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Biology Part 1- Human Biology > Diet > Flashcards

Flashcards in Diet Deck (101):

what is the function of the mouth?

where food enters the alimentary canal and digestion begins


what is the function of the oesophagus?

muscular tube which moves ingested food to the stomach


what is the function of the stomach?

muscular organ that secretes acid and enzymes that digest food.


what is the function of the small intestine (duodenum)?

where food is mixed with digestive enzymes and bile


what is the function of the small intestine (ileum)?

where digested food is absorbed into the blood and lymph


what is the function of the large intestine (colon)?

where water is reabsorbed


what is the function of the large intestine (rectum)?

where faeces are stored


what is the function of the pancreas?

produces digestive enzymes


how is food moved through the gut through peristalsis?

food is moved through the digestive system by the contractions of two sets of muscles in the walls of the gutTheir wave-like contractions create a squeezing action, moving down the gut. This series of wave-like contractions is called peristalsis. One set runs along the gut, while the other set circles it.


how is the small intestine adapted for absorption?

the inside wall of a small intestine is very thin with a large surface area. The inside wall of the small intestine is also lined with tiny villi that stick out and give a big surface area. They also contain blood capillaries to carry away the absorbed food molecules


what is the role of digestive enzymes?

to break down nutrients into small soluble molecules that can be absorbed


what is the role of proteases?

to catalyse the breakdown of proteins into amino acids in the stomach and small intestine


what is the role of lipase?

to catalyse the breakdown of fats and oils into fatty acids and glycerol in the small intestine


what is the role of amylase?

catalyses the breakdown of starch into maltose in the mouth and small intestine


what is the role of maltase?

catalyses the breakdown of maltose into glucose in the small intestine


where is bile produced?

the liver


where is bile stored?

the gall bladder


what is the role of bile?

neutralises hydrochloric acid allowing an alkaline environment for enzymes to work at their optimum pH. Breaks down lipids into smaller molecules with larger surface area to volume ratio so lipase can break them down faster into fatty acids


what is respiration?

respiration is a reaction that occurs in living things to create energy by breaking down glucose


what are the differences between aerobic and anaerobic respiration?

aerobic is with oxygen, anaerobic is without oxygen


what is the word equation for aerobic respiration in living organisms?

glucose+oxygen=carbon dioxide+water


what is the balanced symbol equation for aerobic respiration in living organisms?



what is the word equation for anaerobic respiration in animals?

glucose=lactic acid+energy


what is the word equation for anaerobic respiration in plants?

glucose=ethanol+carbon dioxide+energy


what are the ribs?

a bone structure that protects vital organs such as the lungs


what are intercostal muscles?

muscles between the ribs to control inhalation and exhalation


what is the diaphragm?

sheet of muscle at the bottom of the thorax that helps with inhalation and exhalation


what is the trachea?

windpipe that connects the mouth and nose to the lungs


what are bronchi?

thick tubes that divide into two bronchi, one bronchus for each lung


what are bronchioles?

bronchi split forming smaller tubes called bronchioles in the lungs connected to alevoli


what are alveoli?

air sacks where gas exchange of carbon dioxide and oxygen takes place


what is the pleural membrane?

sticks the outside of the lungs to the inside of the chest cavity so lungs follow the chest movement and it lubricates the lungs to reduce friction


what is the role of the intercostal muscles during ventilation?

when you inhale the intercostal muscles contract, expanding the rib cage. When you exhale they relax dropping the rib cage downwards and inwards


what is the role of the diaphragm during ventilation?

when you inhale the diaphragm contracts pulling downwards to increase the volume of the chest. When you exhale it relaxes moving back up and reducing the volume of the chest.


what is diffusion?

the movement of particles from an area of high concentration to an area of low concentration


what is the role of diffusion in gas exchange?

blood arriving in the alveoli has a high concentration of co2 whereas air in the alveoli has a low concentration of co2 allowing co2 to diffuse out of the blood into the alveolar air. Similarly, blood arriving in the alveoli has a low 02 concentration whilst air in the alveoli has a high 02 concentration. Therefore oxygen moves into the blood by diffusion


how are alveoli adapted for gas exchange?

- folded providing a greater surface area for gas exchange
- one cell thick walls shortening diffusion distance
- each alveolus is surrounded by blood capillaries ensuring a good blood supply and helps to maintain the maximum concentration gradient between blood and the air in the alveoli
- each alveolus is ventilated removing waste co2 and replenishing oxygen levels also helping to maintain the maximum concentration gradient


what are the biological consequences of smoking?

