MUSCULAR AND RESPIRATORY SYSTEM

Functions of the Muscular System

• Support the body

• helps maintain posture

• locomotion

• movement of wings

2 Categories of insect muscles

1. Skeletal muscles - functions to move one part of the skeleton in relation to another, muscles connected to skeleton/joints

2. Visceral muscles - forms layer of tissue enveloping internal organs (heart, gut, reproductive tract)

2 Major types of Flight

1. Direct flight - flight muscles are directly attached to the wing bases, causing the wings to move directly

   • Ephemeroptera (mayflies)

   • Odonata (dragonfly)

2. Indirect flight - flight muscles are attached to the thorax, not directly to the wings, contractions in thorax caused wings to move

   • found in True flies

Hindlegs of insects

1. Femur

2. Tibia

• connected by two antagonistic muscles: flexor tibiae muscle and extensor tibiae muscle

Respiration in insect

Trachea - larger tubes running inwards from the spiracle, breaks into finer branches
- responsible for delivering sufficient oxygen to cells and removing CO₂

• at the end of tracheal branch is a special cell (tracheole)

Respiration in Aquatic Insects

1. Cuticular Respiration - diffusion of gas through body wall

2. Biological Gills - tracheal gills and rectal gills

3. Breathing tubes - siphon or respiratory tubes

4. Air bubbles - diving beetles carry air bubbles when they dive under water