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BIO3B: Physiology To Behaviour > W3: Animal Behaviour (Hormones & Behaviour) [Dr. Madikiza] > Flashcards

W3: Animal Behaviour (Hormones & Behaviour) [Dr. Madikiza] Flashcards

1
Q

Why is it important to understand animal behaviour? / Why are we learning about animal behaviour?

A
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2
Q

Hormones?

A

= chemical substances that are secreted in one part of the body, that causes changes in other parts of the body.

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3
Q

Pathways/Ways in which hormones are secreted by? (2)

A
  • Endocrine glands.
  • Neurons.
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4
Q

Hormones secreted by endocrine glands?

A

= hormones.

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5
Q

Hormones secreted by neurons or nerve cells?

A

= neurohormones.

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6
Q

Hormones vs Neurohormones? (3)

A

1) Hormones
= secreted by endocrine glands.
= take days to have an effect.
= not localised (travel through all vessels of the body).

2) Neurohormones
= secreted by neurons/nerve cells.
= quick but not long-lasting.
= very localised.

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7
Q

Types of hormones? (2)

A
  • Peptide hormones.
  • Steroid hormones.
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8
Q

Peptide hormones?

A

= protein molecules or amino acid chains.

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9
Q

Peptide hormones attributes? (4)

A
  • Water soluble.
  • Fat insoluble (can’t pass through lipid membranes).
  • Binds to the receptors on the cell surface.
  • Short-term changes in the cell membrane & long-term changes in protein function.
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10
Q

How do peptide hormones cause short-term changes in the cell membrane & long-term changes in protein function?

A
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11
Q

Egs of Peptide hormones? (2)

A
  • LH.
  • FSH.
  • All secreted by the pituitary gland.
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12
Q

Mechanism of action of peptide hormones?

A

Hormones bind to the receptors found on the cell membrane and …

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13
Q

Steroid hormones?

A

= chemically derived from cholesterol.

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14
Q

Steroid hormones attributes? (5)

A
  • Highly fat soluble (can pass through cell membranes of lipids).
  • Made of cholesterol.
  • Primarily secreted by gonads & adrenal glands.
  • Divided into 4 major classes.
  • Attach to DNA & affect gene expression and protein synthesis.
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15
Q

4 major classes of Steroid hormones?

A
  • Progestins.
  • Androgens.
  • Estrogens.
  • Corticosteroids.
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16
Q

List of sex steroids? (3)

A
  • Progestins.
  • Androgens.
  • Estrogens.
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17
Q

Mechanism of action for Steroid hormones

A

Hormones pass through the membrane, goes through the cytoplasm and nucleus of the cytoplasm, and then affects gene expression & protein synthesis.

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18
Q

Thing to note about hormones & behaviour?

A

Hormones don’t influence/have a direct influence on behaviour, instead they have an effect at the cellular level (enzymes, etc) & these changes then cause changes in the animal’s behaviour.

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19
Q

How do hormones affect behaviour? (3)

A
  • Sensory systems.
  • Development of the CNS.
  • Effector muscles.
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20
Q

Sensory systems (perceptual mechanism)?

A

= hormones influence the ability to detect stimuli & the preference of a particular stimuli.

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21
Q

Development/Activity of the CNS?

A

= hormones influence the CNS & different regions of the brain.

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22
Q

Muscles important in the execution of behaviour?

A

= hormones influence by affecting the muscles & motor neurons.

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23
Q

Egs of Sensory systems? (2)

A
  • Newts.
  • Sticklebacks.
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24
Q

Explain Newts? (3)

A
  • Effects on sensation & perception.
  • Vasotocin affects how males react to visual. chemical & tactile stimuli from females.
  • Males rely on visual cues (eg, size, shape, colour) & olfactory cues to identify a females & determine whether to mate with a female.
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25
Q

Explain Three-spined sticklebacks? (3)

A
  • Effects on preference.
  • Thyroxine can modify preference in these fish.
  • High levels of Thyroxine influence the migrating behaviour of sticklebacks (change the preference of the fish of whether they are going to stay in marine or stream water.
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26
Q

Eg of How hormones may affect the development of the CNS?

A

Singing behaviour in male birds.

27
Q

Explain Effect on development of CNS example? (2)

A
  • Compared brain differences, particularly the song areas in male & female brains.
  • The hormone responsible for song construction in males was found to increase the brain tissue & all song areas, therefore singing birds had larger song areas.
28
Q

Eg of Hormone effects on effector mechanisms (muscles)?

