cestoda pt.1 Flashcards
(39 cards)
Phylum Platyhelminthes
- is aka
- greek word
- flatworms
in greek:
Platy - flat
helminth - worm
briefly describe the general characteristics of phylum Platyhelminthes
multicellular (metazoan - animal made up of many cells)
dorsoventrally flattened
- looks like scotch tape; leaf like; ribbon like
- flat from top to bottom
bilaterally symmetrical
- bilateral means their body can be divided into 2 equal halves
3 body layers
- ectoderm
- mesoderm
- endoderm
acoelomate
- lacking in organ known as coelom, the true body cavity of worms
no circulatory or respiratory system
incomplete digestive system
- has mouth, no anus
complicated and highly elaborated sexual organs
- hermaphroditic
how many host can the Phylum Platyhelminthes involve
only 1 = single obligatory host
2 or more = consecutive hosts
- before moving to the definitive/ final host
[hey can have either just 1 host or more than 2, depending on their life cycle]
the true body cavity of worms
coelom
- the Phylum Platyhelminthes lack in that organ = acoelomate
3 important classes of flatworms
Class Turbellaria
- [free living flatworms = do not live inside a host]
Class Trematoda
- [unsegmented and having suckers]
Class Cestoda
- [long, segmented, and living in the intestines]
it is classified as parasitic flatworms
Class Cestoda
under the platyhelminthes, there are 2 types of flatworms:
free- living [live on their own, usually in water]
parasitic [live inside other animals]
what is the reproductive system of the class cestoda
Hermaphroditic adult worms (monoecious)
- each worm has both male and female organs (can reproduce on its own)
briefly explain the cestode body structure
Shape:
Long, flat, and ribbon-like
Three Main Parts:
1. Scolex
– head part
- Neck
– where new body segments form - Strobila
– composed of multiple proglottids
true or false:
cestodes has no digestive tract
true - absorbs nutrients directly from the host
it is the organ responsible for the absorption of nutrients and excretion of waste products
tegument
- non ciliated (no hair like structures)
- helps in:
absorbing nutrient from the hosts
excrete waste products
briefly explain the 2 medically important orders of class cestoda
- scolex (head)
- attachment organ
- scolex type
- genital pore location
- found in humans
Order Pseudophyllidea (P)
Order Cyclophyllidea (C)
scolex (head):
P: Spatulate (spoon-shaped)
C: Quadrate (square-shaped)
attachment organ:
P: Has bothria (grooves that help them attach)
C: Has 4 suckers and sometimes a rostellum (tip) with hooks or spines
scolex type:
P: Unarmed (no hooks)
C: Can be armed (with hooks/spines)
genital pore location:
P: In the middle underside (midventral)
C: On the sides (lateral)
found in humans:
P: Belong to Superfamily Bothriocephaloidea
C: Belong to Superfamily Taeniodea
[Pseudophyllidea = Spoon-head, no hooks, grooves to hold on, pore in the middle
Cyclophyllidea = Square-head, often with hooks, 4 suckers, pores on the sides]
common name of cestodes
tapeworms
what are the 3 main regions of the body
Scolex
- plural form: scolices
- “head”
- equipped w hold-fast organs such as suckers, grooves, hooks, spines, glands, tentacles
Neck
- unsegmented
- between the scolex and strobila
- posterior to scolex
Strobila
- multiple segments of proglottids
- unique structure among the metazoan
- polyzoic has it has many segments
- each proglottid has male and female reproductive organs
- they can have 3 to 4000 proglottids
- length: 3mm to over 10 meters
function of scolex
functions as an organ attachment and orientation of the strobila
[orient the rest of the body]
which tapeworms has a well developed psuedoscolex
Fimbriaria fasciolaris
- fake scolex = pseudoscolex
Three Types of Sucker-like Organs
Acetabula/Acetabulum:
- cup-shaped
- circular/oval outline
- with heavy muscular wall
- four acetabula on scolex with retractable
(protrusible), hook-bearing rostellum
Bothria:
- usually 2 – 6
- shallow pits or longer grooves
- non muscular wall [dont grip tightly]
Bothridia:
- groups of four
- have highly mobile (motile) leaf-like margins
- quite muscular
- projecting sharply from the scolex [basically it sticks out]
what does the neck contain in cestodes
germ cells (stem cells)
- giving rise to new proglottids
- this area is called the germinative zone
why are tapeworms called polyzoic
as it has many segments
Three Types of Proglottids
o Immature
newly formed, not developed
o Mature
reproductive organs fully developed
o Ripe/Gravid
full of eggs, ready to release them
Structural Types of Proglottids
Craspedote:
- overlap posteriorly
Acraspedote:
- do not overlap
Apolytic:
- proglottids detach (when eggs are released)
Anapolytic:
- proglottids remain attached (when eggs are released)
Features of Tapeworm Morphology (Reproductive Organs)
ovary
uterus
testes
- minute ovoid [many, small]
where are all the tapeworm eggs are stirred
(stirred - formed)
in the uterus
briefly explain the 2 type of eggs that tapeworms produce
Pseudophyllidea Eggs:
- ovoid, operculated (has one or more structure) with aboperculum which is small knob, usually beneath the egg
- immature (embryonated egg) when passed in the feces
- requires period of incubation in water before they become mature
Cyclophyllidea Eggs:
- apolytic
- spherical, non-operculated, hexacanth (6 hooks or hooklets)
- almost fully embryonated when discharged from ptoglottids
this egg is discharged or released from the uterus via uterine pore
Pseudophyllidea Eggs
