11/5/2015
Not:
The insect circulatory system Dorsal vessel Alary muscle
The Hemocoele/Mixocoele: •
• •
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)
• •
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
1
11/5/2015
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
2
11/5/2015
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
3
11/5/2015
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
4
11/5/2015
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
5
11/5/2015
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
6
11/5/2015
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
7
11/5/2015
Blood Function: Chrysomelidae (leaf beetle)
Hemolymph functions: • • • • •
Coccinellidae (lady beetle)
•
• •
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
8
11/5/2015
Immune function of blood: Encapsulization
Hydrostatic functions of blood Eversible male genitalia
Molting & wing expansion
Hydrostatic skeleton
9
11/5/2015
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
10
11/5/2015
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
11
