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Anatomy 2 > Chapter 20 - Pregnancy, Development and Lactation > Flashcards

Chapter 20 - Pregnancy, Development and Lactation Flashcards

1
Q

Breeding and Fertilization of the Ovum

A

Erection
Copulation
Ejaculation
Sperm
Transport
Fertilization

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2
Q

Erection

A

 Enlargement and stiffening of the penis that prepares it for breeding
*Arteries dilate
*Veins are compressed
 Sexual stimuli
*Smells and behavioral changes from the female

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3
Q

Copulation

A

 The act of breeding
 Allowed by the female during the estrus period
 Positions:
*Standing with mounting the female from behind
*Kneeling (cushed) position
* Camels, llamas, alpacas
 Mounting is followed by intromission, thrusting, and ejaculation

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4
Q

Ejaculation

A

 The reflex expulsion of semen from the penis
 Stage 1:
* Spermatozoa move from epididymis
* Fluids from accessory reproductive glands move into pelvic portion of urethra
* Sphincter muscle around neck of urinary bladder closes
 Stage 2:
* Rhythmic contraction of smooth muscle around urethra
* Semen is pumped out into female reproductive tract
* Through cervix into the uterus

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5
Q

The Transport of Spermatozoa

A

 Semen usually deposited in upper portion of vagina
*By swimming of spermatozoa
*By contraction of uterus and oviducts
*By action of cilia in oviducts
 Spermatozoa must arrive at oviducts before ovum
* Capacitation to enhance fertility

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6
Q

Capacitation

A

 Series of changes that spermatozoa undergo in the female reproductive tract to increase chances of successful fertilization of the ovum
*Ion movement through cell membrane
*Increase in cell’s metabolic rates
*Increase in rate of simple sugar use for energy production
*Exposure of enzymes in acrosome

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7
Q

Fertilization of the Ovum – in the Oviduct

A

 Large number of spermatozoa find and swarm around the ovum
 Many begin tunneling through corona radiata and zona pellucida
 One spermatozoon will physically penetrate the cell membrane of the ovum = fertilization
* Genetic material is delivered into ovum’s cytoplasm
 Ovum’s cell membrane blocks all other spermatozoa from entering

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8
Q

Gestation hormone

A

Progestin - ovary

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9
Q

The Zygote

A

 The ovum, once it is fertilized
 Male pronucleus and female pronucleus joined
*Each contain haploid chromosome number
* Join together to restore diploid chromosome number

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10
Q

Breeding hormones

A

Estrogen - ovary
Oxytocin- Posterior Pituitary

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11
Q

parturition hormones

A

Relaxin - Placenta
ACTH - anterior pituitary (fetus)
glucocorticoids -adrenal glands (fetus)
estrogens - placenta
prostaglandin F2 alpha -placenta and uterine wall (dam)
Oxytocin - posterior pituitary (fetus)

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12
Q

Lactation hormones

A

growth hormone – anterior pituitary
prolactin- anterior pituitary
oxytocin - posterior pituitary

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13
Q

The Zygote

A

 The ovum, once it is fertilized
 Male pronucleus and female pronucleus joined
*Each contain haploid chromosome number
* Join together to restore diploid chromosome number

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14
Q

Cleavage

A

 Rapid mitosis of zygote
* 2 pronuclei join to form a single nucleus
*Each chromosome makes a copy of itself
* Zygote begins to rapidly divide
* number of cells increases, but overall size does not change
 Zygote is moving down oviduct toward uterus
 Cells in morula stage form blastocyst
 Overall size of zygote does not change

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15
Q

Implantation

A

 Blastocyst embeds itself in endometrium
*Enzymes dissolve away a small pit
* Multiple blastocysts are randomly spaced in multiparous species
 Placenta begins to form as soon as blastocyst is implanted

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16
Q

The Placenta

A

 Life-support system for the developing offspring
* Develops around embryo
* Connected by umbilical cord
 Multilayered, fluid-filled membranous sacs
*Amnion - sac
*Allantois -sac
* Chorion
*Attaches to uterine lining
 Where attached to uterus lining, exchange of nutrients & waste takes place

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17
Q

sacs (placenta)

A

 Amnion: membranous layer immediately surrounding the fetus
* Forms the amniotic sac
* Fetus floats in amniotic fluid inside the amniotic sac
 Allantois: layer surrounding amniotic sac; forms the allantoic sac, which accumulates wastes

18
Q

Placental Attachments comparative anatomy

A

(A) Diffuse attachment – horse and pig
– Attachment sites spread diffusely over placenta and uterus
–placenta detaches easily
(B) Cotyledonary attachment – ruminants
–small, discrete, numerous attachment points (placentomes)
—placentomes have a cotyledon that joins the caruncle on the uterus
— Sometimes placentomes are retained in uterus which can lead to illness of the mother
(C) Zonary attachment – dog & cat
— Placenta attaches along a belt like zone
— Detaches fairly easily
(D) Discoid attachment – primates, rodents
— Single, discrete, disc-shaped attachment

19
Q

The Umbilical Cord

A

 The link between the fetus and the nutrient waste exchange structures of the placenta
 Cord contains:
* Umbilical arteries (2)
* Umbilical vein (1)
* Urachus (1)

