urogenital system chap

UROGENITAL SYSTEM

Chapter 11

UROGENITAL SYSTEM Combination of excretory and

reproductive system. Kidney is the main excretory organ of

vertebrates.• Concerned with the elimination of metabolic

waste products. Ovary is the female reproductive organ or

gonad. Testis is the male reproductive organ.

• These are concerned with the production of the reproductive cells (egg and sperm).

Ducts are passageways for the excretory waste products and reproductive cells from where they are produced to the outside.

Ducts of excretory and reproductive systems are intimately associated

EXCRETORY SYSTEM

Waste products of metabolism include: urea, ammonia, uric acid, creatinine, various pigments, inorganic salts, and water.

These are excreted through the kidney.

Nephrons are the functional units of the kidney, where the blood is filtered with these metabolic wastes.

Metabolic wastes pass to the outside through ducts.

ARCHINEPHROS/HOLONEPHROS

Excretory organ of primitive vertebrate ancestors.

It is composed of paired archinephric ducts, located on the dorsal side of the body cavity and extending the length of the coelom.

Each duct has a pair of tubules to a segment.

The tubules open into a coelom through the nephrostome.

ARCHINEPHROS

External glomeruli drain the coelomic fluid and are located in close proximity to the nephrostome.

Larvae of hagfish and caecilians have this type of excretory organ.

Tissue fluid discharge from glomerulus >coelom>nephrostomes>tubules>archinephric ducts>to the outside.

THE ANAMNIOTE KIDNEY: PRONEPHROS

1st embryonic tubules in all vertebrates

called pronephric tubules because they are the 1st to develop & are anteriorly located

The duct that drains the pronephros is called the pronephric duct.

The pronephros is temporary & function only until glomeruli & tubules further back become functional.


Some have external glomerulus, while most have internal glomeruli.

Internal glomeruli are small knots of arterial capillaries surrounded by the Bowman’s capsule.

Renal or Malphigian corpuscle is composed of the glomerulus and the Bowman’s capsule


Bloodafferent arterioleglomerulusefferent arteriole postcardinal vein heart

Filtrate of blood plasma-glomeruluscoelom or cavity of the Bowman’s capsuletubulepronephric ductcloaca

Selective reabsorption of water and other constituents may occur as fluid passes down the tubule.


Pronephric tubules function only until the end of the larval stage in amphibians and equivalent stage in fishes.

Glomus is the term for several united glomeruli.

Pronephric chambers are larger chambers formed by expansion of the pronephric tubules.

THE ANAMNIOTE KIDNEY: OPISTHONEPHROS

The kidney mass caudal to pronephric regionFunctional adult kidney of lampreys, most

fishes and amphibiansDrained by mesonephric (archinephric) duct

Mesonephros similar to opisthonephros but mesonephros is the structure that appears during embryonic development in reptiles, birds, and mammals.When it serves as an adult kidney, it is

sometimes called opisthonephros.

FATE OF NEPHROGENIC MESODERM (RED) (BOOK FIGURE 15.8).


It is different from pronephros because it lacks segmental tubules that is exhibited by the pronephros.

Kidney tubules and coelom are rarely connected.

Renal corpuscles with internal glomeruli are typically present.


An opistonephric tubule has a narrow neck adjacent to the renal corpuscle.

Neck is followed by the: collecting

portions, which joins the archinephric duct and;

secretory part, which forms the proximal and distal convoluted tubules. Urogenital organs of male salamander,


Ureter-like duct is formed by the union of collecting ends of several collecting tubules.

This may open into the archinephric duct or may connect independently with the cloaca.


Opisthonephric kidneys of fishes

Males have longer kidneys than females.

Efferent ductules connect the testes with the archinephric duct.

Archinephric duct becomes the ductus deferens which serve for sperm transport.

Female fishes have the posterior ends of their archinephric ducts enter a common urinary sinus inside a small urinary papilla.


Urinary papilla enters the cloaca in sharks.

It opens directly to the outside in fishes without cloaca.

Seminal vesicles and sperm sacs may develop for the temporary storage of spermatozoa.


Opisthonephric kidneys of Anurans

Tubules are more concentrated on the posterior end and are confined to the posterior part of the abdominal cavity.

Dorsally located, retroperitoneal, and dorso-ventrally flattened

Kidneys of the females have no relation to the reproductive system.


