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Block 5 > Hormones and Gametes > Flashcards

Hormones and Gametes Flashcards

1
Q

What is a gamete?

A

Sperm or ova

Specialised cells that allow us to ass our genes on to the next generation

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2
Q

What type of cell is a gamete?

A

Haploid cell

23 individual chromosomes

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3
Q

What are gametes derived from?

A

Germ cells

Migrate to the gonads at about 6 weeks of development

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4
Q

After colonising the gonad, the germ cells:

A

Proliferate

Reshuffle genetic material

Reduce to haploid

Mature into sperm

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5
Q

List the phases of mitosis

A

Interphase (G2)

Prophase

Prometaphase

Metaphase

Anaphase

Telophase

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6
Q

What happens in interphase (G2)

A

2 copies of centrosome

DNA has replicated

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7
Q

What happens in prophase?

A

Chromosomes condense

Mitotic spindle poles forms

Nucleus wall starts to break down

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8
Q

What happens in prometaphase?

A

Chromosomes condense

Microtubules start to capture chromosomes at the kinetochore

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9
Q

What happens in metaphase?

A

All chromosomes are captured

Line up at metaphase

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10
Q

What happens in anaphase?

A

Microtubules push poles apart making the cell bigger

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11
Q

Where are spermatogonia cells found?

A

XY germ cells colonise medulla of testes in male embryo

Cells proliferate (mitosis) to form spermatogonia

Cords hollow out to form seminiferous tubules

Spermatogonia cluster around the edges of seminiferous tubules

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12
Q

Discuss spermatogenesis

A

At puberty, a group of spermatogonia divide by mitosis a fixed number of times to form 64 linked diploid cells called primary spermatocytes

Meiosis I produces two haploid secondary spermatocytes

Meiosis II results in four haploid spermatids per primary spermatid

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13
Q

Discuss spermatogenesis

A

At puberty, a group of spermatogonia divide by mitosis a fixed number of times to form 64 linked diploid cells called primary spermatocytes

Meiosis I produces two haploid secondary spermatocytes

Meiosis II results in four haploid spermatids per primary spermatid

Spermatagonia are constantly replaced at the edge of seminiferous tubules

Spermatids are close to lumen

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14
Q

Discuss spermiogenesis

A

Maturation of spermatids into differentiated spermatozoa

Spermatids are released into tubule + undergo remodelling/maturation as the pass through the testes, efferent duct and epididymis

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15
Q

What are the major morphological changes that occur during spermiogenesis?

A

Formation of a head containing the nucleus and a mid-piece containing mitochondria

Formation of the acrosome from Golgi apparatus

Elongation of one centriole to form a tail

Loss of excess cytoplasm

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16
Q

What role does the acrosome of the spermatozoa have?

A

Contains digestive enzymes that break down the zona pellucida, a glycoprotein layer that surrounds the ovum

17
Q

Why does spermatozoa contain lots of mitochondria?

A

To provide energy for swimming

18
Q

How often are spermatogonia recruited?

A

Every 16 days

19
Q

How long does the process of spermatogenesis and spermiogenesis take?

A

70 days

20
Q

What 4 things does semen contain?

A

Secretions of seminal vesicle (60%)

Secretions of the prostate (20%)

Sperm

Secretions of bulbo-urethral glands

21
Q

Discuss the process of oogonia

A

XX germ cells colonise the cortex of the ovaries

Proliferate by mitosis forming oogonia

2 million oogonia remain at the end of gestation

They all enter meiosis before birth

Female has developed all stock of potential gametes before birth

22
Q

Discuss the process of oogenesis

A

Meiosis stops at early stage resulting in diploid primary oocyte

From puberty, each month a primary oocyte complete development to form mature ovum

Meiotic division only resumes at ovulation

Meiosis I produces haploid secondary oocyte and polar body

Meiosis II produces mature ovum and second polar body

23
Q

Successful reproduction requires:

A

Fertilisation

A system of support for the conceptus, embryo and foetus

Birth at the right time

24
Q

Successful reproduction requires:

What is it controlled by?

A

Fertilisation

A system of support for the conceptus, embryo and foetus

Birth at the right time

Controlled by the HPG axis

25
Q

How are messages communicated from the hypothalamus to the anterior pituitary gland?

How does this differ in the posterior pituitary?

A

Nerve endings from hypothalamus secrete neurohormones that travel via the blood to the anterior pituitary

The posterior pituitary gland receives the neurohormones directly from the hypothalamus cells

26
Q

What is the main hormone of reproduction found in the hypothalamus?

A

Gonadotrophin Releasing Hormone

27
Q

What are the main hormones of reproduction found in the pituitary gland?

A

FSH

LH

Prolactin

Oxytocin (posterior)

28
Q

What are the main hormones of reproduction found in the gonads?

A

Oestrogen

Progesterone

Testosterone

Inhibin

29
Q

What 6 peptide hormones does the anterior pituitary gland produce?

A

Growth hormone

Adrenocorticotropic hormone (ACTH)

Thyroid stimulating hormone

Follicle stimulating hormone

Luteinising hormone

Prolactin

30
Q

Which hormone is exclusively produced in the posterior pituitary gland?

A

Oxytocin

Role in labour and lactation

31
Q

Discuss gonadotrophin releasing hormone

A

Produced by cleavage of pre-pro-GnRH

Pulsatile release every 1-2hrs

Acts on membrane receptors which stimulate second messengers

Causes release of FSH and LH from anterior pituitary gland

32
Q

How are FSH and LH similar?

A

Same alpha chain, different beta chain

Glycoproteins (protein + sugar)

33
Q

Which cells in the male gonads produce testosterone?

Where are these cells found?

A

Leydig cells lining the seminiferous tubules produce testosterone

34
Q

Which cells in the male gonads produce inhibin?

What is its role?

A

Sertoli cells

Support the developing sperm and push them towards the lumen of the seminiferous tubule

Also converts testosterone to dihydrotestosterone (more active form)

35
Q

List some functions of oestrogen

A

Increases muscular contraction in uterine tube

Proliferation of the uterine lining

Makes cervical mucus think and alkaline

Breast development in puberty and pregnancy

Female body fat distribution, hair, genitals

Supports bone growth

36
Q

Which hormone does the corpus luteum produce?

A

Progesterone

Oestrogen

Block 5 (6 decks)

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