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Endocrinology > The Gonads > Flashcards

The Gonads Flashcards

(49 cards)

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1
Q

where do the testes and ovaries develop from

A

Gonads

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2
Q

What are the functions of the gonads

A

Production of gametes and steroid hormones

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3
Q

How is gametogenesis specific to sex

A 
Males = spermatogenesis
Females = Oogenesis
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4
Q

How is steroidogenesis specific to sex

A

Males = androgens - oestrogen, progestogens

Females - oestrogen, progestogens

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5
Q

Describe the process of spermatogenesis

A
  1. Germ cell proliferates via mitosis to produce spermatogonia
  2. Spermatogonia undergoes the first meiotic division
  3. primary spermatocytes undergo second meiotic division to produce spermatids
  4. Maturation into spermatozoa
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6
Q

How long does spermatogenesis take

A

70 days

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7
Q

Describe the process of oogenesis

A
  1. Germ cell divides by mitosis
  2. Oogonia undergo the first meiotic division to produce primary oocytes
  3. Meiotic arrest in prophase of meiosis 1
  4. At puberty meiosis 1 finishes to produce the secondary oocytes and a polar body
  5. secondary oocytes enter the second meiotic division at fertilisation
  6. Production of the ovum and a second polar body
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8
Q

How long may meiotic arrest occur for

A

12-50 years

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9
Q

Where does spermatogenesis occur

A

Testes - Sertoli cells

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10
Q

How does testes production/development occur

A

Development in the abdomen and descent into the scrotum

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11
Q

Describe the anatomy of the testes

A

Lumen surrounded by Sertoli cells which contain the spermatogonia

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12
Q

What is the function of the Sertoli cells

A

Spermatogenesis + development
Location of the spermatogonia
Forms the seminiferous tubules

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13
Q

What is the relationship of there Sertoli cells with FSH

A

Stimulated by FSH to release inhibit which has a negative feedback effect on FSH release

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14
Q

Where are the Leydig cells located

A

Outside of the seminiferous tubules

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15
Q

What is the function of Leydig cells

A

Synthesis of testosterone in response to LH to have a -ve feedback effect
Source of testicular androgens. mainly testosterone

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16
Q

Describe the anatomy of the ovaries

A 
Graafian follicle:
Ovum 
granulosa cells
Follicular fluid
Thecal cells

Follicles that are under different stages of development in the stroma e.g. follicles undergoing atresia

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17
Q

How long does the menstrual cycle take

A

28 days

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18
Q

When does ovulation occur

A

Day 14

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19
Q

What are the two cycles occurring during the menstrual cycle

A

Ovarian and Endometrial

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20
Q

What are the 3 stages of the ovarian cycle

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A

Follicular phase, ovulation, luteal phase

21
Q

What are the 2 stages of the endometrial cycle

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A

Proliferative phase - oestrogen dominant

secretory phase - progesterone dominant

22
Q

How does basal body temperature change during menstruation

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A

Slight increase in the second half due to the increase in progesterone

23
Q

Describe how cholesterol is converted to androstenedione

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A 
Cholesterol 
Pregnenolone
Progesterone
17-OH progesteron
Androstenedione
24
Q

