Chapters- 11, 18, 19, 20
.List the three steps involved in performing a urinalysis.
Exam of the urine with the naked eye, chemical analysis using a reagent strip, and microscopic analysis.
What are the six structures that make up the urinary system?
Two kidneys, two ureters carrying urine to the bladder, one bladder, and one urethra that carries urine from the bladder to out of the body
Nitrogenous waste materials from protein breakdown are eliminated from the body primarily as what?
Name one hormone whose release is regulated by the kidney, one hormone that directly affects kidney function, and one hormone produced by the kidney.
1) Hormones whose release is regulated by the kidney: ADH (anti-diurectic hormone) and aldosterone; 2) Hormones that directly affect kidney function: both ADH and aldosterone; 3) Hormones produced by the kidney: erythropoietin (EPO), and some types of prostaglandins
What is meant by the term “retroperitoneal”?
Considered to be outside the peritoneal cavity, or abdominal cavity; between the peritoneum and the dorsal abdominal wall.
List, in order, the parts of the nephron. Indicate if a specific part is found in the cortex or the medulla of the kidney.
Nephron: the basic microscopic functional unit of the kidney. Consists of: 1)renal corpuscle (glomerulus and Bowman’s capsule) – cortex; 2)proximal convoluted tubule (PCT) – cortex; 3)loop of Henle – both medulla and cortex; 4)distal convoluted tubule (DCT) – cortex; 5)collecting ducts – cortex and medulla and on to renal pelvis
.What is the difference between “glomerular” filtrate and “tubular” filtrate?
Glomerular filtrate =similar to plasma, except no cells or proteins(they’re too big) for the capillary fenestrations, and is the result of blood being filtered from glomerular capillaries to the capsular space of the Bowman’s capsule, which is part of the renal corpuscle; Tubular filtrate = when the glomerular filtrate enters the proximal convoluted tubule (PCT), and the composition of the liquid changes .
What is the function of the brush border on the epithelial cells of the proximal convoluted tubule?
Increase in surface area for reabsorption and secretion
What is the difference between tubular “reabsorption” and tubular “secretion”?
“Reabsorption” = absorption of substances from renal tubules back into the blood; “Secretion” = secretion of substances from the blood into the renal tubules.
How does ADH deficiency affect urine volume? What is the mechanism?
ADH = anti-diurectic hormone or non-diuresis hormone. If you are drinking caffeine, it is a diuretic and makes you exrete more urine. So anti-diuretic means holding onto the water. If you’re not getting enough production of ADH, it’ll be more like having caffeine with regards to releasing more urine – only much worse! Scientifically speaking it inhibits water reabsorption from collecting ducts
. Explain the concept of the renal threshold of glucose.
This is the maximum amount of glucose that can be reabsorbed from the renal tubules back into the blood. If blood glucose levels are high to begin with, as with diabetes mellitus, the glucose that went into the renal tubule that can’t get reabsorbed back into the blood will appear in the urine.
Explain why proteinuria occurs with renal failure.
As the nephrons are destroyed, they allow space for larger molecules into the urine. Normally protein would be too big to be allowed into urine.
. Why are clinical signs of renal failure not observed until the disease process is advanced?
The kidneys do a great job of compensating for damage until two thirds of the nephrons are destroyed.
Diabetes insipidus gets its name from what physical characteristic of urine produced by patients with this disease?
Insipid means tasteless. The urine in this case does NOT have excess glucose. This is because diabetes insipidus is due to a deficiency in ADH (ADH is produced by the pituitary).
How do the kidneys respond to a decrease in blood pressure?
The renin-angiotensin-aldosterone system in the responds by sending signals for arteries to constrict and stimulate aldosterone from adrenal glands. Aldosterone increases sodium and water reabsorption back into the bloodstream. Increased water in bloodstream ↑blood pressure
Why is it important that the ureters have an inner lining of transitional epithelium?
Transitional epithelium is stretchy, which is important when urine passes through the ureters.
What prevents urine from backing up into the ureters when the bladder wall contracts to expel urine?
The ureters are located at a very small angle (oblique) to the bladder, so that as the bladder distends with urine, it closes or collapses the opening of the ureter to the bladder.
.The ureter is continuous with what structure in the kidney (except in cattle)?
