Download Internal anatomy and physiology

Internal anatomy and physiology
Internal anatomy and physiology
We will not be going over all of these in class! Check
out these slides and your course notes, and just let
me know if you have questions. Most of this is fairly
straightforward.
Muscles and Locomotion
• Sole purpose: convert stored energy into
mechanical energy
• Do this by contracting
Internal anatomy and physiology
3.1
3.2
3.3
3.4
3.5
3.6
Muscles and locomotion
The nervous system
The endocrine system
The circulatory system
The tracheal system
The gut, digestion, and nutrition
Muscles and Locomotion Questions
• How do direct and indirect muscles operate
differently in powering flight?
• How are larval insects able to get around without a
sclerotized cuticle?
Muscles need an anchor… how do they do this in insects?
o Muscle receives signal from nervous system
o Muscle then shortens (or contracts)
• Contractions vary depending on location
and orientation of muscles
Figure 3.2 in textbook
1
A focus on flight…
FLIGHT
Insects power flight by:
Direct flight mechanism (muscles attach to wing)
o Ancestral insects use only this
o More derived insects use this and…
Indirect flight mechansim (wings and muscles don’t
attach)
3.2 Nervous system
Setae/eyes/antennae
3.1 Muscles and Locomotion
2 ways muscles can attach (both appendages and
organs)
o EXTRINSIC
• Muscle attaches appendage to body
cavity
o INTRINSIC
• Muscle remains in appendage or in a
single structure
Central Nervous System
ƒ Brain- Dorsal ganglionic center of the
head.
Afferent neurons
Ganglia
ƒ Subesophageal ganglion- located below
INTERNEURONS
the pharynx.
ƒ Ventral nerve cord- contains chain of
Efferent neurons
thoracic and abdominal ganglia.
Muscles/glands
How do larvae get around with such thin, flexible cuticle?
DIRECT FLIGHT MECHANISM
INDIRECT FLIGHT MECHANISM
2
The hydrostatic skeleton
3.2 Nervous system
Insect nervous system is decentralized
o Instead of going to and from central brain, signals go to and from
GANGLIA
Variable Arrangement of CNS in Different Insects
Most specialized
Least specialized
The endocrine system
Questions
• How are endocrine and exocrine glands similar and
different in function?
• Why would an insect secrete chemicals to the
outside world?
• What are the major endocrine glands?
• Which glands release JH, Ecdysone, and PTTH? Why
are these hormones important?
Cockroach
Fusion of
ganglia
Scarab beetle
The endocrine system
• System = glands and what they produce
• 2 classes of GLANDS
o Both innervated by nervous system
The endocrine system
EXOCRINE GLANDS
Emit - single cells or aggregations of cells
• Can be anywhere in body but usually an
association with epidermal layer… why?
EXOCRINE GLANDS
o Send chemicals/signals outside body
ENDOCRINE GLANDS
o Send chemicals/signals inside body
3
The endocrine system
The endocrine system
EXOCRINE GLANDS
What would an insect excrete?
Pheromones: used in intraspecific communication
only! (used incorrectly by David Attenborough /)
There are several types of pheromones, and we will
talk about these in the Sensory Systems section of
the course. Below, insects using sex pheromones
(left) and aggregation
pheromones (right).
EXOCRINE GLANDS
What would an insect excrete?
Semiochemicals: Chemical odors important in both
interspecific and intraspecific communication (both
across and within species).
The endocrine system
The endocrine system
EXOCRINE GLANDS
What would an insect excrete?
Allelochemicals: Chemical odors important to
interspecific communication only.
EXOCRINE GLANDS
Many chemicals released from the exocrine glands
are Semiochemicals. Some examples include…
1) Defense chemicals/signals
o venoms, alarm pheromones
o Bombardier beetles
The endocrine system
EXOCRINE GLANDS
Many chemicals released from the exocrine glands
are Semiochemicals. Some examples include…
2) Mate attraction chemicals/signals
- Sex Pheromones
The endocrine system
EXOCRINE GLANDS
Many chemicals released from the exocrine glands are
Semiochemicals. Some examples include…
3) Trail-marking pheromones, aggregation
pheromones
4
The endocrine system
ENDOCRINE GLANDS
• Can be one cell or clusters of cells
• No “ducts” and no association with
epidermis
• A LOT more complex than exocrine system
• Cascading affects
• Complex combinations of hormones
• All endocrine functions started and
regulated by nervous system!
