Internal Anatomy & Physiology Hemocoel – insect body cavity • filled with fluid, hemolymph • lined with endoderm & ectoderm • not a true coelom (no mesoderm) Hemolymph • bathes all internal organs • delivers nutrients • removes metabolites • performs immune functions Female Cockroach Muscles • insects have only striated muscles – overlapping of myosin and actin filaments • muscles must attach to internal surface of external exoskeleton tonofibrillae – – fine connecting fibrils linking epidermal end of muscle to epidermal layer. – discarded with cuticle at each molt. Flight direct indirect Wing Beats Insect Wing-beats per second Ephemeroptera --- Odonata 20 - 28 Orthoptera --- Coleoptera 46 - 91 Diptera 44 - 1,047 Lepidoptera 5 - 85 Hymenoptera 108-250 Synchronous – one nerve impulse/beat (<100Hz) Asynchronous – 100 - 1,000Hz How Fast Do Insects Fly? car sphinx moth dragonfly migratory locust flies bees butterfly grasshopper 4 minute mile beetle brisk walk mayfly 0 10 20 30 40 50 60 70 mph The Nervous System Central Nervous System • primitively, 1 pr. of ganglia per body segment • thoracic & abdominal ganglia of each segment fused • ganglia of all head segments coalesced to form 2 ganglionic centers – brain – subesophageal ganglion The Brain the brain is composed of 3 pairs of fused ganglia: • protocerebrum – associated with eyes and include optic lobes • deuterocerebrum – innervating the antennae • tritocerebrum – concerned with handling signals that arrive from the body coalesced ganglia of the three mouthpart–bearing segments form the subesophageal ganglion. Additionally.... • Visceral (or sympathetic) nervous system – stomodeal (stomatogastric) subsystem – ventral visceral subsystem – caudal visceral subsystem all of the above innervate fore– & hindgut, endocrine & reproductive organs & tracheal system • Peripheral nervous system – motor neurons radiating to muscles from ganglia of the CNS and stomodeal NS Endocrine System Neurosecretory Cells – modified neurons producing most insect hormones Corpora cardiaca- store prothoracicotropic hormone (PTTH) that stimulates secretory activity of prothoracic glands Prothoracic glands- secrete ecdysone Corpora allata- secrete juvenile hormone Circulatory System • Hemolymph – may be clear, yellow, blue, green or rarely red. • rarely contains respiratory pigments • Hemocytes – – phagocytosis - ingestion of small particles and substances – encapsulation of parasites & other large foreign materials – hemolymph coagulation – storage and distribution of nutrients Series of muscular pumps move hemolymph through body.
Pages to are hidden for
"Internal Anatomy Physiology"Please download to view full document