Animal Hormones Flashcards

1
Q

Why do only specific target cells respond to a hormone?

A

Because only target cells have receptors for binding with that particular hormone.

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2
Q

Describe the functions of the nervous and the endocrine system:

A

-Nervous system: coordintes rapid, precise responses and mediate the body interaction with the external environment. -Endocrine system: controls processes that require duration rather than speed, especially to maintain homeostasis.

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3
Q

What is a hormone?

A

A chemical mediator that is secreted by endocrine cells into the blood, where it is then transported to target cells.

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4
Q

What are the four different types of extracellular communication:

A

1) Paracrines 2) Neurotransmitter 3) Hormones. 4) Neurohormones.

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5
Q

Describe paracrines:

A

Local chemical messengers whose effect is exerted only on neighbouring cells in the immediate sorroundings of the receptors.

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6
Q

Describe neurotransmitter

A

Released by neurons and are short distances chemical messenger.

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7
Q

Describe neurohormones:

A

Hormones released into the blood by neurosecretory neurons.

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8
Q

What are the 6 different functions of hormones:

A

1) Regulating metabolism, water and electrolyte balance. 2) Inducing adaptive changes to help the body cope with stressful situations. 3) Promoting smooth, sequential growth in development. 4) Controlling sexual differentiation and development.

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9
Q

What are thee factors that influce the plasma concentrations of hormones:

A

1) The hormone rate of secretion into the blood. 2) The rate of metabolic activation or conversion. 3) For lipophilic hormones the extenct of binding to the plasma membrane. 4) Its rate of removal from the blod by metabolic inactivation and excretion in the urine.

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10
Q

What are the 3 means of control of hormone secretion:

A

1) Negative-feedback control. 2) Neuroendocrine reflexes 3) Diurnal (circadian) Rhythms.

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11
Q

Describe negative-feedback control:

A

Maintain the plasma concentration of hormone at a given level.

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12
Q

Describe neuroendocrine reflexes:

A

Include neural as well as endocrine components and it produce a sudden increase in hormone secretion in resposne to specific stimulus.

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13
Q

Describe diurnal (circadian) rhythms:

A

The secretion rates of many hormones fluctuate up and down as a function of time.

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14
Q

What is endocrinology:

A

The study of homeostatic chemical adjustment and other activites accomplished by hormones.

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15
Q

What are the two main kind of hormones based on their chemical classificatio?

A

1) Hydrophilic 2) Lipophilic

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16
Q

What are Hydrophilic hormones and how are they divided?

A

Hormones that are highly soluble in water and have low lipid solubility. They are peptides or amines.

17
Q

What are amines and how are they divided?

A

Amino-acid derivates and can be either catecholamines or indoleamines.

18
Q

Describe lipophilic hormones and how are they divided:

A

High lipid solube and are poorly soluble in water. They can be either thyroid hormones or steroid hormones.

19
Q

What does the solubility of hormones determine?

A

1) How the hormones is synthesized, stored and secreted by the endocrine system. 2) How the hormone is transported by the blood. 3) How the hormone exert its effect at a target cell.

20
Q

How are hydrophilic hormones transported into the blood?

A

They simply dissolve in blood.

21
Q

How are lipophilic hormones transported into the blood?

A

They cannot dissolve in blood and are therefore bound to specific proteins.

22
Q

Where are the receptors of hydrophilic peptides hormoes located?

A

Since they canot permeate the plasma membrane the bind to specific receptors located on the plasma membrane.

23
Q

Where are the receptos for lipophilic hormones located?

A

They can pass through the plasma membrane and bind to specific receptors inside the cell.

24
Q

How do hydrophilic hormones alter cell’s proteins/function?

A

Surface-binding hydrophilic hormones function by activating a second messenger pathway. This direction directly alter the activity of pre-existing intracellular proteins to produce the desired effect.

25
Q

How do lipophilic hormones alter cell’s proteins/function?

A

They function mainly by activating specific genes in target cell to cause formation of new intracellular proteins which in turn produce the desired effect.

26
Q

What are the two hormones responsable for the correct function of molting in arthropods?

A

-PTTH -Juvenile hormone

27
Q

Describe the function of juvenile hormone:

A

Is release continously and as long as it’s present the insects molt into another juvenile individual.

28
Q

Describe the pituitary gland:

A

Is a small endocrine gland located in a bony cavity at the base of the brain just below the hypotalamus.

29
Q

Describe the function of the posterior pituitary:

A

Is an extension of the hypotalamus. It doesn’t produce any hormone, it simpy stores and releases vasopressin and oxytocin.

30
Q

Describe the anterior pituitary:

A

Consists of glandular epithelia tissue which are then released in response to hypophysiotropic hormones.

31
Q

What are the two main kinds of hypophysiotropic hormones?

A

-Stimulatory -Inhibitory.