Lecture 18 Flashcards
Urogenital System (2 components):
- Excretory system
- Reproductive system
Urogenital System (Excretory System) (3):
- Removes nitrogenous wastes (ammonia, urea, or uric acid) and other harmful substances
- Controls osmosid to achieve water and salt balance
- Organs involved: kidneys, gills, skin, part of the digestive system, salt glands
Urogenital System (Reproductive System) (2):
- Produce and release gametes, bring them together, provide nourishment to young
- Organs involved: gonads, dict, cloaca, copulatory organs
Developmental Origin of Kidneys (General) (3):
- Development moves in sequence from anterior to posterior in three secretions with breaks in between them
- More anterior regions usually degenerate as posterior regions become functional
- More posterior break may not form so that two instead of three pairs of kidneys are formed in sequence
Pronephors General (5):
- Segmented, usually first 4 segments
- Drained by pronepgric duct
- Appears in all vertebrates (rudimentary form), but degenerated quickly
- Functional in fiah larvae, adult hagfish and some teleosts
- In most teleosts degenerates into ‘head kidney’
Opisthonephros/Mesonephros General (4):
- Reduced segmentation
- Drained by opisthonephric or mesonephric duct
- In late larval and adult anamniotes (fishes and amphibians), all or most of the mesomere posterior to pronephros forms one kidney (opisthonephros)
- Among amniotes, the middle part of the nephrogenic cord, the mesonephros, develops first, is present in fetuses, and then degenerates
Metanephros Overview (5):
- Never segmented
- Kidney of adult amniotes
- Most posterior part of nephrogenic cord that replaces mesonephros in development
- Old mesonephric duct degenerates in female but persists in males to carry sperm –> vas deferens
- Metanephric kidney is drained by a new duct (ureter)
Nephron Components:
- Renal corpiscle
- Nephric (renal) tubule
Functional Units of the Kidney - Nephron (2):
- Glomerulus = cluster of capillaries (externall or internal)
- Renal or Bowman’s capsule = cup-like sack that collects nitrogenous waste
Variations in Kidney Structure:
Kidney structure across vertebrates depends on the osmoregularatory challenges of different environments and the type of nitrogenous waste produced
Variations in Kidney Structure - Terrestrial Environmental Challenges:
Water loss through skin and lungs –> dehydrating environment
Variations in Kidney Structure - Freshwater Environmental Challenges:
Water uptake, salt loss through skin and gills
Variations in Kidney Structure - Saltwater Environmental Challenges:
water loss, salt uptake through skin and gills
Gonads (General):
- Develop from two sources in the embryo
- Mesomere genital ridges: become supporting tissues of gonads
- Primordial germ cells - become gametes, arise from endoderm and migrate to genital ridge early in development
Principle Urogenital Ducts (4):
- Nephric ducts (pro, meso, opistho)
- Muellerian ducts
- Ureter
- Accessory ducts
Do Cyclostomes Have Sexual Ducts?
- No
- Eggs and sperm released directly into coelom (body cavity) and exit into cloaca by way of genital pores
Variations of the duct system among groups are the results of:
The retention, loss of modification of the fetal structures
Male Ducts - Sharks and Amphibians (2):
- Nephric ducts (vas deferens) carry sperm
- Accessory urinary duct carries waste
Male Ducts - Teleosts:
- Nephric ducts (opisthonephric duct) carry waste
- Testicular duct carries sperm
Male Ducts - Amniotes:
- Nephric ducts (vas deferens) cary sperm, ureter carries waste
Female Ducts - Sharks and Amphibians:
- Opisthonephric ducts carry waste
- Oviduct (Mullerian) carries ova
Female Ducts - Teleosts:
- Opisthonephric ducts carry waste
- ovarian duct (ovarian folding) carries ova
Female Ducts - Amniotes:
- Ureter carries waste
- Oviduct (Muellerian) carries ova
Reproductive Strategies of Vertebrates - Different Types (3):
- Oviparity
- Ovovivparity
- Viviparity
Reproductive Strategies of Vertebrates - Oviparity:
Eggs laid with little or no maternal development
Reproductive Strategies of Vertebrates - Ovovivparity:
Embryos develop inside eggs within mother
Reproductive Strategies of Vertebrates - Viviparity:
Development of live embryo inside mother
Shark / Chondrichthyan Reproductive Strategies (female and males (4):
- Fertilization generally internal
- Male specializations - pelvic fin specialized into claspers (inserted into female during copulation; sperm runs down groove into female cloaca)
- Femal Specializations - nidamental (shell) gland responsible for sperm storage, oocyte fertilization and egg formation
- Some oviparous (lay an egg capsule called a mermaid’s purse), some ovovivparous (eggs develop internally, give birth to live young)
Teleost Reproductive Strategies:
- fertilization generally external (broadcast spawners)
- Male specializations –> in the few species where fertilization is internal, the male anal fin is specialized into a gonopodium (grooved intromittent organ)
Female specializations –> ovaries often fuse or only one is functional (or fails to develop)
Amphibian Reproductive Strategies:
- External fertilization, internal in some salamanders via spermatophores
- males specializations –> many male frogs have modifications for amplexus (grasping female during courtship) such as enlarged toe pads; tailed frogs possess tail-like extension of the cloaca for internal sperm transfer
- Femals specializations –> some female salamanders have a spermatheca to store sperm
Reptile Reproductive Strategies:
- Fertilization is internal via cloacal contact or intromittent organ (penis or hemipenes)
- Eggs typically laid on land, sex of embryos often dependent on environment temp
- Male specializations –> turtles and crocodiles possess hemipenes (in both cases, can be retracted into the body by muscles)
- Female specializations –> females of some species are parthenogenic
Avain Reproductive Strategies:
- Fertilization is internal via cloacal contact, rarely through intomittent organ (penis) (oviparous)
- Reproductive organs for both sexes decrease in size dramatically outside breeding season (adaptation for flight)
- Male specializations –> some species display cloacal (penile) swelling, others have elaborate spiraled penis
- Female specializations –> many possess sprem storage tubules for delayed fertilization; typically have a single ovary; shell gland for eggshell formation
Reproductive strategies - Placental Mammals:
- Fertilization is internal (placental viviparity)
- Male specializations –> baculum (penis bone) present in most placental mammals; penis compared of erectile tissue (blood sinusoids) separated by sheets of connective tissue (trabeculae)
- Female specializations –> absence of epipubic bone allows expansion of abdomen during pregnancy; pelvis widening to allow birth; duplex (two separate), bipartite (two fused at cervix), bicornuate (two fused) or simplex (single) uterus for development of fetus along with placenta
