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92 Cards in this Set
- Front
- Back
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The Liver - Background Define excretion Define metabolic waste |
The removal of unwanted products of metabolism (metabolic waste) from the body.
Substances produced in excess by the reactions inside cells or are toxic. |
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The Liver - Background What are the two main excretory products? |
CO2 - produced by every living cell in respiration
Urea - produced in the liver from excess amino acids |
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The Liver - Background How is CO2 removed from the body? |
CO2 is passed from respiring cells to the bloodstream, is transported in the blood to the lungs where it diffuses into the alveoli to be excreted by exhalation
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The Liver - Background Where is Urea produced? |
In the liver formed from excess amino acids
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The Liver - Background How is Urea secreted? |
It is passed into the bloodstream to be transported in solution dissolved in the plasma to the kidneys. The kidneys absorb urea from the blood and excrete it as urine - dissovled in water. (Stored in the bladder before being expelled via the urethra) |
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The Liver - Background Why does CO2 need to be removed from the body? |
1) REDUCED O2 TRANSPORT - the majority of CO2 is transported as hydrogencarbonate ions which results in H+ ions being formed. This occurs in red blood cells with carbonic anhydrase. H+ ions then compete with O2 for Haemoglobin - therefore there is reduced O2 transport. 2) CARBAMINOHAEMOGLOBIN - CO2 combines with Hb directly to form carbaminohaemoglobin which has a lower affinity for O2 than normal Hb. 3) RESPIRATORY ACIDOSIS - Excess CO2 can cause respiratory acidosis: CO2 dissolves in blood plasma and can combine with water to form carbonic acid: CO2 + H2O -> H+ + HCO3 It then dissociates: HCO3 -> H+ + CO3- See next flashcard pls. |
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The Liver - Background Explain respiratory acidosis |
The hydrogen ions lower the pH of the blood, making it more acidic. - proteins in the blood act as buffers to resist the pH change - if it is a small pH change, the extra H+ is detected by the respiratory centre in the medulla oblongata which increases breathing rate to help remove excess CO2 HOWEVER -If the blood pH does fall below 7.35, it causes slow, difficult breathing, headache, drowsiness, confusion etc. |
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The Liver - Background Where is the liver located? What are liver cells called? |
Beneath the diaphragm Hepatocytes |
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The Liver - Background Describe how blood is brought to the liver |
Blood is brought to the liver by two different vessels - the hepatic artery delivers oxygenated blood from the aorta and the hepatic portal vein which delivers deoxygenated blood from the digestive system, rich in nutrients (glucose, amino acids, insulin, glucagon) from the small intestine and pancreas. |
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The Liver - Background How does the hepatic portal vein differ from the hepatic artery? |
- It carries 3 times as much blood per minute - It carreis deoxygenated blood - The blood is at a much lower pressure as it has already passed through a set of cappillaries in the walls of the small intestine. |
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The Liver - Background Describe the transport of the blood out of the liver What is the function of the bile duct? |
A single vessel, the hepatic vein, returns deoxygenated blood to the vena cava, which then transports it back to the heart. Carries biles from the liver to the gall bladder where it is stored before use in digestion of fats in the small intestine. |
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The Liver - Background Draw and annotate the blood supply to the liver. |
Annotations -Hepatic vein - returns deoxygenated blood and allows amino acids to enter - Hepatic Portal Vein - brings blood rich in glucose and amino acids from the small intestine (and Insulin and Glycogen from the pancreas) - Hepatic artery - delivers oxygenated blood |
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The Liver - Background What is 'histology'? |
The study of tissues |
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The Liver - Background What is the liver made up of? why? |
Lobules to ensure best contact between the blood and the liver cells. |
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The Liver - Background Describe the histology of a lobule. |
Each lobule is made up of many hepatocyhtes arranged in rows that radiate out from the centre of the lobule like spokes from a wheel. In the centre of a lobule there is a branch of the hepatic vein. Between the lobules are branches of the hepatic portal vein and hepatic artery (and the bile duct) Blood flows from between the lobules to the centre, out of the hepatic vein. |
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The Liver - Background How are hepatocytes arranged? |
Arranged in rows that radiate out from the centre of the lobule like bike spokes. They are cuboidal in shape and have microvilli on surface. |