Internal anatomy and physiology
3.4
The circulatory system
The endocrine system
MAJOR ENDOCRINE GLANDS
CORPORA CARDIACA
• Pair of glands behind brain
• Store and release NEUROHORMONES
• Major one: PTTH (prothoraciotropic hormones)
CORPORA ALLATA
• Smaller, secrete JH (Juvenile Hormone)
PROTHORACIC GLANDS
• Large glands in thorax
• Secrete ECDYSONE (molting hormone)
3.4 The circulatory system
• What is a major difference between the circulatory
systems of insects and vertebrates?
• What does hemolymph contain, and what are its
functions?
• How does hemolymph provide protection and
defense?
5
3.4 The circulatory system
3.4 The circulatory system
VERY different from vertebrates
Slow doesn’t mean
random or stagnant…
• DORSAL VESSEL
maintains flow
o Blood not confined in vessels/capillaries
OPEN Circulatory System
o “blood” called HEMOLYMPH
o Functions of both blood and lymph
• Do NOT rely on circulatory system for O2
o Long tube along dorsal midline
o It doesn’t have to be fast!
3.4 The circulatory system
3.4 The circulatory system
DORSAL VESSEL
It’s divided into two parts:
Hemolymph
Flows posterior to anterior
o AORTA (anterior)
o HEART (posterior)
• ALARY MUSCLES on both ends of
heart
• OSTIA (valves) at posterior ends
o i.e. rear to head
o Force forward creates a current inside insect
o Hemolymph infuses organs on its return flow
Accessory pumping structures –
o Next to/in appendages, aid with circulation
o Blood circulates through legs, antennae and
o WINGS
3.4 The circulatory system
6
Hemolymph
Hemolymph contains an array of proteins,
lipids, hormones, carbohydrates, salts, etc
¾ Functions
¾
¾
¾
¾
Hormone transport
Nutrient storage and distribution
Waste removal
Insect defense
¾ 20 - 40% of body weight in soft – bodied
larvae
¾ < 20% of body weight in nymphs and
adults
¾ Usually clear but also green, blue, yellow,
red
Internal anatomy and physiology
3.4 The circulatory system
Insect immune system
Hemolymph provides protection and defense from:
• Physical injury
• Entry of disease organisms, parasites, and foreign
substances
3.5
The tracheal system
How does it do this?
3.5 The tracheal system
Questions
• How does gas exchange occur in insects?
• How does oxygen get all the way into the
center of an insect?
• Do all insects have spiracles? Why or why
not?
3.5 The tracheal system
System responsible for O2 and CO2 transport in MOST
insects
• Internal duct-like tubes called TRACHEA
• Trachea extend out into millions of tiny branches
called TRACHEOLES
o Tracheoles permeate body tissues, organs, muscles, etc.
o Fluid-filled, blind ends
o Less than 1μm in diameter!
7
3.5 The tracheal system
3.5 The tracheal system
Air enters system through SPIRACLES
• Usually have an ATRIUM (chamber) with a VALVE
• Some have filters to protect atrium
Gas Transfer/Air Flow
millions of tracheoles diffuse passively across surface
How does O2 get in/CO2 get all the
way in and out of there?
3.5 The tracheal system
3.5 The tracheal system
How does O2 get in/CO2 get all the
way in and out of there?
1. Natural diffusion gradients
• O2 gradient higher on outside of insect
• CO2 gradient higher on inside of insect
2. Pumping movements of the abdomen
http://www.youtube.com/watch?v=lEMQxsHm8gY
3.5 The tracheal system
3.5 The tracheal system
• Open versus closed tracheal system
• Open versus closed tracheal system
• Modifications may include the formation of
air sacs or bladders
GILLS
Open
Closed
8