Homeostasis

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  • Created by: LBCW0502
  • Created on: 19-10-16 15:13
Which factors must be monitored in the internal environment? (7)
Blood glucose levels, ion levels, water levels, core body temperature, pH of the blood and concentrations of urea and sodium ions in the blood
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How to organisms maintain a dynamic equilibrium?
They use both chemical and electrical systems to monitor and respond to any changes from the steady state of the body
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What is the definition of homestasis?
The maintenance of a stable equilibrium in the conditions inside the body
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What is the function of a sensory receptor?
Sensory receptors detect changes in the internal and external environment of an organism (e.g. sensory receptors in the skin to detect pain)
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What is the function of an effector?
To respond to the stimulus detected (e.g. a muscle contracts or a gland secretes a hormone)
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What is the significance of feedback systems?
Precise control mechanisms (sensory receptors and effectors) in the body are based on feedback systems that enable the maintenance of a relatively steady state around a narrow range of conditions
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What is a negative feedback system?
They work to reverse the initial stimulus
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For which factors is negative feedback used?
Control of blood glucose levels (insulin/glucagon), temperature control and water balance
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What are the principles of positive feedback?
Conditions change, the change is detected and responses reinforce the change
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Give examples of positive feedback
Blood clotting and during childbirth
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What is thermoregulation?
The maintenance of a relatively constant core temperature
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Why is thermoregulation important?
Enzymes controlling metabolic reactions are very temperature sensitive. Each enzyme has an optimum temperature at which it works efficiently and if the temperature is too high ,enzymes can denature
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Changes in temperature as a result of surroundings depend on which physical processes? (5)
Exothermic chemical reactions, latent heat evaporation, radiation, convection and conduction
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What are ectotherms?
Animals that use their surroundings to warm their bodies so their core temperature is heavily dependent on the environment
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Give examples of ectotherms
Invertebrate animals, fish, amphibians and reptiles
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Why do ectotherms living in water not need to thermoregulate?
The high heat capacity of water means that the temperature of their environment does not change much
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Why do ectotherms living on land have problems with thermoregulation?
The temperature of the air can vary between seasons and even over a 24 hour period (from day to night)
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What are endotherms?
Animals that rely on their metabolic processes to warm their bodies and maintain their core temperature
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Give examples of endotherms
Mammals and birds
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What is an advantage for an endotherm?
They are able to maintain their body temperature and take advantage of the warmth in the environment so they can survive a wide range of environments (keep warm in cold conditions and cool down in hot conditions - which are both active processes)
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What is a disadvantage for an endotherm?
The metabolic rate of endotherms is around five times higher than ectotherms so they need to consume more food to meet their metabolic needs than ectotherms of a similar size
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What are the behavioural responses for an ectotherm (during cold temperatures)?
Bask in the Sun (orientate bodies to increase SA) for long periods of time, conduction (press bodies against warm ground), contract muscles, vibrate and gain heat released from exothermic metabolic reactions
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What are the behavioural responses for an ectotherm (during hot temperatures)?
Shelter from the Sun (seek shade), hide in cracks in rocks, dig burrows, press bodies against cool shady earth/stones, move into water/mud, minimise SA exposed to Sun and reduce metabolic heat generated
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What are the physiological responses for ectotherms?
Dark colours (absorb more radiation than light colours), alter heart rate to increase/decrease metabolic rate (affects warming/cooling across body surfaces)
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What is an advantage for an ectotherm?
They need less food than endotherms (use less energy in thermoregulation) so they can survive in habitats where food is in short supply
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What are the adaptations of the Namaqua chameleon (ectotherm)
Appears black on the side exposed to the sun and pale grey on the other side of the body, orientates body sideways towards Sun, increases heart rate, inflates body, presses body against desert sand (opposite of these features occur during the day)
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What is the hypothalamus?
The region of the brain above the pituitary gland that contains osmoreceptors involved in osmoregulation
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What is the function of the temperature receptor in the hypothalamus?
To control the responses that maintain the core temperature in a dynamic equilibrium to within about 1 of 37 degrees Celsius
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What are the behavioural responses for an endotherm when responding to temperature changes?
Basking in the Sun, pressing against warm surfaces, wallowing in water and mud to cool down, dig burrows to keep warm/cool, become dormant (hibernation or aestivation)
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What are addition behavioural adaptations for humans?
Clothes worn to stay warm, houses built (heated/cooled to maintain ideal temperature)
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What are the physiological adaptations for endotherms?