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The Liver - Background What are sinusoids? |
Channels that carry blood between the rows of hepatocytes. |
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The Liver - Background What are bile canaliculi? |
Channels that carry bile that is sometimes produced by some hepatocytes. |
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The Liver - Background Describe the direction of Bile flow |
From the centre of a lobule to between the lobules (opposite to blood flow) where it enters a branch of the bile duct |
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The Liver - Background Why are rows never more than ??? cells thick? |
??? = 2 To ensure that each cell is in close contact with blood in the sinusoids |
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The Liver - Background What are Kupffer cells? |
Specialised macrophages that line the sinusoids. |
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The Liver - Background What is the function of Kupffer cells? |
They capture and destroy bacteria that has entered the liver from the blood in the hepatic portal vein (from the small intestine) and breakdown and recycle old red blood cells. |
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The Liver - formation of urea Why do excess proteins need to be removed? |
The body cannot store exccess proteins and some people consume much more protein than they need (I'm looking at you Timmy ). |
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The Liver - formation of urea What process removes excess proteins? |
Deamination |
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The Liver - formation of urea What is deamination ? |
The breakdown of excess amino acids (from excess proteins). The amino acid group is removed and converted into ammonia NH3 and the rest of the amino acid is converted to a keto acid which can then go on to the Krebs cylce to be respired (to release energy) or converted to fats to be stored. |
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The Liver- formation of urea Draw the deamination of excess amino acids with annotations. |
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The Liver- formation of urea Why must ammonia be removed from the body? |
Because it is very soluble and very toxic. |
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The Liver- formation of urea How is ammonia removed from the blood? |
It is combined with CO2 to form urea - CO(NH2)2 + H2O |
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The Liver- formation of urea Why is urea better than ammonia? |
Although it is still toxic, it is less soluble and therefore less dangerous. |
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The Liver- formation of urea How is Urea excreted? |
The liver releases urea into the blood where it dissolves into the plasma and is transported around the body until it is removed from the blood as it passes through the kidneys. |
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The Liver- formation of urea Draw the Ornithine cycle |
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The Liver- formation of urea What is Ornithine? |
An amino acid that is not used to make proteins |
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The Liver- formation of urea Where are potentially dangerous substances broken down? (be specific) |
The liver, on the smooth endoplasmic reticulum of the hepatocyte. |
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The Liver - Detoxification of other substances What do alcoholic drinks contain ? What is detoxification? |
Ethanol, C2H5OH the conversion of toxic molecules to less/non-toxic molecules. |
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The Liver- Detoxification of other substances Describe the dangerous properties of ethanol |
1) It is a small and lipid soluble molecule so can easily diffuse across a plasma membrane into a cell. 2) It quickly gets into the blood because it simply diffuses across the stomach wall. 3) It can cause damage to cells because it is TOXIC. |
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The Liver- Detoxification of other substances What does the liver do to reduce the harmful effects of ethanol? |
It breaks it down into less harmful substances. 1) Ethanol is dehydrogentate to Ethanal by Alcohol/Ethanol dehydrogenase 2) It is dehydrogenated further to Ethanoate (acetate) by the aldehyde/ethanal dehydrogenase. 3) Ethanoate (acetate) then enters the Krebs cycle (Combined with CoA to form Acetyl CoA) to be metabolised to produce ATP. In each stage of the reaction NAD is reduced to form reduced NAD. |
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The Liver- Detoxification of other substances What can happen if large amounts of alcohol are consumed on a regular basis? |
The tissues in the liver can be damaged. |
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The Liver- Detoxification of other substances How does large quantities of alcohol on a regular basis damage liver tissues? |
The breakdown of ethanol produces reduced NAD. In its oxidised form, NAD oxidises fatty acids in the liver. When reduced, it cannot do this so fatty acids accumulate and are converted to fats and stored in hepatocytes, reducing their effeciency. this is FATTY LIVER.
