DIGESTIVE SYSTEM
● The body wall of the `color{violet}("earthworm")` is covered externally by a thin `color{brown}("non-cellular cuticle")` below which is the epidermis, two muscle layers `color{violet}("(circular and longitudinal)")` and an innermost coelomic epithelium.
● The `color{brown}("epidermis")` is made up of a `color{violet}("single layer of columnar epithelial cells")` which contain secretory gland cells.
● The `color{brown}("alimentary canal")` is a `color{violet}("straight tube")` and runs between first to last `color{violet}("segment of the body.")`
● A `color{violet}("terminal mouth")` opens into the `color{violet}("buccal cavity")` (1-3 segments) which leads into `color{brown}("muscular pharynx")`.
● A small narrow tube, `color{brown}("oesophagus")` (5-7 segments), continues into a `color{brown}("muscular gizzard")` (8-9 segments).
● It helps in `color{violet}("grinding")` the `color{violet}("soil particles")` and decaying leaves, etc.
● The `color{brown}("stomach")` extends from 9-14 segments.
● The food of the `color{violet}("earthworm")` is decaying leaves and `color{violet}("organic matter")` mixed with soil.
● `color{brown}("Calciferous glands,")` present in the `color{violet}("stomach, neutralise")` the humic acid present in humus.
● Intestine starts from the 15th segment onwards and continues till the last segment.
● A pair of short and conical `color{brown}("intestinal caecae")` project from the `color{violet}("intestine")` on the 26th segment.
● The characteristic feature of the `color{violet}("intestine")` between 26-35 segments is the presence of internal median fold of dorsal wall called `color{brown}("typhlosole.")`
● This increases the `color{violet}("effective area")` of absorption in the `color{violet}("intestine.")`
● The `color{violet}("alimentary canal")` opens to the exterior by a small rounded aperture called `color{brown}("anus")`.
● The ingested `color{violet}("organic rich soil")` passes through the digestive tract where digestive `color{violet}("enzymes breakdown
complex food")` into smaller `color{violet}("absorbable units.")`
● These `color{violet}("simpler molecules")` are absorbed through `color{violet}("intestinal membranes")` and are utilised.
● The `color{brown}("epidermis")` is made up of a `color{violet}("single layer of columnar epithelial cells")` which contain secretory gland cells.
● The `color{brown}("alimentary canal")` is a `color{violet}("straight tube")` and runs between first to last `color{violet}("segment of the body.")`
● A `color{violet}("terminal mouth")` opens into the `color{violet}("buccal cavity")` (1-3 segments) which leads into `color{brown}("muscular pharynx")`.
● A small narrow tube, `color{brown}("oesophagus")` (5-7 segments), continues into a `color{brown}("muscular gizzard")` (8-9 segments).
● It helps in `color{violet}("grinding")` the `color{violet}("soil particles")` and decaying leaves, etc.
● The `color{brown}("stomach")` extends from 9-14 segments.
● The food of the `color{violet}("earthworm")` is decaying leaves and `color{violet}("organic matter")` mixed with soil.
● `color{brown}("Calciferous glands,")` present in the `color{violet}("stomach, neutralise")` the humic acid present in humus.
● Intestine starts from the 15th segment onwards and continues till the last segment.
● A pair of short and conical `color{brown}("intestinal caecae")` project from the `color{violet}("intestine")` on the 26th segment.
● The characteristic feature of the `color{violet}("intestine")` between 26-35 segments is the presence of internal median fold of dorsal wall called `color{brown}("typhlosole.")`
● This increases the `color{violet}("effective area")` of absorption in the `color{violet}("intestine.")`
● The `color{violet}("alimentary canal")` opens to the exterior by a small rounded aperture called `color{brown}("anus")`.
● The ingested `color{violet}("organic rich soil")` passes through the digestive tract where digestive `color{violet}("enzymes breakdown
complex food")` into smaller `color{violet}("absorbable units.")`
● These `color{violet}("simpler molecules")` are absorbed through `color{violet}("intestinal membranes")` and are utilised.