The renal pelvis – cattle have multiple urine collection areas that feed into the ureter.
How does the bladder know when to empty itself?
Pressure from distention of the filling bladder activates bladder stretch receptors in the bladder wall. A spinal reflex is then activated and sends efferent motor neurons impulses to contract the bladder muscles. If animals have learned to control the voluntary sphincter around the neck of the bladder, they can void their bladder outdoors (if it’s not overfull).
What part of the urinary bladder is under voluntary control and allows an animal to be housebroken?
As mentioned in the above answer, the voluntary sphincter around the neck of the bladder.
Does urine production stop when the urinary bladder is full?
The kidney is still busy continuously, so no, urine production does not stop when the bladder is full
Besides its urinary function, what other function does the urethra play in a male animal?
Spermatozoa and seminal fluid also travel through the urethra during ejaculation in the male animal, but at that time the sphincter at the neck of the bladder closes so that ejaculated material does not mix with urine.
.How much kidney function must be destroyed before clinical signs of renal dysfunction become evident?
Two-thirds of the total nephrons in both kidneys must be nonfunctional before signs are evident.
Explain the difference between “prerenal” uremia and “postrenal” uremia.
“Prerenal” uremia – waste materials are in the blood because the blood flow to the kidneys is decreased.
“Postrenal” uremia – caused by an obstruction that prevents urine from being excreted and it backs up into the renal pelvis, eventually causing renal damage and dysfunction.
What is a urolith?
Some of the waste products in urine which might precipitate out of solution and become aggregates (clusters) of crystals.
Name two conditions that can predispose an animal to urolith production.
Diet, urine pH, frequency of urination, the presence of urinary tract infections (the presence of certain bacteria can lead to changes in urine pH), water consumption, and urine volume.
How do uroliths in cats differ from uroliths in other species?
Struvite and calcium oxalate are the most common types in cats; struvite in dogs; and calcium carbonate, struvite, and calcium oxalate in ruminants. But in cats, stones are much smaller, like sand, and clumps together into a gelatinous plug which can cause an obstruction.
What is the chemical composition of a struvite crystal?
Struvite is composed of magnesium, ammonium, and phosphate (on the basic side of pH, so best to keep urine acidic so that they don’t precipitate out of solution).
Why is the timing of copulation so important? How is the precise timing accomplished?
The spermatozoa need to get to the oviducts before the ovum (egg) does, so that they have a chance to undergo “capacitation,” a number of changes which enhance their fertility before encountering the egg. Contractions of the uterus and oviducts, as well as action of the cilia in the oviducts, help sperm to get to the oviducts quickly.
Describe what happens to a zygote between fertilization and implantation.
The male and female nuclei join together, and rapid division of the single nucleus takes place (cleavage). A few days later it becomes a solid mass of cells, called a morula. Then a hollow cavity forms and the morula is called a blastocyst, with the future embryo’s cells at one end of the hollow cavity.
Why is the placenta so important to a successful pregnancy?
it provides all the nutrients the fetus needs, and helps eliminate waste from the fetus.
.Describe the relationship between the fetus and the amniotic and allantoic sacs of the placenta.
The amniotic sac is the one closest to the fetus. The allantoic sac surrounds the amniotic sac. There is fluid in each sac.
Describe the main structures that make up the umbilical cord and the function of each.
2 umbilical arteries- carry unoxygenated, waste-filled blood from the fetus to the placenta
Umbilical vein – carries nutrient and oxygen rich blood from the placenta to the fetus
Urachus- tube which carries fetus’ bladder contents to the allantoic sac
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?
Simplest and detaches most easily – diffuse (horse, pig)
Most complicated – cotylendonary (cow, sheep, goat)
What are the basic events of the three trimesters of pregnancy?
1)Embryonic – zygote is implanted and placenta is developing; 2)Fetal development – various parts of the body are taking shape and differentiating; 3)Fetal growth
Describe the three stages of labor.
Uterine contractions, delivery of newborn (including rupture of the placental sacs); and delivery of the placenta (separation and expelling of placenta from uterus)
Why is it important that uterine contractions continue after the fetus and placenta are delivered?
to return the uterus to its non-pregnant size, and to stop bleeding after the placenta is expelled
Why does mastitis in one quarter of a dairy cow’s udder not necessarily spread to the other three quarters?