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The Liver- Detoxification of other substances Where are these fat deposits stored, and what affect does this have? |
In the hepatocytes - it can severely reduce their functions. This is called FATTY LIVER. |
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The Liver- Detoxification of other substances What is Cirrosis? Include: -What it is caused by -What it is |
Chirrosis is caused by a combination of fatty liver and damage to hepatocytes. Damaged hepatocytes are replaced with fibrous tissue and the structure of the blood supply is lost: some blood in the hepatic portal vein passes straight to the hepatic vein without passing through the sinusoids. This means the liver cannot carry out its functions. |
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The Liver- Detoxification of other substances What are other risk factors for Fatty Liver? |
Diabetes and Obeseity. |
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The Liver- Detoxification of other substances What affect on the rest of the body does it have when the liver cannot function ? |
It can no longer convert ammonia to urea so the concentration of ammonia in the blood increases and can cause major damage to the CNS -> this can cause coma or death. |
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The Liver- Detoxification of other substances What other substances does the liver break down? |
Hormones Ex. Testosterone, Oestrogen, Thyroxine. And medicinal drugs. |
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The Liver- Detoxification of other substances Considering this, what other affects might it have if the liver stops functioning? |
One or more hormones may acculmulate, causing disruption to the affects they normally produce. |
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The Kidneys - Background Where are the kidneys located? |
The kidneys are located at the back of the abdominal cavity |
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The Kidneys - Background Draw and annotate the structure and blood supply of the kidneys |
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The Kidneys - Background Describe urine transport in the kidney |
The ureters carry urine away from the kidneys to the bladder where it is stored before being expelled from the urethra. |
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The Kidneys - Background Describe the blood supply to the kidneys |
Each kidney is supplied with blood by the renal artery which brances off from the aorta. The renal vein returns blood to the vena cava. |
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The Kidneys - Background Describe the histology of the kidney |
Kidney tissue is dark red with an outer cortex and inner paler medulla. A whiter area, the pelvis, lies in the centre. |
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The Kidneys - Background What are kidneys made up of? |
Nephrons. |
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The Kidneys - Background Why can't you see a nephron easily with a microscope? |
Because they take a very winding route from the outer cortex to the pelivs, and so when a kidney is cut, the cut passes through many different nephrons. |
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The Kidneys - Background Draw the structure of a nephron. |
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The Kidneys - Background Describe the structure of a nephron |
-Each nephron begins with a cup-shaped structure - the renal (bowman's) capsule in the cortex -The tube runs from the capsule to the centre of the kidney forming a twisted region - the proximal convuluted tubule -The loop of henlé lies in the medulla -The tube forms another twisted loop - the Distal Convuluted Tubule -It then joins a collecting duct leading through the medulla into the pelvis -The collecting duck then joins the ureter. |
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The Kidneys - production of urine What is Ultrafiltration? |
Filtration on a micro-scale, as in the glomerulus where large molecules and cells are left in the blood and smaller molecules pass into the Bowman's capsule. |
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The Kidneys - production of urine What happens at the glomerulus |
Small molecules are filtered out of the blood and into the lumen of the nephron |
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The Kidneys - production of urine How is the blood in the glomerular capillaries seperated from the lumen of the nephron? |
It is seperated by two layers of cells and a basement membrane. The first layer of cells is the endothelium of the blood capillary which has small pores in it that allow plasma to seep through. Lying against the blood capillary epithelium is the basement membrane, and against this is the second layer of cells, podocytes of the nephron. |
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The Kidneys - production of urine What is the strcture of a podocyte? |
They have many projecting fingers that wrap around a loop of blood capillary in the glomerulus. There are slits between the interlocking of podocyte fingers. |
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The Kidneys - production of urine Describe the blood supply to the nephron. (the formation of the glomerular filtrate.) |
