Organisation 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 group of different tissues that work together to perform a certain function
What is an organ system?
group of organs that work together to perform a specific function
What is the main function of the digestive system?
To digest food and absorb the nutrients obtained from digestion.
What is the role of 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 digestion 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 digestion system?
Absorbs water from undigested food and then produces faeces
What is the role of enzymes in the digestive system?
Enzymes act as biological catalysts which speed up the rate of biological reactions (the breakdown of food) 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 reactions in a cell or an organism
What 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?
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 and the enzyme becomes denatured, so it can no longer catalyse the reaction. The optimum temperature is around 37°.
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 shape of the active site may be altered and the enzyme may no longer work.
Where are carbohydrases, proteases, and lipases produced in the body?
● Carbohydrases: amylase - salivary gland and pancreas; maltase - small intestine.
● Proteases: pepsin - stomach; others - pancreas and small intestine.
● Lipases: 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 break 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 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.
Where is bile made and 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?
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 - 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, 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 from 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 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 right 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 beats per minute
How is 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 to their function?
- they have thick layers of muscle to make them strong enough to withstand the high pressure at which they carry blood
- they have strong elastic fibres to allow them to stretch and spring back
What is the veins function?
carry blood back to the heart
How are veins adapted to their function?
- the walls are not thick as blood is not carried at a low pressure
- they have a big lumen to help blood flow
- they have valves to keep blood flowing in the right direction
What is the capillaries function?
Enable transfer of substances between the blood and tissues
How are capillaries adapted to their function?
- they have permeable walls so that substances can diffuse in and out
- their walls are only one cells thick which increases the rate of diffusion by decreasing the distance over which it occurs
- capillaries are really close to every cell in the body to exchange surfaces with them
How would you calculate the rate of blood 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
How are lungs ventilated by the action of intercostal?
Intercostal muscles contract, rib cage moves upwards, diaphragm flattens and volume of the chest increases, increased volume results in decreased pressure no air is drawn into lungs down pressure gradient (the inverse occurs wen air moves out of the lungs)
Describe how gas exchange occurs at the alveoli
● Oxygen diffuses from the alveoli into the capillary bloodstream down its 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 substance carries the different components of blood around the body?
Plasma
What substance 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 oxygen around the body
How are red blood cells adapted to their function?
- Biconcave discs - increases surface area to volume ratio
- No nucleus - more space for haemoglobin
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 a nucleus - contains DNA which codes for proteins
● Can produce antibodies
● Can produce antitoxins
● Can engulf and digest pathogens (phagocytosis)
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 (conversion of fibrinogen to fibrin). As a result, red blood cells are trapped in the fibrin network, forming a clot which prevents excessive bleeding. Scab formation (after the clot has dried) prevents bacteria from entering the wound.
What is coronary heart disease?
When the coronary arteries that supply the blood to the muscle of the heart get blocked by layers of fatty material building up and 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 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
What are statins?
They are drugs which lower the amount of ‘bad’ cholestrol in blood 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 immed
What is a heart bypass surgery?
A surgery where blocked coronary arteries are replaced with sections 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 - made of metal or polymers
● Biological - taken from animals (pigs, sometimes humans)
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 drug
What is health?
A state of complete physical, mental, and social well-being
What is a communicable disease?
A disease that is caused by a pathogen which can be spread from person to person
What is a non-communicable disease?
A disease that cannot be passed from person to person
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.