Opisthonephric kidneys of Anurans

In males, certain anterior kidney tubules became modified as efferent ductules/vasa efferentia. They connect the testis with

the kidney . Archinephric duct

serves to transport spermatozoa and urine.

Urinary bladder is thin-walled and serve for the temporary storage of urine.

THE AMNIOTE KIDNEY Three types of kidneys

that appear in succession during embryonic development of amniotes are: pronephros, mesonephros, and metanephros.

The metanephros persists to become the adult kidney.

Pronephros appears in the very early stages of development but soon degenerates.

THE AMNIOTE KIDNEY

Mesonephros develops as the embryonic kidney in reptiles, birds, & mammals

It is sometimes called the Wolffian body and the mesonephric duct is called the Wolffian duct.

It functions for a short time after hatching or birth

THE AMNIOTE KIDNEY

Wolffian duct serves as urinary passage but when the metanephros becomes functional, it degenerates in the female, but persists in the male.

Remnants of the mesonephros are associated with the reproductive system. This include the epididymis,

ductus deferens, seminal vesicle, paradidymis, and ductus aberrans in the male.

In females, remnants include the epoophoron and paraoophoron in the dorsal mesentery of the ovary, and canal of Gartner in the mesentery of mammalian oviduct.

THE AMNIOTE KIDNEY: METANEPHROS

Arise posterior to the mesonephros.

Nephron is the functional unit.

Each nephron is composed of renal corpuscles, secretory tubules, and collecting tubules.

Differentiation of metanephros begins when a metanephric bud sprouts from posterior end of the mesonephric duct.

Nephrogenic mesoderm surrounds the bud.

THE AMNIOTE KIDNEY: METANEPHROS

Bud grows anteriorly together with the metanephric blastema, and eventually gives rise to metanephric duct or ureter, and pelvis of the kidney.

Fingerlike outgrowths from the pelvis invade the kidney blastema and become collecting tubules.

S-shaped tubules are organizing within the blastema. One end grows toward and encapsulates a

glomerulus to form a renal corpuscle. The other end grows toward and empties into

a collecting tubule.

THE AMNIOTE KIDNEY

Each kidney tubule of mammals is composed of the following parts:Proximal

convoluted tubuleLoop of Henle

with ascending and descending portions

Distal convoluted tubule.

THE AMNIOTE KIDNEY Capsule is a connective

tissue that surrounds the kidney.

Cortex is the outer kidney substance containing renal corpuscles.

Medulla is the inner substance which contains the loops of Henle and common collecting tubules

Renal pyramids are the conical aggregated loops and collecting tubules.

Renal papilla is a blunt tip of each renal pyramid that project into a funnel-shaped outpocketing, the calyx of the pelvis.

COMPARATIVE ANATOMY OF THE METANEPHROS

Reptiles Kidneys restricted to

the posterior half of the abdominal cavity and confined to the pelvic region.

Generally small and compact, with lobulated surface.

Urogenital system of female sphenodon


Birds Kidneys located in

the pelvic region of the body cavity, with the posterior ends usually united.

Lobed structures with short ureters which open into the cloaca.

Male bird’s urogenital system


Mammalian kidney

Compact, bean-shaped organ attached to the body wall.

Ureter leaves the hilum or hilus.

Hilum is also the part where blood vessels and nerves enter and leave the kidney.

URINARY BLADDER

Embryonic origin: ventral cloacal wall and portion of the allantois.

Function: temporary storage of urine before disposal or voiding

It may serve as a reservoir of water in terrestial vertebrates.

Water, reabsorbed from the bladder results from the action of an andiuretic hormone.

This is important to prevent dehydration. In some lower vertebrates, it may serve as

recovery sites for some ions that are scarce in their niche.

URINARY BLADDER: FISHES

It is an insignificant enlargement of the conjoined posterior ends of the urinary ducts.

Not significant because fishes are immersed in water.

Many marine fishes can extract fresh water from sea water by drinking sea water and quickly excreting the salts.

URINARY BLADDER

Amphibians Large and thin

walled It connects with

the cloaca a short distance beyond the openings of the archinephric ducts.

URINARY BLADDER Crocodilians,

snakes, some lizards, and birds do not have urinary bladder.

Birds Absence in birds

reduces the energy requirements for flight.

Urinary wastes, mainly in the form of uric acid are eliminated via the cloaca along with the feces.