- damages walls inside alveoli reducing SA for gas exchange
- tar irritates the bronchi encouraging mucus and damaging cilia in the lungs and trachea
- damaged cilia is unable to clear mucus leading to chest infections or bronchitis
- tobacco smoke contains carcinogens that can lead to cancer
- carbon monoxide reduces the amount of oxygen the blood can carry therefore less aerobic respiration, less energy and more lactic acid
- this increases heart rate and blood pressure which can lead to coronary heart disease


what is the blood made up of?

red blood cells, white blood cells, platelets, plasma


what is the role of plasma?

plasma is a straw-coloured liquid. It transports dissolved substances around the body, including: hormones, nutrients, glucose, amino acids, minerals, vitamins, co2, urea.


what is the role of red blood cells?

to carry oxygen from the lungs to the body tissues and carbon dioxide as a waste product, away from the tissues and back to the lungs


how are red blood cells adapted to transport oxygen?

- they carry haemoglobin to allow the cell to transport oxygen to respiring cells
- no nucleus to allow more haemoglobin to transport more oxygen to respiring cells
- small and flexible allowing them to squeeze through narrow capillaries and blood vessels
- very thin cell membrane so diffusion is quick
- biconcave shaped (flat disk) to increase SA to volume ratio for efficient rate of diffusion of oxygen into cells


what is the role of white blood cells?

help fight infections by attacking bacteria, viruses, and germs that invade the body. White blood cells originate in the bone marrow but circulate throughout the bloodstream


how does the immune system respond to disease using white blood cells (lymphocytes)?

they release anti-bodies that are specific to the pathogen. When a lymphocyte meets a specific pathogen it divides. One cell becomes a memory cell and the other creates anti-bodies. One type of anti-body will attach to the pathogen to attract phagocytes and the other will disable the cell. A third type will group the pathogens together so a phagocyte can engulf them all. If a memory cell meets the pathogen again it will create anti-bodies very quickly.


how do vaccinations work?

a harmless or inert form of pathogen is injected and stimulates a response without putting the body at risk. A lymphocyte will then divide and create memory cells so if the same pathogen enters the bloodstream again the memory cells will produce the required antibodies quicker.


what is the role of platelets?

platelets are small fragments of bone marrow, when you damage a blood vessel platelets will clump together (held together by fibrin) at the damaged area preventing any more blood from escaping and microorganisms getting into you body via the wound. This is known as blood clotting (scabs).


how is the heart structured?

the heart is structured into four chambers being: the right atrium, right ventricle, left atrium, left ventricle


how does the heart function?

- the right atrium fills with blood (from the vena cava)
- this area is squeezed forcing the blood though an atrio-ventricular valve into the right ventricle
- this area contracts forcing the blood through the pulmonary artery where it is oxygenated at the lungs
- the pulmonary vein fills the left atrium with blood
- this contracts forcing the blood into the left ventricle
- when the left ventricle contracts the blood is forced out through the aorta and transported around the body


what prevents blood from flowing backwards?

the four valves in the heart


what is the role of arteries?

- carry blood away from the heart
- carry oxygenated blood around the body


how are arteries structured?

- smooth lining allowing blood to flow smoother and quicker
- narrow lumen: maintains high pressure making sure blood flows to all parts of the body
- muscle fibres contract to push blood along and keep it flowing
- thick outer wall and inner layers of muscle to withstand high blood pressure
- elastic fibre to allow arteries to stretch under pressure
- endothelium


what is the role of veins?

- carry blood back to the heart
- carry deoxygenated blood away from the body


how are veins structured?

- thin outer walls, thin layer of muscle and elastic fibre: blood returning from the body is at a much lower pressure so the veins don't have to be as strong
- valves: muscles contract to push blood towards the heart, they close to prevent blood from flowing backwards
- large lumen
- endothelium


how are capillaries structured?

- permeable walls only one cell thick so substances can easily diffuse in/out


what is the role of capillaries?

- arteries branch into capillaries, then join up to form veins
- carries blood close to every cell in the body to exchange substances
- supplies food and oxygen
- takes away waste products e.g. co2


what is the circulatory system made up of?

the heart and blood vessels


what is the function of the circulatory system?

responsible for getting blood where needed, so useful substances (o2 and glucose) can be delivered, and waste can be removed


what goes to and from the lungs and heart?

- to the lungs, from the heart, pulmonary artery
- to the heart, from the lungs, pulmonary vein


what goes to and from the liver and heart?

- to the liver, from the heart, aorta (hepatic artery)
- to the heart, from the liver, hepatic vein (vena cava)


what goes to and from the kidney and heart?

