Physiology (homeostasis + addiction)

Question 1

Define homeostasis

Answer 1

ability of body to maintain relatively stable internal conditions

Question 2

Describe the response to increase in temperature

Answer 2

Increase in temperature caused by stimulus
thermoreceptors detect increase and send signals to thermoregulatory control centre in hypothalamus
control centre sends signal to effectors (muscles + glands)
[sweat glands, vasodilation of blood vessels near skin surface + shunt blood to skin]
cause temperature to reduce
continuous cycle

Question 3

What changes occur when someone is too cold?

Answer 3

shivering
contraction of erector pili muscles (hairs stick up + trap heat)
increased metabolism
vasoconstriction (lood to key organs + away from peripheries)

Question 4

Define negative feedback

Answer 4

maintains a variable between set parameters

Question 5

Define positive feedback

Answer 5

continuous deviation of a variable from a set point

Question 6

Describe hyperthermia

Answer 6

heat production > heat loss
heat stroke = core body temperature > 41 degrees
confusion, loss of consciousness

Question 7

What causes a fever?

Answer 7

cytokines can increase temperature set level to produce hostile environment for pathogens

temperature set point raised in hypothalamus due to cytokine release
body’s core temperature not at new set level, so body is ‘cold’
effectors carry out actions to increase heat production in order to reach new temperature set level

Question 8

What are the 4C’s of addiction?

Answer 8

compulsion
loss of control
continued use despite harm
cravings

Question 9

Define sensitisation

Answer 9

dopamine receptors are more responsive/sensitive to dopamine

Question 10

Define incentive sensitisation

Answer 10

wanting more + more increases with greater exposure to the drug (eg. nicotine)

Question 11

Define abnormal sensitisation

Answer 11

wanting more drugs/substance/behaviour but the pleasure derived from it is diminishing (eg. heroin)

Question 12

Define cross-sensitisation

Answer 12

taking one drug might increase the urge to take others (eg. nicotine leading to illegal drug taking)

Question 13

Describe desensitisation

Answer 13

continual dopamine over-stimulation generally leads to:

• reduction in number of dopamine receptors
• reduced sensitivity to dopamine
• reduced dopamine production

occurs as body is trying to maintain homeostasis so it uses cellular mechanisms to counteract raised dopamine levels

Question 14

What factors affect dopamine desensitisation?

Answer 14

how much dopamine is released
number of dopamine receptors on post-synaptic membrane
efficiency of neurotransmitter reuptake pump

Question 15

Define tolerance

Answer 15

person no longer responds to a drug in the way they did at first (more needed for desired effect due to fewer receptors)