What is testosterone and oestrone converted to

Study These Flashcards
A

dihydrotestosterone

17β-Oestradiol

25
What can testosterone be converted to
reduction to dihydrotestosterone or aromatisation to oestrogen
26
What is testosterone bound to in seminiferous fluid
androgen binding globulin (ABG)
27
How does testosterone travel in the blood
60% - sex hormone binding globulin (SHBG) 38% - albumin 2% - free
28
What are the actions of androgen
fetus - development of male internal and external genitalia fetal growth adult - spermatogenesis growth and development of male genitalia protein and bone anabolism sexual behaviour pubertal growth spurt
29
Describe oestrogens
any substance which induces mitosis in the endometrium | e.g. 17β-Oestradiol, oestrone, oestriol
30
Give the actions of oestrogen
stimulates proliferation in the endometrium to thicken the womb triggers an LH surge for ovulation secretions from vagina and cervix Stimulated growth of the ductile system in the breasts Decreases sebaceous gland secretion in the skin Feedback regulation of GnRH Stimulation of osteoblasts Metabolic actions Behavioural effects Increases salt and water reabsorption Increases plasma protein synthesis Influences the release of other hormones e.g. prolactin thyrotrophin
31
Describe progestogens
Any substance including secretory changes in the endometrium e.g. progesterone, 17𝛼-hydroxyprogesterone
32
What are the actions of progestogens
Stimulates secretory activity in the endometrium and cervix Negative feedback on hypothalamic GnRH Increase in basal body temperature Decease in sodium chloride re-absorption in the kidney Stimulated growth of alveolar system in the breast.
33
What is the difference between LH and FSH action
LH - stimulates hormones | FSH - stimulates gametes
34
Describe the process of endocrine control of testicular function
1. GnRH is released in pulses every hour, triggering pulses of LH and FSH 2. LH stimulated the Leydig cells to synthesise testosterone 3. FSH stimulates the Sertoli cells (lining of the seminiferous tubules) to support spermatogenesis 4. Testosterone is used in the final stage of spermatogenesis 5. Testosterone has a -ve feedback effect on the hypothalamus + adenohypophysis (OH/LH) Inhibin produced buy the Sertoli cells 4 -ve inhibits LH and FSH
35
What are the 5 phases of the menstrual cycle
``` Early follicular phase Early mid follicular phase mid follicular phase late follicular phase luteal phase ```
36
When is progesterone produced in the menstrual cycle
second half of the cycle or when pregnant
37
How is LH and FSH controlled in females
Oestrodiol produces the -ve feedback
38
Describe what occurs in the early follicular phase
FSH causes the ovaries' follicles to enlarge/grow 5-10 eggs grow under the influence of FSH The follicles begin to produce oestradiol (and little progesterone)
39
Describe what occurs in the early mid follicular phase
LH and FSH remain the same form early follicular phase More oestradiol as the follicles grow larger 1 egg grows more than the rest (Graafian follicle) Positive feedback as the increase in oestrogen from the Graafian follicle stimulates the surrounding granulosa cells to grow which in turn allows for increased oestrogen production etc.
40
Describe what occurs in the mid follicular phase
As the oestrogen levels increase, it causes a -ve feedback effect on the adenohypophysis so LH and FSH levels decrease, causing the other follicles in the ovary die
41
Describe what occurs in the late follicular phase
High oestrogen levels triggers a +ve feedback (hypothalamus and pituitary) to cause an LH surge Ovulation as the follicle breaks open and egg moves to the uterus
42
Describe what occurs in the luteal phase
Once the follicle has broken the corpus luteum is left, which produces progesterone Progesterone prepares the endometrium for implantation (secretory lining) No fertilisation with high levels of oestradiol, inhibin and progesterone causes a decline in LH and FSH which leads to menstruation
43
What is the Graafian follicle
The largest follicle that no longer requires FSH to develop and proliferate Keeps growing and producing large amounts of E2
44
What is amenorrhoea and oligomenorrhoea
``` Amenorrhoea = The absence of menstrual cycles Oligomenorrhoea = infrequent cycles primary = if a women has never had a period secondary = periods that hone stop ```
45
What is infertility defined as
The inability to become pregnant after 12 months of unprotected sex
46
What are the causes of infertility
Pituitary failure Prolactinoma Testicular failure e.g. mumps, Klinefelter's syndrome Ovarian failure e.g. Turner's syndrome Polycystic ovarian syndrome (most common metabolic disorder in women) Infrequent periods Hyper-androgenaemia e.g. increased male pattern hair, acne Polycystic ovaries (increased number of enlarging ovarian follicles)
47
Describe the blood-testes barrier
Sertoli cells are connected via tight junctions to form a blood-testes barrier Prevents large molecules from entering the testes
48
What are thecal cells
Surrounds the ovum in the ovaries | Has LH receptors which allows stimulation of steroidogenesis
49
Describe the pathway of spermatids through the testes
1. Spermatogenesis in the seminiferous tubules 2. Spermatids enter the lumen of the tubules and collected in the Rete testis 3. Drainage into the Vasa efferentia 4. Drainage into the epididymis 5. +nutrient secretion to mature and gain motility 6. Expelled by the vas deference

Endocrinology (9 decks)

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