Peripheral temperature receptors, thermoregulatory centres of the hypothalamus, skin and muscles
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What is vasodilation?
Arterioles near the surface of the skin dilate when the temperature rises. Vessels providing direct connection between arterioles and venules constrict. Blood is forced through capillaries close to skin
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Describe the appearance of skin during vasodilation
Skin flushes/cools due to increased radiation. If the skin is pressed against cool surfaces then the cooling results from conduction
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How does increased sweating cool down organisms during hot temperatures?
Sweat spreads across skin, as the sweat evaporates from the surface of skin, heat is lost and cools the blood below the surface
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Increased sweating (extra information)
In some animals, sweat glands are restricted to less hairy areas of the body e.g. paws. Some animals open their mouths and pant (lose heat as water evaporates). Kangaroos and cats often light their front legs to keep cool in high temperatures
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How do hairs respond to an increase in body temperature?
Erector pili muscles (hair erector muscles) in the skin relax and lie flat on skin to avoid trapping an insulating air of air
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What anatomical adaptation do endotherms have in hot climates?
Large surface area : volume ratio to maximise cooling and pale fur/feathers to reflect radiation
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What is vasoconstriction?
Arterioles near the surface of the skin contract. Arteriovenous shunt vessels dilate so very little blood flows through capillaries close to surface of skin
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Describe the appearance of skin during vasocontriction?
Skin looks place and very little radiation takes place (warm blood kept below surface)
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How does decreased sweating aid thermoregulation?
This reduces cooling by the evaporation of water from the surface of the skin (although some evaporation from the lungs still continues)
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How does raising body hair or feathers aid thermoregulation?
Erector pili muscles in the skin contract, pulling hair/feathers of the animal erect. This traps an insulating layer of air to reduce cooling through skin. It is an effective way to reduce heat loss to the environment (but little effect in humans)
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How does shivering increase core body temperature?
Involves rapid contraction and relaxation of muscles. Metabolic heat from exothermic reactions warm up the body instead of moving it and is an effective way of raising core temperature
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What are the anatomical, behavioural and physiological adaptations for endotherms in cold climates?
Minimise SA:Vol ratio, thick layer of insulating fat underneath skin (e.g. blubber), hibernation (build up fat stores and build a well insulated shelter), lower metabolic rate
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What are the adaptations of polar bears in cold climates?
Small ears, fur on their feet (insulation from ice), hollow hairs (trap permanent layer of insulating air), thick layer of fat under skin, females dig dens in snow (for cubs)
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What is the heat loss centre? (one of the control centres in the negative feedback control from the hypothalamus)
This is activated when the temperature of the blood flowing through hypothalamus increases. It sends impulses through autonomic motor neurones to effectors in the skin/muscles, triggering responses that act to lower core temperature
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What is the heat gain centre? (one of the control centres in the negative feedback control from the hypothalamus)
Activated when the temperature of the blood flowing through the hypothalamus decreases. It send impulses through autonomic nervous system to effectors in skin/muscles, triggering responses that act to raise core temperature
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What are the main metabolic waste products in mammals?
Carbon dioxide (waste product of respiration), bile pigments (from breakdown of haemoglobin from old erythrocytes. They are excreted in bile from liver-small intestine via gall bladder/bile duct. They colour faeces) and nitrogenous waste (urea)
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What are the other examples of nitrogenous waste products?
Ammonia (produced by fish) and uric acid (produced by birds and insects)
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General features of the liver
Largest internal organ, located below the diaphragm, made up of 2 lobes (100,000 hexagonal lobules)
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What are the names of the three blood vessels which supply the liver?
Hepatic artery, hepatic vein and hepatic portal vein
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What does the hepatic artery contain?
Oxygenated blood
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What does the hepatic vein contain?
Deoxygenated blood and waste products (e.g. carbon dioxide, urea etc.)
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What does the hepatic portal vein contain?
Products of digestion (e.g. glucose and amino acids). The hepatic portal vein carries these products from the intestines to the liver
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What are the features of hepatocytes?
Large nuclei, prominent Golgi apparatus, lots of mitochondria (metabolically active), able to regenerate
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What are sinusoids?
Small blood vessels where the blood from the hepatic artery and the blood from the hepatic portal vein mix. This increases the oxygen content in the blood for hepatocytes for respiration can take place (release energy)
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What are Kupffer cells?
Cells which act as resident macrophages of the liver, ingesting foreign particles and helping to protect against disease. Kupffer cells constantly move around.