20
Q

Gestation

A

 Gestation period: time from fertilization of ovum to delivery of newborn
 Divided into three segments (trimesters):
* First trimester – embryonic period
*Placenta develops
* Second trimester – fetal period
*Body tissues, organs, & systems develop
* Third trimester – fetal growth period

21
Q

Parturition

A

 The Birth Process
 Triggered by multiple factors
*Size and weight of uterus and fetus
* Changing hormonal levels
 Fetal changes after birth
* Lungs expand and begin to function
* Foramen ovale and ductus arteriosus close

22
Q

Parturition hormones

A

 2 hormones
*Estrogen – increases myometrium sensitivity to oxytocin
* Oxytocin
* Myometrium contractions
* Milk letdown

23
Q

First Stage of Labor

A

– uterine contractions
* Myometrium contracts
* Fetus is pressed down against cervix
* Cervix gradually dilates

24
Q

2nd stage of labor

A

actual delivery of the newborn
*Amniotic and allantoic sacs of the placenta rupture
* Uterine and abdominal muscles contract in rhythmic pattern
* Newborn is delivered

25
Third stage of labor
delivery of the placenta (afterbirth) *Placenta separates from wall of the uterus *Placenta is expelled by weaker uterine contractions *Placenta is often eaten by dam  Post-partum examination – very important!
26
Involution of the Uterus
 Uterus gradually returns to its non-pregnant 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
27
The Mammary Glands
 Specialized skin glands *Present in both male and female * Normally only function in the female *Vary among species * Number, locations, openings per teat  Produce colostrum and milk  Very important during neonatal period
28
Udder of Cow
 Four 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  Slinglike arrangement of ligaments for support and attachment to body wall  Nipples are called “teats”
29
The Alveoli and Duct System (cows)
 Milk-secreting units of mammary gland = alveoli * Alveoli arranged like clusters of grapes around alveolar duct  Milk secreted into alveolar duct * Smaller ducts join to form larger ducts * Largest ducts empty into gland sinus * Gland sinuses are continuous with teat sinuses  Milk accumulates in 2 large teat sinuses for milk letdown  Streak canal at tip of teat
30
Mares, Ewes, Goats
 2 mammary glands in one udder
31
Mammary Gland Development
 Develop in response to hormones produced at puberty *Prolactin * Growth hormone *Estrogen *Progesterone * Thyroid-stimulating hormone *Adrenocorticotropic hormone  Levels of various hormones must be balanced precisely for complete development
32
Hormones in Mammary Gland Development
 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
33
Mammary Glands & Lactation
 Specialized skin glands * Colostrum – passive immunity * Milk  Present in both males & females  Undeveloped until puberty  Lactation * Milk production *Begins towards end of pregnancy * Continues as long as gland is emptied
34
Lactation
 The process of milk production  Begins toward end of pregnancy  Obvious at time of parturition  Hormones involved in starting lactation *Prolactin * Growth hormone * Hormones from adrenal cortex
35
Lactation Physiology
 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  Lack of hormonal stimulation combined with increased pressure in the mammary gland gradually causes lactation to cease
36
Colostrum
 Pre-milk secretion  Contents: * Larger amounts of proteins, lipids, and amino acids than milk * High levels of various essential vitamins * Laxative effect to help clear newborn’s meconium * High levels of specific antibodies (passive immunity) * Transfer of preformed antibodies from dam to newborn
37
Maintenance of Lactation
 Once begun, lactation continues as long as mammary gland is emptied regularly *Physical stimulation of the teat combined with regular milk removal  Lactation will gradually cease * Lack of hormonal stimulation *Increased pressure in mammary gland *Involution of the mammary gland = “dries up”
38
Milk Letdown
 Immediate effect of nursing or milking  Steps for milk letdown: * Milk accumulates in alveoli and small ducts *Physical stimulation of nipple or teat sends sensory nerve impulses to brain, to release oxytocin * Oxytocin causes contraction of myoepithelial cells around alveoli and small ducts * Milk is squeezed down into large ducts and sinuses
39
Morula
Solid mass of cells Found in upper section of the oviduct, known as the isthmus Does not have a cyst (open area)
40
Blastocyst
hollow ball of cells Found in endometrium of the uterus implantation occurs
41
Labor Comparative Anatomy
**Canine: labor term - whelping, newborn- pups, litter, ok breach *Feline: labor term - Queening, newborn- kittens, litter, ok breach *Equine: labor term -Foaling, newborn- foals, one. twins bad, not ok breach *Bovine: labor term - Calving, newborn- calves. one twins ok if same sex. Freemartin is heifer calf with bull calf twin. She's sterile, breach not ok. *Ovine: labor term -lambing, newborn- lambs, twins good, not ok breach *Porcine: labor term -farrowing, newborn- piglets, litter, ok breach
42
Nipples comparative anatomy
Location, Number of nipples, number glands cats - inguinal/thoracic/abdominal-3 - 7, 10 cattle - inguinal-1, 4 dogs - inguinal/thoracic/abdominal-8 - 20, 10 goats- inguinal-1, 2 horses- inguinal-2 -4, 2 pigs -inguinal/thoracic/abdominal-2-3, 14 sheep -inguinal-1, 2

Anatomy 2 (9 decks)

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