What are nematocysts? What is their role in ingestion?
The nematocysts are the stinging cells embedded in the tentacles of Hydra and other coelenterates (cnidarians). Each nematocyst consists of a hollow thread coiled within a capsule and a tiny hair like trigger projecting outside. These paralyze the prey which is then captured by tentacles.
How does ingestion occur in amoeba?
When Amoeba comes in contact with food particle, it immediately puts out pseudopodia around it. These pseudopodia fuse together around the food particle forming the food vacuole.
How does egestion occur in amoeba?
Undigested matter is expelled from the Amoeba in the surrounding water by egestion at any point of its surface.
Name the parts of three main divisions of the digestive system of cockroach.
- Fore-gut: It includes mouth cavity, pharynx, crop and gizzard. A pair of salivary glands is present in the thorax region of the animal.
- The mid-gut is also called mesenteron stomach. The hepatic caecae open into the anterior end of the midgut.
- The hind-gut: Its terminal part is rectum, which opens to the exterior through anus.
How food is swallowed by you?
- The tongue moves upwards and backwards against the roof of the mouth, forcing the bolus to the back of the mouth cavity.
- The backward movement of the tongue pushes the soft palate up and closes the nasal opening at the back. At the same time the tongue forces the epiglottis into more or less horizontal position thus closing the opening of the windpipe.
- The larynx, cartilage round the top of the windpipe, moves upward under the back of the tongue.
- The glottis is partly closed by the contraction of a ring of muscles.
- The epiglottis diverts the food mass to one side of the opening and safely down the oesophagus.