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What is the name of the fluid which hepatocytes secrete?
Hepatocytes secrete bile from the breakdown of the blood into spaces called canaliculi (from these the bile drains into the bile ductules which take it to the gall bladder)
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What are the functions of bile?
Neutralise acid in the stomach and emulsifies fats
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Describe carbohydrate metabolism
Hepatocytes are in control of blood glucose levels. When blood glucose levels rise, insulin levels rise and hepatocytes convert glucose into glycogen. When blood glucose levels fall, glucagon levels increase and glycogen converts back into glucose
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What is deamination?
The removal of an amine group from amino acids
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What is transamination?
The conversion of one amino acid into another
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What is transamination important?
The diet does not always contain the required balance of amino acids (transamination can overcome the problems this might cause)
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What would happen to excess proteins or amino acids if deamination was not carried out by hepatocytes?
The body cannot store proteins/amino acids so any excess ingested protein would be excreted and wasted
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What are excess amino acids converted into?
Ammonia
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What is the equation for the process of deamination?
2NH3 + CO2 -> CO(NH2)2 + H2O
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Why is ammonia converted into urea?
Ammonia is very toxic and very soluble in blood
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Why is urea diluted to become urine?
Urea is toxic in high concentrations
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Urea is excreted in which organs?
Kidneys
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What is the remainder of the amino acid used for?
The keto acid can be fed into cellular respiration or converted into lipids for storage
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What is the name of the set of enzyme controlled reactions where ammonia (produced in the deamination of proteins) is converted into urea?
The ornithine cycle
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Name three substances which are broken down in the liver (detoxification)
Alcohol, insulin, paracetamol
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Describe the detoxification of ethanol
Ethanol is converted into ethanal using the enzyme alcohol dehydrogenase. Ethanal is converted into ethanoate using the enzyme aldehyde dehydrogenase. Each of these steps produces a hydrogen ion which combines with NAD to form NADH2
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What can ethanoate be used for?
Ethanoate can be used to build up fatty acids or can be used in cellular respiration (Krebs cycle)
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Hepatocytes contain which enzyme (used to break down hydrogen peroxide)
Catalase (used to break down hydrogen peroxide into water and oxygen)
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Name the stages of the liver
Healthy liver, fatty liver, liver fibrosis and liver cirrhosis
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What are the problems with excess alcohol consumption? (Fatty liver)
NAD is used for the detoxification of alcohol instead of being used to oxidise lipids. This leads to fat deposits in hepatocytes (damage hepatocytes/cannot function). This leads to fibres blocking blood vessels and scar tissue
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Where are the kidneys located in the body?
They are located in the lower back and are attached to the back of the abdominal cavity
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What do the layers surrounding the kidneys consist of?
Thick protective layer of fat and a layer of fibrous connective tissue
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What homeostatic roles are the kidneys involved in?
Excretion (filter nitrogenous waste products e.g. urea) and osmoregulation (maintain water balance, pH of the blood and tissue fluid surrounding cells)
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Which blood vessels supply blood to the kidneys?
Renal arteries that branch off from the abdominal aorta
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Which blood vessel removes blood from the kidneys?
The renal vein that drains into the inferior vena cava
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What are the small structures (units) of the kidneys called?
Nephrons
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What is the sterile liquid produced by the kidneys called?
Urine
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Describe the pathway of urine for excretion
Urine passes out of the kidneys down the ureter. It is collected in the bladder (muscular sac for temporary storage). When the bladder almost full, sphincter muscles at the exit to the bladder open and urine passes out of the body down the urethra
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Describe the structure and function of the cortex
The dark outer layer. This is where the filtering of blood takes place. It has a dense capillary network carrying blood form the renal artery to nephrons
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Describe the structure and function of the medulla
Light in colour. Contains tubules of the nephrons that form pyramids of the kidneys and the collecting ducts
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Describe the structure and function of the pelvis
The central chamber where the urine collects before passing down the ureter
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What are the functions of nephrons?
