Presentation on theme: "The Urinary System This system includes the organs that produce and excrete the waste substance urine. These organs are: *kidneys *ureters *bladder *urethra."— Presentation transcript:
The Urinary System This system includes the organs that produce and excrete the waste substance urine. These organs are: *kidneys *ureters *bladder *urethra
The Kidneys (nephro or reno) These are bean shaped organs located on both sides of the vertebral column. Kidneys are retroperitoneal: situated outside the peritoneal cavity. Renal fasciae surrounds the kidneys, holding them in place. Each kidney has a concave depression (hilus) on it’s medial margin. This provides entrance for blood vessels, nerves and the ureter
The kidneys are dark reddish brown (except feline which are yellowish red). A cross section shows the external cortex and the internal medulla
The renal sinus contains the renal pelvis, blood vessels and fat. The renal pelvis is a funnel shaped reservoir that occupies most of the sinus. Passing out of the sinus is the ureter, the outlet tube that extends to the bladder
Medullary pyramids make up the medulla, stud the walls of the renal sinus. Urine collects through ducts
The nephron is the functional unit of the kidney, consisting of the renal corpuscle and the renal tubule. There are about 1 million nephrons I the kidney
The renal corpuscle consists of a double walled cup shaped structure called the glomerular or Bowman’s capsule, which contains a twisted cluster of capillary channels called the glomerulus
Kidney functions as a filter for waste products from the blood and excretes them in the urine. These waste products include: *nitrogenous waste from the breakdown of proteins, toxic substances, mineral salts, excess glucose and water.
Video the urinary system Video the anatomy of the kidney
The speed that the blood filters through the kidneys is affected by the blood pressure. If systemic blood pressure drops, as in shock, it may cause blood filtration to slow to a point to where the kidneys stop functioning. If the blood pressure is too high, kidney damage may result
The kidneys affect the rate of secretion of some hormones, synthesize other hormones and maintain the pH of the blood so it remains neutral.
The Ureters These are muscular tubes extending from the renal pelvis of the kidneys. The walls of the ureters are made up of an outer fibrous tissue layer, two central layers of smooth muscle and a mucous membrane lining.
The ureters enter the neck of the bladder at the trigone. The ureters enter the bladder obliquely, the flow of urine back to the kidney is effectively controlled by a natural valve
Urine enters the bladder on average of every 10 to 30 seconds in spurts, rather than a continuous flow. These spurts are produced by peristaltic waves. At the bladder entrance there is is a ureteral opening that opens every 2 – 3 seconds, then it closes until another peristaltic wave open it again. This prevents urine from flowing back into the ureters during bladder contraction
The Urinary Bladder This is an elastic sac lying in the pelvis.. It is formed of three layers of smooth muscle lines with mucous membrane. The size and position depends on how much urine it contains. It has two openings to receive urine from the ureters and another opening into the urethra
The neck of the bladder, uniting with the urethra contains a sphincter muscle that controls the amount of urine into the urethra. The bladder has two main functions: *to store urine *to excrete urine
The voiding of urine from the bladder is called micturition. The act of preventing or concluding urination is a learned and voluntary action in more intelligent forms of animal life
The urethra is a membranous tubular canal that carries urine from the bladder to the exterior of the body. In the female the urethra length varies by species. The exterior opening of the urethra is called the urinary meatus
In the female the urinary meatus is located between the vagina and the clitoris directly cranial to the vulva. The only function of the urethra is urination.
The male urethra varies in length by species and penile structure. It is narrower than the female and this makes the male more prone to blockages from urolithiasis. (stone formation) It extends from the neck of the bladder through the accessory sex glands, between the fascia and through the penis.
The male urethra is divided in to three sections. *prostatic *membranous *cavernous. The exterior opening is also clled the urinary meatus and serves a dual function, carrying both urine and reproductive secretions
Normal Urine: Urine in most species is clear, pale amber with a characteristic odor. Urine is approx 95% water containing dissolved substances such as nitrogenous waste, electrolytes, toxins, pigments, hormones, and abnormal substances like glucose, albumin or blood
The average urine output in a 24 hour period varies by: *species *temperature *water intake *type of work animal is performing
Male Reproductive Organs: The basic male reproductive organs (gonads) are the testes. The ducts are the epididymides, vas deferentia, ejaculatory ducts and urethra. The accessory sex glands (not present in all species) include the seminal vesicles, prostate, bulbourethral and coagulating glands. The penis, scotum and spermatic cord are the primary structures
The Testes: A pair of egg shaped glands normally located in a sac like structure called the scotum. The size shape and location vary depending on the species. Each testicle is enclosed in a fibrous, white capsule called the tunica albuginea.
The interior of the testicle is divided into compartments each containing a mass of coiled seminiferous tubules and interstitial cells (cells of Leydig), which join into a cluster and enter the head of the epididymis.
The testes have two functions: *producing spermatozoa *secreting hormones the sperm cells are produced by the seminiferous tubules. The primary hormone, testosterone, is secreted by the cells of Leydig.
Testosterone has several functions: *induces and maintains male secondary sex characteristics such as massive head and shoulders, crest of withers, tusks on boars and horns on rams. It also influences muscle and bone growth
Male animals generally have less subcutaneous fat and the meat is less tender and juicy. Castration is performed on all animals intended for meat production to eliminate accumulation of testosterone after maturity.
