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biology- component 3 > Homeostasis And The Kidney > Flashcards

Homeostasis And The Kidney Flashcards

1
Q

Define homeostasis.

A

Homeostasis is the maintenance of a constant internal environment within an organism, despite external changes.

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2
Q

Why is homeostasis important?

A

It ensures optimal conditions for enzyme action and cell function, maintaining factors like temperature, pH, and water balance.

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3
Q

What is negative feedback?

A

A regulatory mechanism where a change in a parameter triggers a response that counteracts the initial change, restoring the system to its set point.

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4
Q

Provide an example of negative feedback in the human body.

A

Regulation of blood glucose levels: when blood glucose rises, insulin is released to lower it; when it falls, glucagon is released to increase it.

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5
Q

List the main functions of the kidneys.

A
  • Filtration of blood to remove waste products
  • regulation of water and electrolyte balance
    -maintenance of acid-base balance
  • hormone secretion (e.g., erythropoietin).
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6
Q

Describe the structure of a nephron.

A
  • Bowman’s capsule and glomerulus
  • proximal convoluted tubule
  • loop of Henle
  • distal convoluted tubule
  • collecting duct
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7
Q

What occurs in the glomerulus?

A

Ultrafiltration: high blood pressure forces water, ions, and small molecules out of the blood into the Bowman’s capsule, forming the filtrate.

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8
Q

How is a high filtration pressure produced inside the glomerulus?

A
  1. the afferent artery brings blood into the gloerulus to be filtered
  2. High hydrostatic blood pressure in the renal artery and the difference in diameter between the afferent (wider) and efferent (narrower) arterioles increase pressure
  3. filtrate formation- urea, uric acid, glucose, water enters bowmans capsule
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9
Q

What is selective reabsorption, and where does it occur?

A

The process by which useful substances like glucose, amino acids, and ions are reabsorbed from the filtrate back into the blood, primarily in the proximal convoluted tubule.

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10
Q

How is the proximal convoluted tubule adapted for reabsorption?

A
  • It has microvilli to increase surface area
  • numerous mitochondria to provide ATP for active transport
  • tight junctions to prevent leakage.
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11
Q

Explain the role of the loop of Henle in urine concentration.

A

It establishes a concentration gradient in the medulla through a counter-current multiplier system, allowing the production of concentrated urine.

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12
Q

What happens in the distal convoluted tubule?

A

Further regulation of ion balance and pH occurs here

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13
Q

How does the collecting duct contribute to water balance?

A

Its permeability to water is regulated by antidiuretic hormone (ADH); increased ADH makes it more permeable, allowing more water reabsorption and producing concentrated urine.

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14
Q

Define osmoregulation.

A

The process by which organisms regulate the water and electrolyte balance in their bodies to maintain homeostasis.

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15
Q

How do the kidneys respond to dehydration?

A

Dehydration leads to increased ADH secretion, making the collecting ducts more permeable to water, resulting in greater water reabsorption and concentrated urine.

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16
Q

What is the role of aldosterone in kidney function?

A

Aldosterone increases sodium reabsorption and potassium excretion in the distal convoluted tubule and collecting duct, aiding in blood pressure regulation.

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17
Q

How is urea produced in the body?

A

Urea is produced in the liver through the deamination of excess amino acids, converting toxic ammonia into urea for safer excretion.

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18
Q

Why is the removal of nitrogenous wastes important?

A

Accumulation of nitrogenous wastes like ammonia can be toxic, so their removal is essential to prevent harm to the body.

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19
Q

How do different animals excrete nitrogenous waste?

A

Aquatic animals often excrete ammonia directly
mammals convert ammonia to urea
birds and reptiles excrete uric acid to conserve water.

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20
Q

What triggers the release of antidiuretic hormone (ADH)?

A

Increased blood osmolarity, detected by osmoreceptors in the hypothalamus, stimulates the posterior pituitary gland to release ADH.

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21
Q

How does ADH affect the kidneys?

A

ADH increases the permeability of the collecting ducts to water, enhancing water reabsorption and reducing urine volume.

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22
Q

What is kidney failure?