Each quarter is separate anatomically from the others.
Describe the suspensory apparatus of the udder.
Medial suspensory ligament – passes down the center between right and left halves of udder, many elastic fibers to stretch and be shock absorber
Lateral suspensory ligaments- down and around the lateral sides of each half of the udder, strong but relatively inelastic, firm support
Why don’t the mammary glands of male animals usually develop or secrete milk?
Males don’t secrete the concentrations of the various types of hormones for milk secretion.
.Describe the importance of colostrum to the health of a newborn animal.
Provides passive immunity in the form of antibodies; lots of nutrients; and has a laxative effect to help newborn pass the meconium
Describe how nursing or milking causes milk letdown and also helps sustain lactation.
Sensory nerve impulses stimulate the hypothalamus to cause the anterior pituitary gland to continue to produce lactation-maintaining hormone prolactin. Also stimulates hypothalamus to release hormone oxytocin from posterior pituitary, which leads to squeezing of milk down to ducts or sinuses “milk letdown.”
How do endocrine glands differ from exocrine glands?
Endocrine – secrete hormones directly into blood; Exocrine – secretions travel through ducts until reaching their intended destination
What is a hormone?
An endocrine chemical messenger produced by endocrine glands and secreted directly into blood (“key”) that travels to a target tissue (receptor or “key hole”)
What is a hormone target?
A cell that has receptors (“key holes”) for a particular hormone.
What are the three main chemical groups of hormones?
Peptide hormones- hydrophilic; steroid hormones –lipid based and made from cholesterol- hydrophobic,;and monoamine hormones made from amino acids.
How does the negative feedback system control the secretion of many hormones?
Very much like a thermostat in your house that keeps the temperature at a certain level. Where there is a high enough temperature (or amount of hormone), the heater turns off for the time being (the body stops secreting more of the hormone).
Through what mechanisms does the hypothalamus control the production or release of hormones from the pituitary gland? How do its effects on the anterior and posterior portions of the pituitary differ?
The hypothalamus is connected to the pituitary via a slender piece or stalk of tissue which contains blood vessels and nerve fibers. The hypothalamus triggers the anterior pituitary to make and release certain hormones. On the other hand, the hypothalamus makes some hormones itself (i.e. ADH and oxytocin) and those are stored and released by the posterior pituitary. The posterior pituitary does not itself make hormones.
Why is the pituitary gland referred to as the “master endocrine gland”?
Many of its hormones direct the activity of other endocrine glands in the body, i.e. thyroid gland, female ovary, male testes.
Other than promoting growth in young animals, what are some other effects of GH?
Also known as somatotropin, GH helps to repair body tissues, and helps regulate the metabolism of proteins, carbohydrates, and lipids in the cells. For example, it helps release of lipids for energy, while discouraging the use of glucose as an energy source.
What stimulates the continued release of prolactin during lactation?
Teat stimulation by nursing or milking
.Do FSH and LH play important roles in male animals? If so, what are they?
FSH in males – stimulates development of male reproductive cells, or spermatozoa.
LH in males – stimulates interstitial cells in testes to produce testosterone
Does ADH help promote or prevent the loss of large amounts of water in the urine? What effect would the inhibition of ADH release have on the body?
ADH helps to prevent the loss of large amounts of water in the urine. Inhibition of ADH release would lead to loss of large amounts of water (diuresis) in the urine, which could lead to diabetes insipidus.
When milking a cow by hand, why does it take a minute or two of teat stimulation before milk starts to flow freely?
There is a lagtime from between stimulation of the mammary gland to release of oxytocin into the bloodstream and get to the mammary gland to allow for milk “letdown.”
What hormone plays an important role in helping an animal maintain its body temperature under cold environmental conditions? How does it produce its effects?
Thyroid hormone. Its calorigenic effect means that it helps control the rate at which cells burn nutrients to produce energy.
How do the clinical signs of hypothyroidism and hyperthyroidism relate to the normal functions of thyroid hormone?
Hypothyroidism causes an animal to burn nutrients more slowly and makes them feel cold and have weight gain; hyperthyroidism can make animals have weight loss and fast heart rate due to increased metabolic rate.
