HL 2 Biology

E.5a Brain Structure

The Human Brain.. medulla oblongata:  automatic & homeostatic activities e.g. breathing, vomiting cerebellum: unconscious activities e.g. posture, balance hypothalamus: maintains homeostasis (nervous & endocrine system) secretes hormones stimulates appetite/thirst, body temp, and sleep pituitary gland: releases hormones release hypothalamic hormones cerebral hemispheres: integrates complex functions e.g. memory, emotion, language many cases of injury here cause difficulty … Continue reading

HL 2 Biology

E.2c Ears

How sound is perceived: eardrum vibrated by sound waves transmits mechanical vibration of air molecules –> middle ear bones of middle ear ossicles = series of very small bones 1st = attached to eardrum 3rd = attached to oval window muscles = attached to ossicles (protect from loud sound) acts as lever to amplify sound … Continue reading

HL 2 Biology

E.2a Perception of Stimuli

p. 323-4 <<Perception of Stimuli>> stimuli: detected by receptors some located in sense organ, nerve endings of sensory neurons Humans have: mechanoreceptors, chemoreceptors, thermoreceptors and photoreceptors. mechanoreceptor perceive movements e.g. in the ear = perceive sound vibrations. movements due to gravity in the skin = perceive pressure changes chemoreceptors perceive chemical substances (taste and smell) membrane receptor … Continue reading


11.2b Muscles & Movement

DBQ: Transverse Sections of Striated Muscle (p.267) 1) Different from a transverse section of the muscle, the longitudinal section goes along the long axis. The transverse section crosses the longitudinal section, or in short stands perpendicular to it.  2) The light band  3) The first diagram consists of both the second and third pattern together, … Continue reading

HL 2 Biology

6.5b Synapses

DBQ: Parkinson’s Disease (p.257) 1 a) L-Dopa acts as a precursor, increases production of dopamine increases as the L-Dopa acts as a precursor to Dopamine. b) Selegeline inhibits MAO-B, which helps the dopamine from breaking down thus the dopamine is preserved for a longer time. c) As tolcapone inhibits the COMT, it would lead the … Continue reading

HL 2 Biology

6.5a Neurons

Neurons: resting potential = an electrical potential across a cell membrane when not propagating an impulse action potential – the localized reversal (depolarization) and then restoration (repolarization) of electrical potential between the inside and outside of a neuron as the impulse passes along it Nerve impulses are conducted from receptors to the CNS by sensory neurons, within … Continue reading