Turtles With a pair of

accessory urinary bladders which is connected with the cloaca, and functions as accessory organs for respiration

These may be filled with water in females, which is used to soften the ground in preparing a nest.

URINARY BLADDER

Mammals Present in all

mammals. It is muscular and

connects to the outside by the urethra

Lower ends of ureters opens directly into the bladder on its posterior dorsal surface.

URINARY BLADDER Much of the muscles of the

bladder continues down into the urethra.

In males, the urethra is longer and passes through the penis and open at the tip through the external urethral orifice or meatus.

Female rats and mice have their urethra that opens independently to the outside, passing through the clitoris.

In other mammals, the urethra enters a urogenital sinus or vestibule.

EFFECT OF ENVIRONMENT ON KIDNEY STRUCTURE AND FUNCTION

Kidney is not only involved in waste elimination but also involved in the maintenance of water balance in the body.

Regulates the amount of water given off in the urine and controls the amount of salts and other electrolytes eliminated through the urine.

Vertebrate kidneys have adaptations to their environments

Size of glomeruli is related to the amount of filtrate removed from the blood.

Larger glomeruli indicates an increase of filtrate moving out from the blood into the kidney tubules.


Terrestial forms have reduced glomeruli.

Marine teleosts do not have glomeruli in their kidneys.


Kidney tubules vary among vertebrates but all have proximal convoluted tubule

Aglomerular kidneys of marine teleosts have their proximal convoluted tubule as the only functional, but their urine does not differ from the urine of fishes with glomeruli.

The distal convoluted tubule is involved in ionic and water reabsorption.

Amphibians have a degree of selective reabsorption in their distal convoluted tubule.

Reptiles, birds, and mammals have tubules in their kidneys but their development depends on the amount of water available to the animal.


In desert forms, the distal convoluted tubules are very long and are capable of resorbing nearly all water, so they have a very concentrated urine.

Animals which are accessible to water sources have shorter tubules and their urine is less concentrated.

EXTRARENAL SALT EXCRETION

Present in vertebrates that live in salt-rich environment or that live in arid environments.

Chloride-secreting glands are present on the gills of marine fishes.

Rectal glands are present in elasmobranchs.

Nasal or orbital glands are present in marine reptiles and birds that feed on fish from salt water.

Sweat glands in mammals eliminate some salt of the body.

REPRODUCTIVE SYSTEM

Vertebrates exhibit sexual reproduction.

Zygote results from the union of male and female gametes.

Ova and spermatozoa are produced in the gonads, the testes and ovaries respectively.

Gonads are derived from the mesoderm.

Deferent ducts in male, and oviducts in female transport gametes to the outside of the body.

REPRODUCTIVE SYSTEM

Deferent ducts are usually the archinephric or the Wolffian ducts which also transport urine from the kidney.

Wolffian ducts in amniotes persists to become the ductus deferens.

Accessory sex organs bring the germ cells together.Reproductive ductsAssociated glads Intromittent or copulatory organs.

FEMALE REPRODUCTIVE SYSTEM

OVARY Two layer of a typical ovary

in mammals are:1. cortex, outer with

developing Graafian follicles.- ovum with each follicle is nourished by follicular cells.- at maturity, certain follicles push to the surface of the ovary and either rupture to liberate the ovum (ovulation), or are reabsorbed.

2. medulla, which is inner and made up of connective tissue, blood vessels, lymphatic vessels, smooth muscle, and nerve fibers.

OVARY

Ovarian follicles vary in size depending upon the season when it is examined and upon the volume characteristic of each species.

Larger ova in lower forms because of their yolk content.

Ovary attains maximum size during the breeding season in some vertebrates

OVARY: FISHES

Paired or fused. Only the right ovary

fully develops and the left degenerates in some elasmobranchs.

Most teleosts have saccular type ovaries which produce large number of ova during the breeding season. Ripe ova-->central

ovarian cavity--->oviduct--->outside

Adult teleosts lack cloaca and have separate openings from urinary and digestive systems.

OVARY: FISHES

Most are oviparous while others are ovoviviparous.

Some have fertilized eggs that develop while inside the ovarian follicles

Others have their young that develop within the cavities of the ovaries.

OVARY: AMPHIBIAN

Saccular Ova escape into

the coelom through their external walls.

Shape varies with the shape of the body.

Fat bodies are closely associated with the ovaries.

OVARY: REPTILES Snakes and

lizards’ ovaries are saccular and elongated.