What two hormones play important roles in maintaining homeostasis of blood calcium levels in the body? Which one prevents hypercalcemia? Which prevents hypocalcemia?
Calcitonin from the thyroid gland – prevents hypercalcemia; and parathyroid hormone from the parathyroid gland prevents hypocalcemia
What three groups of hormones are produced in the adrenal cortex? What are their effects?
Glucocorticoids - increase blood glucose through gluconeogenesis ; Mineralocorticoids - regulate levels of electrolytes, especially the hormone aldosterone which affects sodium, potassium and hydrogen ions; and sex hormones - androgens (male hormones) and estrogens (female hormones) . All are called steroids because their chemical structure is similar to cholesterol.
.How are the hormones of the adrenal medulla involved in the fight-or-flight response?
Epinephrine (also known as adrenaline) and norepinephrine secretion from the adrenal medulla are controlled by the sympathetic nervous system, which is the “fight or flight” response.
.Which four hormones have hyperglycemic effects in the body? What is the only hormone that acts to lower the blood glucose level?
only list 3: Glucocorticoids, GH, glucagon have hyperglycemic effects. Insulin acts to lower blood glucose.
Which hormone are anabolic steroid drugs related to?
How do the basic actions and purposes of estrogens and progestins differ?
Estrogens – preparation for breeding and pregnancy; Progestins- pregnancy-promoting.
Why are patients with kidney failure often anemic?
The damaged kidney does not produce enough erythropoietin in the presence of hypoxia.
Why are prostaglandins referred to as “tissue hormones”?
They travel only a short distance from where they are produced.
Why do hormone-like drugs generally have a high potential for undesirable side effects?
You need a higher amount of the drugs to do the job of the natural hormone amounts released by the body; so all of the effects of the hormone-like drug, good and bad, are present.
How does the reproductive system differ from other body systems?
The reproductive system serves to ensure the survival of the species, not the survival of the individual animal. Other body systems are there to help the survival of the individual.
Why is the reproductive system of an individual animal considered only half a system?
It requires a second animal of the opposite sex in order for offspring to be produced.
What is the difference between the “diploid” chromosome number and the “haploid” chromosome number? In which body cells is each found?
Diploid chromosome number – found in the nucleus of all cells except for mature reproductive cells. Diploid chromosome number is referred to as 2n. Haploid chromosome number is the number of chromosomes in the reproductive cells (half the number of chromosomes of a regular cell), and are abbreviated as n (which is the same as 1n) to indicate that they are haploid.
Which gamete, the ovum or the spermatozoon, determines the genetic sex of the offspring when fertilization occurs?
How does cell division by meiosis differ from cell division by mitosis?
In mitosis,cell chromosomes are duplicated before cell divison occurs . Also, 2 identical diploid daughter cells result from mitosis. With meiosis, there are 2 cell divisions, called Meiosis I and Meiosis II. Chromosome duplications does NOT take place before the first cell division, only after the first cell division and before the second cell division. These resulting daughter cells are haploid.
. How does spermatogenesis differ from oogenesis? Why are the basic processes so different?
There are several differences: 1)Many more sperm are produced compared to oocytes (eggs). 2)Spermatozoa are produced continuously, but a female animal is born with a specified and limited number of (immature) oocytes. 3) The process of making mature sperm (including meiosis) from one spermatocyte yields 4 viable sperm; however, the same process for oocytes yields only 1 viable ovum. The basic processes are so different because one oocyte waits for a bunch of sperm to arrive and for one of them to fertilize it. The ovum or oocyte or egg is much bigger also because it has lots of cytoplasm which will help nourish the fertilized egg before it implants in the uterus.
What are the two main functions of the testes? Where in the organ does each take place?
Two main functions: spermatogenesis, which takes place in the seminiferous tubules of the testes; and hormone production, which takes place in the testes between the seminiferous tubule . In interstitial cells which are under the influence of LH from the anterior pituitary. LH in the male stimulates these cells to make testosterone
What are the three main parts of a spermatozoon? What is the main purpose or function of each?
Head – contains nucleus and acrosome cap which contains digestive enzymes to help penetrate the layers of the oocyte ; midpiece – contains lots of mitochondria to produce energy for the sperm ; tail – resembles flagellum, and are used for propulsion
Why is a bilaterally cryptorchid animal usually sterile?
