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MCAT Biology > Chapter 2.3 > Flashcards

Chapter 2.3 Flashcards

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1
Q

What causes sex-linked disorders? Are they recessive or dominant?

A
  • mutations in the gene of the X-chromosome
  • most of them are recessively inherited
  • > therefore, women inherit less of these sex-linked disorders
  • > because they have two sex chromosomes
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2
Q

Why are males termed hemizygous with respect to the X chromosome

A

-because they have only one copy of each gene on the X chromosome

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3
Q

What is a notable gene on the Y chromosome that initiates testis differentiation

A

-the SRY gene

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4
Q

What are the two functional parts of the testis

A

1) seminiferous tubules

2) interstitial cells(of Leydig)

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5
Q

Where are sperm produced in? What are they nourished by?

A
  • sperm are produced in the seminiferous tubules

- >they are nourished by the Sertoli cells

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6
Q

What hormone do cells of the Leydig secrete?

A
  • cells of the Leydig produce testosterone

- >they also produce other androgens

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7
Q

Where is the location of the testies? What is the temperature like there in comparison to the rest of the body?

A
  • the testies is located in the scrotum

- >the temperature there is 2 degrees to 4 degrees lower than the body

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8
Q

Where do sperm gain motility? Where do they go for ejaculation?

A
  • sperm gain motility in the vas deferens

- they go to the ejaculatory duct during ejaculation

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9
Q

Where do the two ejaculatory ducts?

A
  • in the urethra

- >it carries the sperm through the penis as they exit the body

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10
Q

What is the role of the seminal vesicles

A
  • contribute fructose to nourish the sperm
  • give sperm fluid mildly alkaline properties
  • > so it can survive in the vagina
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11
Q

What is the role of the prostate gland

A

-give sperm fluid mildly alkaline properties

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12
Q

What is the role of the bulbourethral gland

A
  • produces clear viscous fluid
  • > cleans out any remnants of urine
  • > lubricates the urethra during sexual arousal
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13
Q

What is semen

A

-a combination of sperm and seminal fluid

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14
Q

Describe the process of spermatogenesis

A

-it is the formation of haploid sperm through meiosis

  • in males diploid sperm are known as spermatogonia
  • after replicating their genetic material in the S stage
  • > they develop into primary spermatocytes
  • first meiotic division results in secondary spermatocytes
  • second meiotic division results in haploids called spermatids
  • finally spermatids mature to become spermatozoa
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15
Q

What do mature sperm consist of

A

-they consist of a head, midpiece and a flagellum

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16
Q

What is the midpiece filled with

A
  • it is filled with mitochondria

- >generates energy as the sperm swims through the female reproductive tract

17
Q

What is each sperm head covered by

A
  • an acrosome

- >is necessary to penetrate the ovum

18
Q

What is a major difference between the positioning of the female reproductive organs and the male reproductive organs?

A
  • unlike male reproductive system

- >all female reproductive organs are internal

19
Q

What hormones do the ovaries produce

A

-the ovaries produce estrogen and progesterone

20
Q

Describe where the egg goes after ovulation

A
  • it is released into the peritoneal sac
  • > in the abdominal cavity
  • it is then drawn into the fallopian tube
  • > which is lined with cilia to propel the egg forward
21
Q

What is the external female anatomy known as

A

-it is known as the vulva

22
Q

What kind of oocytes are the oogonia considered to be by birth? What do they develop into after menarche(menstrual cycle)

A
  • by birth
  • > all of the oogonia are considered to be primary oocytes
  • > these cells are 2n
  • > arrested in prophase 1
  • develop into secondary oocytes after menarche
  • > this is when one primary oocyte completes meiosis 1
  • > produces secondary oocyte
  • > secondary oocyte remains arrested in metaphase 2
23
Q

When does the secondary oocyte complete metaphase 2 and finish the remainder of meiosis 2

A
  • the secondary oocyte completes metaphase 2 once fertilization occurs
  • > then meiosis 2 is finished
24
Q

What two layers are the oocyte surrounded by

A
  • surrounded by:
  • > zone pellucida
  • > corona radiata
25
Q

What is the purpose of the zone pellucida

A
  • surround the oocyte itself
  • > an acellular mixture of glycoproteins
  • > protects the oocyte
  • > contains compounds necessary for sperm cell binding
26
Q

What is the purpose of the corona radiata

A
  • lies outside of the zona pellucida

- >layer of cells adhered to the oocyte during ovulation

27
Q

Is GnRH allowed to be produced prior to puberty?

A
  • no
  • > it is only released at the start of puberty

-which then triggers the anterior pituitary to release FSH and LH

28
Q

What is the role of LH and FSH in males

A
  • FSH is to stimulate Sertoli cells
  • > triggers sperm maturation

-LH cells causes interstitial cells to produce testosterone
->maintains male reproductive system
->responsible for secondary sexual characteristics
eg; facial/axillary hair, deepening of the voice and changes in growth patterns

29
Q

How does testosterone interact with the hypothalamus and the anterior pituitary

A

-it has a negative feedback on both of these structures

30
Q

What is estrogen secreted in response to

A

-it is secreted in response to FSH
->results in the development of the female reproductive system and female secondary sexual characteristics
eg; breast growth, change in fat distribution and widening of the hips

31
Q

What is progesterone

A
  • secreted by the corpeus luteum
  • involved in the development and maintenance of the endometrium
  • > not involved in the initial thickening of the endometrium
  • > that is the job of estrogen
32
Q

Describe the characteristics of the follicular phase. When does it start? What hormones are in high amounts during this phase?

A
  • begins when the menstrual flow starts
  • higher concentrations of GnRH=higher concentrations of FSH and LH
  • the ovarian follicles develop
  • follicles begin to produce estrogen
  • > estrogen has a negative feedback on the GnRH, LH and FSH
33
Q

What are estrogen levels like during ovulation

A
  • they reach a threshold
  • > results in positive feedback of GnRH, LH and FSH
  • > surge in LH is crucial, as this releases the ovum from the ovary
34
Q

What hormone has high levels in the luteal phase? How does it affect GnRH, FSH and LH

A
  • progesterone

- > it has negative feedback on the three hormones mentioned in the question

35
Q

What is hCG or human chorionic gonadotropin?

A
  • hormone is an analog of LH
  • > maintain the corpus luteum
  • it is crucial during the first trimester of development
  • > as the corpus luteum secrete estrogen/progesterone
  • > this keeps the uterine lining in place
36
Q

Why do estrogen and progesterone need to be maintained at a high level during pregnancy

A

-so that there is negative feedback on GnRH secretion

37
Q

What happens to FSH/LH levels during menopause? Also talk about estrogen and progesterone levels

A
  • since there is no negative feedback on these two
  • > blood levels rise
  • estrogen and progesterone levels drop
  • > so endometrium lining is not maintained

MCAT Biology (30 decks)

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