Arthropods II: Metamorphosis Hormones Flashcards
What the 4 major groups of Arthropods?
- Myriapods
- Chelicerates
- Crustaceans
- Hexapods
Myriapods aka
“countless feet”
How many body regions do myriapods have?
2
What are the two regions of myriapods?
head and runk
chelicerates have ___ body regions
2
what are the two body regions of chelicerates
- chepalothorax: appendages
- abdomen: no appendages
How many pairs of appendages do chelicerates have?
6
what are the 6 pairs of appendages chelicerates have?
1: fangs
2: copulatory organs, pinchers
3, 4, 5, 6: walking legs
what are the three body regions of custaceans
- head
- thorax
- abdomen
what makes up the group of hexapods?
insects and other groups
what are the three body regions of a hexapod
- head: antennae, mouthparts
- thorax: 3 pairs of walking legs (possibly wings)
- Abdomen: no appendages
are springtails insects?
no but they are considered hexapods
when did wings evolve?
around 320 mya
the wing of a ____ and the gill of a ___ ____ are homogolous
insect ; cray fish
how do most insects and myriapods breathe?
through holes (spiracles) open into tubular tracheae which branch to finer tubes - carry O2 to body cells
What kind of circulatory system do arthropods have?
open system
what drives hemolymph into hemocoel
dorsal tubular heart with pores
what kind of valves do arthropods have?
one way valves
most species of arthropods are
dioceous
most species of arthropods…
lay eggs
Arthropods can reproduce on ___ and in ____
land ; water
How do Arthropods reproduce on land?
- internal fertilization
- some use spermatophores (= packets of sperm_
How do Arthropods reproduce in water?
internally (crabs) or externally (barnacles)
How do males prevent females from eating their sperm?
by giving it this extra layer that takes a long time to eat
Why do females compete for males?
because they get nutrients from the males
What does moulting enable?
changes in morphology aka metamorphosis
when do insects stop moulting?
when they are adults
what kind of Arthropod continues moulting as adults?
crustaceans
Indirect of holometabolous development
complete metamorphosis
what regulates moulting?
Wigglesworth’s experiment
Wigglesworth’s experiment using
Rhonidus porlixus
Rhonidus prolixus
a blood sucking insect moults after blood meal
Hormones are secreated by
endocrine cells
Hormones are distrubted by the ____ and bind to ___ ____ _____
blood; target cell receptors
some chemical signals act locally meaning they can…
act without entering the blood stream
How do hormones work?
- affect the expression of a gene
- alternate the activity of an existing enzyme
- change the permeability of a cell membrane
what are the three chemical families of hormones
- peptides and polypeptides
- amino acid derivatives
- steroids
what is the hormone involved in Arthropod moulting?
PTTH: ProThoracicoTropic Hormone
where is PPTH produced and stored?
in the brain
PTTH controls the activity of what gland?
prothoracic gland
What does the prothoracic gland produce?
Ecdysone
Where is the ecdysone secreted?
into the blood
What cells does the ecdysone targe?
epidermis
what releases ecdysone?
corpus allatum
what determines when its time to moult?
pulses in the brain
What are the two body control systems?
endocrine system and nervous system
What is the endocrine system?
- hormones
- diffuse via blood
- slower, longer term
What is the nervous system?
- action potentials
- electrical signals along neurons
- quicker: shorter term
what happens when both systems work together?
- neurons trigger hormone release
- neurons in hypothalamus make hormones released by the posterior pituitary gland
- hormones feed back onto nervous system
what are the responses of nervous and endocrine system to stimuli?
- brain detects danger and signals an action
- brain signals adrenal gland to release epinephrin
3 epinephrine causes:
- the liver to convert clycogen to glucose
- the heart to beat faster
- Blood vessels to gut and skin to constricut - shunting more blood to muscles
- fat cells release fatty acids (fuel) into blood
The Hypothalamus integrates …
information about the state of the body
ADH stands for
anti-diuretic hormone
what triggers ADH?
Increased salt concentration in the blood
what is the function of ADH?
water is conserved and urine is more conentrated
what does ADH target?
kidneys
what does ADH do?
Increases the absorption of water
Eating a bag of chips
- Sodium levels go up
- body tries to flush out some of the Na (this requires water)
- body loses water
- if you lose too much you’ll shrivel up
- hypothalamus releases hormone to the kidney so it reabsorbs the water so you don’t shrivel up
Oxytocin’s 1st targe
the smooth muscle of the uterus
First action of Oxytocin
contractions
2nd target of oxytocin
mammary glands - milk is released
2nd action of oxytocin
milk release
where is oxytocin produce?
in the hypothalamus
where is oxytocin released?
from the posterior pituitary glands
what does the hypophyseal portal system carry?
neuro-endoprime signals from the hypothalamus down to the anterior pituitary which then releases its own set of hormones
