Why are biosignals from the body said to be continuous? Whether we talk about EEG, ECG or EKG aren't all these signals discrete as we are reading the voltages from the electrodes that are due to certain bio-chemical or bio-electrical activities. I do not get why people say that EEG is continuous and hence we need to convert it to digital when it is already digital.
Biological signals are analogues and hence continuous. Early EEG systems simply recorded the analogue signals and displayed it as a continuous signal graphically as wiggly lines written by little pens on a roll of paper (Fig. 1). Only after analogue-to-digital converters became available, could EEG signals and the likes be digitally sampled. 


Fig. 1. Analogue EEG signal. source: Britton et al., 2016)  

Reference
- Britton et al., Electroencephalography (EEG): An Introductory Text and Atlas of Normal and Abnormal Findings in Adults, Children, and Infants, 2016. Chicago: American Epilepsy Society