W6: Vertebrate Physiology (Homeostasis & Phenotypic Plasticity) [Dr. Matt] Flashcards

1
Q

Responses of animals to environmental changes: what are the changes that animals would need to respond to? (3)

A
  • Acute (short-term) changes in individuals.
  • Chronic (long-term) changes in individuals.
  • Evolutionary changes in population traits via NS.
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2
Q

Response of animals to acute changes?

A

Homeostasis.

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3
Q

Response of animals to chronic changes?

A

Phenotypic plasticity.

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4
Q

Responses of animals to evolutionary changes?

A

Genetic adaptation (over generations).

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5
Q

Homeostasis?

A

= processes to maintain fairly stable conditions in the body.

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6
Q

Phenotypic plasticity?

A

= the ability of a genotype to produce multiple phenotypes.

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7
Q

Egs of Phenotypic plasticity? (2)

A
  • Acclimatisation.
  • Acclimation.
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8
Q

Strategies of responding to the external environment? (3)

A
  • Regulation.
  • Conformity.
  • Mixed conformity & regulation.
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9
Q

Regulation?

A

= when an animal’s internal environment is held constant when its external environment changes.

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10
Q

Conformity?

A

= when an animal’s internal environment varies so that it matches the external environment.

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11
Q

Mixed conformity & regulation?

A

= when an animal’s internal environment either remains constant or varies to match the external environment for different conditions.

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12
Q

Eg of Mixed conformity & regulation?

A

Salmon.

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13
Q

Explain the Salmon eg? (2)

A
  • These salmon are temperature conformers, as their internal environment matches the temperature of the water that they are in (river or ocean water).
  • These salmon are also blood concentration regulators, as their internal environment remains constant irrespective of the salt concentration of the water.
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14
Q

Types of feedback systems? (2)

A
  • Negative feedback.
  • Positive feedback.
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15
Q

Negative feedback attributes? (5)

A
  • Regulatory processes that maintain homeostasis.
  • Sensors continuously sample controlled variables (eg, temperature, pH).
  • Deviations from setpoints stimulate immediate corrective measure.
  • Respond using physiological, biochemical, behavioural or other mechanisms.
  • Opposes deviation to bring the variable back to the setpoint.
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16
Q

Egs of negative feedback systems? (3)

A
  • Regulation of blood glucose levels.
  • Regulation of CO2 levels.
  • Regulation to changing temperatures.
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17
Q

Regulation of blood glucose levels? (11)

A

1) If the blood glucose level rises:

  • Beta cells in pancreas secrete insulin into the blood.
  • Body cells take up glucose.
  • Liver takes up glucose & stores it as glycogen.
  • Blood glucose level declines.
  • Homeostasis.

2) If the blood glucose level declines:

  • Alpha cells in the pancreas secrete glucagon.
  • Liver breaks down glucagon & releases glucose.
  • Blood glucose level rises.
  • Homeostasis.
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18
Q

Regulation of CO2 levels? (11)

A
  • Physical activity increases.
  • Cellular respiration increases.
  • CO2 production increases.
  • Medulla oblongata stimulated.
  • Impulses sent to the heart & lungs.
  • Heart rate increases.
  • Blood with CO2 brought faster to the lungs.
  • Breathing rate increases.
  • CO2 exhaled more rapidly.
  • CO2 level drops.
  • Normal CO2 level.
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19
Q

Regulation to changing temperatures? (14)

A

1) Brain signals to skin via nerves that it’s Too cold (low temperatures):

  • Vasoconstriction, shivering & MR rising.
  • Response = heat conservation/production.
  • Blood temperature rises.
  • “Homeostasis”.

2) Brain signals to skin via nerves that it’s Too hot (high temperatures):

  • Vasodilation & sweating.
  • Response: heat dissipation.
  • Blood temperature drops.
  • Homeostasis.
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20
Q

Positive feedback attributes? (3)

A
  • Amplifies changes, not stabilises.
  • Accelerates processes & initiates changes.
  • Less common in homeostasis.
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21
Q

Eg of positive feedback?

A

Childbirth.