A

Singing behaviour in male birds.

29
Q

Explain Effect on effector mechanisms (muscles) example? (2)

A
  • Singing males were found to have larger, well-developed syringeal muscles than male birds that don’t sing.
  • Singing males were also found to have more muscle fibres in their syringeal muscles (muscles in trachea) compared to males that don’t sing.
30
Q

Methods of studying hormone-behaviour? (2)

A
  • Interventional studies.
  • Correlation studies.
31
Q

Interventional studies?

A

= removing the source of the hormone (endocrine gland), studying subsequent effects after removal, followed by the replacement of hormones by implanting a new gland or injecting a synthetic hormone (observe once again).

32
Q

Correlation studies?

A

= changes in behaviour that parallel fluctuations in hormone levels.

33
Q

Correlation studies attribute?

A

Done in natural environments.

34
Q

Pro of interventional studies?

A

Enables one to prove causation regarding the hormone-behaviour.

35
Q

Con of correlation studies?

A

Does not enable one to prove causation due to multiple hormones influencing the behaviour/acting simultaneously.

36
Q

Eg of Interventional studies?

A

Courtship behaviour of male green anoles.

37
Q

Explain male green anoles? (4)

A
  • Q: Is it under the influence of a hormone?
  • Behaviour = Displays of courtship behaviour.
  • Courtship behaviour suggests reproductive behaviour which further suggests that it is a sex steroid hormone influencing the behaviour.
  • So, they castrated the organism & found that behaviour was no longer portrayed but after injecting the animal with androgen replacement, animal exhibited the same behaviour as before castration.
38
Q

Eg of Correlation studies?

A

Testosterone levels & aggression in song sparrows.

39
Q

Explain song sparrows? (3)

A
  • High testosterone levels were found during times of establishing territory & egg laying.
  • Low testosterone levels were found during migration & feeding of nestlings.
  • Differences in the levels of testosterone in egg laying (Brood 1 & brood 2) is due to the father still feeding nestlings from Brood 1 while in Brood 2 as aggression is unnecessary.
40
Q

Why high testosterone levels during establishing territories?

A

Because of high competition, territory defence needs to happen to succeed in obtaining resources against competitors.

41
Q

Why high testosterone levels during egg laying?

A

It’s because males have to protect the chicks and the nest from predators.

42
Q

Things to note about hormones? (2)

A

• Affect sex differentiation (1st trimester is critical in sex differentiation).

• Amount of receptors that a cell has determines the strength of the hormone.

43
Q

Hypotheses that explain the effects steroid hormones have on behaviour? (2)

A

• Organisational hypothesis.
• Activational hypothesis.

44
Q

Organisational hypothesis/effects?

A

= exposure to hormones in early life organises the neural circuitry for certain behaviours.

45
Q

Organisational effects attributes? (2)

A

• Occurs during embryonic stages to 5 days after birth.

• Embryo is exposed to mother’s hormones as well (this is external environment).

46
Q

Activational hypothesis/effects?

A

= exposure to hormones later in life (adulthood) activates neural circuitry already organised.

47
Q

Activational effect attribute?

A

At puberty, the already organized neural pathways are then activated.

48
Q

Egs of behaviour that follows Organisational effects? (2)

A
  • Sexual differentiation in brain & behaviour of rats.
  • Female spotted hyenas.
49
Q

Explain Sexual differentiation in brain & behaviour of rats? (4)

A
  • No treatment: male rat in early development is exposed to androgen steroids & later activated in adult behaviour patterns typical of mounting in males.
  • Castrated at age 1 day & no further treatment: when the steroid organising structure was absent during E-5 days after birth via castration, they later follow behaviour that is typical of females & not males; if testosterone is injected within E-5, then male behaviours are maintained.
  • No treatment: if no changes/interruptions, female rat exhibits typical female patterns (lordosis).
  • Castrated at age 1 day & no further treatment: if testosterone is injected before age 5 days then female rat exhibits typical male patterns (mounting).
50
Q

Case study: Lordosis attributes? (6)

A
  • Highly pronounced with females even though male rats exhibit it, the same goes for females with mounting.
  • Shows how the time period in which treatment is introduced is critical in determining the kind of sexual behaviour expressed (dominant hormone needs to be maintained).
  • Shows how change in environment affects the behaviour expressed.
  • A particular hormone needs to be maintained.
  • Treatment/Injection with sex steroids was done within E-5 days after birth.
  • Particular hormone has to be in high concentration during E-5 & during puberty to be expressed.
51
Q

Lordosis?