Filter blood (majority of filtered material is returned to the blood), nitrogenous waste is removed, mineral ions/water are balanced
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Describe the structure of the Bowman's capsule
Cup-shaped structure that contains the glomerulus (tangle of capillaries). More blood goes into glomerulus than leaves it due to ultrafiltration taking place
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Describe the structure of the proximal convoluted tubule
The first coiled region of the tubule after the Bowman's capsule. This is found in the cortex of the kidney. This is where many of the substance needed by the body is reabsorbed into the blood
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Describe the structure of the Loop of Henle
Long loop of tubule, creates a region of very high solute concentration in the tissue fluid in the medulla. Descending limb runs down from cortex through medulla to hairpin bend at bottom of loop. Ascending limb travels through medulla to cortex
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Describe the structure distal convoluted tubule
A second twisted tubule where fine-tuning of the water balance of the body takes place. Permeability of walls to water varies in response to levels of ADH. Further regulation of ion balance and pH of blood takes place
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Describe the structure of the collecting duct
Urine passes down the collecting duct through the medulla to the pelvis. More fine-tuning of the water balance takes place. Walls in the collecting duct are sensitive to ADH
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The nephron has a network of capillaries around it and leads to which blood vessels?
Into a venule and then to the renal vein
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Describe the content of the blood that leaves the kidney
Reduced levels of urea, levels of glucose/amino acids are almost the same (may be slightly less as some glucose is used in selective reabsorption). Mineral ion concentration is blood is restored to ideal levels
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What is ultrafiltration?
The process by which blood plasma is filtered through the walls of the Bowman's capsule under pressure (first stage in excretion and osmoregulation)
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Describe the structures of the blood vessels supplying the glomerulus
The glomerulus is supplied with blood by a wide afferent arteriole from the renal artery and blood leaves through a narrower efferent arteriole (increases pressure in glomerulus)
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Why is it important to have a high blood pressure in the glomerulus?
This forces blood out through the capillary wall (acts like a sieve)
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What are the three layers of the three part filter?
Endothelium of the blood capillary, the basement membrane and the epithelium of the renal capsule
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Why can't red blood cells proteins pass through the basement membrane?
They are too large to pass through the basement membrane (relative molecular mass above 69000). Proteins are repelled by the negative charge of the collagen fibres in the basement membrane
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What are podocytes?
An additional filter. They have extension (pedicels) that wrap around capillaries, forming slits that make sure any cells, platelets or large plasma proteins that have passed the other two filters do not get through the tubule
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Compare the content of the filtrate and the content of the blood plasma
The filtrate entering the capsule contains glucose, salt, urea etc. in the same concentrations as they are in blood plasma
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What is the glomerular filtration rate?
A test used to estimate the volume of blood filtered by the glomeruli each minute, used to indicate a loss of function in the kidneys
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What is selective reabsorption?
The reabsorption of selected subtances i.e those needed by the body in the kidney tubules
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Describe the concentration of the ultrafiltrate compared to the blood plasma
The ultrafiltrate is hypotonic to (less concentrated than) the blood plasma)
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What is the main function of the nephron after the Bowman's capsule
To return most of the filtered substances back to the blood
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What substances are reabsorbed in the PCT?
Glucose, amino acids, vitamins, hormones (moved from the filtrate back into the blood by active transport)
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What are the adaptations of the cells lining the PCT?
Covered in microvilli (brush border) which increases SA over which substances can be reabsorbed. They have many mitochondria to provide ATP needed in active transport systems
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Describe the concentration of the filtrate at the end of the PCT (moving towards the Loop of Henle)
The filtrate is isotonic (at same concentration) with the tissue fluid surrounding the tubule and isotonic with the blood
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What is the Loop of Henle?
A long loop of nephron that creates a steep concentration gradient across the medulla
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Explain the term hairpin countercurrent multiplier
Hairpin (shape of the structure), countercurrent (blood plasma and filtrate flow in opposite directions), multiplier (increase reabsorption of water).
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How is energy used in a countercurrent multiplier?
Energy is used to produce concentration gradients. Cells use ATP to transport ions (active transport), producing a diffusion gradient in the medulla
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Describe the features of the descending limb of the Loop of Henle
Leads from PCT, water moves out of filtrate and down a water potential gradient, upper part is impermeable to water but lower part is permeable to water (runs down into medulla -high solute concentration in tissue fluid). Impermeable to ions
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Describe the concentration of the filtrate entering the descending limb of the Loop of Henle
Filtrate is isotonic with blood
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Describe the concentration of the fluid that reaches the hairpin bend
Very concentrated and hypertonic to blood in capillaries
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Describe the features of the ascending limb of the Loop of Henle
Permeable to ions, impermeable to water. Upper part has a wider lumen and lower part has narrower lumen
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Describe the concentration of the fluid in the lower part of the ascending limb
Becomes increasingly dilute (solute concentration of tissue fluid of medulla increases)
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Describe the concentration of the fluid in the upper part of the ascending limb
Dilute fluid is hypotonic to blood
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How are the cells lining the DCT adapted to carry out active transport?
