15 - Homeostasis Flashcards

Question

Hepatocytes lining the SINUSOIDS absorbs ....

Answer 1

products in blood and secrete products into the blood as it flows over them.

Answer 2

Specialised macrophages The role of these is to destroy worn out red and white blood cells, bacteria and foreign matter arriving from the digestive tract

Answer 3

Special cells produce bile, which flows through BILE CANALICULI.

Answer 4

carbohydrate metabolism deamination of excess amino acids detoxification

Answer 5

in the liver -> when BGL too high insulin rises, and the hepatocytes are stimulated to convert glucose into carbohydrate storage. same for the revers

Answer 6

removal of amino group from amino acids Amino acids are broken down into ammonia & various molecules such as keto acids. =-> Ammonia is highly toxic and very soluble, so as soon as the ammonia is made, it enters the next stage of the process.

Answer 7

Removal of waste products of metabolism from the body

Answer 8

the chemical processes that occur within a living organism in order to maintain life

Answer 9

Maintenance of a constant internal environment

Answer 10

A type of blood vessel that serves as a location for mixing of the oxygen-rich blood from the hepatic artery and the nutrient-rich blood from the portal vein

Answer 11

blood vessel that supplies oxygenated blood to the liver

Answer 12

blood vessel which transports the liver's deoxygenated blood and blood which has been filtered by the liver to the inferior vena cava

Answer 13

Due to the high toxicity and solubility of ammonia (NH3), following its production by deamination, it is immediately converted into a less soluble and less toxic substance called urea. This conversion, which occurs in 3 stages, is called the ornithine or urea cycle

Answer 14

Ornithine is an amino acid, which is used to generate the urea Needs energy in the form of ATP One turn of the cycle: consumes 2 molecules of ammonia consumes 1 molecule of carbon dioxide creates 1 molecule of urea CO(NH2)2 regenerates a molecule of ornithine for another turn.

Answer 15

hepatocytes branched space store Less α 1, 4 and 1, 6 hydrolysis respiration

Answer 16

Detoxification is the process of converting toxic substances into harmless ones or removing them from the body. Most of which happens in the liver & kidneys.

Answer 17

-> breadown of hydrogen peroxide. catalase splits hydrogen peroxide into oxygen and water -> alcohol dehydrogenase breaks down ethanol to ethanal. ethanal is converted to ethanoate (can used fo build up fatty acids or cellular respiration)

Answer 18

The kidneys are supplied with blood from the renal artery branching off the aorta Blood is taken away via the renal vein connecting to the inferior vena cava

Answer 19

cortex- dark outer layer where he filtering of the blood takes place *(has dense capillary network carrying blood form the renal artery to nephrons) medulla- lighter in colour and contains the tuble of the nephrons that form the pyramids and collecting ducts pelvis- where the urine collects

Answer 20

The kidney is made of millions of specialised filtering units called NEPHRONS… …which drain into the renal pelvis… …which empties into the ureter… …which carries urine to the bladder for storage… …before the bladder opens and urine passes out of the body through the urethra

Answer 21

Bowman’s capsule - cortex proximal convoluted tubule - cortex (descending) Loop of Henle (ascending) - medulla distal convoluted tubule - cortex collecting duct - medulla

Answer 22

The first part of the nephron is the Bowman’s capsule and a specialised bundle of capillaries called the glomerulus which, together, carry out ULTRAFILTRATION.

Answer 23

The second part is the proximal convoluted tubule and SELECTIVE REABSORPTION occurs here.

Answer 24

The third part is a long hairpin called the Loop of Henle that passes from the cortex into the medulla. This region is essential for establishing an ion concentration gradient in the surrounding tissue fluid

Answer 25

The fourth part is a second twisted tubule called the distal convoluted tubule and is where further selective reabsorption occurs to fine tune the water balance of the body in response to ADH.

Answer 26

The final is called the collecting duct, where water balance of the body continues to be fine-tuned in response to ADH.

Answer 27

glucose, water, inorganic mineral ions, urea, amino acids Whether a substance is filtered out of the glomerulus and into the nephron is dependent upon the size of the molecule (< mr 69 000) Small molecules are filtered and become part of the filtrate whereas the large molecules are trapped in the blood

Answer 28

A is the afferent arteriole B is the efferent arteriole - glomerulus pressure rises

Answer 29

capillary endothelium - provides a barrier to cells but not plasma proteins basement membrane - water and small molecules can pass through Epithelium of renal capsule contains podocytes

Answer 30

- very thin - perforated with thousands of pores of about 10 nm diameter - provides a barrier to cells but not plasma proteins

Answer 31

- mesh of collagen and glycoprotein fibres - - water and small molecules can pass through - proteins are too large and are repelled by negative charges on fibres

Answer 32

Cells, platelets and plasma proteins cannot pass through the filter and remain in the capillary

Answer 33

Small molecules such as; water glucose amino acids ions Urea (waste product of protein metabolism)

Answer 34

NO red blood cells NO platelets NO large plasma proteins

Answer 35

. Ultrafiltration . Proteins have a much lower conc in the glomerular filtrate . Because most are too large to pass through filter Or because only some (0.05) small enough to pass through filter . At least 3 of: water, inorganic ions, urea, uric acid, glucose, amino acid concentrations the same . Because all get filtered out . As all are small molecules

Answer 36

proximal convoluted tubule

Answer 37

All glucose, amino acids, vitamins and hormones reabsorbed back into blood by active transport. Approx. 85% water and sodium chloride reabsorbed. Na+ moved by active transport Cl- follows by diffusion Water moves out of tubule into blood by osmosis