The afferent arteriole (bringing blood to the nephron) has a wider diameter than the efferent arteriole which carries blood away. This causes an increase in hydrostatic pressure inside the glomerular capillaries. This forces blood plasma through the pores of the blood capillary endothelium, through the basement membrane and then the slits between the podocytes.The fluid that seeps through into the cavity of the renal capsule is the glomerular filtrate. |
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The Kidneys - production of urine a) What cannot get through this filter? b) How are the 1) Endothelium 2) Basement membrane 3) Epithelial (podocyte cells) adapted to their function? |
a) Large, insoluble proteins and cells b) 1) Has narrow gaps between cells that blood plasma can pass through 2) Consists of a fine mesh of collagen fibres and glycoproteins which act as a filter to prevent the passage of large molecules- so, proteins and blood cells do not enter the glomerular filtrate. 3) Have many finger-like projections that ensure there are gaps between the cells. Fluid from the blood in the glomerulus can pass between these cells, into the lumen of the bowman's capsule. |
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The Kidneys - production of urine Why is selective reabsorption necessary? |
Because the glomerular filtrate contains many substances that are needed. |
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The Kidneys - production of urine When does selective reabsorption occur? |
As the glomerular filtrate passes through a nephron. |
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The Kidneys - production of urine Where does most reabsorption take place? |
In the Proximal Convuluted Tubule |
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The Kidneys - production of urine How is the PCT adapted for selective reabsorption? |
1) The walls of the PCT are in contact with the tubual fluid and is highly folded to form microvilli and is made of layers of cuboidal cells to increase surface area for reabsorption 2) Blood capillaries lie close to the outer surface of the proximal convuluted tube 3) Membrane contains special co-transporter proteins which transport glucose or amno acids in association with sodium ions into the cell: facilitated diffusion. 3) The opposite membrane of the cell close to the tissue fluid and blood capillaries is folded to increase surface area. it contains sodium-potassium pumps that pump sodium ions out of the cell and potassium ions in. 4) The cell cytoplasm has many mitochondria indicating involvement of an energy requiring process. |
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The Kidneys - production of urine Describe the properties of the outer membrane of the PCT. |
The outer membrane of the PCT actively transport Sodium ions out of the cytoplasm (of the cells in the outer membrane) and into the blood capillary. This creates a concentration gradient between the cells of the outer membrane and the glomerular filtrate inside the nephron: there is a high concentration of sodium ions in the glomerular filtrate and a low concentration in the cells of the outer membrane, so sodium ions passively diffuse into the cytoplasm of the cells of the outer membrane passing through transport proteins in the plasma membrane. |
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The Kidneys - production of urine What is co-transport? |
Transporter proteins in the plasma membrane of the PCT epithelium can transport something else at the same time as sodium ions - even against their concentration gradient. For example, as a sodium ion is diffusing through one kind of transporter, it might carry a glucose molecule with it up/against it concentration gradient. |
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The Kidneys - production of urine How does co-transport work? |
The diffusion of the sodium ion across the transporter provides energy for a glucose molecule to move against its concentration gradient. |
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The Kidneys - production of urine What else happens at the PCT? |
All glucose in the PCT is reabsorbed by co-transport into the blood. Amino acids, vitamins, sodium ions and chloride ions are also reabsorbed here. |
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The Kidneys - production of urine What affect does the removal of these solutes have? |
It increases the water potential of the glomerular filtrate and decreases the water potential in the blood capillary and the cells in the walls of the PCT. This creates a water potential gradient, which water moves down and into the blood: this is how most water is reabsorbed. |
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The Kidneys - production of urine Describe the reabsorption of urea. |
Urea is a small molecule, which can easily diffuse through cell membranes. It is in high concentration in the glomerular filtrate and in low concentration in the capillaries, so diffuses passively through the PCT wall and into the blood. |
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The Kidneys - Osmoregulation Define osmoregulation |
The control of the water content of body fluids.
