organisation (T2) Flashcards
what is a cell?
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 tissues working together to perform a particular 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 food and absorb the nutrients obtained from digestion
what is the role of the pancreas and the salivary gland in digestion?
the pancreas and salivary gland are glands which produce digestive juices containing enzymes
what is the role of the stomach in digestion?
produces HCl which kills any bacteria present and provides the optimum pH for protease to function
what is the role of the small intestine in digestion?
the small intestine is the site where soluble food molecules are absorbed into the blood
what is the role of the liver in digestion?
produces bile (stored in the gallbladder) which emulsifies fat and allows the lipase enzyme to work more efficiently on a larger surface area
what is the role of the large intestine in digestion?
absorbs water from undigested food forming faeces
what is the role of enzymes in the digestive system?
enzymes act as biological catalysts, proteins 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 reaction in a cell or an organism
what type of metabolic reactions do enzymes catalyse?
- Building larger molecules from smaller molecules (glucose -> starch)
- changing one molecule to another (glucose-> fructose)
- breaking down larger molecules to smaller molecules (carbohydrates-> glucose)
what is the lock and key hypothesis of enzyme function?
the shape of an enzyme active site and substrate are complementary so can bind together to form an enzyme-substrate complex
how does temperature affect rate of reaction?
Up to a certain point, increasing temperature increases the rate of reaction as molecules have higher kinetic energy so collisions are more frequent. after the optimum temperature, the enzyme becomes denatured because the active site has changed shape so the substrate no longer fits and so the enzyme cannot catalyse the reaction
how does pH affect rate of reaction?
the optimum pH for most enzymes is 7 (apart from protease), if the pH is too high above or below the optimum pH, the enzyme denatures as the active site has changed shape so the substrate no longer fits.
where is amylase, protease and lipase produced in the body?
- amylase: salivary gland, pancreas, small intestine
- protease: stomach, pancreas and small intestine
- lipase: pancreas and small intestine
what is the role of amylase in the digestive system?
break down carbohydrates into simple sugars e.g. glucose
what is the role of protease in the digestive system?
break down proteins into amino acids
what is the role of lipase in the digestive system?
break down lipids into fatty acids and glycerol
how are the products of digestion used?
- simple sugars to build new carbohydrates
- some of the glucose is used in respiration
- amino acids to build new proteins
- fatty acids and glycerol to build new lipids
where is bile made and stored in the body?
bile is made in the liver and stored in the gallbladder
what is the role of bile in 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?
the organ that pumps blood around the body
what is the purpose of the circulatory system?
carries oxygen and useful substances to bodily tissues, and the remove waste substances
how does the double circulatory system work?
- one pathway carries from the heart to the lungs - where the gaseous exchange of O2 and CO2
- one pathway carries blood from the heart to the rest of the body
where does the blood pumped by the right ventricle go?
to the lungs through the pulmonary artery
where does the blood pumped by the left ventricle go?
to the rest of the body through the aorta
why is the double circulatory system important?
it makes the circulatory system more efficient - 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 all around the body
what are the 4 main blood vessels associated with the heart?
- aorta: carries oxygenated blood from the heart to the rest of the body
- pulmonary vein: carries oxygenated blood from the lungs back to the heart
- vena cava: carries deoxygenated blood from around the body back to the heart
- pulmonary artery: carries deoxygenated blood from the heart to the lungs
what is the purpose of valves in the heart?
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 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 enter 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 the heart rate controlled?
heart rate is controlled by a group of cells in the right atrium which is the pacemaker. they generate electrical impulses that cause the heart to contract
how can abnormal heart rhythms be treated?
artificial pacemaker - sends out electrical impulses to correct the hearts rhythm
what are the three types of blood vessels in the body?
arteries, vein, 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 the 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 to calculate rate of blood flow
volume of blood/ number of minutes
what are the components of blood?
red blood cell, white blood cell, platelets, plasma
what substances are transported by plasma?
urea, CO2, products of digestion, red blood cell, white blood cell
what is plasma?
straw-coloured liquid in blood that transports substances
what is the purpose of the red blood cells in blood?
transport oxygen around the body
how are red blood cells adapted for their function?
- flattened biconcave shape: ensures a large surface area to volume ratio for efficient gas exchange
- large amount for haemoglobin: for transporting oxygen
- diameter (6-8μm) larger than capillary diameter: slows blood flow to enable diffusion of oxygen
- no nucleus or organelles: maximises space for haemoglobin so more oxygen can be transported
what is the purpose of white blood cell in blood?
fight against invading pathogens
how are white blood cells adapted for their function?
two types of white blood cells:
- phagocytes: can engulf pathogens
- lymphocytes: produce antibodies
can produce antitoxins
what is the structure of platelets
small fragments of cells, they do not have a nucleus
what is the function of platelets?
important role in blood clotting
how do platelets help blood clotting?
go to site of wound, form a mesh to catch other blood cells to form a scab
what is coronary heart disease?
when the coronary arteries that supply the heart muscle with oxygen get blocked by fatty deposits. this restricts the supply of oxygen to the heart, which can cause a potentially fatal heart attack.
what is a stent and how does it work?
a stent is a metal mesh 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 the 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 infection
- risk of blood clots at site of stent
what are statins?
drugs that 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 stroke, coronary heart disease and heart attacks
- increase level of HDL (good) cholesterol
disadvantages:
- have to be taken continuously
- may have side effects
- effects not immediate
what is a heart bypass surgery?
where blocked coronary arteries are replaced with sections of veins taken from other parts of the body
what are the consequences of faulty 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 type of valves can replace faulty valves?
- mechanical: made of metal or polymers
- biological: taken from animals (pigs) or sometimes humans
what are the advantages and disadvantages of mechanical valves?
advantages:
- lasts 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 and no medication is required
disadvantages:
- only lasts 10-15 years
what is the purpose of an artificial heart?
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
