Internal morphology and physiology Flashcards
explain insect gas exchange
- Not pigment based, nor in blood like us
- they use ‘passive diffusion’
gas exchange - ‘passive diffusion’
- as in no active transport across membrane
- But air is actively moved around body to enhance diffusion
- uses much less water than human lungs
gas exchange - How do they get air through the exoskeleton
Spiracle
gas exchange - How to get air to the body?
- Trachea
- air sac
gas exchange - what is the spiracle
- it is an opening for air in the cuticle
- it can close to prevent water loss when heat stressed
gas exchange - what is the trachea
- a tube that come out of the spiracles and is used to transport air
- branches into tracheoles
gas exchange - what is the tracheoles
little branching tubes used for diffusion
gas exchange - what is the air sac
- flexible area, used for regulating air flow
- Not all have it, but most flying insects do
gas exchange - how does the air sac work
- Can be ballooned up or squeezed down
- insects use muscles to actively push air through their body to increase rate of diffusion
- Take old air out, bring new air in
gas exchange - very small insects
- all have closed systems
- can have two types of ventilation: passive and active
gas exchange: very small insects - closed systems
- no spiracles
- some have gills to exchange with water
gas exchange: very small insects - passive ventilation
insects just sit there and let air go through the exoskeleton
gas exchange: very small insects - active ventilation
pump body to move air around
gas exchange - active ventilation in flying insects
Air sacs coordinate to bring air in via thoracic spiracles, ‘exhale’ CO2 through abdominal ones
gas exchange - problems with passive diffusion
- it limits size
- if they were big, it is inefficient to travel more than a few mm
gas exchange - why could ancient (carboniferous) large insects survive
they could survive because there was more O2 and denser air
explain circulation in insects
- Insects do not have hemoglobin, instead they have hemolymph
- circulation plays no role in O2 transport
circulation - define hemolymph
combines blood + lymph functions
circulation - define Open system (semi-open)
Hemolymph disperses everywhere unlike humans who have veins (open part) but it also has the dorsal vessel (closed part)
circulation - define Dorsal vessel (“heart”)
- Long muscular tube that pumps hemolymph from abdomen to head
- Hemolymph goes through vessel towards the head and ‘pumps’ out and disperses throughout the body
explain the excretion system in insects
- they use the Malpighian tubules – analog to kidneys
- Look like spaghetti noodles
excretion system - what do dry climate insects do
they have adaptations to reabsorb water before excretion
excretion system - what do aquatic insects do
they need to concentrate nutrients and expel water (often involves gut adaptations rather than Malpighian tubules)
excretion system - what do the Malpighian tubules do
- it concentrates waste (like kidneys), put it into hind gut
- Used to process nitrogenous waste
- Rectum is last chance to get water out, useful ions before excretion