Answer 38

Microvilli give large surface area for exchange of materials Large numbers of mitochondria (ATP from respiration for active transport)

Answer 39

- Na+ ions are pumped out of the epithelial cells (active transport) - Na+ concentration gradient is created between the PCT and the epithelial cytoplasm - Diffusion of Na+ down its concentration gradient provides the energy to move glucose and amino acids through co-transporters into the epithelial cell (indirect active transport) - Amino acids and glucose move by facilitated diffusion down their concentration into the capillary

Answer 40

As water moves down the descending limb into the medulla the water potential gradient increases because…. There is a high concentration of ions in the surrounding tissue fluid of the medulla (as a result of activity of the ascending limb) Descending limb is permeable to water but impermeable to ions, so water moves out by osmosis. Water in the tissue fluid continues to move into the capillary network surrounding the loop of Henle Tubule fluid reaching the bottom of the hairpin is VERY concentrated (and HYPERTONIC) to the blood in the capillaries

Answer 41

Filtrate is very concentrated because… water has left in the descending limb It is permeable to sodium and chloride ions This causes… diffusion of ions e.g. salts out of the loop down their concentration gradient

Answer 42

As the water potential of the filtrate becomes close to the water potential in the surrounding tissue fluid... Active transport of sodium and chloride ions out of the nephron into surrounding medulla tissue causes : Water potential of filtrate… to increase (becomes more dilute) Solute concentrations of filtrate…to decrease Ultimately, this means... tissue fluid of the medulla develops a very high concentration of ions so that water will move out by osmosis (in the collecting duct) and urine will be more concentrated than blood

Answer 43

Fluid in the tubule entering the DCT is hypotonic to blood again (more dilute) If the body lacks salt, sodium ions are actively pumped out of nephron into blood, and chloride ions follow passively down their electrochemical gradient. Permeability of the DCT to water changes, depending on requirements of the body. Water can leave the DCT to conserve water and produce a smaller volume of concentrated urine.

Answer 44

The walls of the collecting duct can be made more or less permeable to water according to the needs of the body. This allows more or less water to be reabsorbed back into the blood. Controlled by antidiuretic hormone (ADH) in the blood

Answer 45

Less ADH in the blood means that less water is reabsorbed. The cell surface membrane folds inwards to create new vesicles that remove the aquaporins from the membrane. The wall is less permeable and more water passes out in urine.

Answer 46

Neurosecretory cells in the hypothalamus produce ADH in their cell body, which flows down the axon to the posterior pituitary gland where it is stored until needed. Osmoreceptors in the hypothalamus monitor the blood’s water potential

Answer 47

Dehydration Decreased water potential of blood Osmoreceptors cells in hypothalamus lose water (so shrink) Stimulates posterior pituitary gland to release ADH ADH carried in the blood ADH arrives at the collecting duct ADH stimulates cAMP and the insertion of aquaporins into the wall

Answer 48

Kidney infections- structure of podocytes and tubule may be damaged – blood and /or protein in urine Raised blood pressure- can damage epithelial cells and basement membrane of Bowman’s capsule - blood and/or protein in urine Genetic conditions e.g. polycystic kidney disease, where kidney tissue is replaced by fluid filled cysts or the cysts damage the kidney tissue Diabetes (high blood sugar can damage blood vessels in kidneys) Overuse of some drugs e.g. aspirin

Answer 49

The body is no longer able to control the balance or excretion of urea, mineral ions & water. This causes: Electrolyte imbalance : excess Na+ , K +and Cl- cannot be excreted creating osmotic imbalance in tissues which can be fatal. Urea builds up and poisons cells causing illness & death. High blood pressure - water balance is not maintained, so causes rise in blood pressure leading to heart problems and strokes. Joint Pain – due to build up of certain proteins in the blood. Weakened bones – calcium/phosphorus balance cannot be maintained, affecting the mineralisation of bones. Anaemia – kidneys produce hormone erythropoietin which stimulates bone marrow to produce erythrocytes. Decreased hormone production leads to decreased number of erythrocytes and tiredness and lethargy as a result.

Answer 50

First sign blood and /or protein in urine Detection of other symptoms associated with kidney failure How is this tested & quantified? Measuring the “glomerular filtration rate”

Answer 51

Indication of the rate at which blood is filtered at the Bowman’s capsule into the tubule. It is estimated indirectly by measuring creatinine levels in blood Creatinine not reabsorbed or secreted, exclusively filtered through the kidneys. rate of excretion = rate of filtering Higer blood creatinine levels = lower GFR

Answer 52

1. Kidney dialysis 2 types: a) Haemodialysis b) Peritoneal dialysis 2. Kidney transplant

Answer 53

Passive process relies on concentration gradients No active processes Takes about 8 hours per session Must be repeated several times a week Must manage diet carefully- low protein and salt diet. Control water intake. Why? Can eat and drink what they like at start of dialysis process

Answer 54

1. Blood enters under pressure from radial artery. 2. Pump controls pressure /flow 3. Blood thinners prevent clotting 4. Blood flows between selectively permeable dialysis membranes 5. Filtered blood passes through trap for air bubbles before returning to radial vein. Concurrent flow

Answer 55

Always contains Water Glucose Mineral ions Also may contain (bicarbonate, acetate, amino acids etc.) These all must be in appropriate proportions to maintain the delicate balance in the blood. Never contains Urea Other waste products (e.g. urobilin)

Answer 56

Dialysis fluid introduced into abdomen. Left for several hours Diffusion occurs across the membranes (especially peritoneal membrane), moving waste products into the dialysis fluid. Dialysis fluid containing waste is drained.

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15 - Homeostasis Flashcards

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