Lecture Notes on Earthworm Digestive and Circulatory Systems

Flashcards covering key concepts and details about the digestive and circulatory systems of earthworms.

What distinguishes organisms with complete digestive systems from those with gastrovascular cavities?

Complete digestive systems allow for regional specialization and continuous eating, unlike gastrovascular cavities where all processes occur in one large space.

What are the primary regions of the complete digestive system?

Foregut, midgut, and hindgut.

What is the function of the hindgut in a digestive system?

The hindgut is primarily responsible for absorption of nutrients.

Define deposit feeders.

Deposit feeders are organisms that ingest sediment or substrate to extract organic material.

What role does the muscular pharynx play in deposit feeders?

The muscular pharynx helps to grind up sediment for better digestion and assimilation.

What is the function of the crop in many organisms?

The crop stores material until it is ready to be processed further.

Describe the structure and function of an earthworm's gizzard.

The gizzard is a muscular structure that physically breaks down food into smaller particles for digestion.

How does the circulatory system of annelids differ from that of vertebrates?

Annelids often have a closed circulatory system with large dorsal blood vessels, and many lack red blood cells.

What is hemoglobin and how does it differ in earthworms?

Hemoglobin is the oxygen-carrying protein, but in earthworms, it is large with many binding sites, unlike vertebrate hemoglobin.

What is the difference between evaginations and invaginations in respiratory structures?

Evaginations protrude outward (like gills), while invaginations extend inward (like lungs).

What is the function of metanephridia in annelids?

Metanephridia are osmoregulatory structures that filter body fluids to maintain water and ion balance.

How do annelids achieve nutrient absorption in their intestines?

They increase surface area with folds, villi, and microvilli to enhance nutrient transport across membranes.

Why do fish suffocate when taken out of water despite having oxygen in the air?

Fish gills collapse out of water, reducing surface area for gas exchange.

What adaptations do some annelids have for surviving in extreme environments, like hydrothermal vents?

They modify their respiratory structures and can withstand high temperatures and other extreme conditions.