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Biology - Unit 6 > Chapter 16 - Homeostasis > Flashcards

Chapter 16 - Homeostasis Flashcards

1
Q

Define homeostasis

A

A set of physiological systems that maintain a stable and constant internal environment

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2
Q

Why is temperature maintained in the body

A
  • Metabolism controlled by enzymes which have an optimum temperature
  • Too hot causes denaturation
  • Too cold slows reaction
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3
Q

Why is pH maintained in the body?

A
  • Metabolism controlled by enzymes which have an optimum pH

- Too extreme causes denaturation and slows reaction

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4
Q

Why is glucose maintained in the body?

A
  • Minimum amount of glucose needed
  • Too much decreases water potential so water leaves by osmosis
  • Cells shrivel up
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5
Q

Define negative feedback system

A

When the product of a reaction leads to a decrease in that reaction. In this way, a negative feedback loop brings a system closer to a target of stability or homeostasis

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6
Q

How does a negative feedback system operate?

A
  • Receptors detect change away from normal

- Effectors activate mechanisms to return to normal

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7
Q

Why does the body have separate negative feedback systems?

A
  • More control
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8
Q

What is a positive feedback system?

A

A system that results in effectors amplifying the change away from the normal more produces more

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9
Q

What is the point of a positive feedback system?

A
  • Rapid changes and responses
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10
Q

Give two examples of positive feedback systems

A

Action potentials and blood clotting

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11
Q

How is high blood glucose controlled?

A
  • Concentration increases
  • Receptors in the pancreas detect this
  • Beta cells in the isle of langerhans secrete insulin
  • Binds to receptors in the liver and muscle
  • Increases permeability to glucose
  • More glucose absorbed by facilitated diffusion
  • Glycogenesis occurs
  • Increase in rate of respiration
  • Blood glucose concentration decreases
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12
Q

How is low blood glucose controlled?

A
  • Concentration decreases
  • Receptors in the pancreas detect this
  • Alpha cells in the isle of langerhans secrete glucagon
  • Glucagon binds to receptors on the liver cells
  • Rate of respiration decreases
  • Glycogenolysis occurs
  • Gluconeogenesis occurs
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13
Q

What is glycogenolysis

A

The breaking down of glycogen to produce glucose molecules promoted by glucagon and adreanline

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14
Q

Define gluconeogensis

A

The production of glucose from non carbohydrate respiratory substrates promoted by glucagon

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15
Q

Define glycogensis

A

The production of glycogen from glucose promoted by insulin

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16
Q

Summarise the glucagon hormone

A
  • Secreted by alpha cells
  • When blood glucose low
  • Attached to liver receptors
  • Increases blood glucose
  • Decreases rate of respiration, causes glycogenolysis and gluconeogensis
17
Q

Summarise the adrenaline hormone

A
  • Secreted by alpha cells
  • When blood glucose low
  • Attached to liver receptors
  • Increases blood glucose
  • Activates glycogenolysis and inhibits glycogenesis
18
Q

Summarise the insulin hormone

A
  • Secreted by B cells
  • When blood glucose high
  • Attaches to liver and muscle receptors
  • Decrease blood glucose
  • Increases rate of respiration, causes glycogenesis and increases permeability to glucose
19
Q

How does insulin increase permeability to glucose?

A
  • Glucose carrier proteins stored in vesicles inside the cells
  • Insulin binds to receptors and vesicles fuse with cell membrane
  • Carrier proteins join membrane and glucose absorbed by facilitated diffusion
20
Q

Define diabetes

A

Illness where the body fails to control blood glucose levels

21
Q

Distinguish between hyperglycaemia and hypoglycaemia

A

Hyper = too much glucose and hypo = too little glucose

22
Q

Summarise type I diabetes

A
  • Caused by immune system destroying B cells that produce insulin
  • Hyperglycaemia so glucose in urine
  • Inject insulin/pump
  • However this can cause low glucose (hypoglycaemia) so avoid carbs, eat regularly and exercise
23
Q

Summarise type II diabetes

A
  • Obesity, lack of exercise and poor diet so lack of production/stop responding
  • Hyperglycaemia so glucose in urine
  • Eat healthy, lose weight, regular exercise and use drugs to increase sensitivity to insulin, produce more insulin and reduce glucose released

Biology - Unit 6 (6 decks)

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