smc-3663-10-Kidneys

BIOLOGY, M8 EQ-Bank 16

How effective is renal dialysis in compensating for the loss of kidney function? (7 marks)

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Normal kidney function

→ The kidneys are the main components of the mammalian urinary system. They are organs which filter blood and maintain water, pH, ion and salt concentration in the body through varying concentrations of each in excreted urine dependent on the body’s needs.

→ Each kidney contains 1 million nephrons, the main unit responsible for filtration.

→ Each one also contains a Bowman’s capsule, proximal and distal tubules as well as the Loop of Henle which acts as a site for selective re-absorption of certain components of the blood. This is controlled by both passive diffusion of unwanted substances through a concentration gradient (e.g. urea) or by hormonal control.

→ Aldosterone and ADH are hormones secreted by the hypothalamus which increase the permeability of the distal convoluted tubule to salt and water respectively.

Kidney disfunction and dialysis

→ Kidney function can however be impaired by diseases or disorders (such as polycystic kidney disease), many of which can kill affected individuals in a number of months if left untreated.

→ When kidney function drops below 80%, haemodialysis is an effective treatment to replace kidney function.

→ Haemodialysis involves the removal of blood from the body into the dialysis machine, which will clean the blood before returning it to the body. This is achieved by running a fluid known as dialysate, countercurrent to the blood.

→ The dialysate contains a similar composition to the blood with low urea and toxins to allow the passive diffusion of the substances via the concentration gradient into the dialysate. This is then removed and constantly replenished during a session. The countercurrent direction also improves effectiveness of this process. The dialysate can also be altered to have varying amounts of salt and ions depending on the concentration in the patients body.

→ Haemodialysis can provide an effective treatment for individuals until death or an effective transplant can be found, however the process often requires 3-4 sessions per week each of which is 4 hours long.

→ Without haemodialysis loss of kidney function is often fatal, but this life-saving technology is extremely effective in preventing many deaths despite its inconvenience.

Show Worked Solution

Normal kidney function

→ Each kidney contains 1 million nephrons, the main unit responsible for filtration.

→ Aldosterone and ADH are hormones secreted by the hypothalamus which increase the permeability of the distal convoluted tubule to salt and water respectively.

Kidney disfunction and dialysis

→ Kidney function can however be impaired by diseases or disorders (such as polycystic kidney disease), many of which can kill affected individuals in a number of months if left untreated.

→ When kidney function drops below 80%, haemodialysis is an effective treatment to replace kidney function.

→ Without haemodialysis loss of kidney function is often fatal, but this life-saving technology is extremely effective in preventing many deaths despite its inconvenience.

BIOLOGY, M8 EQ-Bank 14

Identify a disorder or disease, and describe how it affects the normal function of an organ. (2 marks)

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Evaluate the effectiveness of a technology in managing the disorder or disease described in part (a). (4 marks)

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a. Polycystic kidney disease

→ A disease in which cysts grow in the kidney.

→ This interferes with filtration and overtime, adversely affects the overall function of the kidney.

Other disorders/disease can include

→ Astigmatism, myopia or hyperopia.

→ Single sided deafness, hearing loss.

b. Use of technology in treating polycystic kidney disease

→ Polycystic kidney disease will often progress in patients until kidney failure has occurred.

→ When 80% of kidney function is lost and a transplant cannot be found, dialysis is often the only viable option.

→ There are two types of dialysis, both of which replace the function of the kidney and clean the blood.

- Haemodialysis is where blood is removed from the body and passed through a dialysis machine. The main component of the machine runs a special fluid known as dialysate countercurrent to the blood next to a permeable membrane. This allows the blood to effectively remove the toxins into the dialyse by diffusion. While this is extremely effective, it involves multiple visits per week and is very time consuming for the patients.
- Peritoneal dialysis involves the flushing of dialysate directly into the abdominal cavity through a catheter. The peritoneal membrane then acts as the filter and blood is cleaned via diffusion. The dialysate containing the waste products then exits the body into another section of the catheter. In contrast to haemodialysis, this method requires a more involved initial surgery but provides the benefit of patients being able to do this by themselves at night.

