Class:
Name:
(
) Date:
19 Homeostasis in mammals
19.1 What is homeostasis? (Book 3, p.54)
!
•
(1)!
Homeostasis
(
᧯փؓᘝ) is the maintenance of a constant internal environment
inside our body.
•!
Homeostasis ensures the best conditions in our body for body cells to function efficiently.
•!
Examples of homeostasis in mammals:
(2)! Osmoregulation (
and (3)!
excretion
ዶຘᓳᆏ)
(ඈइ) by
the kidneys
•
E
Regulation of body
Regulation of blood glucose
temperature by the
level by the (5)!
(4)!
and the (6)!
Homeostasis is maintained by (7)
mechanism
skin
negative
liver
pancreas
feedback
.
19.2 How are the amounts of water and minerals regulated by
the kidney? (Book 3, p.55)
•!
The regulation of the amounts of water and minerals is important to avoid unnecessary
changes in the (8)!
water
potential
inside cells which greatly affect
normal metabolism.
•!
The amount of water and minerals in our body are regulated by the (9)!
the urinary system (
20¬
ࣼ‫ߓݟ‬อ).
kidneys
of
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The mammalian urinary system (Book 3, p.55)
dorsal aorta
inferior vena cava
A
B
C
D
E
F
G
♦ The mammalian urinary system
Structure
(1)
A
Renal
artery
(2)
B
C
(3)
Kidney
D
(4)
Ureter
(5)
Urinary
(
࿽೯౧)
࿽ᙩ౧)
( ࿽)
(ᙁ‫ݟ‬ጥ)
bladder
(6)
F
G
(
Renal
vein
E
Function
Sphincter
muscles
(7)
Urethra
(
ፎ౞)
ਔપۜ)
(‫ݟ‬ሐ)
(
•!
Carries blood from the aorta to the kidney
•!
Returns blood from the kidney to the inferior
vena cava
•!
Purifies blood and produces urine
•!
Carries urine to the urinary bladder
•!
For temporary storage of urine
•!
Relax when the bladder is full so that urine is
!
passed to the outside, i.e. urination
•!
Passes urine from the urinary bladder to the outside
Go To …
Practical 19.1 Examination of the mammalian urinary system
(Student’s Book 3 p.55; Activity Book 3 p.31)
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Class:
E
•
Name:
(
Kidney (Book 3, p.56)
A kidney consists of:
1 outer, lighter coloured (1)
2
•
) Date:
cortex
inner, darker coloured (2)
medulla
‫ؼ‬ᔆ)
(᧮ᔆ)
(
Inside the medulla, a number of cone-like structures stick out
into the (3)
pelvis
(
࿽ल).
♦ Longitudinal section of a kidney
E
•
Nephron (Book 3, p.56)
A (4)
nephron
(
࿽ց) is the functional unit of the kidney. A kidney is composed of
one to two million nephrons.
•
The structure of a nephron:
(5)
glomerulus
(
࿽՛෺)
(6)
(11)
Bowman’s
proximal
convoluted
capsule
(
ᚁ೷ּᦖ)
(7)
tubule
(
efferent
arteriole
(
(12)
ᙁ‫נ‬՛೯౧)
(8)
tubule
᎛‫ڴ‬՛ጥ)
arteriole
(
ᙁԵ՛೯౧)
(9)
(13)
loop
renal
vein
renal
artery
(10)
distal
convoluted
afferent
(
२‫ڴ‬՛ጥ)
of
(14)
capillary
(15)
collecting
Henle
duct
‫ּܓۮ‬୚)
(
(
Key:
ႃ‫ݟ‬ጥ)
blood flow in arteries
blood flow in veins
flow of glomerular filtrate
Go To …
Practical 19.2 Examination of the mammalian kidney (Student’s Book 3 p.56; Activity Book 3 p.32)
22¬
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Functioning of a nephron (Book 3, p.58)
1
Ultrafiltration (Book 3, p.58)
•
(1)
၌ៀ‫ )ش܂‬is the process in which plasma is filtered under high
pressure into the Bowman’s capsule. (2)
Glomerular
filtrate
(࿽՛෺ៀ෈)
Ultrafiltration
(
will be formed.
•
The glomerulus of a nephron is adapted to ultrafiltration:
The efferent arteriole is (3)
high (4)
narrower
hydrostatic
than the afferent arteriole. The
pressure
developed at the glomerulus
forces small molecules from the plasma out into the Bowman’s capsule.
The capillary walls of the glomerulus are (5)
differentially
permeable
and allow only small molecules to pass through.
♦ Diagram showing ultrafiltration in a glomerulus and a Bowman’s capsule!
•
The contents of glomerular filtrate are similar to those of blood plasma but no
(6)
proteins
are present in the glomerular filtrate.
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2
Reabsorption (Book 3, p.59)
•!