Testosterone also has an influence on fluid and electrolyte metabolism as well as as an excitatory effect on the kidney tubule and suppresses anterior pituitary secretions
Epididymus: a pair of tightly coiled tube like structures. They act as a place for sperm to mature, store sperm before ejaculation and they secrete a small portion of the seminal fluid
Vas Deferens: a pair of muscular tubes with diameters that vary by species. They are the continuation of the tail of the epididymis and runs through the inguinal canal. Each epididymis is encased in the spermatic cord. Then they travel to the bladder and connect with the seminal vesicle and form the ejaculatory duct. The vas deferens moves sperm from the tail of the epididymis to the ejaculatory duct
Ejaculatory ducts: two short tubes formed by the joining of the vas deferens with the ducts of the seminal vesicles. They pass through the prostate gland and extend to the urethra
Vesicular glands (seminal vesicles, term used in stallions): two twisted pouches lying along the dorsal and caudle surface of the bladder, ventral to the rectum. They are lacking in the dog and cat. They secrete the mucid, liquid part of the semen
Prostate gland: smooth muscle and glandular tissue. It secretes a viscous, alkaline substance that makes up most of the seminal fluid. The alkalinity protects the sperm.
Spermatic cords: White fibrous tissue encasing the vas deferens, blood and lymph vessels and nerves
Scrotum: saclike structure that houses the testicles. It is separated internally by the scrotal septum. The scrotum regulates the temperature of the testicles
Penis: made up of three rounded masses of erectile tissue encased in a fibrous capsule. The penis contains the urethra which carries both reproductive secretions and urine
Female reproductive organs: The ovaries: located caudle to the kidneys. Each ovary is connected to the uterus by a ligament. A single layer of cells forms the ovarian surface. The interior consists of a network of connective tissue where the follicles are embedded, and these contain the ova.
The functions of the ovaries are ovulation and hormonal secretion (estrogen and progesterone) Estrogen induces female characteristics and uterine preparation. Progesterone prepares the uterus to receive the fertilized ovum
Fallopian tubes (ovaducts): consist of an inner ciliated mucous membrane layer, a middle smooth muscle layer and outer layer of serous tissue. This acts as ducts to the uterus for the ova. Fertilization usually takes place in the fallopian tubes
Uterus (metro, hystero): This is thick walled hollow organ. It is made up of the body (corpus), the cervix (neck), and two horns (cornus) The walls are made of three layers * endometrium (inner) myometrium (middle) perimetrium (external) The perimetrium is continuous with a band of the peritoneum known as the broad ligament.
The uterus has several functions: * prepares for the acceptance of the fetus * develops specialized structures for attachment of placenta * produces uterine milk to nourish the embryo before implantation * maintains and supports developing fetus * contracts to move fetus into birth canal
The Cervix: Composed of smooth muscle arranged in a ring like structure called a sphincter. It prevents foreign bodies from entering the uterus during gestation. It is usually tighly closed exceot during estrus when it relaxes to allow sperm to enter. During pregnancy the cervix is filled with a mucous plug.
The Vagina: an elastic tube lined with a mucous membrane. Before sexual maturity the external vaginal orifice may be occluded by a fold of mucous membrane called the hymen. The vagina acts as a sheath to accept the penis during copulation and provides passage for uterine secretions and the neonate during pregnancy
The Vulva: The vulva consists of the vaginal orifice, vestibular glands, clitoris, hymen, and the urethral orifice.
Mammary Glands: These are milk producing glands composed of connective and adipose tissue. The milk secreting cells (alveoli), these form larger ducts called the udder cistern. This transports milk to the base of the teat. Milk production is stimulated by the lactogenic hormone prolactin. The emptying of milk secreting tissue is caused by the hormone oxytocin.
The estrous cycle: The purpose of the estrous cycle is to prepare the uterus to receive a fertilized ovum. At the beginning of the cycle, ova within the follicles in the ovaries begin to develop. They will continue to develop until they reach ripened follicle size (graafian follicle). One or more of the graafian follicles rupture and the ovary is expelled
Ovuation usually occurs during estrus. The ruptured follicle grows larger and fills with a yellow lipoid material and becomes the corpus luteum. The corpus luteum secretes progesterone. If fertilization occurs, the corpus luteum continues to secrete progesterone and prevent future estrous cycles during pregnancy.
If fertilization does not take place the corpus luteum and its secretions deminish forming a corpus albicans.
The Stages of Estrus: The estrus cycle is divided into four phases *proestrus *estrus *metestrus *diestrus and in some species *anestrus
Proestrus this is the building up phase. During this phase, follicle stimulating hormone (FSH) is secreted by the pituitary gland and causes the follicle to develop within the ovary. FSH stimulates the ovary to release increased amounts of estrogen which causes changes to the vagina, uterus, oviducts and ovaries.
Estrus This is the period of sexual receptivity. Ovulation occurs during this phase and in some cases right after this phase. FSH levels decrease and luteinizing hormone (LH) increases causing the ripened follicle to rupture
Metestrus this is the postovulatory phase. During this phase the corpus luteum forms and produces progesterone. Amounts of estrus decrease. Progesterone is responsible for proper implantation and maintaining pregnancy. If pregnancy does not occur the corpus luteum decreases in size to a corpus albicans. The cycle continues metestrus will be followed by pregnancy, false pregnancy, diestrus, anestrus.
Diestrus and Anestrus Diestrus is a short inactive phase before the onset of the next proestrus in polyestrus animals Anestrus is a period of sexual inactivity. Canines are in estrus twice a year and have long periods of anestrus between cycles
Pregnancy: This is the period between conception and parturition. After fertilization, the ova moves from the uterine tube to the uterus. Until implantation the organism is called an embryo. After implantation the organism is called a fetus. The placenta is the only connection between the dam and the fetus.
Gestation periods vary: bovine: 280 days equine: 336 days caprine, ovine: 150 days porcine: 114 days canine and feline: 63 days