VM 13600 Exam Two Study Guide: Reproductive & Digestive Systems

Reproductive system function

The biological processes and structures involved in reproduction.

Prostate

Largest accessory gland and is present in all animals; secretes prostatic fluid that is thin, milky, very alkaline.

Scrotum

Thick sack of skin that surrounds the testicles.

Sperm

Produced by the males and is deposited into the female reproductive tract for fertilization.

Seminiferous tubules

Location where spermatogenesis production, development and maturation occurs; lined by Sertoli cells.

Gametes in the female

Female gametes are Ova or Egg cells, which produce estradiol and progesterone.

Endometrium

Inner lining of the uterus and is supplied with blood vessels and glands.

Myometrium

The uterine muscle layer.

Amnion

Also known as the second water bag and is located between the chorion and amnion; it stores fetal excretory products.

Chorion

Makes the attachment with the endometrium.

Corpus luteum

Secretes progesterone to support the pregnancy and secretes estrogen; created from the remaining follicular tissue in the ovary.

Fertilization

Fusion of the ova and sperm and signals the beginning of pregnancy.

Gestation

Pregnancy.

Parturition

The act of giving birth.

Dystocia

Difficulty giving birth.

Placentation

Development of the placenta, which is required to meet the increasing nutritional needs of the embryo.

Ovulation

Release of the ovum.

Stages of labor

3 stages of labor: Stage 1 involves early myometrial contractions and dilation of the cervix; Stage 2 involves the fetus entering the cervix.

Stage 1 of labor

Early myometrial contractions and dilation of the cervix; short in the mare (~2.5 hours), longer in the sow (~7 hrs), may be as short as 1-2 hrs in either species.

Stage 2 of labor

Takes about 20 minutes in the mare, 45 minutes in the cow, 75 minutes in the ewe, and 3 hours in the sow.

Ferguson's reflex

Once the fetus enters the cervix, the stretch stimulates the hypothalamus to release oxytocin from the posterior pituitary.

Estrogen

Induces formation of oxytocin receptors in the myometrium.

Oxytocin

Causes powerful contractions of the myometrium, resulting in expulsion of the fetus.

Expulsion of the placenta

Takes ~ 1 hr in the mare, 2.5 hours in the sow, between ½ to 8 hours in the ewe, and ~9 hrs in the cow.

Retained placenta

A debilitating condition that occurs if the placenta is not expelled.

Colostrum

First milk released to the offspring, important for passive immunity.

Colostrum consumption time

Consume in the first 24 hours for optimal protection.

Colostrum immunoglobin content

Has a high immunoglobin (antibody) content, providing protection to the newborn.

Colostrum composition

Has less lactose than normal milk, but is higher in vitamin A, riboflavin, proteins, and minerals.

Ovary characteristics

Enclosed with a protective capsule and contains many ova, each enclosed within a follicle.

Ova formation

All the ova a female will ever have are already formed at birth and stored in the ovaries.

Follicular phase

The first phase of the ovarian cycle, includes proestrus and estrus.

Luteal phase

Phase of the ovarian cycle during which the corpus luteum (CL) is developed and active.

Corpus luteum (CL)

Serves as an endocrine gland that secretes predominantly progesterone.

Regression of the CL

Signals the beginning of a new follicular phase in the ovary.

Estrous cycle

The period from the time the animal shows sexual receptivity (estrus) to the next.

Menstrual cycle

Only humans and primates have menstrual cycles; ovulation occurs after the endometrium thickens.

Estrus

The phase of the estrous cycle when the animal shows sexual receptivity.

Metestrus

The phase of the ovarian cycle following estrus.

Diestrus

The phase of the ovarian cycle following metestrus.

Proestrus

The phase of the ovarian cycle preceding estrus.

Anestrus

Period of inactivity between breeding seasons in seasonally polyestrous animals.

Gestation length for Bitches

63 days.

Gestation length for Sheep

150 days.

Gestation length for Cows

~ 270 days.

Gestation length for Mares

~ 333 days.

Fertilization process

1. Sperm migrates through any cells that may still be surrounding the zona pellucida of the oocyte.

Sperm attachment

Sperm attach to the zona pellucida, where the acrosomal reaction occurs, and the sperm head attaches to the ZP3 receptor.

Acrosomal reaction

The process where the acrosomal cap of the sperm breaks down, releasing enzymes that digest the oocyte plasma membrane.

Enzymes released during acrosomal reaction

Includes acrosin and hyaluronidase.