(1)
Reabsorption
(
) Date:
ૹ‫ )ش܂گܮ‬is the process in which useful substances are absorbed
back into the blood when the filtrate flows through the kidney tubules.
•
The kidney tubules are coiled in order to increase their (2)
surface
area
and the time taken for the filtrate to flow through them.
•
Reabsorption of glucose and amino acids only takes place along the (3)
convoluted
tubule
proximal
, while salts, water and urea are reabsorbed throughout
the renal tubules and the collecting ducts.
•
Different substances are reabsorbed by different processes:
glucose
amino acids
salts
water
blood
flow
urea
blood
proximal
convoluted tubule capillary
(4)
Key:
diffusion
and active transport
(5)
osmosis
(6)
diffusion
♦ Reabsorption of different substances along the proximal convoluted tubule
•!
The remaining glomerular filtrate after reabsorption is called (7)
urine
.
It contains urea, water, salts and other metabolic waste.
•
Urine passes through the collecting ducts to the pelvis, then through the (8)
ureters
!
to the urinary bladder for temporary storage.
24¬
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Functions of the kidneys in homeostasis (Book 3, p.61)
Osmoregulation (Book 3, p.61)
The osmoregulatory function of the kidneys in terms of water and salt regulation when the body is
facing different conditions:
When taking in a large amount of water
Concentration of blood
(1) Dilute / Concentrated
Proportion of water reabsorbed
into capillaries
(2) Greater / Smaller
Volume of urine produced
(3) Larger / Smaller
Concentration of urine
(4) Dilute / Concentrated
When losing a large amount of water e.g. by sweating
Concentration of blood
(5) Dilute / Concentrated
Proportion of water reabsorbed
into capillaries
(6) Greater / Smaller
Volume of urine produced
(7) Larger / Smaller
Concentration of urine
(8) Dilute / Concentrated
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When taking in excess salts
Concentration of salt in
glomerular filtrate
(1) Higher / Lower
Volume of water flows from
blood into tubules
(2) Larger / Smaller
Volume of urine produced
(3) Larger / Smaller
Salt concentration in urine
(4) Higher / Lower
2
Excretion (Book 3, p.62)
•
(5)
Metabolic
waste
is constantly produced and a high concentration of
the waste in the body is toxic. That is why excretion is necessary.
•
The kidneys produce (6)
to get rid of the metabolic waste, such as urea,
urine
from the blood.
Go To …
STS connection 19.1 Kidney failure and the related community supports
(Student’s Book 3 p.63; Activity Book 3 p.36)
STS connection 19.2 Issues associated with kidney transplants
(Student’s Book 3 p.63)
Section concept diagram (Student’s Book 3 p.65)
Quick check (Student’s Book 3 p.65)
19.3 How is body temperature regulated by the skin? (Book 3, p.66)
Importance of regulating body temperature (Book 3, p.66)
•
A constant body temperature enables mammals to stay (7)
•
A constant body temperature keeps the (8)
(9)
26¬
metabolic
rate
enzyme
active
activity
at all times.
and the
relatively constant.
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Go To …
Practical 19.3 Examination of the mammalian skin
(Student’s Book 3 p.66; Activity Book 3 p.34)
Structure and functions of skin (Book 3, p.67)
The skin consists of two layers: (1)
epidermis
(
।‫ )ؼ‬and (2)
dermis
(
ట‫)ؼ‬.