They have many mitochondria
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What happens in the DCT when the body lacks salt?
Sodium ions are actively pumped out of the DCT with chloride ions following down a electrochemical gradient
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What happens in the DCT when there is a low water potential in the blood?
Water can leave the DCT, concentrating the urine if the walls of the tubule are permeable (response to ADH)
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Where is the concentration and volume of urine produced determined?
In the collecting duct
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How is water reabsorbed from the collecting duct?
Water moves via osmosis from an area of high water potential (lumen of collecting duct) to an area of low water potential (tissue fluid of medulla). Water is then reabsorbed into the blood
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Describe the concentration of urine when more water is reabsorbed
Very hypertonic (when the body needs to conserve water)
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What is the permeability of the collecting duct determined by?
The level of ADH (antidiuretic hormone)
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What is osmoregulation?
The balancing and control of the water potential of the blood
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What is ADH?
A hormone that increases the permeability of the DCT and the collecting duct to water
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Where is ADH produced?
In the hypothalamus (secreted by neurosecretory cell and flows down axon)
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Where is ADH stored?
In the posterior pituitary gland
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Describe the mechanism of ADH action
ADH binds to receptors on plasma membrane and triggers formation of cyclic AMP (cAMP) as a second messenger inside cell which relays a signal received at cell surface receptors to molecules inside the cell
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Describe the cascade of events cAMP causes
Vesicles in cells lining collecting duct fuse with plasma membrane (side with tissue fluid), aquaporins become permeable to water, provides a route for water into tissue fluid and capillaries via osmosis
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Explain the effect when more ADH is released
More water channels are inserted into membranes of tubule cells. Easy for water to leave via osmosis. Small amount of concentrated urine formed. Water returned to capillaries to maintain water potential in blood and tissue fluid
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Explain the effect when less ADH is released
Levels of cAMP fall, water channels are removed from tubule cell membranes and enclosed in vesicles again. Collecting duct becomes impermeable to water. Large amounts of dilute urine formed. Maintains water potential in blood and tissue fluid
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What are osmoreceptors?
Sensory receptors that respond to changes in the water potential of the blood. It is located in the hypothalamus of the brain. They are sensitive to concentration of inorganic ions in the blood and linked to release of ADH
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Describe negative feedback control and ADH (when water is in short supply)
Concentration of inorganic ions in the blood increases and water potential decreases. Osmoreceptors send impulses to posterior pituitary gland to release ADH in blood. ADH is picked up by collecting duct to increases permeability of water
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Describe negative feedback control and ADH (when water is in excess)
Water potential increases in blood, osmoreceptors detect this and send an impulse to posterior pituitary gland to reduce release of ADH. There is little absorption of water as walls of collecting duct are impermeable to water.
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How are urine samples used in diagnostic testing?
If you are affect by one of a number of different diseases, new substances will appear in urine e.g. creatinine in urine indicated muscle damage and glucose in urine indicated a symptom of type 1 and type 2 diabetes
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Which hormone is detected in urine during pregnancy?
Human chorionic gonadotrophin (hCG)
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What are monoclonal antibodies?
Antibodies from a single clone of cells that are produced to target particular cells or chemical in the body
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How are monoclonal antibodies produced?
A mouse is injected with hCG so it makes the appropriate antibody. B-cells that make the antibody are removed from the spleen of the mouse and fused with myeloma. A hybridoma forms, divides rapidly and monoclonal antibodies are collected/purified
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Describe the first stage in a pregnancy test
Wick is soaked in first urine passed in morning (this will have the highest levels of hCG)
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Describe the second stage in a pregnancy test
Test contains mobile monoclonal antibodies with small coloured beads attached. They only bind to hCG. If the woman is pregnant the hCG binds to mobile monoclonal antibodies and forms a hCG/antibody complex (hCG acts as an antigen), with coloured bead
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Describe the third stage in a pregnancy test
The urine carries on along the test structure until it reaches a window
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Describe the fourth stage in a pregnancy test
At the window, there are immobilised monoclonal antibodies arranged in a line/pattern (e.g. + sign) that only bind to hCG/antibody complex. If the woman is pregnant, a coloured line/pattern appears in the first window
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Describe the fifth stage in a pregnancy test
The urine continues up through the test to a second window
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Describe the sixth stage in a pregnancy test
In the second window, there is a line of immobilised monoclonal antibodies regardless of whether they are bound to hCG or not. This coloured line forms whether or not a woman is pregnant (indicates the test is working)
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What do two coloured pattens indicate and what does one coloured pattern indicate
Pregnant (two coloured patterns) and not pregnant (one coloured pattern)
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How are anabolic steroids detected in urine?
