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A&P - vic > Chapter 18 pregnancy, development, and lactation > Flashcards

Chapter 18 pregnancy, development, and lactation Flashcards

1
Q

What is copulation?

A
  • the act of breeding -mounting
  • intromission - insertion of penis into the vagina
  • thrusting and ejaculation (semen is usually deposited in the upper portion of the vagina) - spermatozoa transported by swimming, by contractions of uterus and oviducts, and by action of cilia in oviducts
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2
Q

What does copulation trigger?

A

oxytocin release from posterior pituitary gland of the female
0xytocin causes contraction of smooth muscle of the female reproductive organs

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3
Q

What is capacitation?

A

series of changes that spermatozoa undergo in the female reproductive tract to increase changes of successfully fertilizing the ovum
- changes in ion movement through the cell
membranes; increase in cells metabolic rates
- release of digestive enzymes from acrosome
- help the spermatozoa penetrate through
layers surrounding the ovum to accomplish
fertilization

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4
Q

What do spermatozoa do in the fertilization process?

A
  • large number of spermatozoa find and swarm around the ovum in the oviduct
  • some begin tunneling through the layers surrounding the ovum - aided by digestive enzymes of their acrosomes
  • once a single spermatozoon penetrates cell membrane of the ovum, a change in the membrane blocks other sperm from entering
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5
Q

What is the zygote?

A
  • once the ovum is fertilized, it gets another name change and becomes a zygote
  • immediately after fertilization the nucleus of the
    spermatozoon is called the male pronucleus;
  • the nucleus of the ovum is called the female
    pronucleus
  • each pronuclues contains the haploid chromosome
    number
  • male and female pronuclei join together - restores the diploid chromosome number
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6
Q

What is cleavage?

A
  • rapid mitosis of zygote
  • overall size of zygote does not change
  • morula stage - solid mass of cells
  • blastocyst - hollow ball of cells - ready to implant
    itself in the lining of the uterus
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7
Q

What is implantation?

A

when the enzymes produced by the blastocyst dissolve away a small pit in the endometrium. - blastocyst attaches to endometrium in this pit

  • in multiparous species, the multiple blastocysts randomly space along the horns and body of the uterus
  • placenta begins to form as soon as the blastocyst implants in the uterus
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8
Q

What is the placenta?

A

a life support system for the developing fetus

  • multilayered, fluid-filled, membranous sac
  • outermost layer of placenta attaches to uterine lining in some areas
    • fetal and maternal blood vessels are in close proximity to each other in this area
    • site of exchange of blood nutrients and wastes
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9
Q

In the placenta, there are layers of soft membranes that form two fluid-filled sacs around the developing fetus. What are those layers?

A

amnion
allantois
chorion

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10
Q

What is the amnion in the placenta?

A

membranous layer immediately surrounding the fetus

  • forms the amniotic sac
  • fetus floats in amniotic fluid inside the amniotic sac
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11
Q

What is the allantois in the placenta?

A

layer surrounding amniotic sac; forms the allantoic sac, which accumulates wastes

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12
Q

What is the chorion in the placenta?

A
  • covers the allantoic sac
  • attaches to the lining of uterus
  • linked to fetus by the umbilical cord
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13
Q

Placental attachments varies between species, what are those attachments?

A
  1. diffuse attachments
  2. cotyledonary attachment
  3. zonary attachment
  4. discoid attachment
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14
Q

What is diffuse attachments?

A

attachment sites are spread over the whole surface of the placenta and uterine lining

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15
Q

What is cotyledonary attachment?

A

many small, separate attachment sites (placentome): cotyledon on placental surface joins with caruncle in the uterine lining

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16
Q

The attachment type cotyledonary are found in what kind of animals?

A

ruminants (cattle, sheep, and goats)

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17
Q

What is the zonary attachment?

A

belt-shaped attachment that encircles the placenta

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18
Q

What animal is the zonary attachment found in the uterus?

A

cats and dogs

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19
Q

What is discoid attachment?

A

placenta and uterus attached at a single disk-shaped area

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20
Q

What animal is the discoid attachment found in the uterus?

A

primates, rabbits and many rodents

also Humans

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21
Q

What is the gestation period?

A

time from fertilization of ovum to delivery of newborn
- time varies in different species
- divided into three segments (trimesters)
1st, 2nd, 3rd

22
Q

What is the 1st trimester in the gestation period?

A

embryonic period - placenta develops

23
Q

What is the 2nd trimester in the gestation period?

A

fetal period - body tissues, organs, and systems devleop

24
Q

What is the 3rd trimester in the gestation period?

A

fetal growth period

25
Q

What is the gestation period of cats?

A

56 - 69 days - approx. 2 months

26
Q

What is the gestation period of dogs?

A

59 - 68 days - approx. 2 months

27
Q

What is the gestation period of goats?

A

146 - 155 days - approx. 5 months

28
Q

What is the gestation period of horses?

A

321 - 346 days - approx. 11 months

29
Q

What is the gestation period of pigs?

