Now that you have the concept engrained, they talk about how this buffers the body, and how the curve shifts with change in pH.

References

Life in the Fast Lane. (Producer). (2014, August). Haemoglobin-Oxygen Dissociation Curve – Physiology – Answer [Online video]. Retrieved from http://vimeo.com/102595267

Life in the Fast Lane. (Producer). (2014, August). Haemoglobin-Oxygen Dissociation Curve – Physiology – Explanation [Online video]. Retrieved from http://vimeo.com/102595593