22
Q

Childbirth? (7)

A
  • Head of baby pushes against the cervix.
  • Nerve impulses from cervix transmitted to brain.
  • Brain stimulates the pituitary gland to secrete oxytocin.
  • Oxytocin is carried in the bloodstream to the uterus.
  • Oxytocin stimulates uterine contractions & pushes bay towards the cervix.
  • Process is repeated until the baby is delivered.
  • It’s a continuous process (amplifies).
23
Q

Recap: Homeostasis & feedback systems? (3)

A
  • Homeostasis.
  • Regulation vs conformity in animals (can be intermediate & mixed responses for different conditions).
  • Negative feedback regulatory systems.
24
Q

Dynamic equilibrium in homeostasis attributes? (3)

A
  • Balanced state in systems.
  • Conditions fluctuate within an acceptable range.
  • Tied to circadian rhythms.
25
Q

Egs/Instances of circadian rhythms? (2)

A
  • Human body temperature fluctuates throughout the day around the setpoint value.
  • Fever responses to infection.
26
Q

Brief explanation of fever response to infection? (5)

A
  • Normal thermoregulation before fever (37C).
  • Set point rises & shivering and vasoconstriction is activated.
  • Regulation of body temperature at the elevated level during fever (40C).
  • As the setpoint returns to normal, sweating & vasodilation are activated.
  • Normal thermoregulation after fever.
27
Q

Egs of the sickness behaviours? (4)

A
  • Fever.
  • Lethargy (fatigue).
  • Sleepiness.
  • Social withdrawal.
28
Q

Fever instances? (2)

A
  • Fever in a kudu.
  • Fever in vervet monkeys.
29
Q

Fever in a kudu?

A

Shows the changes in body temperature in a kudu with fever (febrile) and one without fever (afebrile).

30
Q

Fever in vervet monkeys? (2)

A
  • It was observed that vervet monkeys with fever had temperature spikes caused by a fever, indicated by a sustained upward shift in body temperature, & hyperthermia, indicated by a single spike in temperature due to it being very hot that day.
  • Vervet monkeys with fevers were more agressive & frequently fought with other monkeys, but get severely injured in the fights. Therefore, they would have to trade-off between fighting or getting injured.
31
Q

Recap: Dynamic equilibrium & fever? (2)

A
  • Dynamic equilibrium in homeostasis.
  • Fever responses to infection (elevated Tb temp. setpoints, associated sickness behaviours & trade-offs in wild animals).
32
Q

Genotype?

A

= genetic make-up of an organism.

33
Q

Genotype attributes? (2)

A
  • Inherited, DNA-coded information.
  • Determines a trait/group of traits.
34
Q

Phenotype?

A

= observable characteristics of an organism.

35
Q

Phenotype attributes? (2)

A
  • Pattern of gene expression.
  • Influenced by genotype & environment.
36
Q

Phenotypic plasticity attributes? (5)

A
  • Adaptive responses within an individual to different environmental conditions.
  • Changes in behavioural, physiological, morphological & life-history traits.
  • Increases fitness & survival.
  • Controlled by homeorhetic processes.
  • Functions to maintain a form of balance between transitional periods.
37
Q

Categories of phenotypic plasticity? (2)

A
  • Phenotypic flexibility.
  • Development plasticity.
38
Q

Phenotypic flexibility?

A

= reversible adjustments within individuals in response to environmental changes.

39
Q

Phenotypic flexibility attributes? (3)

A
  • Can occur throughout an individual’s life.
  • Allow an animal to maintain/enhance performance in environments that have rapid fluctuations in conditions.
  • Acclimatisation vs acclimation.
40
Q

Acclimatisaton VS Acclimation?

A
  • Acclimatisation
    = response to natural changes in the environment.
  • Acclimation
    = response to artificial changes in the environment (eg, in a lab).
41
Q

Egs of Phenotypic flexibility? (2)

A
  • Thermal acclimation in rodents in response to cold environments.
  • Marine iguanas.
42
Q

Explain thermal acclimation in rodents in response to cold environments?

A
43
Q

Marine iguanas? (2)

A
  • Variations in body size in relation to food availability.
  • Smaller iguanas (more flexible ones) are more likely to survive than those who don’t change their body size/length (bigger ones), as they are able to adapt to food shortages.
44
Q

Development plasticity?

A

= phenotypic changes during the developmental stages of an individual’s life in response to environmental conditions.

45
Q

Development plasticity attributes? (2)

A
  • Changes are not reversible after developmental stages.
  • There are physiological trade-offs involved.
46
Q

What physiological trade-offs are involved in development plasticity? (2)

A
  • Adaptive during developmental stages.
  • May lead to negative fitness consequences later in life.
47
Q

Egs of Development plasticity? (2)

A
  • Hokkaido salamander.
  • Zebra finches.
48
Q

Hokkaido salamander?

A

Typical morph developed a deeper tail in the presence to a predator threat than in the absence of predators compared to broad-tailed morphs.

49
Q

Zebra finches?

A

Pro of being a small chick in hot conditions are less loss of heat to the environment due to having a small SA (chick size is in response to parent calls to heat).

50
Q

Recap : Phenotypic plasticity? (2)

A
  • Genotype vs phenotype.
  • Phenotypic plasticity (phenotype flexibility & development plasticity).