Because the internal body temperature is too high for ideal sperm production.
Would a bilaterally cryptorchid animal exhibit normal male behavior? Why or why not?
Yes, because he would still be making all of the male hormones, particularly testosterone.
What is important about the scrotum’s ability to adjust the position of the testes relative to the body?
To keep sperm production going at its specialized temperature, the cremaster muscle helps to bring the testes closer to the body if the environmental temperature is colder, and can relax and allow the testes to be further from the body when the environmental temperature is warmer
What are the main components of the spermatic cord?
Spermatic cord – links the testes with the rest of the body. Contains tubelike, connective tissues which contain blood vessels, including the meshwork of vessels called the pampiniform plexus, nerves, lymphatic vessels and the vas deferens(the tube through which sperm move).
From what are the visceral and parietal vaginal tunics that cover the testes derived?
From layers of peritoneum that have been pushed ahead of the testes as they descended through the inguinal ring
Where are spermatozoa stored before ejaculation?
Will the volume or gross appearance of the semen of an animal that has had a vasectomy be significantly different from that of a normal animal? Why or why not?
No. Only the spermatozoa are trapped and can’t be ejaculated
How does the function of the bulbourethral glands differ from that of the other accessory reproductive glands?
These are also known as Cowper’s glands. They secrete a mucus-containing fluid which clears and lubricates the urethra just before the passage of semen (not present in dogs).
What are the three main parts of the penis?
Roots, body, and glans.
What structures do spermatozoa pass through from their site of production to their eventual deposition in the female reproductive tract?
Seminiferous tubules in testes to epididymus to vas deferens to urethra
. What two main types of hormones are produced in the ovary? Where is each produced?
Estrogens - produced by cells of developing ovarian follicle and prepare animal for breeding and pregnancy; Progestins such as progesterone – produced by corpus luteum (CL) that develops from empty follicle after ovulation and help prepare uterus for implantation and maintenance of pregnancy
What changes does an ovarian follicle undergo as it develops from a primordial follicle to a mature follicle?
Activated primordial follicle is called a growing follicle. Layers of follicular (granulosa) cells form around it, secreting estrogen. Fluid filled spaces form between granulosa cells, forming one large fluid filled space called the antrum. At its maximum size it is called a mature follicle and feels like a bump/blister on the ovary.
After ovulation has occurred, what cells in the ovary multiply to form the corpus luteum?
Granulosa cells leftover in the empty follicle after follicular rupture or ovulation. They switch to producing progesterone under the influence of LH from the anterior pituitary.
.When ovulation occurs, what causes the ovum to enter the oviduct?
The infundibulum’s fingerlike projections, attached to the oviduct, guide the ovum into the oviduct.
Describe the functions of the uterus relating to pregnancy and parturition.
Pregnancy- uterus serves as place where fetus lives until birth. Uterus binds to placenta to supply oxygen and nutrients to fetus
Parturition – uterus contracts to push out the fetus, and then has to contract quickly after parturition to stop bleeding after placenta has separated from it.
.Where is the urethral opening located in the female?
The urethra opens on the ventral floor of the vestibule of the vulva, (ventral to the vaginal entrance).
What is the difference in the estrous cycle intervals of polyestrous, seasonally polyestrous, diestrous, and monoestrous animals?
Polyestrous – cycle continuously if not pregnant, i.e. cows, pigs
Seasonally polyestrous – seasonal variations , i.e.horse, sheep, and cats
Diestrous – 2 cycles per year, i.e.dog
Monoestrous – one cycle per year, i.e. fox and mink
.How do the stages of the estrous cycle relate to the events of the ovarian cycle?
– When the estrogen level is at its peak and the female is most receptive to breeding, both behaviorally and physically, and ovulation (rupture of the egg from the ovary) occurs
– follicular development
– period after ovulation, corpus luteum develops and produces progesterone, which supports a pregnancy if it happens
– Corpus luteum reaches its maximum size and effectiveness, if animal is not pregnant, it dies (degenerates) at end of diestrus.
– arrested cycle (in some species), no cycling occurring, resting state in ovary
What does FSH stand for?
Follicular stimulating Hormome
What is Estrogen mainly for?
A hormone to prepare for breeding and starting pregnancy
What does LH stand for?