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Fish and Fisheries > Fish endocrinology > Flashcards

Fish endocrinology Flashcards

1
Q

The hypothalamus can be referred to as what?

A

master regulator of hormones

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2
Q

The hypothalamus tells the brain when to _____ __ and communicates that to the ________.

A

wake up

pituitary

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3
Q

What is directly connected to the hypothalamus?

A

Pituitary gland

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4
Q

The pituitary gland is separated into what?

A

Anterior and posterior portions.

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5
Q

Is ACTH anterior or posterior?

What tissue does it act on?

A

Anterior

Kidney

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6
Q

Is TSH anterior or posterior?

What tissue does it act on?

A

Anterior

Thyroid

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7
Q

Is GTH anterior or posterior?

What tissue does it act on?

A

Anterior

Gonads

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8
Q

Is GH anterior or posterior.

What tissue does it act on?

A

Anterior

Acts on chloride cells and multiple tissues

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9
Q

Is PRL anterior or posterior?

What tissue does it act on?

A

Anterior

Osmoregulation

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10
Q

Is SL anterior or posterior.

What tissue does it act on?

A

anterior

plays a role in fat metabolism (adipocytes)

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11
Q

The hypothalamus is greatly affected by what?

A

Temperature, light availability and season

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12
Q

Is MCH anterior or posterior?

What tissue does it act on?

A

Posterior

Pigment cells

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13
Q

Is AVT anterior or posterior? What tissue does it act on?

A

Posterior

kidneys

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14
Q

Is isotocin anterior or posterior?

What tissue does it act on?

A

Posterior

osmorgulation

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15
Q

What is ACTH.

What does it do.

A

Adreno corocotropic hormone

ACTH tells the kidney to release cortisol.

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16
Q

What is cortisol?

A

Major stress hormone.
Also important in osmoregulation for making chloride cells.
(Important in growth effects)

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17
Q

The hypothalamus, through the anterior pituitary gland and ACTH thus regulates the _______ response, _________ and helps regulate _______.

A

stress
osmoregulation
growth

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18
Q

What is TSH?

What does it do?

A

Thyroid stimulating hormone.
Stimulates the thyroid to release thyroid hormone (different hormone) which is important in development and metamorphosis in fish.

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19
Q

What is GTH?

What does it do?

A

Gonadotropin hormone.
Tells the gonads to release stuff.
Controls the making of eggs.

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20
Q

What is GH?

What does it do?

A

Growth hormone.
Big effect on chloride cells, remaking them when moving into freshwater.
Helps with fish growth.

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21
Q

What is SL?

What does it do?

A

Plays a large role in fat metabolism.
During good times - store fat
During bad times - catabolize.

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22
Q

What is fat used for?

A

Make eggs or fight animals.

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23
Q

Both male and female fish will have __________ hormone, the effect will be different based on ____.

A

gonadotropin

sex

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24
Q

What is MCH?

What does it do?

A

Melanin concentrating hormone.

Concentrates melanin in pigment cells so the fish gets a darker colour.

25
Q

Besides its use in colour, melanin causes something else. What is it?

A

Increases food intake.

26
Q

What is the dual role of MCH?

A

Colour and food intake

27
Q

______ controls changing colour for spawning.

A

MCH

28
Q

What is AVT?

What does it do?

A

arginine vasotocin.
Largely controls water intake - similar to vasopressin.
Directly acts on kidney tubules and bladder.

29
Q

When would AVT be secreted?

A

As migrating in habitats, teleosts want to change water balance in the kidneys.

30
Q

What is isotocin?

What does it do?

A

In fish, isotocin is mostly used for osmoregulation, it affects salt balance in teleosts and osmobranchs.

31
Q

In humans, what does isotocin do?

A

Same hormone co-opted for different function. Receptors are found in mammalian breast tissue and in uterine contraction tissue.

32
Q

What is thyroid hormone implicated in?

