Stages of Pregnancy
During the first trimester, the newly implanted zygote is getting itself organized and developing its life-supporting placenta. The developing offspring is often referred to as an embryo.
During the second trimester, the developing offspring is usually ca
Stages of Labor
First stage - uterine contractions
-Myometrium contracts and presses fetus down against the cervix
-Sustained contractions cause the cervix to gradually dilate
Second stage - delivery of the newborn
-Results from combination of strong uterine and abdomina
Why is the timing of copulation so important? How is the precise timing accomplished?
Timing is important because the spermatozoa must arrive at the oviducts before the ovum to have time to undergo capacitation, a process that enhances their fertility. Nature has an exquisite method for arranging the proper timing. Breeding is only allowed
Describe what happens to a zygote between fertilization and implantation.
The fertilized ovum is called a zygote. Immediately after fertilization, the nucleus of the spermatozoon is called the male pronucleus, and the nucleus of the ovum is called the female pronucleus. Each carries the haploid chromosome number. The male and f
Why is the placenta so important to a successful pregnancy?
The placenta is a life-support system for the developing fetus. The fetus receives all the nutrients and other substances it needs to grow and develop from its mother. Through the placenta, it also depends on her to dispose of the waste products it produc
Describe the relationship between the fetus and the amniotic and allantoic sacs of the placenta.
The placenta consists of layers of soft membranes that form two fluid-filled sacs around the developing fetus. The layer immediately around the fetus is called the amnion. It forms a sac around the fetus called the amniotic sac. The fetus floats in amniot
Describe the main structures that make up the umbilical cord and the function of each.
The umbilical cord is a tubelike structure that contains blood vessels (the umbilical arteries and vein) and a drainage tube from the fetus' urinary bladder (the urachus). The two umbilical arteries carry unoxygenated, waste-filled blood from the fetus to
Which type of placental attachment to the uterus is the simplest and detaches most easily after parturition? Which is most complicated and often results in retention of the placenta?
Diffuse attachment is the simplest and detaches most easily. Cotyledonary attachment is the most complicated type and often results in retention of the placenta.
Why is it important that uterine contractions continue after the fetus and placenta are delivered?
Uterine contractions continue so that involution can occur. The contractions cause the sloughed endometrium to be expelled so that the sites where the placenta was attached can heal. Pressure from the continued uterine contractions usually stops bleeding
Why does mastitis in one quarter of a dairy cow's udder not necessarily spread to the other three quarters?
Each quarter is a completely separate unit from the other three, with its own milk-secreting systems and ducts leading down to their own teats. Infection does not directly spread from one quarter to another. It has to spread down through the teat and duct
Describe the suspensory apparatus of the udder.
This suspensory apparatus of the udder consists of a slinglike arrangement of ligaments that run down the center and around the sides of the udder. The medial suspensory ligament contains many elastic fibers that allow it to stretch. It passes down the ce
Why don't the mammary glands of male animals usually develop and secrete milk?
Males' mammary glands don't develop and secrete milk because they do not have the balance of hormones required.
Describe the importance of colostrum to the health of a newborn animal.
Before producing actual milk, the mammary gland produces colostrum, which contains larger amounts of proteins, lipids, and amino acids than milk and also contains high levels of various essential vitamins. Colostrum supplies important nutrients to the new
Describe how nursing or milking causes milk letdown and also helps sustain lactation.
When milk is produced, it accumulates up high in the mammary gland in the alveoli and small ducts. It does not move down into the larger ducts and sinuses where it is accessible for nursing or milking until milk letdown occurs. Continued physical stimulat