Urogenital apparatus (urinary viscera).docx

The urogenital apparatus is composed of the kidneys and the urinary tract. The urinary tract is composed of ureters, urethra, urinary bladder, and renal pelvis. Kidneys Right kidney is more cranial than the left The kidneys are normally surrounded by fat The kidneys are located: In the lumbar region...

The urogenital apparatus is composed of the kidneys and the urinary tract. The urinary tract is composed of ureters, urethra, urinary bladder, and renal pelvis. Kidneys Right kidney is more cranial than the left The kidneys are normally surrounded by fat The kidneys are located: In the lumbar region Attached to the ceiling of the abdominal cavity Peritoneum covers the ventral aspect of the kidneys but not the dorsal aspect. The kidneys functions include: Filtering plasma Endocrine function (erythropoietin, renin) The external features of the kidneys include: It is bean shaped The hilus is medially orientated (faces medially). The hilus is the space/opening of the kidney that allows veins/arteries to enter and exit it. The medial side of the kidney is concave in shape and houses the hilus. While, the lateral side of the kidneys has a convex shape. Think of concave being a bowl holding water, and convex shape being a bowl that is upside down on a table and unable to hold water. The concave shape that can hold water, will hold the hilus (opening) of the kidney. The kidney’s structure includes the: Cortex Medulla The medulla contains the renal pyramids, and renal crest. Each renal pyramid drains into the renal pelvis. Renal sinus The renal sinus is a fat filled space that houses the renal pelvis. Renal pelvis The renal pelvis collects urine from the renal crest and passes it to the ureters. The renal pelvis is located inside of the renal sinus and the expanding part of the ureter. Ureters The ureters emerge from the renal hilus and runs caudally towards the dorsal aspect of the urinary bladder. There is oblique passage through the urinary walls. The ureters are compressed if intravesical pressure rises. Function: drain urine. Urinary Bladder Function: Deposits urine between micturition (AKA: urination). Position of the bladder depends on it’s plentitude (or fullness). It’s location could be at the floor of the pelvic inlet or at the floor of the abdomen. Urinary bladder external features include: Apex This is the most cranial part of the bladder. Body Neck This is the most narrow part of the bladder and continues with the pelvic urethra. There is no visible sphincter, but the urethral muscles keep the urethra constricted. Damage to this muscle can lead to incontinence. Inflammation in the prostate can cause fecal incontinence due to it’s location being ventral to the anus. Inflammation in the prostate can also cause urinary incontinence due to it being located directly cranial to the urethral muscle. If the ureteral orifice is visible, it signals that you are viewing the ceiling of the bladder. Urinary bladder structure includes: Outer layer: adventitia Middle layer: detrusor muscle The detrusor muscle is under involuntary control and is composed of smooth muscle. Inner layer: mucosa with urothelium (special impermeable lining) No reabsorption or excretion processes happen within this layer. Urethra Females have a shorter urethra than males. In females, their urethra is only at the neck of the urinary bladder, and is therefore referred to as the “pelvic urethra”. In females, the urethra runs caudally in the pelvic cavity and opens at the vaginal and vestibule junction. Males have a pelvic urethra, but their urethra is much longer than the females and leads towards the penis. Therefore, males, in addition to the pelvic urethra, also have a “penile urethra”. In males, the pelvic urethra receives the ducti deterrents. The penile urethra is located inside of the penis Female reproductive viscera It is composed of: ovaries (female gonads), uterine tube, uterus with cervix, vagina, vestibula, and vulva. Ovaries The ovaries are located: In the dorsal part of the abdomen, within the lumbar region Close to the tips of the horns of the uterus Attached to the abdominal wall and uterus via ligaments The ovaries are enclosed in a ovarian bursa. The ovary functions include: Female gametogenesis Endocrine function (estrogen, progesterone, testosterone, etc.) Ovary structure includes: Being ovoid in shape and being composed of two layers (medulla and cortex) The medulla contains nerves and vessels. Containing a reserve of follicles Uterine tube (AKA: Fallopian Tube or Salpinx) The uterine tube’s function includes: Catching the oocyte during ovulation Being the site of fertilization Delivering the fertilized ova to the uterine horn. The uterine horn is where the fetus develops. The infundibulum is the funnel-shaped part of the uterine tube that covers the ovary to capture the oocyte, after the rupture of the mature follicle. Uterus The uterus is a y-shaped organ that is located in the abdomen. Although the location within the abdomen can vary depending on number of gestations that have taken place. Specifically, the uterine horns (long portion) and the uterine body (short portion) are located within the abdomen. The cervix is located within the pelvic cavity. The uterus’ function includes: Being the site of gestation Ensuring the physiological exchange between fetus and mom Uterus structure includes: Endometrium (mucosa) Myometrium (muscle) Perimetrium, which leads to the broad ligament The broad ligament can loosen with each litter of babies birthed. Cervix The cervix controls access to and from the vagina. The cervix partially projects into the vaginal lumen. The cervix includes: the cervical canal, internal uterine orifice, external uterine orifice Vagina and Vestibule The vagina and vestibule are copulatory organs (organs used for sexual intercourse) and are used as the birthing canal. The urethral orifice separates the vagina from the vestibule. The vestibule combines reproductive and urinary functions. The vestibule allows the penis to enter the vagina during sexual intercourse. This is because the vestibule is entered prior to the vagina. The urethral opening is located where the vestibule meets the vagina. Vulva The ventral commissure has a pointed shape. It houses the clitoris and clitoridis. The dorsal commissure has a rounded shape. Placenta The placenta is a temporary organ used for gestation, and it’s structure varies per species. A bitch has a zonary placenta with 3 zones. These zones include: Transfer zone Pigmented zone This is located at either end of the transfer zone. Relatively non-vascular zone Mammary Glands Mammary glands are modified sweat glands that are used for lactation. The number of pairs varies per species. Bitches normally have 5 pairs with 2 being located in the abdominal area, 2 being located in the thoracic area, and 1 being located in the inguinal area. It is important to take into account their lymphatic drainage during surgical removal of tumors. The axillary and superficial lymph nodes drain the mammary glands.