A

1 - Promotes growth but has to work in conjunction with GH and IGF-1
2 - Metamorphosis in flatfish
3 - Salmon migration and metamorphosis

33
Q

What is the role that TH plays in the metamorphosis of flatfish?

A

Eye migration and change in body shape.

34
Q

What occurs if TH is blocked in flatfish and tadpoles?

A

Get large baby flatfish

Get really big tadpoles

35
Q

What happens if TH is blocked in general?

A

May not grow as fast but will block development.

36
Q

What does TH do for salmon migration?

A

Plays a role in upregulating the salt chloride cells and stimulating the production of a pigment giving the salmon a silvery colour.
May also be involved in homing/imprinting.
- may help olfactory system lock in the smell of natal stream

37
Q

Where is the pineal gland located?

A

Under the skull

38
Q

The pineal gland releases ________.

A

melatonin

39
Q

_________ play a role in extraretinal photoreception.

A

pinealocytes

40
Q

The pineal gland is a small gland sitting at the base of the _____ which can sense ______.

A

skull

light

41
Q

Pinealocytes are ______-sensitive cells.

A

light

42
Q

If a fish loses its eyes, how can it tell if it is day or night?

A

Can sense light levels through photoreceptors in pineal gland

43
Q

What is a major role of melatonin?

A

Circadian rhythm

44
Q

What does melatonin do?

A

Melatonin made in pineal gland, feedsback to hypothalamus which allows it to know what time of day it is.

45
Q

If a fish is in complete darkness, will it still make melatonin?

A

Yes, still roughly 24hr cycle but, exposure to light fine tunes the cycle.

46
Q

What are endocrine disruptors?

Give some examples.

A

Hormone-mimicking chemicals that alter reproductive cycles.

PCBs, plasticizers, synthetic estrogens

47
Q

The antidepressants that we take affect fish through their ________ system.

A

endocrine

48
Q

What are PCBs?

A

Common waste product of industrial activity which can, once broken down, act like fish hormones.

49
Q

What are plasticizers?

A

Chemical used in water bottles to make them flexible which can have an estrogenic effect when they break down.

50
Q

What is vitellogenin?

A

Important hormone for egg development, shouldn’t be present in male fish

51
Q

What does vitellogenin do to fish?

A

Skewed sex ratios
Seeing eggs in male fish
Inhibition of spermatogenesis in adult males.

52
Q

Hormones can change _______ through its effect on the hypothalamus.

A

seasonally

53
Q

What are the 3 environmental controls that affect reproductive controls and behaviour?

A

Light
Pheromones
Temperature

54
Q

How is light an environmental control?

A

Life’s indicator of seasonality, can tell if summer or winter by how long light is, picked up by retina and pineal.

55
Q

How can temperature function as an indicator of seasonality?

A

If in shallow water in a thermally changing environment.

56
Q

What is a pheromone?

A

Natural smell that comes out of animals

These smells are picked up by the olfactory system and have direct effects on the hormone cycle.

57
Q

If there is lots of light, temperature is just right and lots of pheromones, it must be?

A

Breeding season

58
Q

When its breeding season, lots of pheromones, how is the hypothalamus affected?

A

(JUST DRAW THE DIAGRAM)
Hypothalamus releases GRN (gonadotropin releasing hormone) which activates the gonads: testies or ovaries.

Male gonadotropin will cause the testes to release testosterone and 11-keto-test (basically the same).
- 11 keto test can act as pheromone when released in fish pee or from the gills

Two things these two do:
1 - Stimulate sperm production in the testes
2 - Stimulate male secondary sexual characteristics production (tubercles or hooknose for example)

Female gonadotropin:
- causes release of 17b-estradiol from ovaries and acts on the liver to cause release of vitellogenin.
17b-estradiol is the main fish estrogen and causes secondary sex characters in female fish
vitellogenin feedbacks to ovary causing egg maturation and finalizes yolk production

Fish and Fisheries (28 decks)

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