Lipids Flashcards

1
Q

how many classes there are?

A

There are two classes of lipid-based reproductive hormones, the steroids and the eicosanoids.

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2
Q

Are lipids less soluble in aqueous fluids of the body than are proteins and monoamines?

A

Lipids are in general less soluble in the aqueous fluids of the body than are proteins and monoamines.

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3
Q

how are they often?

A

They are often either modified for transport through the body fluid or carried on transporters.

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4
Q

1) Steroids

A

title

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5
Q

What do steroid hormones comprise/from what are they all derived?

A

The steroid hormones comprise a large group of molecules all derived from a common sterol precursor: cholesterol.

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6
Q

From what is cholesterol synthesized and what is cholesterol’s role?

A

Cholesterol is synthesized from acetate in many tissues of the body, and is an important structural component of cell membranes.

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7
Q

what is the first and common step in the formation of all major steroid hormones?

A

The conversion of cholesterol to pregnenolone marks the first and common step in the formation of all major steroid hormones.

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8
Q

where does the conversion occur?

A

The conversion occurs on the inner mitochondrial membrane.

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9
Q

where is Pregnenolone then converted?

A

Pregnenolone is then converted to the sex steroids in the adjacent smooth endoplasmic reticulum.

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10
Q

How many main families of steroids are there?

A

There are four main families of steroid: the progestagens, androgens, oestrogens and corticosteroids.

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11
Q

What are the first 3 steroids considered as?

A

The first three steroids are considered as the sex steroids.

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12
Q

How is the interconversion from one class of steroid to another undertaken?

A

The interconversion from one class of steroid to another is undertaken by a series of enzymes arranged together as a biosynthetic unit.

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13
Q

What do the structural features shared by members of each steroid class give?

A

The structural features shared by members of each steroid class are reflected in common functional properties.

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14
Q

Androgens

A

androgens are associated with the development and maintenance of male characteristics and fertility

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15
Q

Oestrogens

A

oestrogens with the development and maintenance of female characteristics and fertility

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16
Q

Progestagens

A

progestagens are associated with the preparation of pregnancy and its maintenance

17
Q

What is dihydrotestosterone (DHT)?

A

Dihydrotestosterone (DHT), is a product of the conversion of testosterone by the enzyme 5α-reductase.

18
Q

What happens without DHT?

A

Without DHT, regardless of the genetic or gonadal sex, the external genitalia will develop along the female template.

19
Q

2) Eicosanoids

A

title

20
Q

what are eicosanoids?

A

The eicosanoids are non-steroidal molecules that pass through plasma membranes by means of specific transporters.

21
Q

What do they comprise?

A

They comprise two major classes of messenger: the prostaglandins (PGs), which are of principal interest for reproductive processes, and the leukotriens, which play a lesser role.

22
Q

what is the common precursor for a series of prostaglandins?

A

The arachidonic acid is the common precursor for a series of prostaglandins.

23
Q

where are PGs synthesized?

A

PGs are synthesized in most tissues of the body including the ovary and the uterine myometrium, cervix, ovary, placenta and fetal membranes.

24
Q

describe eicosanoids

A

Eicosanoids have very short half-lives, are not transported to distant cells and therefore differ from the classic hormones.

25
Q

how do they act?

A

They act as local hormones, either by paracrine or after a short passage through the local bloodstream.