Turtles and crocodilians have solid ovaries.

Certain ovoviviparous snakes and lizards have corpora lutea that form from ruptured follicles after ovulation.

OVARY: BIRDS

Both ovaries are present in embryonic development.

In most birds, the right ovary degenerates, and the left becomes the functional gonad.

Stigma or cicatrix is a band located on the surface of the follicle through which mature ova escape from the ovarian follicles into the coelom.

MAMMALIAN OVARIES

Located in the lumbar or pelvic region.

Considered small in relation to the size of the body of mammals.

Placental mammals have compact ovaries with an antrum within the graafian follicles.

Covered by germinal epithelium from which oocytes arise.

Some of this oocytes become mature ova during the life of the individual.

MAMMALIAN OVARIES

Ovum escape the ovary when the wall of graafian follicle ruptures.

Cells that remain after follicle rupture organize to form corpus luteum.

Corpus luteum is one source of progesterone needed to maintain pregnancy.

Before ovulation, estrogen is the predominant secretory products of the follicle cells.

Atretic follicles are those that fail to rupture and degenerate.

OVIDUCTS

Modifications of the Mullerian ducts, which degenerates in the males.

Differentiates into regions .

Posterior portion expands to become the uterus.

Serves as temporary storage site for eggs or a place where the young develops.

OVIDUCTS: FISHES Some teleosts have

modified abdominal pores where eggs escape from the coelom.

Elasmobranchs have ostium tubae, which opens into the coelom.

Narrow distensible oviduct on either side.

Shell gland is an enlargement of the oviduct.

Beyond the shell gland is the uterus that opens into the cloaca.

Ovisac shelters and nourishes the embryo in viviparous species.

OVIDUCTS: AMPHIBIANS

Paired, elongated tubes with ostia.

Enlarged posteriorly to form a short uterus or uterine enlargement .

Uterus opens independently into the cloaca.

Uteri in most amphibians serve for temporary storage for ova.

Lining of the oviducts have glands that secrete jellylike material to envelop the passing eggs.

Fertilization is external Male grasp the female in

amplexus.

OVIDUCTS: REPTILES Open into the coelom through slit-like ostia. Turtles and crocodilians have glands in the upper part

that secrete albumen. Shell is deposited in the uterus or shell gland in snakes

and lizards. Uteri enter cloaca independently. Fertilization occurs in the upper part. Some snakes and lizards are oviparous. Other reptiles are ovoviviparous.

OVIDUCTS: BIRDS

Most except birds of prey have only the left oviduct that is functional.

Long, coiled, and consists of several regions.

Ostium is bordered by fimbriae.

Albumen is secreted by the glandular portion.

Isthmus is found posterior to the glandular portion where inner and outer shell membranes are deposited around the albumen.

Oviduct of a laying hen1 Infundibulum, 2 Magnum, 3 Isthmus, 4 Shell Gland, 5 Uterus with egg

inside

OVIDUCTS: BIRDS

Uterus or shell gland is where the hard calcareous shell of the egg is formed.

Uterus opens into cloaca.

Fertilization is internal and accomplished by cloacal kiss.

OVIDUCTS: MAMMALS Paired, with various

degrees of fusion between the two sides.

Three distinct regions in some: narrow oviduct or fallopian tube, the expanded uterus, and a terminal vagina.

Cervix is the narrow lower part of the uterus which leads into the vagina.

Opening of the uterus into the vagina is called os uteri

OVIDUCTS: MAMMALS

Marsupials have paired duplex uteri and paired vaginae.

OVIDUCTS: MAMMALS

Other placental mammals have horns of the uterus, uterine body, and a single vagina.

Uterus are classified:1. Bipartite when there

are two complete lumens within the body of the uterus.

2. Bicornuate uterus has a single lumen within the body and with two horns

3. Simplex, has no uterine horns, and the vagina opens directly into the body.

OVIDUCTS: MAMMALS Body of simplex uterus is

where the fetus become implanted.

Uterine wall is made up of:1. Endometrium – uterine

lining which becomes highly vascular under the stimulus of hormones.

2. Myometrium – thick muscular layer

3. Visceral peritoneum – thin outer serous membrane.

- Menstruation results from degeneration or sloughing of the uterine lining followed by hemorrhage from blood vessels.

- Estrogen and progesterone control these endometrial changes.

OVIDUCTS: MAMMALS Vagina is the fused

terminal portion of the mullerian ducts.

