Embryonic Development Part II Flashcards
What does the development of a digestive tract enable?
specialization of gut regions
what does the stomach do?
it stores food until it can be readily processed
- disinfects food
what does the intestine do?
breaks down the food
What does the development of a digestive tract enable?
Sequential food processing
What does the development of a digestive tract enable?
continuous operation
What’s the gizzard?
muscular structure that grinds food particles
How do cows eat their food?
they regurgitate their food and chew it some more and make it more processable and then food gets swallowed again and is in the omasum
what does the omasum do?
takes in a lot of water and minerals from the food
what odes the abomasum do?
disinefcts the food with hydrochloric acid - like our stomach
what does the intestine of a cow do?
secretes enzymes and process all of the molecules
what’s the digestive system of a rabbit?
rabbit eats the food –> stomach –> small intenstine but not much can happen here since the cellulose is in the way –> large intestine: water extraction –> cecum: corresponds to our appendix - lots of microorganisms: break down of cellulose –> gut –> produces two types of poop
what are the two types of poop rabbits produce?
- soft poop with the goodies and then they eat it…
2. poop with all the waste
What are the two ways a digestive tract develops in bilateria?
Protosomes
- 1st is mouth
- blastopore –> mouth
- new opening –> anus
What are the two ways a digestive tract develops in bilateria?
Dueterostomes
- humans
- 2nd is mouth
- blastopore –> anus
- new opening –> mouth
What are the tree different body plans with respect to body cavities?
- coelomate
- pseduocoelomate
- acoelomate
Coelomate
mesoderm lines the entire cavity as a “peritoneum”
Pseudocoelomate
“false colem”
- the mesoderm lines the outside of psedocoel
Acoelomate
- no body cavity
- solid except digestive space
- flat organisms (not much in terms of organs)
What the two ways to make a coelom
- schinzocoely
2. enterocoely
schinzocoely
splitting with the mesoderm
- protosomes
enterocoely
mesoderm forms pockets from the gut
-deuterostomes
LOPHOphore
ciliated feeding gas exchange strucutre
TROCHOphore
a ciliated free living larval form
what kind of animals are Endysozoans
moulting animals
how do animals moult?
they have an external covering secreted by the epidermis that must be shed in order to grow
when are endysozoans vulnerable?
directly after moulting
when did moulting evolve?
more than 500 million years ago
how does moulting work?
- they inflate and are soft
- then they harden and replace air space inside the body (grow mass but don’t grow in size)
- adults stop moulting and stop growing
are worms a monophyletic group?
nope
Nematoda are also known as
roundworms
characteristics of nematoda?
- multi-layered
- flexible cuticle
- allows diffusion of gases
- must live in moist habitat
how do nematodas move?
move by trashing - snake like movements
body cavity of a nematoda is filled with
fluid
what kind of skeleton do nematoda’s have?
hydrostatic
what systems do nematoda’s NOT have
respiratory and circulatory
how many species of nematoda are there?
25,000
what is the major model organism of genetics, developmental biologists and neurobiologists
C. elegans
the largest nematode is
9 m long
where is the hookworm common ?
in tropics and subtropics
Earthworms convert dead organic matter into what?
mature compost
how do earthworms provide a rich natural fertilizer?
by concentrating nutrients in their waste
annelida are known as
segmented worms
why is segmentation advantageous?
multiple copies of organs, structures
why is segmentation advantageous?
efficient nervous control
- ganglion in each segment
- faster responses
why is segmentation advantageous?
increases body size by unit repetition
Each segment has…
- longitudinal and circular muscles
- coelomic space (hydrostatic skeleton)
how do circular muscles contract?
coelomic fluid trapped in each segment –> anterior ends elongate
longitudinal muscles contract when
the posterior ends is brought forward
Annelids have ___ brains
anterior
the circulatory system of annelid’s are
closed
what are the two types of blood vessels in annelids?
dorsal and ventral
what are the advantages of a circulatory system?
improved exchange between
- deeper tissues and surface
- gut and muscles (nutrient delivery)
what are the advantages of a circulatory system?
permits development of a thicker body (free of diffusion limit)
what is the largest group of annelids?
polychaeta
polychaeta means
many hairs
clitellata are
oligochaeta - “few hairs”
are polychaeta mainly marine or terrestrial
marine
are oligcohaeta mainly marine or terrestrial?
terrestrial
both polychaeta and oligcohaeta are
detrivores
oligcohaeta are h…
hermaphroditic
Hirudinea live mainly in
freshwater
hirudinea are
parasitic and carnivours
do hirudinea have setae?
noe
hirudinea are also …
hermaphroditic
an example of a hirudinea are
leeches