Oocyte penetration

The sperm fuses with the oocyte plasma membrane, penetrating it and entering the oocyte cytoplasm.

Spermatogonium

The cell that sperms develop from and divides into two primary spermatocytes.

Spermatogenesis

The process of sperm development, divided into three phases.

Spermatocytogenesis

The proliferative phase where spermatogonia multiply by mitotic divisions to produce primary spermatocytes, which are diploid (2N).

Meiosis in spermatogenesis

Primary spermatocytes undergo meiosis to form secondary spermatocytes, which undergo a second meiosis to form spermatids, resulting in haploid (1N) cells.

Round spermatids

The end product of spermatocytogenesis.

Spermiogenesis

The phase where spermatids undergo morphological changes to become nonmotile spermatozoa.

Spermiation

The last phase of spermatogenesis where non-motile spermatozoa are released into the lumen of the seminiferous tubules, controlled by LH.

Leydig cells

Cells that produce the androgen testosterone, important for sperm production, influenced by Luteinizing hormone (LH).

Sertoli cells

Cells that nurture and protect developing sperm under the regulation of follicle stimulating hormone (FSH).

Granulosa cells

Cells that protect the developing ovum, have FSH receptors, and produce aromatase.

Aromatase

An enzyme produced by granulosa cells that migrates to granulosa cells.

LH

Luteinizing hormone, which influences Leydig cells and controls spermiation.

FSH

Follicle stimulating hormone, which regulates Sertoli cells.

Aromatase

This enzyme converts testosterone to estrogen

Passive immunity

Immunity provided to newborns from consuming colostrum from the mother from the high immunoglobin content

Gamma globulins

Gamma globulins are important because they play a crucial role in the immune system

Follicles

Converts testosterone to estrogen for the follicles

Pseudopregnancy

Occurs when the CL persists in the absence of pregnancy

Persistent CL

In pseudo pregnant animals the persistent CL continues to secrete progesterone

Endometrium

The endometrium thickens, the udder develops, the animal may exhibit maternal behavior

Prostaglandins

Stimulate contractions of the uterine muscles to move the semen inside the uterus

Estrogen

Plays a role in regulating reproduction, development of the uterus and mammary glands and ovulation

Prolactin

Helps to sustain pregnancy and initiate milk letdown

Progesterone

Helps support the pregnancy

Oxytocin

Helps to expel the fetus and placenta

Relaxin

A protein hormone that is secreted by the corpus luteum, endometrium and placenta

Avian reproduction

Only the left ovary functions throughout the hen's life

Hen ovulation

They ovulate once every day

Oviduct

The Oviduct is made up of 3 parts: infundibulum, magnum, and isthmus

Magnum

The magnum is large and muscular that pushes the egg towards the uterus

Shell gland

The shell gland secretes a substance that makes the egg's shell

Cloaca

The shelled egg enters the vagina, then the cloaca

Rooster testicles

Rooster testicles rest within the abdominal cavity

Sperm transfer

Sperm is passed from the rooster's cloaca to the hen's cloaca in a brief copulatory period

Tongue/mouth

Prehension (grasping) - forms a bolus of food and pushes it back into the pharynx for swallowing

Esophagus

Moves boluses of ingesta from the pharynx to the stomach

Stomach

Sac-like muscular organ situated on the LEFT side of the abdomen under/behind the diaphragm

Liver

Secretion of bile for digestion and absorption of dietary fats

Pancreas

It has 2 portions: exocrine (secretes digestive juices (enzymes and sodium bicarbonate) and an endocrine portion (secretes hormones (insulin and glucagon which regulate blood sugar levels)

Small intestine

Small intestine connects the stomach to the large intestine, and is where most digestion and absorption of nutrients take place

Large intestine

The Large Intestines function changes depending on the species of dogs it is short and simple while in horses it is large and complex

Cecum

Consists of the cecum and the colon.

Colon

It is part of the large intestine.

Fermentation in Horses

In the horse, it completes fermentation of complex carbohydrates, such as cellulose.

Volatile Fatty Acids

Volatile fatty acids are absorbed in the large intestinal wall into the blood.

Feces Storage

Feces are stored in the large intestine.

Forage Fermentation

Forage is fermented here in equine.

Transport Mechanisms

There are proteins located within the membranes of enterocytes that transport amino acids and glucose.

Amino Acid Transport

Amino acids bind to their transport proteins, which take them across the intestinal cell membrane and into the cell.