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A2 Biology > 9.9 Osmoregulation > Flashcards

9.9 Osmoregulation Flashcards

(58 cards)

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1
Q

How many kidneys do we have?

A

Two

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2
Q

Where are the kidneys found?

A

Rear of the abdomen

Either side of the aorta

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3
Q

Explain the structure of a kidney

A 
Outer layer is the cortex
Inner is medulla
Inside medulla is the pelvis
Ureter leading off
Renal artery and vein
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4
Q

What is the main function of the structures in the cortex?

A

Filtering toxins such as urea

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5
Q

What is the main function of the structures in the medulla?

A

Osmoregulation - regulating water potential

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6
Q

What is osmoregulation?

A

The regulation of the water potential of the body within narrow limits by controlling the concentration of water and salt

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7
Q

What are the main organs involved in osmoregulation?

A

Kidneys and liver

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8
Q

Where are amino acids deaminated?

A

In the liver

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9
Q

Explain how amino acids are deaminated?

A

Amino group removed
Converted to ammonia
Converted to urea

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10
Q

Why does ammonia need to be converted to urea?

A

Urea is non-toxic, ammonia is toxic

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11
Q

What are the two main functions of the kidney?

A

Waste filtration

Osmoregulation

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12
Q

What is the function of the ureter?

A

Carrying urine to the bladder

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13
Q

Where does ultrafiltration take place?

A

Glomerulus

in the cortex

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14
Q

What are the three layers which the filtrate goes through during ultrafiltration?

A

Endothelium
Basement membranes
Podocytes

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15
Q

Explain the process of ultrafiltration

A

High blood pressure in glomerulus
Forces blood through three stage filtration mechanism:
Fenestrations in the endothelium –> basement membrane –> gaps in the podocytes
Proteins and blood cells can’t pass through bc too big

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16
Q

What causes the high blood pressure in the glomerulus?

A

Afferent arteriole is wider than the efferent arteriole

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17
Q

What substances are found in the glomerular filtrate?

A

Glucose
Urea
Water

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18
Q

Where does selective reabsorption take place?

A

Proximal convoluted tubule

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19
Q

Where does the filtrate from the glomerulus go?

A

To the Bowman’s capsule

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20
Q

Name some of the adaptations of the PCT?

A

Brush border of microvilli - increases surface area for reabsorption
Mitochondria - ATP for active transport
PCT is one cell thick - short diffusion distance
Close to capillaries - conc gradient and short diffusion distance

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21
Q

Explain the process of selective reabsorption in the PCT

A

Na+ actively pumped out of PCT wall into the blood using ATP
Na+ and glucose co-transported into the PCT wall from PCT lumen by facilitated diffusion down conc gradient with protein carrier
Na+ and glucose levels build up - move into blood by diffusion
Increases water potential of the PCT wall - water leaves

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22
Q

What is reabsorbed by the body during selective reabsorption?

A

All of the glucose and amino acids

Some water

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23
Q

Explain how the loop of Henle works

A

Ascending and descending limb
Asc. impermeable to water
Na+ and Cl- actively removed from ascending
Lowers water potential in the medullary region
Longer loop of Henle - lower water potential
Water moves out of descending limb by osmosis
Some Na+ diffuses into descending limb
Vasa recta acts as a counter current multiplier

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24
Q

What does a counter current multiplier do?

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A

Maintains the low water potential in the medullary region
Allows water to be reabsorbed
Stops water being lost through urine

