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

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