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Biology Unit 5 > Homeostasis > Flashcards

Homeostasis Flashcards

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1
Q

What is a hormone

A

Chemical messenger transported in the blood

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2
Q

What increases glucose levels

A

Eating or break down of starch

Breakdown stored glycogen

Making new glucose from glycerol and amino acids in the liver

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3
Q

Why do glucose levels fluctuates

A

Respiration levels
Eating
Different demand depending on what activity doing

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4
Q

What are the Islets of Langerhans

A

Group of hormone producing cells

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5
Q

What hormone does alpha cells produce

A

Glucagon

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6
Q

What hormone does beta cells produce

A

Insulin

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7
Q

What is glucagon

A

Hormone that raises blood glucose

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8
Q

What is insulin

A

Hormone that lowers blood glucose

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9
Q

How does adrenaline raise glucose levels

A

Activated enzyme that breaks glycogen into glucose

Inactivates enzyme that synthesises glycogen from glucose

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10
Q

How does adrenaline affect glucose levels

A

Raises them

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11
Q

What happens when blood glucose levels increases

A

Pancreas detects rise in glucose levels
Beta cells secrete insulin
Insulin binds to cell surface receptors
Respiration increases so more glucose taken up by cells
Glucose transporters change shape so Moore glucose absorbed into cells
Negative feedback = beta cells reduce insulin secretion when glucose levels return to normal

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12
Q

What happens when blood glucose levels decreases

A

Pancreas detects fall in glucose levels
Alpha cells secrete glucagon
Glucagon bonds to cell surface receptors
Increase in conversion of amino acids and glycerol to glucose
Enzyme activated to convert glycogen to glucose
Negative feedback = alpha cells reduce glucagon secretion when glucose levels return to normal

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13
Q

What is diabetes

A

Inability to metabolise carbohydrates properly

Either due to lack of insulin (type 1)
Or loss of responsiveness to insulin (type 2)

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14
Q

Explain diabetes symptoms

A

Frequent weeing (getting rid of excess glucose)

Thirsty (wee lot taking water)

Blurred vision (glucose build up in lense)

Tiredness (glucose not entering cells)

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15
Q

What is conduction, convection and radiation?

A

Conduction = energy transfer solids

Convection = energy transfer liquids

Radiation = energy transferred by electromagnetic waves

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16
Q

What are endotherms

A

Heat from metabolic activities from inside body

Eg mammals

17
Q

What are ectotherms

A

Heat from environment

18
Q

2 methods of losing heat

A

Evaporation of water

Lose to environment

19
Q

2 methods of gaining heat

A

Metabolism of food during respiration

Gain from environment

20
Q

How do ectotherms control body temperature using the environment

A 
Expose to sun
Take shelter
Gain warmth from ground
Generate metabolic heat
Colour variations
21
Q

How do endotherms control body temperature

A

Using thermoregulatory centre

22
Q

How does the thermoregulatory centre work

A

Measures temperature

Sends impulses along autonomic nervous system to hypothalamus

23
Q

What happens when you’re too hot

A

Sweat glands produce sweat which evaporates from skin to cool us down
Erector muscles relaxes so hair lies flat so no air trapped under hair for insulation
Arteriolar dilate so blood flow increases so more heat radiates from surface
Negative feedback = temperature returns to normal so body stops altering it

24
Q

What happens when we’re too cold

A

Metabolic rate increases so more heat generated
Arterioles constrict so blood flow in capillaries decrease so less hear radiated from skin
Muscles contract and relax rapidly (shiver) and respiration generates heat
Sweat production stops
Erector muscles contracts and hair pulls up - layer of trapped air under hair acts as insulation
Negative feedback = temperature normal so body stops altering it

25
Q

The importance of homeostasis

A

Enzymes sensitive to PH and temperature changes

Water potential changes can stop cells operating properly as shrink or burst

26
Q

What does glucagon do

A

Stimulate conversion of stored glycogen to glucose

27
Q

suggest one way in which insulin receptors might be abnormal

A

different amino acid sequence so different tertiary structure

28
Q

explain why the glucose conc. falls in diabetics even when there is no insulin present in the blood

A

glucose excreted in urine

29
Q

where is glycogen stored

A

liver

30
Q

name an organ in the human body containing cells with glucagon receptors

A

liver

31
Q

describe the role played by negative feedback in maintaining a constant blood temperature

A

triggers effects which return set level

Biology Unit 5 (12 decks)

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