Lecture 8: Guts, Blood and Gas

Question 1

Alimentary canal 3 parts:

Answer 1

• Foregut
• midgut & malpigian tubules
• hindgut

Question 2

each part of the alimentary canal has a different embryological origin, as a result

Answer 2

each has a markedly different histology

Question 3

which parts of the alimentary canal are lined with cuticle:

Answer 3

-foregut and handgun (midgut is not to allow diffusion)

Question 4

Alimentary canal description:

Answer 4

Foregut: 
-Pharynx 
-oesophagus 
-crop
-gizzard 
Midgut:
-Caeca 
-Gut 
-Malpigian tubule 
Hindgut

Question 5

Foregut:

Answer 5

usually unspectacular - but modified in blood sucking insects

Question 6

Foregut: the crop:

Answer 6

food reservoir - a staging post for food

Question 7

Foregut: the gizzard:

Answer 7

also known as proventriculus - a second mouth, lined internally with sharp cuticular teeth

Question 8

the foregut is completely lined with

Answer 8

endocuticle

Question 9

Midgut is lined with

Answer 9

epithelial cells and a village border TO increase SA

Question 10

midgut: purpose of caecae

Answer 10

increases SA by drawing out gut into tubes

Question 11

where are most of the digestive enzymes secreted in the alimentary canal?

Answer 11

midgut

Question 12

food is covered in the ___________ - protects the gut and insect

Answer 12

peritrophic membrane

Question 13

mapilgian tubules

Answer 13

• long thin blind-tubes
• insects kidneys
• They lie freely in the body cavity, bathed in haemolymph
• Walls are one cell thick - and internal surface is villate.
• Huge surface area
• An amazing physiological tissue

Question 14

Hindgut:

Answer 14

• another physiological marvel
• responsible for removal of last few “goodies” from the gut
• major site of water resorption

Question 15

hindgut lining

Answer 15

cuticle lined; cuticle acts as semi permeable membrane

Question 16

hindgut other uses:

Answer 16

• Some insects use it as a jet-propulsion system

- Others force air out and hiss to scare off predators

Question 17

haemolymph is

Answer 17

insect ‘blood’

Question 18

body cavity of insects is called the

Answer 18

haemocoel - a cavity with little circulatory system

Question 19

the haemocoel contains blood =

Answer 19

the haemolymph

Question 20

haemolymph is the only

Answer 20

extra cellular-fluid in insects - it contains nutrients and salts and blood cells

Question 21

insect blood cells:

Answer 21

haemocytes

Question 22

the haemocytes are responsible for

Answer 22

immune function and rebuilding at metamorphosis

Question 23

Gas is transported around the insect body in

Answer 23

trachea

Question 24

trachea:

Answer 24

• ramify throughout the body

- and communicate with the atmosphere via spiracles

Question 25

Aquatic insects have a ___ tracheal system

Answer 25

closed

Question 26

spiracles:

Answer 26

- paired openings in each segment | - passage of air into ) out of the tracheal system is regulated by these valves

Question 27

what is the site of major water loss in living insects

Answer 27

spiracles

Question 28

trachea passive/not passive

Answer 28

not passive- can be forces through | -they expand & compress

Question 29

trachea made of:

Answer 29

- well defined network inside the insects body | - made of cuticle and are continuous with the body wall

Question 30

how does trachea end

Answer 30

in very fine tracheoles

Question 31

trachea: some are so fin they pass:

Answer 31

between cells and sometimes even into cells

Question 32

large flying insects have gas reservoirs where?

Answer 32

within the tracheal system - air sacs!

Question 33

Respiratory physiology: -Tracheal cuticle is very thin and therefore

Answer 33

permeable to gas

Question 34

Respiratory physiology: - gas exchange is often facilitated by

Answer 34

ventilatory movements

Question 35

Respiratory physiology: - lack of O2 stimulates

Answer 35

CNS to open spiracles