A

=

52
Q

Organisational & Activational effects of lordosis in males points? (3)

A
  • Treatment 1 (T1).
  • Treatment 2 (T2).
  • Treatment 3 (T3).
53
Q

Explain T1: Organisational & Activational effects of lordosis in males? (4)

A
  • Adult male rat was castrated & treated with female sex steroids.
  • Upon observation male rat showed no lordosis.
  • Male rat was then treated with testosterone.
  • Upon observation, male rat copulated in the presence of females (mounting).
54
Q

Explain T2: Organisational & Activational effects of lordosis in males? (5)

A
  • Newborn male rat was castrated & left to mature.
  • Male rat was treated with female sex steroids within E-5.
  • Upon observation, male rat exhibited lordosis (female behaviour).
  • Male rat was then treated with testosterone.
  • Upon observation, male rat showed no sexual behaviour in the presence of receptive females.
55
Q

Explain T3: Organisational & Activational effects of lordosis in males? (5)

A
  • Newborn male rat was castrated, treated with testosterone & left to mature.
  • Male rat was then treated with female sex steroids.
  • Upon observation, male rat exhibited no lordosis.
  • Male rat was then treated with testosterone.
  • Upon observation, male rat copulated in the presence of receptive females (mounting).
56
Q

Organisational & Activational effects of lordosis in females points? (3)

A

-Treatment 1 (T1).

  • Treatment 2 (T2).
  • Treatment 3 (T3).
57
Q

Explain T1: Organisational & Activational effects of lordosis in females? (4)

A
  • Adult female rat is spayed & treated with female sex steroids.
  • Upon observation, female rat exhibits lordosis.
  • Female rat is then treated with testosterone.
  • Upon observation, female rate exhibits no sexual behaviour typical of males (lordosis).
58
Q

Explain T2: Organisational & Activational effects of lordosis in females? (5)

A
  • Newborn female rat was spayed & left to mature.
  • Female rat was treated with female sex steroids.
  • Upon observation, female rat exhibited lordosis.
  • Female rat was then treated with testosterone.
  • Upon observation, female exhibited no sexual behaviour typical of males (lordosis).
59
Q

Explain T3: Organisational & Activational effects of lordosis in females? (5)

A
  • Newborn female rat was spayed, treated with testosterone & left to mature.
  • Female rat was then treated with female sex steroids.
  • Upon observation, female rat exhibited no lordosis.
  • Female rat was then treated with testosterone.
  • Upon observation, female rat exhibited male sexual behaviour in the presence of receptive females (mounting).
60
Q

Explain E-5 days after birth in relation to hormone expression? (2)

A
  • Development does not start from E-5, it starts prior to this & organisation is continual and gradual until 5 days after birth (5 days after birth is when the neural pathways are fully organised & so, if any sex steroid is introduced after that it will have little to no effect on the sexual behaviour expressed as the sexual behaviour would have already been determined by he dominant & already fully organised hormone/neural pathway).

BUT

  • If a sex steroid is introduced within the organisational period (i.e., before 5 days after birth), that sex steroid has an effect on/can determine the resulting sexual behaviour expressed, irrespective of the predetermined sexual behaviour of the rat/organism.
61
Q

Explain Organisational effects in Female spotted hyenas? (2)

A
  • Females develop masculine features & male-like structures.
  • Females have a pseudopenis.
62
Q

Female spotted hyenas pseudopenis attributes? (4)

A
  • Is actually a clitoris.
  • Full erectile function.
  • Used in displays, urinating & giving birth.
  • First time mothers experience infant death during birth due to small clitoris size in comparison to infant head size.
63
Q

Role of prenatal androgens (i.e., during organisational/developmental stages)? (4)

A
  • In “normal” female androgens: have ovaries that produce androgen which then produces estradiol (via large amounts of enzyme aromatase being secreted) & testosterone (via small amounts of enzyme 17B-HSD being secreted).
  • In spotted hyena females: have ovaries that produce androgen which then produces estradiol (via small amounts of enzyme aromatase being secreted) & testosterone (via large amounts of enzyme 17B-HSD being secreted).
  • Therefore, testosterone levels in spotted hyena females, in comparison to “normal” mammals, is higher & abnormal, which affects their structure & behaviour (aggression).
  • Know how to apply the organisational & activational effects to behaviours observed (mostly seen in sexual behaviours as a consequence of the steroid with a higher affinity & sensitivity).

BIO3B: Physiology To Behaviour (15 decks)

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