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BIOL 327 > Lecture 8: Regulation of Food Intake > Flashcards

Lecture 8: Regulation of Food Intake Flashcards

1
Q

How is feeding stimulated?

A

Feeding is governed by the excitatory state which is affected by the sensory input

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2
Q

Regulation of food intake (3)

A

External Stimuli
Internal Stimuli
Other factors

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3
Q

External Stimuli

(3) + Description

A

Olfaction: used to smell the food, consisting of olfactory receptor on the antenna

Gustation: used to taste the food, there are gustatory receptor on the mouthpart

Vision: consisting of the compound eye, used to detect the shape of the food

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4
Q

Internal Stimuli (2)

A

a. Crop volume

b. Nutrient concentration in the hemolymph

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5
Q

Crop volume

A

This is apart of the foregut where the food is stored, some digestion occurs through salivary enzymes in the crop

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6
Q

Nutrient concentration in the hemolymph

(3)

A

Right after the meal, the crop is extended and the insect will not eat until the food that is stored in the crop has passed to the midgut

The midgut is where there is complete digestion and absorption

Insect will not eat when there is high levels of amino acids and sugar in the hemolymph

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7
Q

Other factors associated with regulating food intake

(4)

A

State of hunger

Nutritional State

Neurohormone levels

Nonassociative learning

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8
Q

Nonassociative Learning

Eg + Description

A

Habituation: a response as a result of a continuous response of stimuli (Eg. Food)

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9
Q

Stages of Feeding (3)

A

Biting (Initiation)

Continuation

Termination

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10
Q

Biting Stage (Initiation)

A

This occurs when there is a direct stimulus of the food where the sensilla (does not only have to be on the mouthpart) is activated

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11
Q

Example of Biting: Blowfly

(2)

A

The mouth part is present on the tarsi of the blowfly and in this experiment it can be stimulated by sugar

The reason why they were able to find that the mouthpart is located on the tarsi is by presenting sugar to the tarsi leading to the proboscis to extend

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12
Q

Example of Continuation: Blowfly

A

There are sensilla on the labellum that allows for feeding to proceed

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13
Q

Example of Biting: Locust

(2)

A

Biting involves the stimulation of the tarsal, maxillary and labial palp sensilla

Ultimately this stimulation leads to the activation of 2000 receptors on the roof of the mouth

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14
Q

Example of Continuation: Locust

A

After the first bite, the quality of food is then monitor by the cibarial receptor (pouch space in the mouth used to store or chew the food)

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15
Q

Termination of Feeding

(3)

A

The termination of feeding is due to a decay in the excitatory state

This means that the habituation has decreased leading to the foregut volume to expand as the stretch receptor is activated

When there is high levels of sugar or amino acid in the hemolymph, this would result in a negative feedback to the brain

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16
Q

What can change the Stages of Feeding?

(2)

A

Temperature and Environmental Factor

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17
Q

Suboesophageal Ganglion

(2)

A

All the information about the food is going to the suboesophageal ganglion which is apart of the brain located in the head below the esophagus

It controls the insect mouth part, salivary glands and the muscle of the neck

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18
Q

How do insects differ in their feeding behavior?

(2)

A

Different mouthparts

Various Ingestion mechanism

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19
Q

Phagostimulants

(2) + Eg

A

Chemical in the food that stimulate the feeding of the insect
In order for the insect to continue feeding, stimulants&raquo_space;» Deterrents

eg: Sugar

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20
Q

Phagodeterrents

A

Chemical in the food that inhibits the feeding even in the presence of a stimulants

21
Q

Feeding Ratio

(2)

A

This is defined as the ratio or balance of stimulants and deterrents

Sensory input from deterrents “outweighs” input from the stimulant by ratio of 8:1 found in caterpillars

22
Q

Types of Feeding Behaviour (2)

A

Monophagous
Oligophagous
Polyphagous

23
Q

Monophagous

A

These individuals tend to feed on a single plant family

Due to this, they only need few receptors for feeding decisions and few sensory inputs

24
Q

Oligophagous

A

These individuals tend to feed a few plant families

25
Q

Polyphagous (Generalist)

A

These individuals tend to feed on a number of plant families

26
Q

Number of Mouthparts in insects

(2) + Description

A

Caterpillars consisting of 24 mouthpart sensilla
- This indicates that caterpillars are evolutionary evolved compared to grasshopper because they consists of less mouthparts

Grasshoppers consists of 2000 mouthpart sensilla

27
Q

What happens if you surgically remove the maxillae of the caterpillar?

