ENTM Lec 3 Internal Morphology

what does the digestive system consist of

Mouth, foregut, midgut, malpighian tubules, hindgut, anūs

The diet influences the structure & function

What does the foregut have

• Mouth

• Pharynx

  • suction cup for liquid sucking bugs

  • tube for chewing

  • throat essentially

• Oesophagus

  • tube connecting the pharynx to the crop

• Crop

  • Storage area

• Salivary gland

  • where digestive enzymes come in to play

• Proventriculus

  • Grinding organ

what does the midgut have

• Gastric caecum

  • Projects forward & encircles the gut

• Ventriculus

  • small intestine

  • responsible for absorption of nutrients

• Peritrophic membrane

  • protective sleeve & chemical filter that surrounds the ball of food

what does the hindgut have

It is the excretory system

• Ileum

  • The reabsorption of water & salts

• Rectum

  • The waste holder, absorbs more water

• Anüs

  • Solid fecal pallet ejection

• Colon

  • where the fecal accumulates

• Malpighian tubule

  • Controls movement

  • spaghetti like floating in body

  • fills the body cavity & moves waste to hindgut

What is the repiratory system responsible for

1. Movement of oxygen to all tissues in the body

2. Removal of CO₂

The respiratory system of insects is separate from the circulatory system

How does the respiratory system work

Through gas exchange through series of air-filled tubes & sacs (tracheal system)

• Tracheoles

  • where the oxygen is delivered

• Air sacs

  • Kind of like lungs

  • Oxygen reservoirs

  • Ventilation

• Tracheae

  • Responsible for delivering oxygen directly to the body’s tissues & removing CO₂ waste

• Spiracles

  • Valved external openings to air filled tubes

  • Can occur on thorax or abdomen

How does body side affect the respiratory system?

• Small insects rely on passive diffusion & physical activity

• Large insects require active ventilation of the tracheal system

What is the circulatory system in an insect

Open system, hemolymph (blood) flows freely within the body & is in direct contact with all internal body tissues & organs

What is the circulatory system responsible for

• Nutrients, hormone & waste transport

• Thermoregulation

• Defense

• Molting

• Movement

What is hemolymph

• insect version of blood

• it is made of 90% plasma where the remaining is composed of hemocytes

  • Hemocytes is the human equivalent to white blood cells

  • clotting (sealing a wound)

  • phagocytosis (cell eatinf, hunt down bacteria)

  • encapsulation of foreign bodies (parasitic defense)

What is the circulatory system composed of

Dorsal heart(dorsal vessel) + abdominal pumping to aid circulation

What are the characteristics of the male reproductive system

• paired testes

  • generating sperm

• testicular tube

  • where the sperm is matured

• vas deferens

  • where mature sperm is moved

• accessory gland

  • keeps sperm healthy & adds protection to give to females

• seminal vesicle

  • temporary holding tank where sperm is stored

• ejaculatory duct

  • where the left & right side meet & channels the packed sperm

• intermittent organ

  • the pp essentially,

• gonopore

  • the opening of the tip

What are the characteristics of the female reproductive system

• paired ovaries

  • where eggs are generated

• ovariole

  • eggs travel down these tubes slowly growing bigger

• mature oocyte

  • where fully developed unfertilized egg sits, waiting to be released

• lateral oviduct

  • the pipes that catch eggs

• common oviduct

  • where the left & right pipes converge

• spermatheca

  • where male sperm is kept alive waiting for a fertilized egg

• spermathecal gland

  • pumps nutrient to the spermatheca to keep stored sperm healthy

• accessory gland

  • coat the eggs with protective coating

• gonopore

  • the pipe connecting the common oviduct & the genital chamber

• genital chamber

  • the vagina where mating takes place

• vulva

  • opening where the eggs are laid

What is the endocrine system

network of glands & tissues that produce hormones

• hormones

  • produced in neuronal, neuroglandular,glandular centers & in some organs

  • hormones reach their targert tissue by transport in the hemolymph

What is the endocrine system composed of

• brain

  • coordinating the nervous & endocrine system

• neurosecretory cells of brain

  • located inside the brain tissue, this makes major master hormones

• corpus cariacum

  • storage warehouse for hormones waiting to be pumped into the blood

• Corpus allatum

  • produce juvenile hormone (youth potion) keeping insect in it’s larval stage when it sheds skin

• neurosecretory cells of subesophageal ganglion

  • nerve tissue that secrete hormones that regulate diapause (hibernation/arrested development)

• prothoracic gland

  • pumps out ecdysone (molting hormone), tells body that it’s time to shed it’s own shell & build a new one

• Neurosecretory Cells of Ventral Nerve Cord

  • insect spinal cord, this ‘highwa'y’ releases hormones to control local muscle movement, water balance, & heartbeat

• ovary

  • communicates with the reproductive organs to signal when the bug is mature enough to start developing & laying eggs

What are the hormone types

• Ecdysteroids

  • steroids with molt-promoting activity, produced by prothoracic glands

• Juvenile hormones

  • play a diversity of roles in development & physiology, produced by corpora allata

• Neurohormones

  • regulators of many aspects of development, homeostasis, metabolism, & reproduction, produced by corpora cardiacta & neurosecretary cells

What is the nervous system?

Central nervous system with a dorsal brain linked to a ventral nerve cord