→ Both forms of dialysis are extremely effective in replacing kidney function. Despite being time consuming and uncomfortable, they allow patients suffering from polycystic kidney disease to survive for extended periods, during which a transplant may become available.

Other technologies can include

→ Glasses.

→ Any form of hearing aid dependent on the ear disease/disorder, including standard hearing aids, bone conduction implants or cochlear implant.

Show Worked Solution

a. Polycystic kidney disease

→ A disease in which cysts grow in the kidney.

→ This interferes with filtration and overtime, adversely affects the overall function of the kidney.

Other disorders/disease can include

→ Astigmatism, myopia or hyperopia.

→ Single sided deafness, hearing loss.

b. Use of technology in treating polycystic kidney disease

→ Polycystic kidney disease will often progress in patients until kidney failure has occurred.

→ When 80% of kidney function is lost and a transplant cannot be found, dialysis is often the only viable option.

→ There are two types of dialysis, both of which replace the function of the kidney and clean the blood.

- Haemodialysis is where blood is removed from the body and passed through a dialysis machine. The main component of the machine runs a special fluid known as dialysate countercurrent to the blood next to a permeable membrane. This allows the blood to effectively remove the toxins into the dialyse by diffusion. While this is extremely effective, it involves multiple visits per week and is very time consuming for the patients.
- Peritoneal dialysis involves the flushing of dialysate directly into the abdominal cavity through a catheter. The peritoneal membrane then acts as the filter and blood is cleaned via diffusion. The dialysate containing the waste products then exits the body into another section of the catheter. In contrast to haemodialysis, this method requires a more involved initial surgery but provides the benefit of patients being able to do this by themselves at night.

Other technologies can include

→ Glasses.

→ Any form of hearing aid dependent on the ear disease/disorder, including standard hearing aids, bone conduction implants or cochlear implant.

BIOLOGY, M8 2017 HSC 7 MC

Which waste product does renal dialysis remove?

Urea
Urine
Lipids
Vitamins

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`A`

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`=>A`

BIOLOGY, M8 2016 HSC 9 MC

Why is passive transport alone inadequate for the production of urine that is high in nitrogenous wastes?

Osmosis cannot target specific solutes.
Solutes cannot move against a concentration gradient.
Solute transport increases at low concentration gradients.
Osmosis moves water from a low concentration to a high concentration.

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`B`

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By elimination:

→ `A` and `C` are incorrect

→ Water is moved from high concentration to low concentration during osmosis (`D` is incorrect).

`=>B`

Mean mark 53%.

BIOLOGY, M8 2016 HSC 7 MC

The diagram shows a simplified model of a mammalian nephron and three processes labelled 1, 2 and 3.

Which row of the table correctly identifies each of the processes?

\begin{align*}
\begin{array}{l}
\rule{0pt}{2.5ex} \ \rule[-1ex]{0pt}{0pt}& \\
\rule{0pt}{2.5ex}\textbf{A.}\rule[-1ex]{0pt}{0pt}\\
\rule{0pt}{2.5ex}\textbf{B.}\rule[-1ex]{0pt}{0pt}\\
\rule{0pt}{2.5ex}\textbf{C.}\rule[-1ex]{0pt}{0pt}\\
\rule{0pt}{2.5ex}\textbf{D.}\rule[-1ex]{0pt}{0pt}\\
\end{array}
\begin{array}{|l|l|}
\hline
\rule{0pt}{2.5ex}\ \ \ \quad \quad 1 \rule[-1ex]{0pt}{0pt}& \ \ \quad \quad 2 & \ \ \quad \quad 3 \\
\hline
\rule{0pt}{2.5ex}\text{Reabsorption }\rule[-1ex]{0pt}{0pt}&\text{Filtration } &\text{Secretion }\\
\hline
\rule{0pt}{2.5ex}\text{Filtration }\rule[-1ex]{0pt}{0pt}& \text{Reabsorption } &\text{Secretion }\\
\hline
\rule{0pt}{2.5ex}\text{Secretion }\rule[-1ex]{0pt}{0pt}& \text{Reabsorption } &\text{Filtration }\\
\hline
\rule{0pt}{2.5ex}\text{Filtration }\rule[-1ex]{0pt}{0pt}& \text{Secretion } &\text{Reabsorption}\\
\hline
\end{array}
\end{align*}