By using gas chromatography and mass spectrometry. The urine sample is vaporised with a known solvent and passed along a tube. The lining of the tube absorbs the gases and is analysed to give a chromatogram than can be read to show presence of drugs
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Describe the process of drug testing using urine
The urine sample of divided into two. The first sample may be tested by an immunoassay, using monoclonal antibodies to bind to drug. If this is positive, the second sample is run through gas chromatography/MS and confirm presence of drug
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Give examples of drugs that can be tested in the urine
Ethanol (alcohol), amphetamines, cannabis and cocaine
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Give some of the causes of kidney failure
Kidney infections, structures of podocytes/tubules damaged, raised blood pressure (damages three layer filter), genetics (polycystic kidney disease)
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Describe the effects of kidney failure
Protein in urine, blood in urine (filter process not working), loss of electrolyte balance, build up of urea in blood, high blood pressure, weakened bones, pain/stiffness in joints, anaemia
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What is erythropoietin?
A hormone that stimulates the formation of red blood cells (produced by kidneys)
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What is creatinine?
A break down product of muscles
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What does the GFR measure?
The level of creatinine in the blood
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What are the units for GFG?
cm3/min
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Describe the trend in age with the average GFR in healthy adults
As the age increases, the average GFR increases (males have more creatinine due to having more muscle fat)
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Describe the trend in age with the average GFR in healthy adults
As the age increases, the average GFR decreases (males have more creatinine due to having more muscle fat)
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What is haemodialysis?
Involves the use of a dialysis machine. Blood leaves artery and flows through partially permeable dialysis membrane (mimics renal capsule). Substances diffuse from blood to dialysis fluid
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Describe the content of the dialysis fluid
Normal plasma levels of glucose to ensure there is no net movement of glucose out of the blood, normal levels of ions (excess ions in blood diffuse into dialysis fluid), no urea (countercurrent exchange system)
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Which process does haemodialysis rely on?
Diffusion
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Describe the precautions patients take during haemodialysis
They remain attached to dialysis machine for several times for many hours, need a diet with little protein and salt (can only eat/drink what they like at the beginning of dialysis)
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What are the advantages of haemodialysis?
Waste products removed, an alternative to kidney transplant, conventional haemodialysis doesn't need to be carried out everyday, home dialysis is more flexible, carried out by trained staff
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What are the disadvantages of haemodialysis?
Requires a strict lifestyle and diet, can cause low blood pressure/blood clots, increase risk of bloodstream infections, permanent internal access through fistula, use needles
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What is peritoneal dialysis?
Involves use of natural dialysis membranes formed by lining of abdomen (peritoneum)
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Describe the procedure of peritoneal dialysis
Usually done at home Dialysis fluid introduced into abdomen using a catheter. Left for several hours for dialysis to take place. Fluid is drained off/discarded (blood is balanced and urea/excess minerals are removed)
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What are the advantages of peritoneal dialysis?
Can be carried out at home, portable equipment, fewer restrictions on diet, waste products removed, alternative to transplant, no needles
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What are the disadvantages of peritoneal dialysis?
Carried out everyday, uncomfortable, risk of peritonitis, peritoneum thickened/scarred (need to switch to haemodialysis), result in lack of energy, difficult to carry out independently
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Describe the process of a kidney transplant
A single healthy kidney from a donor is placed within the body. Blood vessels are joined and ureter of new kidney is inserted into bladder (kidney will function for many years)
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What is an advantage of a kidney transplant?
No restrictions on diet and regular dialysis sessions, less expensive (compared to dialysis)
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What are the problems with a kidney transplant?
Risk of rejection (immune system activated when foreign antigens are detected causing immune system to attach organ). When the organ starts to fail, patients return to dialysis. Shortage of donors
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What are the procedures for reducing risk of rejection?
Match the antigens of the donor to the recipient as close as possible (tissue type, blood group), use immunosuppressant drugs (suppress immune system)
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What is the disadvantage of taking immunosuppressants?
Prevents patients from responding effectively to infectious diseases
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