(2) + Description

A

This would lead to hyperphagia
- Therefore causing the maxillae to become more sensitive and leading the insect to eat more

Due to the insect eating more, this would lead to acceptance of normally receptor hostplants

28
Q

Sugar concentration in different insects
BlowFly:

A

When there is an increase in sugar concentration in the hemolymph, this would result in a decrease in the emptying of the crop into the midgut and increase in meal interval

29
Q

Sugar concentration in different insects: Locust

(4)

A

When trehalose is injected into the hemolymph, this would result in a decrease in the emptying of the crop into the midgut

When there is an injection of water into the hemolymph, this would result in crop emptying

There are amino acid receptors in the maxillary palp of the locust. When there is an increase of amino acid in the hemolymph, this would make the sensilla less responsive to amino acid

This is because the receptor of the maxillary palp will become less sensitive

30
Q

Feeding and Digestion: Salivary glands

(1) + Eg

A

Are present in piercing / sucking insects
(Diptera/Hemitera)

31
Q

Saliva of the mosquito

(3)

A

(Local anesthetic, vasodilator, anticoagulant)

32
Q

Saliva of the Hemiptera (2)

A

These digestive enzymes are injected into the food, which breaks down the food to become liquified and sucked up again

These include amylase used to convert starch into sugar or invertase used to convert sucrose into glucose

33
Q

Aphid Saliva

A

Consists of pectinases used to drill into the plant tissue and suck up its vascular tissues (phloem) and used in cell wall degradation

34
Q

Midgut Digestion Enzymes

(3)

A

Digestion in the form of enzyme secretion occurs in the midgut secreting enzymes known as (3)

Secretagogue
Neural Stimulation
Hormonal Stimulation

35
Q

Secretagogue

A

Enzyme stimulating the substance in the food

36
Q

Neural Stimulation

A

Stretch receptor on the midgut becomes activated based on the presence of food

37
Q

Hormonal Stimulation

A

As the nutritional state of the insect increases, the hormonal stimulation is secreted

38
Q

Rate of Digestion in the Midgut

A

Determine by the rate of degradation of polysaccharides to monosaccharides

39
Q

There are insects that lack an enzyme or nutrient therefore would need to harbor other microorganisms inside their gut to help digest food

A

This is known as symbiotic relationship

40
Q

Examples of Symbiotic Relationship

(3) + Description

A

Transferred on eggshells (eaten by neonates)

Wood wasps need fungus to digest cellulose in the wood

Wood termites obtain cellulase on enteric protozoa and bacteria
- These enteric protozoa and bacteria thrive in an anaerobic region of the hindgut known as the paunch

41
Q

In the 1760’s an attempt to establish silkworm industry in Georgia (USA) failed

(3)

A

This is due to the silkworm larvae grew but did not pupate

The method of this experiment is housing the silkworm in a rear cage made out of bald cypress wood

This wood releases a volatile 2 furaldehyde, a natural antiseptic that inhibits 7 bacterial and 2 fungal endosymbionts of silkworm

42
Q

Essential Nutrition needed in Insect’s diet: Phenylalanine

(2)

A

Is one of the most important amino acid for larval growth

It is also used for sclerotization

43
Q

Essential Nutrition needed in Insect’s diet: CHO (2)

A

Some Diptera can live just on protein without CHO

Some larval stage requires just protein and lipids whereas some adult would just require sucrose

44
Q

Essential Nutrition needed in Insect’s diet: Cyclitols

A

This is a nutrition that is important for membrane synthesis (Eg. Plant feeders)

45
Q

Essential nutiriton needed for the insect diet:
Fat Soluble Vitamin

A

Vitamin A complex used for vision

46
Q

Essential Nutrition needed in Insect’s diet: Water Soluble Vitamin

A

Eg. Ascorbic Acid (B complex)

47
Q

Essential Nutrition needed in Insect’s diet: Free Fatty Acids (C18)

(2)

A

Some insects do not require fatty acids

However lepidoptera would need fatty acids in order to pupate and adult form would require free fatty as without it there will exist wing deformities (Slight deficiency)

48
Q

Essential Nutrition needed in Insect’s diet: Sterols

(2)

A

Insect cannot synthesize sterols therefore would need to feed on plants to modify phytosterols into cholesterol

Sterol is essential as it allows for the synthesis of ecdysteroids (molting hormone)

49
Q

Other function of sterol include
(2)

A

Exerting surface waxes on the epicuticle

Making membrane production

BIOL 327 (13 decks)

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