It opens into a urogenital sinus.

Higher primates’ vagina extends almost to the exterior, opening into a shallow vestibule.

Lining of vagina is cornified for reception of the penis.

Marsupials have a median vagina which continue as paired lateral vaginae.

Penis of male marsupials is forked at the tip.

MALE REPRODUCTIVE SYSTEM

Scrotum • A sac containing the

testes • Intrascrotal

temperature is kept constant by two sets of muscles:

• Dartos: smooth muscle that wrinkles scrotal skin

• Cremaster: bands of skeletal muscle that elevate the testes

Functions of the male reproductive system are:

Production of sperm cells

Sustaining and transfer of the sperm cells to the female

Production of male sex hormones

Testes Seminiferous

tubules “sperm factories”:

Produce the sperm

Mature spermatozoa will move to the rete testis efferent ductules epididymis ductus deferens

Also an endocrine gland as they produce testosterone

ELASMOBRANCHS’ TESTES

Paired symmetrical structures

Suspended by mesorchium

Other fishes have elongated and lobulated testes.

AMPHIBIAN TESTES

Shape corresponds to body shape

Elongated in caecilians, short or irregular in urodeles

Oval or rounded and more compact in anurans

REPTILES’ TESTES

Oval rounded or pyriform compact structures Snakes’ and lizards testes’ have onetestes that

occupies farther forward in the body cavity than the other

BIRDS’ TESTES

Oval or round-shaped and changes in size depending on the period of the year.

MAMMALIAN TESTES

Tunica albuginea a thin tough fibrous envelop of the testis

Scrotum serves to regulate the temperature ideal for the testes to be able to produce viable sperm cells

Vaginal sac is a diverticulum of the peritoneum into the scrotum

Tunica vaginalis is the extension from vaginal sac that comes in close contact with the tunica albuginea

.

MAMMALIAN TESTES

Maybe found in the pelvic region or descend into a scrotum

Some mammals’ testes descend into the scrotum only during the breeding season

inguinal canal - passage between abdominal cavity & scrotum

SPERMATOZOA

Vary in vertebrates and are several times smaller than the ova

All possess tails for locomotion

Number produced by the human male is about 4ml or 300 million per ejaculation

Boar produces about ½ liter

MALE GENITAL DUCTS

Some fishes (e.g., gar & sturgeon) & amphibians - mesonephric duct transmits sperm & urine

Some amphibians - mesonephric duct transports only sperm; new accessory urinary duct drains the kidney

MALE GENITAL DUCTS Sharks - mesonephric

duct is used primarily for sperm transport; accessory urinary duct develops

Teleosts - mesonephric duct drains kidney; separate sperm duct develops

Amniotes - embryonic mesonephric ducts transport sperm in adults

1.Testis / testicles (present as a pair)

2. Ductus epididymidis (a pair)

3.Deferent duct / Vas deferens (a pair)

4. Ampulla of the deferent duct (a pair)

5. Glandula vesiculosa / Seminal gland(a pair)

6. Ejaculatory duct (a pair)

7. Prostate (single)

8. excretory duct of the prostate(several present)

9. Bulbourethral gland (Cowper's glands) (a pair)

10. Urethral gland (Littre's gland)(several)

11. Urethra (single)

12. Urinary bladder(single)

COPULATORY ORGANS/INTROMITTENT ORGANS

Found in vertebrates that practice internal fertilization

Used for introducing sperm into the female reproductive duct

cartilaginous fish - appendages of pelvic fins called claspers direct sperm into female reproductive tract


snakes & lizards - have pair of HEMIPENES (pocketlike diverticula of wall of cloaca)

turtles, crocodilians, a few birds, & mammals - exhibit an unpaired erectile penis


penis - usually a thickening of floor of cloaca consisting of spongy erectile tissue (corpus spongiosum) with grooves to direct sperm & ending in a glans penis (sensory endings that reflexly stimulate ejaculation)

mammals (except monotremes) - penis extends beyond body

The embryonic corpus spongiosum becomes a tube with urethra inside & 2 additional erectile masses develop (corpus cavernosa).

END …QUIZ/RECITATION NEXT…

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urogenital system chap

Education

anamniote kidney

kidney tubules andcoelom

testis withthe kidney

kidney mass caudal

glomeruli tubules

embryonic tubules

distalconvoluted tubules

opisthonephros ureter