A

Kidney failure is a condition where the kidneys lose their ability to filter waste and regulate water, salt, and pH balance in the blood.

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23
Q

What are common causes of chronic kidney disease (CKD)?

A

• Diabetes (high blood glucose damages kidney blood vessels).
• Hypertension (high blood pressure strains the kidneys).
• Glomerulonephritis (inflammation of glomeruli).
• Polycystic kidney disease (genetic condition causing cyst formation).

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24
Q

What are the symptoms of kidney failure?

A

Fatigue, swelling (oedema), shortness of breath, nausea, confusion, and changes in urination frequency.

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25
What is dialysis?
A treatment that removes waste, excess fluids, and toxins from the blood when the kidneys can no longer function properly.
26
What are the disadvantages and risks of a kidney transplant?
Disadvantages: Risk of organ rejection (immune system attacks the new kidney); lifelong use of immunosuppressant drugs, which increase infection risk; limited availability of donor kidneys.
27
How can kidney disease be prevented?
• Control blood pressure and blood sugar levels. • Maintain a healthy diet and hydration. • Avoid excessive use of NSAIDs (e.g., ibuprofen), which can damage kidneys. • Monitor kidney function regularly if at risk.
28
what is the process of urine production in loop of henle and collecting duct
1. Na* and Cl are actively pumped out of ascending limb, causing the solute potential (4, )in the medulla tissue fluid to decrease (water potential y decreases) Water moves out of the descending limh by osmosis. It does not dilute the solute potential of the medulla because the water moves directly into the blood capillaries of the nearby vasa recta (ie is reabsorbed into the blood) . 3. The fluid in the descending limb becomes more concentrated as it moves down due to this loss of water 4. The filtrate in the descending limb and the tissue fluid of the medulla are most concentrated at the tip of the loop of Hence 5. water diffuses out of the collecting duct into interstitial space to diffuse into blood by vasa recta
29
30
what is in the filtrate that enters bowmans capsule after ultrafiltation
urea, uric aicd, ions, glucose, water
31
what doesnt pass from the blood into nephron during ultrafiltration
RBC, WBC, plasma proteins as are too large to fit through pores
32
what 3 layers does filtrate pass through
- capillary wall- endothelium cells - basment membrane - bowmans capsule wall- squamous epithelial cells- podocytes
33
why is protein in urine a sympton of chronic high blood pressure
the high pressure forces the proteins which are otherwise too big, out of the pores which damages capillary and basement membrane
34
what are the stages of selective reabsorption
1. 3 na+ leaves and 2 k+ enters through na/k pump using active transport using ATP to create an electrochemical gradient 2. due to na+ leaving, more needs to enter. A symporter allows glucose and na+ to enter epithelial but only if coupled-using secondary active transport, no ATP 3. glucose tranports through transporter into the intersitial fluid by passive diffussion 4. glucose passively diffuses into blood by capillaries as theres high conc in intersititial fluid
35
function of loop of henle
reabsorbs water back into blood stream without thus, very dilite urine would be excreted
36
what is hairpin counter current multiplier
the amount of ions that get pumped out the ascending loop is amplified by the amount of water diffused out of the descending loop
37
what is ADH
antidiuretic hormone
38
whats the function of ADH
- involved in osmoregulation - changes the permeability of the plasma membrane in the collecting duct
39
how does ADH specifically make the membrane permeable
1. ADH binds to membrane receptors as it cant pass throgh the membrane 2. there are secondary messengers that travel through the cytoplasm 3. these cause the vesicles containing aquaporins to fuse with the membrane (exocytosis) 4. this increases permeabilty for water so water is able to be reabsorbed
40
how does ADH reduce effects of decreaseing water potential/concentrated solutes- osmoregulation
1. osmoreceptors in hypothalamus detect the deacrease in water potentail of blood flowing through it 2. posterior lobe of pituitary gland releases ADH 3. cells of collecting ducts and DCT of the kidney nephron (target cells) become more permeable to water due to aquaporins fusing with the cell membrane 4. more water is reabsorbed from the collecting duct into the blood- a small volume of concentrated urine is produced
41
how does ADH reduce effects of increasing water potential/ less solutes- osmoregulation
