Chapter 15- Excretion Flashcards
Why uncertain diagnosis may occur in px over 65?
Older people may have more complex medical problems
How peritoneum may differ in its function from artificial membrane in a dialysis machine used in haemodialysis?
- can perform active transport
- can perform facilitated diffusion
Why px receiving peritoneal dialysis need to have the fluid replaced 4 times a day but those receiving haemodialysis only need treatment three times a week?
- can remove less waste
- in haemodialysis, dialysis fluid is constantly changed
- haemodialysis maintains conc gradient as uses counter current flow. In peritoneal dialysis, the conc gradient reduces
Type of cell which RBC are formed and where this is found?
Erythropoietic cell
Bone marrow
Where is glucose selectively reabsorbed?
pct
Regions of nephron in cortex?
- PCT
- DCT
- Collecting duct
- bowman’s capsule
How longer loop of Henle able to prevent excessive water loss?
- More Na+ C l- ions pumped out of ascending limb into medulla
- builds up high water potential gradient
- allows removal of more water from CD
Drugs for body building?
Anabolic steroids
Blood in glomerulus has high what pressure?
Hydrostatic
What does hydrostatic pressure do?
Forces small molecules such as water, urea, amino acids, it amino out of glomerulus
Process at glomerulus + BC?
Ultrafiltration
Where cells that detect decrease in water potential of blood found?
Hypothalamus
Cells that detect decrease in water potential of blood?
Osmoreceptors
Walls impermeable to water?
Ascending limb
Most of water reabsorbed into blood?
PCT
Role of loop of Henle in production of urine?
- role of loop of Henle is to cause a decrease in the water potential of medulla
- descending limb permeable to water. Water removed from DL
- AL impermeable to water. Active transport outwards of Na+ Cl-
- water potential of tissues surrounding CD lower than fluid inside it
- water
Organ that produces urea?
Liver
Pregnancy hormone?
hCG
Why high intake of protein will result in high conc of urea in urine?
- high intake of protein leads to large amount of amino acids
- excess amino acids cannot be stored
- amino acids concerted to ammonia by deamination
- NH3 enters ornithine cycle for conversion to urea
- increased blood conc of urea leads to more urea in urine
How glomerulus able to perform its function?
- afferent arteriole has bigger diameter than efferent arteriole
- high hydrostatic pressure
- endothelium wall of capillary wall has fenestrations
- these allow ultrafiltration
Specialised cells in BC?
Podocytes?
Kidney failure. Composition of blood
- high in urea
- high in water
- high in ions
Need for closely matching donated kidney to recipient?
- if not closely matched, donated kidney will be recognised as foreign as the antigens will be different. Causes rejection by recipients immune system
- need for suitable size of kidney in specific case e.g. if recipient is small child
How BC can perform function effectively?
- basement membrane stops removal of large molecules
- podocytes have ginger like projections which ensure gaps to allow passage of substances
How structure of Aquaporins prevent passage of ions?
- positive charge in channel repels positive ions
- ions too large to pass through channel
Glomerulus + PCT damaged. Differences in composition of urine compared to healthy person?
- blood present
- large amino acids present
- glucose present
- more water
Effect on blood cells if water potential of plasma allowed to increase significantly?
- water potential of plasma higher than that of blood cell
- water enters blood cell
- might burst
What cells produce ADH?
Osmoreceptors
What do osmoreceptors do?
Detect changes in the water potential of the blood flowing through the hypothalamus
What gland is ADH secreted from?
Posterior pituitary gland
Where ADH is removed from and what happens to it?
-in liver, hepatocytes will remove an amine group in deamination reaction to produce ammonia. passed to ornithine cycle and forms urea
How pregnancy stick works?
- testing for hCG
- monoclonal antibodies on stick
- these antibodies are attached to dye
- hormone complementary to antibody
Should steroids be permitted?
- gives unfair advantage
- have health risks e.g. depression, aggression
- does not reflect athlete’s natural talent
Why anticoagulant added to blood?
-so that clots don’t form during dialysis
Why no anticoagulant added towards end of dialysis session?
Preventing low bp
What happens at PCT?
- selective reabsorption of glucose + amino acids
- water follows by osmosis so conc of urea, ions increases
Why can hCG be detected in urine?
-has a molecular mass of less than 69000
Characteristics that must be considered when using GFR to diagnose kidney damage?
- age bc kidney function declines with age
- gender bc men + women have different muscle mass + this will alter production of creatinine
Electron microscope?
- 2D image
- internal details visible
- high magnification
- high resolution
Compare processes at PCT and DCT?
Similarities -both involve selective reabsorption -both use active transport Differences -DCT involves ions only -PCT involves ions + molecules e.g. glucose + amino acids
Why podocytes are unable to undergo mitosis?
- already differentiated so cannot divide
- shape too irregular
- if mitosis occurred, it would alter no. Of fenestrations + would alter ultrafiltration
Which organelle supplies CO2 + ammonia for ornithine cycle?
Mitochondrion
How can you tell it’s HPV?
- bigger lumen
- blood from gut entering through branched vessel
Similarities between ultrafiltration + formation of tissue fluid?
- both processes occur in capillaries
- high hydrostatic pressure in both
- blood vessels become narrower to maintain pressure
- hydrostatic pressure greater than oncotic pressure
- both involve basement membranes
Differences between ultrafiltration + tissue fluid formation?
- filtrate enters BC + then PCT. tissue fluid bathes cells
- molecules jot reabsorbed by capillaries form urine. Molecules that are not reabsorbed will form lymph
- blood filtered through 3 layers in ultrafiltration but only 1 in tissue fluid formation
What would happen to person with lack of ADH?
- frequent need to urinate
- dehydration
- mineral imbalance
Why unusual for proteins to appear in urine?
- too large
- relative molecular mass greater than 69000
- to pass through basement membrane
Why proteins in urine symptom of chronic high blood pressure?
- glomerular bp is greater
- proteins forced through
- damage to capillaries
- damage to basement membrane
Caffeine inhibits release of ADH. Effect of drinking coffee?
- volume will increase
- conc will decrease
- fewer Aquaporins in membrane of CD
- less water reabsorbed by osmosis
What is transamination and why is it necessary?
- conversion of one amino acid to another
- amino acids in body may not match body’s requirements
Macromolecules that are broken down to form excretory nitrogenous waste products?
- nucleic acids
- proteins
Why urea excreted rather than ammonia?
- NH3 is alkaline and so highly toxic
- more soluble so would require large volumes of water to excrete it
- would cause dehydration
Feautures of glomerulus and BC that allow them to perform their function?
- afferent artiole is wider than efferen arteriole
- this causes high bp in glomerulus
- thus higher hydrostatic pressure in glomerulus than BC
- endothelium which is wall of capillary has gaps to allow passage of substances
- basement memebrane stops removal of large molecules
- podocytes of BC have finger like projections which allow passage of substances
Why high intake of protein results in high conc. of urea in urine?
- high intake of preotin leads to large amount of amino acids
- excess amino acids cannot be stored
- amino acids deaminated
- large amounts of NH3 enter ornithine cycle for conversion to urea
Condition indicated by glucose in urine?
- diabetes
- kidney failure
Cells of the collecting duct prevented from responding to ADH. symptom expected?
- high vol of urine
- fewer aquaporins in membrane
what features of adult stem cells make them suitable for regeneration of tissues in kidneys?
- they are multipotent
- can differentiate to become any cell type within kidney
What does it mean if error bars overlap?
no significant difference