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\(B\)

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→ The only correct sequence is filtration, reabsorption and secretion.

\(\Rightarrow B\)

BIOLOGY, M8 2018 HSC 15 MC

Which row of the table is correct with respect to the substances that pass through the nephron?

\begin{align*}
\begin{array}{l}
\rule{0pt}{2.5ex}\text{}\rule[-1ex]{0pt}{0pt}\\
\text{}\rule[-1ex]{0pt}{0pt}& \\
\rule{0pt}{2.5ex}\textbf{A.}\\
\text{} & \text{} & \text{} \\
\text{} &\rule[-1ex]{0pt}{0pt}\text{} & \text{}\\
\rule{0pt}{2.5ex}\textbf{B.}\\
\text{} & \text{} & \text{} \\
\text{} &\rule[-1ex]{0pt}{0pt}\text{} & \text{}\\
\rule{0pt}{2.5ex}\textbf{C.}\\
\text{} & \text{} & \text{} \\
\text{} &\rule[-1ex]{0pt}{0pt}\text{} & \text{}\\
\rule{0pt}{2.5ex}\textbf{D.}\\
\text{} & \text{} & \text{} \\
\text{} &\rule[-1ex]{0pt}{0pt}\text{} & \text{}\\
\end{array}
\begin{array}{|l|l|l|}
\hline
\rule{0pt}{2.5ex} \quad \ \textit{Bowman's capsule}& \ \ \ \textit{Proximal convoluted} & \quad \ \ \textit{Collecting duct}\\
& \quad \quad \quad \quad \textit{tubule}\rule[-1ex]{0pt}{0pt}& \\
\hline
\rule{0pt}{2.5ex}\text{Chloride ions are at the} &\text{All chloride ions are} & \text{Water is reabsorbed}\\
\text{same concentration as in} & \text{reabsorbed} & \text{in the presence of} \\
\text{plasma} &\rule[-1ex]{0pt}{0pt}\text{} & \text{aldosterone}\\
\hline
\rule{0pt}{2.5ex}\text{Plasma proteins are at} &\text{Water is reabsorbed by} & \text{Water is reabsorbed in}\\
\text{the same concentration} & \text{osmosis} & \text{the presence of ADH} \\
\text{as in plasma} &\rule[-1ex]{0pt}{0pt}\text{} & \text{}\\
\hline
\rule{0pt}{2.5ex}\text{Glucose is at the same} &\text{All glucose is reabsorbed} & \text{Water is reabsorbed}\\
\text{concentration as in} & \text{} & \text{in the presence of} \\
\text{plasma} &\rule[-1ex]{0pt}{0pt}\text{} & \text{aldosterone}\\
\hline
\rule{0pt}{2.5ex}\text{Sodium ions are at the} &\text{Sodium ions are} & \text{Water is reabsorbed in}\\
\text{same concentration as in} & \text{reabsorbed} & \text{the presence of ADH} \\
\text{plasma} &\rule[-1ex]{0pt}{0pt}\text{} & \text{}\\
\hline
\end{array}
\end{align*}

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\(D\)

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By Elimination

→ ADH is a hormone that results in the increased permeability of the walls of the collecting duct to water. Aldosterone is used for salts. (Eliminate A and C).