A

110 - 116 days - approx. 3 months, 3 weeks, and 3 days

30
Q

What is the gestation period of rabbits?

A

30- 32 days - approx. 1 month

31
Q

What is the gestation period of sheep?

A

143 - 151 days - approx. 5 months

32
Q

What is the gestation period of elephants?

A

615 - 650 days - 21 months

33
Q

What is parturition?

A
  • birth process
  • multiple factors trigger parturition
    • size and weight of uterus
    • hormonal changes
  • fetal changes at birth
    • lungs expand and start functioning
    • formamen ovale and ductus arteriosus close
  • increased level of glucocorticoid hormones from
    adrenal glands of fetus stimulate estrogen level
    increase in dam and release of prostaglandin
    F2a (alpha)
  • oxytocin released from dam’s posterior pituitary gland
34
Q

What hormone declines in the bloodstream of dam during parturition and during the pregnancy prevented fetus from prematurely expelling?

A

progesterone

35
Q

What stimulates myometrium to contract, which starts the labor process?

A

oxytocin

36
Q

There are three stages of labor, what is the first stage?

A

uterine contractions

  • myometrium contracts and presses fetus down against the cervix
  • sustained contraction cause the cervix to gradually dilate
37
Q

There are three stages of labor, what is the second stage?

A

delivery of the newborn

  • results from combination of strong uterine and abdominal muscle contractions
  • rupture of amniotic and allantoic sacs of the placenta usually precedes actual delivery of the newborn
38
Q

There are three stages of labor, what is the third stage?

A

delivery of the placenta

- placenta separates from wall of the uterus and is expelled by weaker uterine contractions

39
Q

What is involution of the uterus?

A
  • uterus gradually returns to its nonpregnant size
  • endometrium sloughs into lumen of uterus at sites of placental attachment
  • myometrium continues mild contractions to move remaining uterine contents out through birth canal
  • may take from a few weeks to a month or more for involution to be complete
40
Q

What are mammary glands?

A
  • specialized skin glands
  • produce colostrum and milk
  • present in both male and female animals
    • males do not secrete the proper blend of
      hormones to make them work
  • number and appearance of mammary glands
    differs among common species of animals
41
Q

The udder of a cow consists of?

A
  • 4 mammary glands (quarters
  • Quarters are completely separate units from each
    other
  • each quarter has its own milk- secreting systems
    and ducts leading down to separate teats
42
Q

What is mastitis?

A

infection of the mammary gland

- test for mastitis using California mastitis test

43
Q

What supports the udder that can weigh more than 100 pounds at milking time?

A

Medial suspensory ligament - many elastic fibers -
passes between left and right halves of the udder
- lateral suspensory ligaments - strong inelastic
collagen fibers - pass down and around the lateral
sides of each half of the udder

44
Q

How often do milk cows need to birth to keep milk flowing?

A

every other year

45
Q

What are the milk-secreting units of the mammary gland?

A
  • mammary alveoli - saclike arrangement of cells that secrete milk into the alveolar duct
46
Q

The duct system of the mammary gland is similar to the arrangement of ______ in a tree.

A

branches
- arranged like clusters of grapes around the alveolar ducts are similar to the leaves
- smaller alevolar ducts joint to form larger ducts similar to small tree branches joining to form larger branches
- largest ducts empty into the gland sinus located just dorsal to the teat similar to the trunk of a tree
- gland sinus is continuous with the teat sinus
inside the teat
- the gland sinus and teat sinus are where milk
accumulates when milk letdown has occurred

47
Q

What causes mammary gland development?

A
  • mammary glands develop in response to hormones produced at puberty
  • prolactin and growth hormone directly encourage mammary gland development
  • estrogen and progesterone encourage the mammary alveoli and duct systems to develop
48
Q

Before it starts to produce milk, the mammary gland produces a sort of premilk secretion called?

A

colostrum
- contains large amounts of proteins, lipids, amino
acids, and vitamins
- supplies important nutrients to the newborn
- laxative effect helps clear (dark, sticky) meconium from newborn’s intestinal tract
- imparts “passive immunity” - transfer of preformed
antibodies from dam to newborn

49
Q

What is the most critical of colostrums role?

A

transfer of passive immunity form the dam to the newborn

50
Q

Lactation will continue if….

A
  • physical stimulation of teat or nipple and regular
    removal of milk from the gland stimulates anterior
    pituitary to continue production of hormones that
    keep lactation going
51
Q

What stops lactation?

A

lack of hormonal stimulation combined with pressure in the mammary gland gradually causes lactation to cease - this is called involution of the mammary gland

52
Q

What is milk letdown?

A

immediate effect of nursing or milking
- milk accumulates high up in the mammary gland in
mammary alveoli and small ducts
- physical stimulation of the nipple or teat sends
sensory nerve impulses that cause release of
oxytocin from posterior pituitary
- oxytocin casues contraction of myoepithelial cells
around the alveoli and small ducts
- moves milk down into the large ducts and
sinuses (milk letdown has occurred)

A&P - vic (21 decks)

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