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IB Biology Review
Excretory System
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Definitions
ExcretionThe disposal of nitrogen-containing waste products ofmetabolism
Osmoregulation
How organisms regulate solute concentrations and balancethe gain and loss of water
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Why is excretion important?
Body needs to get rid of waste
Otherwise, waste will build up
Take up space
Prevent metabolic processesPoison organism
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What are the two types ofwaste produced by the body?
Solid waste
Liquid waste (urea)
Where is solid waste processed?Large intestine
Where is solid waste excreted?
Rectum and anusWhere is liquid waste processed?
Kidney
Where is liquid waste excreted?
Urinary tract
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Excretory System Overview
You do not need to know this, just adding the visual
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Overview of Excretory System,Kidney, and Nephron Structure
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Kidney Structure
Be able to draw: cortex, medulla with pyramids,pelvis, ureter, renal artery, and renal vein
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Identify the components of a kidney.
cortex
medulla
renal pyramids
pelvis
ureter
renal artery
renal vein
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Nephron Structure
Be able to draw a nephron
Must include
glomerulus
Bowman's capsuleproximal convoluted tubule
loop of Henleascending and descending
both labeleddistal convoluted tubule
collecting duct
Ascendingportion ofLoop of Henle
Descendingportion ofLoop of Henle
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Identify the components of a nephron.
glomerulus
Bowman's capsule
proximal convolutedtubule
loop of Henle
ascending and descending
portions of the Loop/Henle
distal convoluted tubule
collecting duct
Ascendingportion ofLoop of Henle
Descendingportion ofLoop of Henle
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How do solutes and water get into theproximal convoluted tubule?
High pressure inarteries/arterioles leadinginto the nephron
This leads to ultrafiltration
in the capillaries of theglomerulus
Water and solutes such asurea, glucose, salts, andamino acids drain into theBowman's capsule
Water and solutes dumpedinto the proximalconvoluted tubule
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How are salt, amino acids, and water reabsorbedinto blood from the proximal convoluted tubule?
Salt (NaCl), glucose, andamino acids aretransported back to the
blood by active transport
Water follows in to theblood by osmosis
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Solute Reabsorption Diagram
H th ll th ll f th
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How are the cells on the wall of theproximal convoluted tubule specially
adapted for selective absorption?
microvilli increase the surface area for absorptionthrough active transport
mitochondria produce ATP for active transport
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What happens after filtration and reabsorption?
3. Secretion
Toxins, excess ions andother substances areactively transported out ofthe filtrate
4. ExcretionThe filtrate is sent out ofthe nephron and out of the
body as urine
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What are some reasons an individualsblood solute concentration increase?
vomiting and diarrhea makes the body lose water
increased salt intake (from eating those potato chips...)
drinking alcohol adds ethanol and sugar
drinking coffee adds sugar and caffeine
excess sweating makes the body lose water
if the individual isnt drinking enough water
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Anti-Diuretic Hormone (ADH) Function
Osmo-receptors in the brainmonitor blood solute concentration
It is a hormone that is synthesizedin the brain (hypothalamus)
When solute concentrations arehigh, ADH is released into the
blood stream
ADH travels to the nephrons of the
kidney and tell kidney to reabsorbmore water
This is a negative feedback controlof ADH secretion
IB E Q ti
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1. Blood vessels carry blood to and from the kidney.Draw a labelled diagram to show the internal structureof the kidney, including the vessels that are connected
to it. (5 marks)cortex shown at the edge of kidney;
medulla shown inside the cortex (with pyramids);
pelvis shown on the concave side of the kidney;
ureter shown connecting with the pelvis
renal artery shown connected
renal vein shown connected
IB Exam Question
IB E Q ti
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2. Draw a labelled diagram of a nephron.(6 marks)
glomerulus;
Bowman's capsule;
proximal convoluted tubule;loop of Henle;
ascending and descending both labeled;
distal convoluted tubule;
collecting duct;
IB Exam Question
IB E a Que tio
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3. Which part of the nephron shown belowis impermeable to water molecules? (1 mark)
A. I
B. II
C. IIID. IV
Correct answer: C
IB Exam Question
IB Exam Question
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4. Describe how the liquid and solutes that flow through
the proximal convoluted tubule are produced. (2 marks)
high pressure in arteries/arterioles leading into thenephron;
this leads to ultrafiltration in the capillaries of the
glomerulus;Water and solutes such as urea, glucose, salts, andamino acids drain into the Bowman's capsule which
leads to the proximal convoluted tubule;
IB Exam Question
IB Exam Question
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5. Explain how the structure of the proximal convoluted tubule
cell is adapted to carry out selective re-absorption. (2 marks)
microvilli increase the surface area for absorption /active transport;
mitochondria produce ATP for active transport;
IB Exam Question
IB Exam Question
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6. Name three solutes that are selectively reabsorbedback into the blood in the proximal convoluted tubule.
(1 mark)glucose
amino acids
salt (NaCl)
7. Describe how these solutes and water are reabsorbed
by the blood from the proximal convoluted tubule.
Salt (NaCl), glucose, and amino acids are transportedback to the blood by active transport
Water follows in to the blood by osmosis
IB Exam Question
IB Exam Question
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8. Where in the kidney does ultrafiltrationtake place? (1 mark)
A. Glomerulus
B. Loop of Henl
C. Proximal tubuleD. Collecting ducts
Correct answer: A
IB Exam Question
IB Exam Question
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9. What can be changed in the kidney over a period of timein order to carry out the process of osmoregulation?(1 mark)
A. The amount of blood flowing to the kidney
B. The amount of fluid filtered from the blood in theglomeruli
C. The amount of solutes selectively reabsorbed inthe proximal convoluted tubule
D. The amount of water reabsorbed in the collecting
ducts
Correct answer: D
IB Exam Question
IB Exam Question
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10. State three reasons why a persons bloodplasma solute concentration may increase.
(3 marks)
vomiting / diarrhoea
increase salt intake;
drink alcohol / coffee;excess sweating / lack of water intake;
IB Exam Question
IB Exam Question
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11. How does anti-diuretic hormone(ADH) function in osmoregulation.
It is a hormone that is synthesized in the brain(hypothalamus)
Osmo-receptors in the brain monitor blood soluteconcentration.
When solute concentrations are high, ADH is releasedinto the blood stream
The hormone travels to the nephrons of the kidneyand signal kidney to reabsorb more water.,
This is a negative feedback control of ADH secretion;
IB Exam Question
IB Exam Question
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12. Anti-diuretic hormone has its main effect
on which part of the nephron? (1 mark)
A. Proximal tubule
B. Bowmans capsule
C. Loop of HenleD. Collecting duct
Correct answer: D
IB Exam Question