Parasitology #3 Flashcards
What is the sexuality of nematoda?
most are dioecious; considerable sexual dimorphism (separate male and female)
how big can nematoda can be?
from < 1 mm to > 10 meters, elongated, tapered at both ends.
how is the digestive track in nematoda?
usually complete; mouth at extreme ANTERIOR and anus near POSTERIOR tip
how is the form of nematoda?
- Bilaterally symmetrical, posses a PSEUDOCOEL (have a false coelom before the center)
- Not true body cavity
- Only has mesoderm surronding ectoderm
- Body cavity filled with hemoglobin
What is the type of skin that nematoda has?
-Noncellular cuticle that is secreted by an underlying hypodermis
Chitinous cuticle is shed 4 times during ontogeny (4 molts, for growth)
Nematoda: Form and function
- Bilaterally symmetrical, posses a pseudocoel
- Most are dioecious; considerable sexual dimorphism
- Elongated, tapered at both ends; from < 1 mm to > 10 meters
- Digestive tract usually complete; mouth at extreme anterior and anus near posterior tip
- Noncelullar cuticle that is secreted by an underlying hypodermis
- Chitinous cuticle is shed 4 times during ontogeny (4 molts)
in Nematoda, noncellular cuticle is secreted by _____?
an underlying hypodermis.
What is the nematoda body wall consists of?
cuticle –> hypodermis (syncytial) –> body wall musculature
what is the important function of the hypodermis in nematoda?
secretion of cuticle
In nematoda, what is the shape of hypodermis and where is the nuclei?
Hypodermis is syncytial in adult worms; nuclei lie in 4 epidermal cords
in nematoda, where are the epidermal cords?
Epidermal cords run longitudinally and divide body into 4 quadrants
- -dorsal and ventral cords contain longitudinal nerve trunks
- Lateral cord contain lateral canals of the excretory system in most species
in nematoda, which cords contain longitudinal nerve trunks?
dorsal and ventral cords
in nematoda, what is specfic about the lateral cords?
contain lateral canals of the excretory system in most species
how is the musculature of the body wall in nematoda?
they are all longitudinally with no circular layer
what type of muscles does nomatoda have ?
contractile portion and a noncontractile cell body (myocyton)
How does muscles contraction occurs in nematoda?
they occurs similar to vertebrate striated muscle with myosin & actin
in nematoda, what functions as a hydrostatic skeleton?
- cuticle
- hypodermis
- somatic musculature
- fluid filled pseudocoel
Nematoda: Form and Function (Body Wall)
- Nematoda body wall consists of cuticle, hypodermis, and body wall musculature
- An important function of the hypodermis is secretion of cuticle
- Hypodermis is syncytial in adult worms; nuclei lie in 4 epidermal cords
- Epidermal cords run longitudinally and divide body into 4 quadrants
- Dorsal and ventral cords contain longitudinal nerve trunks
- Lateral cords contain lateral canals of the excretory system in most species
Nematoda: Form and Function (Musculature)
- Muscles of the body wall are all longitudinally with no circular layer
- Nematode muscles have a contractile portion and a noncontractile cell body (myocyton)
- Muscle contractions occurs similar to vertebrate striated muscle with myosin & actin
- Cuticle, hypodermis, somatic musculature, fluid filled pseudocoel functions as a hydrostatic skeleton
in nematoda, what does pseudocoel functions as a hydrostatic skeleton depends on?
1) Enclosed volume on non-compressible fluid
2) Ability of muscle contraction to apply pressure to that fluid
3) Transmission of the pressure in all directions
in nematoda, pseudocoelomic fluid is known as ____?
hemolymph
how does nematodes moves and describe the mobility?
alternation of contraction and relaxation in dorsal and ventral muscles produces the characteristic S-shaped motion seen in nematode locomotion
how does psudocoel differs in nematoda?
Pseudocoel differs from a true coelom in that it has no peritoneal (mesodermal) lining
what is pseudocoel in nematoda?
is a fluid-filled cavity enclosed by body wall