuses from the capillary into the alveoli down its concentration gradient
Describe how alveoli are adapted for gas exchange?
Small and arranged in clusters - larger surface area
Rich blood supply - maintains concentration gradient
Thin alveolar wall - short diffusion pathway
How would you calculate the breathing rate?
Number of breaths / number of minutes
What substances carries the different components of blood around the body?
Plasma
What substances are transported by plasma?
Red blood cells
White blood cells
Platelets
Carbon dioxide
Urea
Products of digestion
What is plasma?
A yellow liquid within blood that transports substances around the body
What is the purpose of red blood cells in blood?
Transport of oxygen around the body
How are red blood cells adapted for their function?
Biconcave shape - increased surface area
No nucleus - more room for haemoglobin
Contain haemoglobin - binds oxygen
What is the purpose of white blood cells in blood?
They form part of the immune system, which protects the body from invading pathogens
How are white blood cells adapted for their function?
Have nucleus - contains DNA which codes for proteins
Can produce antibodies
Can produce antitoxins
Can engulf and digest pathogens
What is the purpose of platelets in blood?
Platelets are small cell fragments which aid the clotting of blood at the site of a wound
Why is the function of platelets important?
Platelets aid in the process of blood clotting. As a result, reed blood cells are trapped in the crib in network, forming a clot which prevents excessive bleeding. Scab formation (after clot has dried) prevents bacteria from entering the wound
What is coronary heart disease?
Coronary heart disease occurs when the coronary arteries that supply the heart muscle become blocked with a buildup of fatty material. This restricts the supply of oxygen to the heart, possibly leading to a heart attack or death
What is a stent and how does it work?
A stent is a metal mesh tube that is inserted into a blocked artery so that it remains open. The stent is inflated using a balloon, which is later removed to allow blood to flow freely.
What are the advantages and disadvantages of stents?
Advantages:
- Insertion can be carried out without general anaesthetic
- Quick recovery time
- Lower the risk of a heart attack
Disadvantages:
- Risk of postoperative infection
- Risk of blood clots at sire of stent
What are statins?
Statins are drugs which reduce the level of LDL (bad) cholesterol which contributes to the development of coronary heart disease
What are the advantages and disadvantages of statins?
Advantages:
- Reduce risk of strokes, coronary heart disease and heart attacks
- Increase level of HDL (good) cholesterol
Disadvantages:
- Have to be taken continuously
- May have side effects
- Effect may not be immediate
What is a heart bypass surgery?
A surgery where blocked coronary artieries are replaced with section of veins taken from other parts of the body
What are the consequences of leaky heart valves?
Blood flows in the wrong direction, causing the heart to become less efficient. Patients may become breathless and die as a result
What types of valves can replace leaky valves?
Mechanical - mad of metal or polymers
Biological - taken form animals
What are the advantages and disadvantages of mechanical valves?
Advantages:
- Last for a very long time
Disadvantages
- Need to take medication to prevent blood clotting around valve
What are the advantages and disadvantages of biological valves?
Advantages:
- Work very well - no medication required
Disadvantages:
- Only lasts 12-15 years
What is the purpose of an artificial heart?
Artificial hearts are intended to support a patient’s heart while they wait for a suitable donor heart
What are the advantages and disadvantages of artificial hearts?
Advantages:
- Less likely to be rejected by immune system
- Allows damaged heart to rest to help recovery
Disadvantages:
- Risk of infection due to surgery
- Risk of blood clots
- Have to take blood-thinning drugs
What is health?
Health is the state of physical and mental wellbeing
What is a communicable disease?
A disease caused by a pathogen which can be transmitted from one personal to another
What is a non-communicable disease?
A disease which can not be transmitted from one person to another
How can diet affect health?
Too little food / lack of nutrition - anaemia, vitamin deficiencies
Too much food/ too much unhealthy food - obesity, type 2 diabetes
How can stress affect health?
Prolonged stress in linked to a wide range of health problems including heart diseases, cancers and mental health issues
What is a risk factor?
A risk factor is an aspect of a person’s lifestyle or a substance found in the body or the environment which can increase the risk of a disease
What is a causal mechanism?
A mechanism which demonstrates how one factor biologically influences another
How do diet, smoking and exercise affect the development of cardiovascular disease?