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The Kidneys - Osmoregulation What structures are involved? |
Pituitary gland, kidneys, hypothalamus |
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The Kidneys - Osmoregulation Describe the function of the hypothalamus in osmoregulation |
The hypothalamus contains sensory neurones called osmoreceptors which are sensitive to the water potential of the blood that passes through it. Their cell bodies produce ANTI-DIURETIC HORMONE - which is passed along their axons which terminate in the posterior pituitary gland. |
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The Kidneys - Osmoregulation What urine is produced with a) low water potential b) high water potential |
a) small volumes of concentrated urine b) large volumes of dilute urine |
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The Kidneys - Osmoregulation What response occurs a) too little water in blood b) too much water in blood |
The walls of the collecting duct respond to the level of ADH in the blood. a) ADH binds to membrane-bound receptors in the wall of the collecting duct, causing a chain of enzyme-controlled reactions inside the cell. In the end, vesicles containing water permeable channels (aquaporins) move to the plasma membrane, making it more permeable to water, thus more water is reabsorbed by osmosis into the blood. b) osmoreceptors in the hypothalamus are not stimulates so only a little ADH is released. Much less ADH binds to receptors in the plasma membranes of collecting duct cells so the aquaporins move back into the cytoplasm, thus it is impermeable to water and most water flows to the bladder. |
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The Kidneys - Osmoregulation How do osmoreceptors work? |
When the water potential of the blood is low, osmoreceptors lose water by osmosis, causing them to shrink and stimulate neurosecretory cells in the hypothalamus. They then send action potentials down their axons to cause ADH release. |
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The Kidneys - Osmoregulation What is osmoregulation an example of? |
NEGATIVE FEEDBACK you ding dong |
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The Kidneys - Kidney Failure What is kidney failure? |
A condition in which the kindeys stop working properly. |
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The Kidneys - Kidney Failure causes of kidney failure? |
Hypertension Acute - caused by diabetes mellitus, inflammation of glomeruli/sepsis (infection of the blood and body tissues by bacteria) Chronic - inflammation of glomeruli |
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The Kidneys - Kidney Failure What is dialysis? |
The use of a partially permeable membrane to allow certain substances to diffuse from one fluid to another, down their concentration gradients. It removes wastes, excess fluid and salt from the blood by passing over a dialysis membrane. |
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The Kidneys - Kidney Failure What is a dialysis membrane? |
A partially permeable membrane that separates the dialysis fluid from the patient's blood in a dialysis machine |
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The Kidneys - Kidney Failure What is haemodialysis ? |
when blood from the patient's vein is passed through dialysis tubing surrounded by dialysis fluid so exchange can occur across a partially permeable membrane |
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The Kidneys - Kidney Failure What is peritoneal dialysis? |
the treatment of kidney failure by pumping dialysis fluid into the body cavity so that exchange can occur across the peritoneal membrane. The peritoneum is the layer of tissue that lines the abdominal cavity. |
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The Kidneys - Kidney Failure Describe the process of peritoneal dialysis |
1) a catheter is inserted into the peritoneal cavity 2) dialysis fluid is passed through 3) it is left for exchange to occur and is then drained off |
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The Kidneys - Kidney Failure What are the advantages and disadvantages of Haemodialysis? |
✓ More efficient at removing unwanted substances from the blood X takes several hours X Patient has to be connected to the dialysis machine several times a week X machines are expensive and in short supply X Between treatments a patient has to take care of what they eat |
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The Kidneys - Kidney Failure What are the advantages and disadvantages of Peritoneal dialysis? |
✓ Patient doesn't need to be connected to the machine ✓ It is a continuous process so there are no large swings in blood volumes or content X It has to be done more often X Relatively high risk of infection because pathogens sometimes get into the abdomen through the catheter. |
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The Kidneys - Kidney Failure Disadvantages of kidney transplants? |
X short supply X must come from a healthy person with a similar tissue type to avoid rejection X ethical issues- black market kidneys |
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The Kidneys - Kidney Failure What are xenotransplants? and disadvantages? |
transplants from a different species X ethical issues X religious issues X introduction of new disease |
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The Kidneys - Steroids and pregnancy Describe how pregnancy tests work |
Once implanted in the uterine lining, the human embryo secreted HUMAN CHORIONIC GONADOTROPHIN - HCG. Pregnancy tests contain monoclonal antibodies which are specific and only binds to HCG. 1) any HCG in the urine attaches to an antibody that is tagged with a blue bead 2) The HCG-antibody complex moves up the strip until it sticks to a band of immobilised antibodies 3) As a result, all the antibodies carrying a blue bead and attached to HCG are held in one place, forming a blue line 1 line = contol 2 = pregnancy |
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The Kidneys - Steroids and pregnancy What are anabolic steroids? |
Steroids that stimulate anabolic reactions in body cells (large molecules built from smaller ones) They can increase performance in competitive sports |
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The Kidneys - Steroids and pregnancy Describe the action of steroids |
Steroids are soluble in lipids so move easily through plasma membranes, combine with a receptor molecule in the cytoplasm which sets off a chain of events that results in the transcription of a particular gene, which increase protein synthesis in the cell. |
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The Kidneys - Steroids and pregnancy Disadvantages of using steroid hormones? |
X Decreases bodies own production of hormones and decrease immune system's ability to deal with pathogens X Can damage the liver as hepatocytes take up the hormone and break it down |
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The Kidneys - Steroids and pregnancy How can you test for misuse of steroids? |
GC. |