- to the kidney, from the heart, aorta (renal artery)
- to the heart from the kidney, renal vein (vena cava)


structure of circulation system


describe the circulation of oxygenated blood

systemic circulation carries oxygenated blood from the left ventricle, through the arteries, to the capillaries in the tissues of the body. From the tissue capillaries, the deoxygenated blood returns through a system of veins to the right atrium of the heart


what is the difference between pulmonary and systemic circulation?

pulmonary circulation only occurs between the heart and the lungs. Systemic circulation refers to the circulation of blood in which oxygenated blood is pumped from the heart to the body and deoxygenated blood is returned back to the heart. Systemic circulation occurs between the heart and the entire body


how do the valves open and close?

The heart valves open and close passively because of pressure differences on either side of the valve. When pressure is greater behind the valve, the leaflets are blown open and the blood flows through the valve. However, when pressure is greater in front of the valve, the leaflets snap shut and blood flow is stopped.


describe the circulation of deoxygenated blood

pulmonary circulation is the portion of the circulatory system which carries deoxygenated blood away from the right ventricle of the heart, to the lungs, and returns oxygenated to the left atrium and ventricle of the heart


what is the excretory product of the lungs?

carbon dioxide- the lungs will excrete carbon dioxide as a waste product of aerobic respiration during exhalation


what are the excretory products of the kidneys?

excess water, salts and urea- they produce urine by osmoregulation


what are the excretory products of skin?

excess water and salts- through the sweat glands on the skin by producing sweat


how do the kidneys carry out their role in excretion?

kidneys are part of the urinary system. Urea is produced in the liver, from excess amino acids (amino acids contain nitrogen, which is toxic to the body if in excess). The kidneys do this by removing stuff like urea out of the blood under high pressure, then reabsorbing the useful things. The urea is then added to water to form urine, which travels down the ureters to collect in the bladder


what is osmoregulation?

the maintenance of constant osmotic pressure in the fluids of an organism by the control of water and salt concentrations


how do the kidneys carry out their role of osmoregulation?

1. the hypothalamus detects detects either too much or too little water in the blood
2. pituitary gland releases ADH if there's too little water, but releases less if theres too much water
3. the kidneys maintain the blood water level, or reduce it if its too high by reabsorbing less water
4. if there was previously too little water, less water is lost in urine, but the opposite happens if there's too much water
5. then blood water levels is able to return to normal


what is the urinary system made up of?

- the kidneys
- the bladder
- the ureter
- the urethra


what is the function of the kidneys?

filters out blood to prevent dehydration and manage the soluble substances in your blood and turns unwanted substances into urine


what is the function of the bladder?

stores urine


what is the function of the ureter?

carries urine from kidneys to bladder


what is the function of the urethra?

carries urine from the bladder to outside of the body


describe the process of the urinary system

the renal arteries take blood with waste products to the kidneys to be filtered. Renal veins then return the filtered blood to be circulated around the body. Blood vessels take the blood through the kidneys where the waste products are removed into convoluted tubules. The tubules join together to form the ureter, which transports urine to the bladder where it is stored. Urine is then passed from the bladder to the urethra to be released


how is a nephron structured?
the glomerulus filters blood and produces glomerular filtrate. This filtrate contains water, glucose, salts and urea. Large molecules such as protein are too large to fit through the blood capillary walls. The bowman's capsule collects the filtrate and it enters the tubules. All glucose is reabsorbed immediately into the blood capillaries. As the rest of the filtrate travels through the tubules, water and salts needed by the body are reabsorbed into blood capillaries. The loop of Henlé helps maintain the correct water balance in the body by filtering out salts. The waste, consisting of excess water, salts and urea, is urine. The collecting duct collects the urine, which is then transported in the ureter to the bladder until the body is ready to expel it through the urethra.


what are/what is the function of a nephron?

urine is produced in microscopic structures in the kidney called nephrons. There are approximately 1 million in each kidney. A nephron's job is to filter any parts of waste out of the body and reabsorb any useful minerals and water


how can the urinary and nephron system be summarised?