25
What is the advantage of a long loop of Henle?
Long loop of Henle means larger osmotic gradient. More ions actively transported out of ascending limb Water potential of medullary region more negative More water leaves descending limb by osmosis
26
What is ADH?
Anti-diuretic hormone
27
What does ADH do?
Makes the collecting duct more permeable to water More water reabsorbed Urine is more concentrated
28
Where is ADH produced and stored?
Produced in hypothalamus | Stored in the PPG
29
Explain the mechanism of ADH
ADH binds to membrane receptors Triggers cAMP Series of reaction Vesicles of aquaporins fuse with membrane Aquaporins inserted - membrane more permeable
30
What is diabetes insipidus?
ADH isn't produced Urine v dilute - water isn't reabsorbed Person feels v thirsty
31
What areas of the kidney does ADH affect?
The distal convoluted tubule | Collecting duct
32
What is the role of the distal convoluted tubule?
Controls blood pH Controls levels of sodium and potassium ions Controls water levels - ADH
33
What is the role of the collecting duct?
Most osmoregulation takes place here | Transports urine to pelvis of the kidney
34
How do desert animals like kangaroo rats get the water they need?
Water from cellular respiration Condensation reactions which take place in the body Water in food
35
How is low water potential detected by the body?
Osmoreceptors in the hypothalamus
36
How does the body respond to low water potential of the blood?
Osmoreceptors in the hypothalamus detect change ADH secreted by PPG ADH makes DCT and collecting duct more permeable More water reabsorbed
37
How is diabetes insipidus treated?
Drugs given to replace ADH | Drugs given to make kidney produce more concentrated urine
38
Why is thermoregulation important?
Enzyme controlled reactions in the body only happen in a narrow region of temperatures
39
Which organisms don't need to control body temperature?
Proctotista | Organisms living in the sea - stable temperature bc high specific heat capacity of water
40
What is an endotherm?
An organism which relies on its own metabolic processes for heat. Has a temperature higher than ambient temperature
41
What is an ectotherm?
An organism which relies on the environmental temperature for heat
42
What is an advantage of endotherms?
They can survive in a wide number of environements with different temperatures
43
How do ectotherms regulate body temperature?
Behavioural and anatomical adaptations
44
What is the largest organ involved in thermoregulation?
The skin
45
Explain the ways in which endotherms can stay cool
Arteriovenous shunt - vasodilation increases heat loss by radiation Erector pilli are relaxed - hairs lie flat Sweat production increases - increased evaporation Little subcuntaneous fat - less insulation so more heat loss
46
How is the arteriovenous shunt used in thermoregulation?
Closes when organisms gets hot - more blood flow through capillaries near the surface so more heat loss via vasodilation Opens when organisms get cool - blood doesnt flow through capillaries so less heat loss
47
How do endotherms stay warm?
Arteriovenous shunt opens - vasoconstriction Little sweat produced Erector pilli contract - hairs stand up so air gets trapped Metabolic rate of body speeds up Thick layers of fat produced
48
Explain the role of superficial blood vessels in keeping an animal warm
Vasodilation Muscles around arterioles to superficial capillaries relax - allow for more blood flow to surface Less blood to deeper shunt vessels More cooling by conduction and radiation
49
Explain the role of superficial blood vessels in keeping an animal warm
Vasoconstriction Shunt opens - less blood to capillaries at the surface Arterioles contract - less blood flow to capillaries and more too deeper vessels Less heat loss by conduction and radiation bc smaller temp gradient
50
What are the two receptors involved in thermoregulation?
Receptors in the brain | Receptors near the surface of the skin
51
What do thermoregulatory receptors in the brain detect?
Changes in the temperature of the blood
52
What do thermoregulatory receptors in the skin detect?
Temperature of the environment
53
Where do thermoregulatory receptors send impulses?
To the thermoregulatory centre in the hypothalamus
54
Explain how thermoregulation in an endotherm works (briefly)
``` Change in temperature Detected by receptors Signals sent to thermoregulatory centre in hypothalamus Effectors do their thang Return to norm ```
55
What are physical characteristics of animals which prevent heat loss?
Small surface area to volume ratio Small extremities - such as ears Counter current echange systems Fat
56
How does hibernation help survival of animals?
Eat more than usual to store fat - energy store and insulation Metabolic rate slows right down Core body temp lowered
57
Why do animals go into hibernation?
Short day length | Low temperatures
58
What are behaviours that animals can use to regulate temperature?
Basking in the sun - warms them up Sheltering - cools down Evaporation - panting or wallowing in water Moving in or out of the sun

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