Diet: high levels of LDL cholesterol causes arteries to become blocked, increasing blood pressure and the risk of a heart attack
Smoking: nicotine increases heart rate; other chemicals damage the artery lining and increase blood pressure
Exercise: lowers blood pressure, reducing strain on the heart
How does obesity affect the development of type 2 diabetes?
Obesity is strongly linked with the onset of type 2 diabetes - a disease in which the body stops responding to insulin
How does alcohol affect liver and brain function?
Excessive long-term alcohol use may lead to liver cirrhosis (scarring of the liver).
Increases the risk of liver cancer
Damages brain tissue and nerve cells
How does smoking affect the development of lung disease and lung cancer?
Tar in tobacco can damage the alveoli of the lungs, leading to chronic obstructive pulmonary disease (COPD).
Tar also damages the cells which line the lungs, leading to lung cancer.
How do smoking and alcohol affect unborn babies?
Carbon monoxide from tobacco smoke reduces the amount of oxygen the foetus receives, which can lead to premature birth or stillbirth
Alcohol passes across the placenta and damages the developing foetus. Once born, the baby may have a number of deformities and health problems as part of the foetal alcohol syndrome
How do carcinogens affect the development of cancer?
Ionising radiation is a type of carcinogen which can cause mutation in the DNA, potentially leading to cancer
What is cancer?
Cancer is the development of a tumour as a result of uncontrolled cell division
What is a benign tumour?
A tumour that is contained in one location, usually within a membrane
They are not cancerous and do not invade other parts of the body
Can grow large very quickly - may cause damage to another organ
What is a malignant tumor?
A tumor that can spread around the body via the blood and lymphatic system
Can invade other tissues
Cells divide more rapidly and have a longer lifespan
Disrupts healthy tissues and may lead to death
Give examples of factors which can lead to cancer?
Genetics - certain genes increase the risk of breast and ovarian cancer
Smoking
Obesity
Ionising radiation
Viral infections
How is epidermal tissue adapted for its function?
Epidermal tissue covers the entire plant. It has a waxy cuticle which helps reduce water less from the leaf surface
How is palisade mesophyll tissue adapted for its function?
Palisade mesophyll tissue contains lots of chloroplasts which allows photosynthesis to progress at a rapid rate
How is spongy mesophyll tissue adapted for it’s function
Spongy mesophyll tissue has lots of air spaces which allow gases (including oxygen and carbon dioxide) to diffuse in and out
How is the xylem adapted for its function?
Made up of dead cells which form a continuous hollow tube - allows movement of water and mineral ions form the roots to the leaves
Strengthened by lignin - makes the vessel strong and water proof
Has bordered pits - allow minerals to be transported to specific places
How is the phloem adapted for its function?
Made up of elongated living cells
Cells have sieve plates that connect them together - cell sap can move through plates into other cells
Side tube cells have few organelles to allow the efficient transport of substances
How is the meristem adapted for its function?
Made of of stem cells which can differentiate into many different cell types, allowing the plant to grow
What tissues deos the leaf organ contain?
Epidermis
Palisade mesophyll
Spongy mesophyll
Xylem
Phloem
Guard cells
What is the function of guard cells?
Guard cells control the opening and closing of the stomata, according to the water content of the plant
How are stomata adapted for their function?
Stomata allow the control of gaseous exchange and water loss from the leaf
- More stomata on the base of the leaf, minimises water loss as this side is cooler and shaded
- Have guard cells which control their opening and closing
How are root hair cells adapted for their function?
Root hair cells allow the uptake of water and mineral ion form the soil
- Large surface area, maximises rate of absorption
- Contain lots of mitochondria, release energy for active transport of mineral ions
What is translocation?
Translocation is the movement of dissolved sugars form the leaves to other parts of the plant
What is transpiration?
Transpiration is the evaporation of water vapour from the surface of a plant
How does transpiration work?
Water evaporates from the leaf surface via the somata
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 temperature affect the rate of transpiration?
Increasing the temperature increases the rate of transpiration
How does humidity affect the rate of transpiration?
Increasing relative humidity decreases the rate of transpiration
How does wind speed affect the rate of transpiration?
Increasing wind speed/air movement increases the rate of transpiration
How does light intensity affect the rate of transpiration?
Increasing the light intensity increases the rate of transpiration