→ Active reabsorption of sodium ions occurs in the proximal convoluted tubule and water is moved out passively by osmosis. (Eliminate B).

\(\Rightarrow D\)

Mean mark 52%.

BIOLOGY, M8 2018 HSC 7 MC

Students dissected a mammalian kidney and drew the following diagram.

Which row in the table shows the correct labels for \(X, Y\) and \(Z\)?

\begin{align*}
\begin{array}{l}
\rule{0pt}{2.5ex} \ \rule[-1ex]{0pt}{0pt}& \\
\rule{0pt}{2.5ex}\textbf{A.}\rule[-1ex]{0pt}{0pt}\\
\rule{0pt}{2.5ex}\textbf{B.}\rule[-1ex]{0pt}{0pt}\\
\rule{0pt}{2.5ex}\textbf{C.}\rule[-1ex]{0pt}{0pt}\\
\rule{0pt}{2.5ex}\textbf{D.}\rule[-1ex]{0pt}{0pt}\\
\end{array}
\begin{array}{|l|l|}
\hline
\rule{0pt}{2.5ex}\quad \quad \quad \quad X\rule[-1ex]{0pt}{0pt}& \quad \quad \quad \quad Y & \ \quad \quad \quad Z\\
\hline
\rule{0pt}{2.5ex}\text{Cortex}\rule[-1ex]{0pt}{0pt}&\text{Medulla} &\text{Ureter}\\
\hline
\rule{0pt}{2.5ex}\text{Renal pyramid}\rule[-1ex]{0pt}{0pt}& \text{Bowman's capsule}&\text{Renal artery} \quad \quad \\
\hline
\rule{0pt}{2.5ex}\text{Medulla}\rule[-1ex]{0pt}{0pt}& \text{Cortex} &\text{Ureter}\\
\hline
\rule{0pt}{2.5ex}\text{Bowman's capsule}\rule[-1ex]{0pt}{0pt}& \text{Cortex} &\text{Renal artery}\\
\hline
\end{array}
\end{align*}

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\(C\)

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By Elimination:

→ The outer layer \(Y\) is the cortex, which contains glomeruli and Bowman’s capsules. (Eliminate A and B).

→ \(Z\)is the ureter, which takes urine to the bladder. The renal artery is the feature above it, which takes unfiltered blood to the kidney. (Eliminate D).

\(\Rightarrow C\)

BIOLOGY, M8 2015 HSC 31

'Renal dialysis and kidney transplants are very different treatments for the same medical condition. Each treatment was developed from a new application of biological knowledge.'

Justify these statements. (8 marks)

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Consider each element of the statement separately:

Medical Conditions

→ Kidney failure is a recognised medical condition that can be treated using both kidney transplants or renal dialysis.

Different Treatments

→ Renal dialysis is the cleansing of wastes from the blood externally using a dialysis machine.

→ During a kidney transplant the diseased organ is removed and replaced with a healthy organ provided by a donor.

New Application of biological information: Renal dialysis

→ The movement of substances from regions of high concentration to regions of low concentration is known as diffusion.

→ Diffusion can occur across a semi-permeable membrane.

→The dialysis machine allows blood to flow through tubing which is permeable to urea.

→ The solution around the tubing is continually replaced to maintain a steep concentration gradient so the urea can be removed out of the blood through diffusion.

New Application of biological information: Kidney transplant

→ Increased knowledge of the immune system allowed for an improved understanding of organ rejection following organ transplantation.

→ B and T cells on donated organs are recognised by the immune system as foreign and it then attacks the transplanted organ.

→ Once an infection has been removed, suppressor T cells stop the immune cells and switch off the immune response.

→ This knowledge lead to the development of immunosuppressants or anti-rejection drugs designed to fight the immune symptoms’ response to reject donated organs.

→After transplantation, anti-rejection drugs are used by recipients for their lifetime.