Lecture 4 Flashcards
What are the three chambers in the heart?
The atrium, ventricle and sinus venosus
What is the hepatic portal vein?
Transports substances from the gut to the liver for processing, detoxification and storage
What is the renal portal vein?
Returns from the tail and posterior trunk to the kidneys. Lost in mammals, not well developed in jawless vertebrates
What is the job of the archinephric duct?
Drains urine from kidneys to cloaca. Also used by gnathostomes to transport sperm: vas deferens
What do kidneys do?
Dispose of waste products and regulate water and minerals
Name the three parts of the kidneys
Pronephros, opistonephros and metanephros
Explain the pronephros, opistonephros and metanephros
Pronephros: Functional only in embryos, Opistonephros: forms kidneys in adult fish & amphibians, Metanephros: kidney in adult amniotes & drained by ureter
Describe the general location of gonads
They usually lay on the posterior body wall behind the peritoneum, paired.
Describe the path of the sperm and egg in jawed vertebrates
The sperm exit via the archinephric tubule and the egg is released into the coleom and drawn into an oviduct where its fertilized
What are the vestibular apparatus and the cochlea?
A membranous labyrinth that has balance organs. In tetrapods its the cochlea, responsible for hearing
What is the vestibular apparatus contained within?
The optic capsule
What does the optic capsule contain
The endolymph, a fluid that transmits waves of pressure that stimulates sensory hair cells
What parts of the optic capsules detect which way is up & linear acceleration?
The sacculus and utriculus. They house sensory crystals that contain CaCO3 crystals resting on hair cells, sensations are detected on these
Which part of the optic capsule detect angular acceleration?
The semicircular canals. The ampullae at each end have hair cells embedded in jelly that monitor the displacement of the haemolymph
Describe the evolution of feeding in non-vertebrates
A suspension feeder developed more of a muscular pharynx then cartilage replaced collagen in pharyngeal bars which created a suction to suck in water, squeeze to expell water
Describe the evolution of feeding in agnathans
Exploited muscular pharyngeal pump, would draw sediment inwards. Cilia still transported particles to oesophagus
Describe the evolution of feeding in gnathostomes
Plucking individual foods, increased effort, favoured sudden/forceful expansion of pharyngeal cavity. Elastic recoil system not strong enough for forceful cpature = jaw
What are the primitive features of agnathans/cyclostomes (e.g. hagfish/lamprey)?
No jaws, lack paired fins, no specialized reproductive tracts: coelom - contractions - archinephric duct - external fertilization
Name the features of the agnathans
Only notochord, single nostril linked to olfactory sac, heart has one atrium and one ventricle & pore-like external gill openings
What is the balancing organ in a hagfish and what does it have?
The vestibular apparatus or ear that includes a single semicircular canal. Lampreys have two
What is the osmotic flow like in hagfish and why?
There’s no osmotic flow in or out because the salt concentration in the body fluid is similar to the sea
What are petromyzontiformes?
Lampreys
What kind of fins do lampreys have and lack?
Dorsal fins and lack lateral fins
What is one difference between the hagfish and the lamprey?
The lamprey’s tissues can experimentally produce a mineralised skeleton, the hagfish cannot
How does a lamprey respire?
Using tidal ventilation through seven gill slits. The velum prevents water back-flow into the mouth
What does anadromous mean?
Adults live in large lakes/the sea and swim upstream to spawn
Describe the breeding of lampreys
Both sexes dig out a hole in gravel, female attaches to rock, male attaches to her, eggs are fertilized as they’re produced.
Name the larvae of lampreys and what they do
Ammoecoetes float downstream and burrow in the sediment, water filtering through pharynx & feeding on organic matter. 3-7 years later it emerges and the parasite moves downstream
What is another name for the splanchnocranium and what is it the oldest part of?
The branchial basket, it is the oldest part of the contemporary skull in vertebrates
What structure is crucial to the evolution of jaws in gnathostomes?
Branchial arches
What are myomeres?
Metamerically arranged W-shaped muscles
Describe the digestive system in cyclostomes
A simple, straight tube and no pancreas
What could be considered as the stomach in lampreys?
The liver tissue that surrounds a region of the gut. lampreys have no bileduct.
Describe the liver of a hagfish
Tthey have two lobes and a bile duct that connects them to the gut.
Describe the circulatory system in cyclostomes
Blood is pumped from heart to the gills then caudally in the dorsal aorta to the body. Blood returns to the heart via a simple system of veins