A
B
C
F
D
E
G
H
I
J
♦ Diagram showing a longitudinal section through the mammalian skin
Epidermis (Book 3, p.67)
Structure
Outermost layer
A
Function
•
Reduces water loss by (3)
•
Protects the body from (4)
evaporation
mechanical
injury
Middle layer
B
•
Prevents the entry of (5)
•
When pushed towards the surface, cells die and form the
pathogens
outermost layer
Innermost layer
C
•
Produces new cells by cell division
•
Contains (6)
melanin
(
႕ై) which protects the
body against harmful ultraviolet light
•
Produces (7)
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vitamin
D
27¬
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Dermis (Book 3, p.68)
Structure
D
Function
Sensory receptors
•
Detect (1)
(2)
•
Secretes (3)
•
Evaporation of sweat helps cool down the body
•
Supply (4)
Sweat
E
gland
(
‫ۀ‬ᆯ)
Blood vessels and
F
capillaries
(7)
Sebaceous
(
oxygen
•
Help regulate (6)
•
Secretes (8)
a
‫ؼ‬౟ᆯ)
and nutrients to the
waste
body
temperature
(
‫ؼ‬౟) which
keeps the hairs and skin (9)
supple
sebum
(
ਫຌ)
and waterproof
b
reduces the growth of harmful
(10)
(11)
sweat
skin cells and remove (5)
gland
G
stimuli
micro-organisms
Hair
H
(
follicle
•
Produces new hair from the base
Erector
•
Controls the erection of hair to help regulate
ֻᦖ)
(12)
muscle
(
body temperature
ᓻֻۜ)
I
erector muscles contract
to pull hairs upright
erector muscles relax and
hairs lie down
♦ Action of erector muscles on hairs
(13)
J
28¬
Subcutaneous
fat
•
Stores (14)
•
Forms a heat insulating layer
fat
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Regulation of body temperature by skin (Book 3, p.70)
Structure in the skin
Response under hot conditions
greater amount of heat loss
1
Erector muscles
(1) Relax / Contract
2
Hairs
(2) Lie flat / Pulled upright
3
Sweat glands
Secrete (3) more / less sweat
4
Arterioles supplying
blood to the blood
capillaries in the skin
(4) Dilate (vasodilation
5
Subcutaneous fat
(5) Thinner / Thicker
Structure in the skin
ۨጥင്) /
Constrict (vasoconstriction ۨጥ‫گ‬ᜍ)
Response under cold conditions
very little
heat loss
1
Erector muscles
(6) Relax / Contract
2
Hairs
(7) Lie flat / Pulled upright
3
Sweat glands
Secrete (8) more / less sweat
4
Arterioles supplying
blood to the blood
capillaries in the skin
(9) Dilate (vasodilation) /
Subcutaneous fat
(10) Thinner / Thicker
5
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Constrict (vasoconstriction)
29¬
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Go To …
STS connection 19.3 Heat exhaustion, heatstroke and hypothermia
(Student’s Book 3 p.72; Activity Book 3 p.38)
Section concept diagram (Student’s Book 3 p.73)
Quick check (Student’s Book 3 p.73)
!
E 19.4 How is blood glucose level regulated? (Book 3, p.73)
Roles of liver and pancreas in regulating blood glucose level (Book 3, p.73)
The pancreas releases different amounts of (1)
insulin
and (2)
glucagon
which
lead to a number of actions by the liver to bring the blood glucose level back to normal.
Consequences of failing to regulate blood glucose level (Book 3, p.74)
•
If the blood glucose level is too high, cells lose water by osmosis and their metabolic
activities will be affected. Glucose may be lost in urine, causing (3)
mellitus
(
diabetes
ᗷ‫ݟ‬ఐ). This disease is usually caused by insufficient (4)
insulin
production in the body.
•
After the intake of glucose, the blood glucose level of a healthy person returns to normal
within a short period of time. However, that of a diabetic (
ᗷ‫ݟ‬ఐ൛ृ) will remain high for a
long time.
♦ The graph showing the changes in blood glucose
levels of a healthy person and of a diabetic
•
If the blood glucose level is too low, the (5)
30¬
♦ The graph showing the change in
glucose level in the urine of a diabetic
brain
cannot function properly.
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Go To …
STS connection 19.4 Discussion on the control of diabetes (Student’s Book 3 p.75)
Section concept diagram (Student’s Book 3 p.75)
Quick check (Student’s Book 3 p.75)
Review (Student’s Book 3 p.76)
Summary concept diagram (Student’s Book 3 p.77)
!
Practice question
The glucose tolerance test measures the body’s ability to metabolize glucose. It is used by doctors to
diagnose diabetes. After an overnight fast (no eating), a blood sample is drawn from the patient for
measuring the blood glucose level. The patient then drinks a solution containing 75 g of glucose and
blood is drawn again at intervals for up to 3 hours. The table below shows the test results of two
persons, A and B.
3
Blood glucose level (mg / 100 cm )
Time (hour)
E a
Person A
Person B
0
84
150
0.5
140
220
1
150
245
2
100
255
3
80
260
Plot the test results of the two persons in the form of a graph.
(4 marks)
Person B
3
blood glucose level (mg per 100 cm blood)
GlusoeGlucose tolerance test results
300
Person B
250
200
150
100
Person A
50
0
1
2
3
time (hr)
(4m)
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One of the two persons can metabolize glucose normally and the other person has diabetes.
Which one is the diabetic?
(1 mark)
Person B (1m).
E c
After one hour, what happens to the blood glucose level of the person with normal glucose
metabolism? Describe how the blood glucose level is regulated in his body after drinking
the glucose solution.
(5 marks)
After one hour, the blood glucose level drops slowly and eventually returns to the normal
level (1m). After drinking the glucose solution, the blood glucose level increases (1m).
This stimulates the pancreas to secrete more insulin (1m). Insulin decreases the blood
glucose level by converting more glucose to glycogen (1m) and increasing the glucose
uptake by cells for oxidation (1m).
E d
Apart from performing the glucose tolerance test, suggest another screening test for
possible diabetes.
(2 marks)
Test for glucose in urine (1m) using Clinistix paper (1m).
Total: 12 marks
Ё END Ё
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