Download The insect circulatory system

11/5/2015
Not:
The insect circulatory system
Dorsal vessel
Alary
muscle
The Hemocoele/Mixocoele:
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Not a true coelom, which
is lined with mesoderm
(small remnants only)
Instead, it’s lined with
ectoderm & endoderm
Hemolymph is thus
separated from organs by
basement membrane
(amorphous mucopolysaccharide + collagen
– very complex)
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Heart
Aorta
An open system
small size, short diffusion
distances
no blood gasses to
distribute
Ostium
PERICARDIAL
SINUS
PERIVISCERAL
SINUS
PERINEURAL
SINUS
PERINEURAL
PERIVISCERAL PERICARDIAL
SINUS
SINUS
Ostium
SINUS
Dorsal vessel
(dorsal septum)
(ventral septum)
The insect circulatory system: some details
alary
muscle
heart
PERICARDIAL SINUS
os = ostium; v = valve (Diptera)
dorsal
septum
PERIVISCERAL
SINUS
gut
pleuro-sternal
boundary
ventral
septum
PERINEURAL
SINUS
ventral nerve cord
X
septum (diaphragm)
fenestra
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Pattern of circulation
antennal wing
ampulla ampulla
wing
heart
excurrent ostium
antenna
incurrent
ostium
leg ampulla
leg
dorsal vessel
(aorta)
heart
dorsal & ventral septa
with fenestrae at
edges
nerve
cord
one-way
valve of
incurrent
ostium
ampulla
leg
ganglion
extension of
ventral septum
Accessory pulsatile organs (APO)
in a cockroach
dilator muscle
distal vessel
of ampulla accessory
proximal
vessel
dilator
muscle
ampulla
eye
aortal dilation
brain
corpus cardiacum
& corpus alatum
aorta (dorsal vessel)
esophagus
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Circulation in the wing venation of three beetles
Cupedidae
Scarabaeidae
Carabidae
Lateral segmental vessels
2 thoracic, 4 abdominal
heart
septum
vessel
Some roaches & mantids
(Dictyoptera)
4 abdominal
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Segmental vessels
in Blaberus
aorta or
dorsal vessel
(2 pairs thoracic,
4 pairs abdominal)
segmental or
lateral vessel
heart
incurrent
ostium
dorsal
diaphragm
tergo-sternal
muscle
segmental or
lateral vessel
alary (aliform)
muscle
Thermoregulation and the “rete mirabile”
aorta
heart
convolutions (rete mirabile)
Bees & wasps
(Hymenoptera)
(116.6° F)
rete mirabile
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Bumble bee circulation
& thermoregulation
(tidal air)
(radiator)
rete mirabile
Centralization
(shortening) of the heart
Drosophila
melanogaster
aorta
3 pairs of ostia
heart
certain Diptera & mayflies
(Ephemeroptera)
Number of pairs of ostia:
• 3 to 9 in mayflies & roaches
• 3 in higher Diptera
• 1 in a highly specialized mayfly
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aorta or
dorsal vessel
Number &
placement of ostia;
nature of alary
muscles
segmental or
lateral vessel
Ex. = ancestral
condition
heart
incurrent
ostium
Heartbeat:
dorsal
diaphragm
tergo-sternal
muscle
segmental or
lateral vessel
alary (aliform)
muscle
• Heartbeat and alary
contraction synchronous
• Heartbeat and alary
contraction asynchronous
• 14–150 beats/minute (stag
beetle vs. house fly)
• Varies with O2, temperature,
diet, life stage (or instar)
• myogenic not neurogenic
• also from neurosecretions of
corpora cardiaca, etc.
Hemopoietic organ (“lymph glands”)
Hemolymph (“blood”):
• Clear & colorless or yellowish
or greenish
• pH 6–7.5
• Na+, Cl-, Ca++, K• 5–40% of body weight **
• Filled with fats, organic
acids, amino acids, carbs,
proteins, & pigments
• 1k–275k cells/mm3
Prohemocyte
Prohemocyte
** 7–8% of a person’s weight is blood
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Cells in the hemolymph (hemocytes)
BASOPHILIC
(hematoxylin)
Prohemocyte
ACIDOPHILIC
(eosin)
Plasmatocytes
Granular
hemocytes
neg– pos+
Spherule cell
Cystocytes
(coagulocytes)
Adipohemocyte
Oenocytoid
vermiform cell
Yeager (1945)
described 10 classes
with 32 types of blood
cells
Pericardial cells
Oenocytes
(can be in phagocytic organs)
(epicuticle, wax &
cement, enzymes)
cuticle
basement
membrane
epithelium
(170-180µ)
cytoplasmic
strand
oenocyte
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Blood Function:
Chrysomelidae (leaf beetle)
Hemolymph functions:
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Coccinellidae (lady beetle)
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Water storage
Osmoregulation (organics)
Transport (e.g. hormones)
Food storage (e.g.
trehalose, a disaccharide)
Respiration (at the cellular
level of diffusion)
Protection
• reflex bleeding
• clotting
• phagocytosis
• encapsulization
• immune response
(innate not “learned”)
• antifreeze (glycols)
Mechanical (hydrostatic)
Thermoregulation
Wound-healing and clotting
entrance wound
a blood clot
nematode parasite
Diptera larva
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Immune function of blood: Encapsulization
Hydrostatic functions of blood
Eversible male genitalia
Molting & wing expansion
Hydrostatic skeleton
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3 masses
on each side
of body
Fat body
fat body cells (= trophocytes,
urocytes, and mycetoctyes)
GUT
(may also
surround gut)
Fat body functions:
• Food storage (trophocytes)
• Secretion, synthesis, &
catabolism (metabolic)
• Waste storage (urocytes) –
storage excretion as uric acid
• “Real” excretion
• Nutritional endosymbiosis
(mycetocytes)
• Bioluminescence
Coleoptera: Lampyridae
Muscles: categories
intrinsic
muscle
extrinsic
muscle
Labium of a cricket
Muscle contraction:
Metathoracic leg of a grasshopper
levator (extensor)
depressor
extrinsic
muscle
1. Nerve impulse
2. Secretion of
acetylcholine
3. voltage change across
muscle membrane
4. chemical changes in
muscle:
a. flooding in of Ca++
b. changes bonding of
actin & myosin
intrinsic
muscles
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nerve
axon
Muscle
T-tubule
Ultrastructure
glial
sheath
I -band
neural
lamella
actin
molecule
(filament)
I -band
nerve/
muscle
junction
A-band
myosin
filament
H-band
A-band
nucleus
basement
membrane
sarcolemma
mitochondria
I -band
heads
forming
cross-bridges
Z-disc
actin filament
Sarcomere
Z-disc
fibrils (myofibrils)
muscle fiber
(or muscle cell)
Flight myosin filament Visceral
muscle
muscle
Muscle fiber (or muscle cell)
Fibril (myofibril)
Sarcomere
Muscle
Ultrastructure II
(the sarcomere is
the contractile element)
X-sec. Myofilaments
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