(a) Define the following in (i) elimination (ii) excretion (iii) secretion. (b) Describe the digestion...
(a) Define the following in
(i) elimination
(ii) excretion
(iii) secretion.
(b) Describe the digestion of boiled fish in the gut of humans
(c) Make a diagram 8cm - 10am long of a longitudinal section of a villus and label fully.
Explanation
(a) Definition of terms:
(i)Elimination: Removal of undigested food; from the body of living organisms.
(ii)Excretion: Removal of waste products of metabolism; from the cells/tissues of an organism; may be toxic if retained in the body.
(iii)Secretion: Production and release of substances; useful to the body; by specialized glands of living organism.
(b) Digestion of boiled fish in the gut of humans:Boiled fish is a source of protein; chewed and swallowed into the stomach; digestion of protein starts from the stomach; stomach secrets gastric juice; containing pepsin, rennin and hydrochloric acid; pepsin in acidic medium acts on the boiled fish and convert it to peptides; peptides move into the duodenum/small intestine; into which pancreatic juice is secreted; undigested protein is acted upon by trypsin in alkaline medium; into peptides/peptones, erepsin finally acts on peptides/peptones in alkaline medium; and converts it into amino acids.
(c) Diagram of villus
Title TL: - Longitudinal section of villus. Size: (8 — 10cm long).
Quality (Q): Clarity of lines. Neatness of labels.
Details: Epithelium layer shown (EL) Conical shape of villus (one cell thick) (CV).
Labels (L): Epithelium layer blood capillary, lacteal, lymphatic vessels, goblet cells, venule, arteriols, cryps of lieberkuhn, cells of paneth, muscularis mucosa.