1. osmoreceptors in hypothalamus detect the increase in water potential 2. stops released of ADH from potsreior lobe of pituitary gland 3. cells become less permeable to water due to aquaporins moving out of the membrane 4. less water is reabsorbed so less concentrated urine released
42
what are the two types of kidney failure
acute and chronic
43
what is acute kidney failure
develops within hours or days and has a chance of recovery
44
possible causes of acute kidney failure
- traumatic (post surgical) - acute intoxications - part of multi-organ failure - various other diseases
45
what is chronic kidney failure
kideny failure develops over years, irreversible at the end
46
what are possible causes of chronic kidney failure
- secondary to high blood pressure/diabetes - chronic bacterial inflammation of kidneys - cystic kidneys - various autoimmune disease
47
how can most kidney problems be treated
controlling dietary intake or drugs
48
how does high protein effects kidneys
- high protein increases urea levels which can be converted to uric acid which can crystallise and form kidney stones - these tear and damage tissues leading to bleeding
49
how does high blood pressure effect kidney diseases
- high blood pressure can caue excessive filtration by the glomeruli and loss of nutrients - can also lead to damage of glomerulus which is severe can lead to cells and plasma proteins being lost in urine
50
how does controlling potassium levels help to control kidney disease
too high or too low conc of potassium can disrupt nerve transmissions
51
how does controlling calcium levels help to control kidney disease
- excess loss of calcium can lead to reduction of calcium in bones and cause osteoporosis - reduce loss of calcium can lead to hormone probelms and deposistion of calcium salts in tissues, muscles and joints
52
technology that can be used to treat kidney diseases
- ultrasound to break down kidney stones - keyhole surgery can remove fragments and is less invasive
53
what ae the two forms of kidney dialysis
- haemodialysis- using a dialysis machine to remove excess water, urea and ions from the plasma - pertoneal dialysis- uses selectivelty permeable membranes in the body to achieve the same end result
54
what is haemodialysis
- fresh dialysate is constantly moving in opposite direction to that of blood flow (counter current system) so equilibrium isnt reached - the conc of solutes can be adjusted to control the amount of difefrent solutes that are removed from the blood - pore size in the membarnes is controlled to prevent protein loss
55
advantages of haemodialysis
- effective removal of waste - care given by trained professionals - regular contact with other patients - rapid correction of elecetrolyte imbalances - no equipment to store at home - treatments only occur 3 times a week
56
disadvantages of haemodialysis
- vascular access surgery required - use of large needles - schedule inflexibility - must travel to centre - cramping with ultrafiltartion - rick of bacteremia
57
advantages of peritoneal dialysis
- flexible scehdule - frew risk of cramps - clinic visits limited to 1-2x a month - patient/family involved in care - no neededs - steady sate therapy
58
What is the only treatment for complete kidney failure?
kidney transplants
59
What is crucial for a successful kidney transplant
A match between the donor and the recipient to reduce the risk of rejection
60
How does the relationship between the donor and recipient affect the transplant success
The more closely related they are, the better the chance of a match
61
What can cause an immune response during kidney donation
Differences in blood groups and antigens on cell surfaces
62
What happens if the immune system attacks the donated kidney
The cells in the donated organ are attacked and destroyed
63
What does it mean to be "sensitised" in the context of kidney transplants
It means the person has had a transplant before and is more likely to produce antibodies against the donor organ's antigens
64
advantages of living donor
- Shorter waiting time - Less risk of rejection - Shorter time between removal of kidney from donor and transplant into recipient - Donor makes an informed decision - Lasts longer (20+ years)
65
disadvantages of living donor
- Pressure on potential donors - Donor only has one kidney - Risk to donor and recipient from surgery
66
advantages of deceased donor
- No need for dialysis - Feel healthier - Have more energy - Be able to work, travel and do other activities - Deceased donors not harmed by surgery
67
diasadvantages of deceased donor
- Long waiting time - Pain following surgery - Could reject the kidney - Need to take immunosuppressive drugs for the rest of your life - Increased risk of infection Only lasts 10 to 15 years

biology- component 3 (5 decks)

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