1. Filtration- where lots of water, ions, urea and sugar are squeezed from the blood into the tubules
2. Selective reabsorption- the useful substances (ions and sugars) are reabsorbed back into the blood from the tubules. The amount of water in the blood is regulated here to maintain it at a constant rate. This is known as 'osmoregulation'
3. Excretion of waste- urea and excess water and ions travel to the bladder as urine, to be released from the body


what is the bowman's capsule?

this is where ultrafiltration occurs. High pressure blood from the glomerulus forces blood into the bowman's capsule where small molecules are filtered through


what is the glomerulus?

a network of capillaries where blood is filtered from the capillary walls to bowman's capsule. A basement membrane acts as a filter


what is the loop of Henlé?

its function is to concentrate the fluid coming from the proximal convoluted tubule


what is the proximal convoluted tubule?

this is the first tubule after bowman's capsule. Reabsorption of salts, amino acids, glucose and minerals all occur here


what is the collecting duct?

wastes, consisting of some water, salts and urea creates urine which is collected by the collecting duct and transported in the ureter to the bladder


how is the kidney structured and what are its functions?
1. Medulla- this is where all the nephrons are contained and where urine is produced. It aids with the reabsorption of water alongside osmoregulation
2. Renal cortex- this is where ultrafiltration occurs. ;The renal cortex lies between the medulla and the wall of the kidney. It's lined with capillaries
3. The adrenal gland- this is where hormones like testosterone and adrenaline are produced


what is ultrafiltration?

when substances are filtered at high pressure in the kidneys. Occurs in the glomerulus due to the high pressure of the blood


describe ultrafiltration in the bowman's capsule

- blood from the renal artery flows through the glomerulus
- the high pressure that's built up squeezes the water, urea, salts and glucose out of the blood, and into the bowman's capsule
- membranes between the glomerulus and bowman's capsule act like filters
- big molecules (like proteins and blood cells) aren't squeezed out (they stay in the blood)
- the filtered liquid in bowman's capsule is called glomerular filtrate


what is glomerular filtrate made up of?

water, glucose, salts and urea


what is reabsorption?

this is the process in the kidneys where some substances are reabsorbed back into our blood. All glucose, some water and some minerals are reabsorbed


how is water reabsorbed into the blood from the loop of henlé?

- water that is filtered by the kidney is reabsorbed into the blood by the collecting duct depending on the levels of ADH produced by the pituitary gland
- more ADH produced= more water will be reabsorbed at the collecting duct
- less ADH produced= less water will be reabsorbed at the collecting duct


where does reabsorption take place?

- proximal convoluted tubule- most of the glucose, some salt and some water
- Loop of Henle- more water and salts
- Second convoluted tubule- more mineral salts
- Collecting duct- more water and some salts. Water reabsorption controlled by hormone ADH


where does selective reabsorption of glucose occur?

- after the glomerular filtrate enters the bowman's capsule, all glucose is immediately reabsorbed at the proximal convoluted tubule by active transport
- nephrons are adapted by having mitochondria to provide energy for ATP for the active transport of glucose molecules
- nephron also adapted to this by having thin membranes so distance of active transport is short, allowing the efficient rate of active transport


what is ADH?

ADH stands for anti-diuretic hormone. It is a hormone released from the pituitary gland on the brain. It is responsible for osmoregulation. This means controlling the water content in our blood


how does ADH regulate the water content in our blood?

- if there is a low level of water in our blood this is detected by special cells in the hypothalamus region in our brain
- these cells are sensitive to the solute concentration in our blood and cause the pituitary gland to release more ADH into our blood
- the ADH travels in our bloodstream to our kidneys. Here it causes the collecting ducts to become more permeable to water so more water is reabsorbed into the blood by osmosis
- this makes the urine more concentrated (low volume of urine) so the body loses less water and the blood becomes more dilute
- when the water content of blood returns to normal the PG stops producing ADH and the kidney tubules reabsorb less water


what is urine made up of?

water, salts and urea


how do you test for glucose?

- add drops of Benedict's solution into sample solution in a test tube
- heat at 60-70° in water bath for 5 minutes
- take the test tube out of the water bath and record the colour
- if glucose is present, the solution should turn brick red
- if glucose is not present, the solution should stay blue


how do you test for starch?

- take a sample of solution and put it onto a tile using a pipette
- add drops of iodine solution and leave it for 1 minute (to allow reaction to take place)
- if starch is present, solution should turn blue/black
- if starch is not present, solution should stay brown


how do you test for protein?

- add drops of biuret solution into sample solution in a test tube
- leave for 1 minute to allow reaction to take place
- record the colour
- if protein is present, solution should turn violet
- if protein is not present, solution should stay blue


how do you test for fat?

- mix test substance with 2cm3 of ethanol
- add an equal amount of distilled water
- leave for 3 minutes to allow reaction to take place
- record colour
- if fat is present, a milky- white emulsion forms
- if fat is not present, solution will remain colourless


what is in a human cell?

- nucleus
- cytoplasm
- cell membrane
- mitochondria
- ribosomes