Entomology Midterm #2 Flashcards
Lectures 8-13
what is the main toxic element produced from amino acid metabolism?
nitrogen
what are the three methods of packing nitrogen?
ammonium, urea, uric acid
what are the disadvantages of the ammonium method of oxygen packing?
very toxic, requires a lot of water to rid the body of this waste
what two methods of oxygen packing are relatively non-toxic?
urea and uric acid
what are Malpighian tubules?
the “kidney” of insects
what do malpighian tubules look like?
long, thin tubules (2-200) that wave freely in haemolymph
what is the function of Malpighian tubules?
filter and remove wastes (especially nitrogenous products), and absorption of amino acids, salt, and water
where do Malpighian tubules empty their secretions?
into the gut at midgut-hindgut junction
what is the end product of breakdown in malpighian tubules?
ammonia
in most terrestrial insects what is ammonia converted into?
uric acid (insoluble and crystallized out easily)
how does uric acid move out of haemolymph into Malpighian tubules?
passive diffusion (down its concentration gradient)
what does the lining in Malpighian tubules do?
protects rectal cells from relatively large amounts of toxic material in faces
where are the anal lobes/ anal papillae located in mosquitos?
rear end of the larva
what is the function of anal lobes/ anal papillae?
absorb salt
how do the size of anal lobes vary?
based on the concentration of salt in the rearing medium
when is metabolic water produced?
when sugars are broken down into energy, carbon dioxide, and water
what are the three different feeding strategies?
phytothagnous - plant eating
saprophagnous - dead or decaying organic matter
carnivorous - meat eating
what are some physical defences that provide challenges to digestion?
hooks, spines, trichomes, tough leaves
what are the three types of challenges when it comes to digestion?
chemical, physical, low nitrogen levels or low nitrogen/ water levels
what problems do sap feeding insects face when ingesting huge amounts of water?
overloads digestive systems, dilutes enzymes, dilutes haemolymph
what do fat bodies consist of?
loose aggregation of cells invested in connective tissue
what are fat bodies concerned with?
fat metabolism and metabolism of sugars and proteins
what type of regulation are fat bodies involved in?
hormone regulation
what are the four functions of fat bodies?
- metabolism of carbohydrate, lipids and proteins
- regulation of blood sugar
- synthesis of haemolymph proteins
- storage os fats, proteins, and glycogen
what is the trachea?
a ventilation system where air enters the body through spiracles and are carried through the body by increasingly fine branching structures to within 3-4 cells of all parts of the body
what amount of spiracles are present through out an insects body?
max of 2 pairs in thorax and max of 8 pairs in abdominal segments
how is air carried through the body by spiracles?
by increasingly fine branching structures to within 3-4 cells of all parts of the body
what is insect blood not involved with
gas transport
what does diffusion account for
gaseous requirements of tissues in most insects at rest
how does the insect pump air when at activity or when it is simply larger in size?
pumps air in and out through tracheal system by collapsing and expanding air sacs
how are tracheae formed?
invagination of the ectoderm and are thus lined with cuticle
what is the first region that is supplied with oxygen?
head region
where are spiracles that supply wing muscles?
isolated from rest of body
what is an advantage to spiracles that supply wing muscles being isolated?
large amounts of Co2 produced in flight are largely confined to the thorax
what is the spiracular entrance lined with?
hairs to keep dust out
why are spiracles generally kept shut for short amounts of time?
to prevent water loss
what is opening of spiracles controlled by?
CO2 production in haemolymphs
when do spiracles become more resistant to opening?
if water levels are low
when are cuticular linings of trachea shed?
after each moult
immediately after a moult, what are there spiracles filled with?
water. later replaced by gas (gas does not enter through spiracles)
how does a cuticle change
changes from hydrophilic to hydrophobic as it becomes tanned
what is forced out when cuticle changes from hydrophilic to hydrophobic
water
what is the tympanic organ generally backed by
air sacs
how is sound produced through the tympanic organ?
allows vibration of organ which produces sound
how do aquatic insects obtain air?
get it from the air (when they resurface) or from dissolved air in the water
how is air held underwater in diving beetles?
under elytra
what is a plastron?
a permanent bubble which is a film of thin air on outside of body held by specialized hairs
plastron function?
permanent interface between water and air, acts like a grill
what are gills?
leaf0like structures of very thin cuticle with a network of tracheoles
what is pudding in butterflies (male specifically)?
sipping moisture from mud puddles to take in salts and minerals
what do male butterflies do with the extra salts and minerals obtained from pudding?
incorporates them into their sperm
what are ganglion?
bundles of neurons from which peripheral nerves run to sense organs, muscle system, internal organs, and secretory glands
what makes up an insects brain?
fused ganglia
how many ganglia are in each body section?
3 in head, 5 in body
what are thoracic ganglia important for?
movement
what are abdominal ganglia important for?
digestion, excretion, and reproduction
what is a neurosecretory function?
secretion of hormones which initiate events like moulting, sexual maturation, and diapause
how do muscles contract?
ganglia send signals through nerve cells causing them to contract
how many neurons does an insect brain have?
~200,000
what are dendrites?
cell bodies where nuclei are located
what are ganglia formed from?
aggregated neurons that come together to form ganglia
what forms nerves?
bundles of axons
what are action potentials?
nerve impulses that are conducted along axons
how can Neve impulses be enhanced or suppressed?
by regular inputs received from dendrites
what does it mean when insect neurons are unipolar?
the neurons have only single axonal projections
what neurons are bipolar and multipolar?
bipolar = some sensory neurons
multipolar = neurons in brain and stretch receptors
what are the three types of neurons?
unipolar, bipolar, multipolar
what are unipolar neurons? and what do they stimulate?
have only one structure that extends away from the cell body. stimulates muscles or glands
what do bipolar neurons do?
receive signals from photoreceptor cells that are sensitive to light and transmits the signals to ganglion cells which take them to the brain
(photoreceptor cell signal -> bipolar neuron -> ganglion cells -> brain)
what do multipolar neurons do and what is their structure?
may be found between sclerites to detect “stretching”. many extensions but only one axion
what are afferent (sensory) neurons? and what is their function?
dendrites associated with sense organs or receptors.
function: carry info to CNS
what type of neurons are afferent neurons?
bipolar or multipolar
what are efferent (motor) neurons?
unipolar cells which conduct signals away from the CNS and stimulate muscle and glandular responses
what are interneurons (association) neurons?
unipolar cells (with several branching axons) that conduct signals within the CNS
where do individual neurons connect?
synapses
what is the process of synaptic transmission?
1) nerve impulse reaches synapse
2) chemical messenger released
3) neurotransmitter diffusion across synapse
4) potential membrane potential change in dendrites of one or more connecting neurons
what are the two types of postsynaptic neurons?
excitatory and inhibitory
what are the four neurotransmitters?
acetylcholine, 5-hydroxytryptamine, dopamine, noradrenaline
what do neurotransmitters do?
transmit nerve impulses and stimulate muscle contractions
what is the only “solid: organ in the insect body?
ganglia