brain bee

Number of Neurons in the brain

100 billion neurons

Dendrite

primary site for receiving and integrating information from other neurons

Axon

fiberlike extension of neuron by which it sends information to target cells

Action Potential

electrical charge that travels along the axon to the neuron's terminal where it triggers release of a neurotransmitter

Neurotransmitter

a chemical released by neurons at synapse for purpose of relaying information to other neurons via receptors

Nodes of Ranvier

gaps occurring in the myelin sheath that allow for faster conduction of action potential

Frontal Lobe

initiating and coordinating motor movements; higher cognitive skills (problem solving, thinking, planning); personality; emotion; etc.

Parietal Lobe

sensory processes, attention, language

Occipital Lobe

vision

Temporal Lobe

auditory information, memory

Cerebrum

largest part of the human brain

Cerebral Cortex

Sheet of tissue covering the outermost layer of the cerebrum, voluntary actions

Ventricles

hollow spaces in brain containing cerebrospinal fluid

Gray Matter

cell bodies of neurons

White Matter

axons of neurons (white in appearance because of fatty myelin that covers axons)

Corpus Callosum

large white matter structure linking the left

and right cerebral hemispheres

Thalamus

gate and modulate flow of information to cortex

EXAMPLE: visual information from retina is not sent directly to visual cortex but instead is relayed through lateral geniculate nucleus of thalamus

Hypothalamus

responsible for hormone production (ex:

GnRH, CRH), communicates with pituitary gland

**also location of several important groups of cells

Contains cells with orexin which are important for wakefulness

Ventrolateral Preoptic Nucleus

nerve cells containing GABA and

galanin, important for sleep, also part of Hypothalamus

Suprachiasmatic Nucleus

Small group of nerve cells that acts as

a master clock, also part of Hypothalamus

Substantia Nigra

Part of the basal ganglia (important for

movement); dopaminergic neurons here degenerate in Parkinson's disease

Hippocampus

Shaped like a seahorse, very important for

MEMORY

Amygdala

Important in fear, emotion; responsible for

emotional aspect of memory

Pons

upper brainstem, attached to cerebellum, respiration

Medulla

lower brainstem, involved in controlling breathing, heart rate, and blood pressure

Cerebellum

helps us adjust motor output to deal with

changing conditions; important for coordination and balance;

attached to the pons

ACETYLCHOLINE (ACh)

ACETYLCHOLINE (ACh)

• first neurotransmitter to be identified

• released by neurons connected to voluntary muscles causing them to contract

• antibodies that block one type of ACh receptor cause myasthenia gravis

(disease characterized by fatigue and muscle weakness)

**also important for memory

GABA

Amino Acid!

• inhibit firing of neurons

• activity increased by benzodiazepines (anti-anxiety drugs)

GLUTAMATE

Amino Acid!

• excitatory signals,

• activate NMDA receptors (important in learning/memory; however

overstimulation of these receptors can cause nerve cell damage or cell death)

DOPAMINE

Catecholamine!

Important in three functions:

A. Movement

• deficits in dopamine associated with Parkinson's disease (symptoms

include muscle tremors, rigidity, difficulty moving)

• most common treatment for Parkinson's is LDOPA (or levadopa), a precursor to dopamine

B. Cognition and Emotion

• abnormalities in dopamine have been identified in patients with schizophrenia

• in fact, many antipsychotic drugs inhibit dopamine receptors, increasing risk for tardive dyskinesia (movement disorder in which symptoms include aimless, uncontrollable movements; rapid eye blinking; etc).

C. Endocrine system

NOREPINEPHRINE

Catecholamine!

• released from adrenal medulla (innermost part of adrenal glands) in times of stress

• secreted by sympathetic nervous system to regulate heart rate/blood pressure

SEROTONIN

• important in sleep, mood, depression, and anxiety

HORMONES

• important in sleep, mood, depression, and anxiety

• ex. cortisol (released by adrenal glands in response to stress)

GASEOUS NEUROTRANSMITTERS

1. nitric oxide

2. carbon monoxide

SECOND MESSENGERS

• important in sleep, mood, depression, and anxiety

• ex: the enzyme adenylyl cyclase converts ATP to the second messenger cAMP

Brain Development (3 Stages)

1. induction

2. proliferation

3. migration

Plasticity

ability of the brain to modify itself and adapt to challenges of the environment

Apoptosis

programmed cell death initiated in the cells

Cornea

does 3⁄4 of focusing

Lens

does the remainder of focusing after light has passed through cornea

Iris

adjusts size of pupil

Fovea

centermost part of retina

Macula

area around fovea, important for reading/driving

**macular degeneration = leading cause of blindness in elderly

Retina

location of photoreceptors

Photoreceptors in Eye

a) cones: color, bright light, acute detail

b) rods: dim light

Pathway by Which Light Travels in the Eye

cornea --> lens --> photoreceptors --> bipolar cells --> ganglion cells

Lateral Geniculate Nucleus

In Thalamus, takes signal from optic nerves and acts as an intermediate relay

-sends information to primary visual cortex (occipital lobe)

Optic Nerve

Made of axons of ganglion cells

Pathway of Sound

sound waves --> external ear (pinna + auditory canal) --> tympanic membrane (eardrum) --> malleus (hammer) --> incus

(anvil) --> stapes (stirrup) --> oval window (separates middle ear from inner ear) --> cochlea (separates frequencies) --> Hair Cells in Cochlea --> Auditory Nerve --> Auditory Cortex (Temporal Lobe)

Hair cells in Cochlea

On the cohclea's basilar membrane, converts mechanical vibration into electrical signals

Touch information is sent through...

Spinal Cord

Nociceptors

Sensory fibers that respond to stimuli that damage tissue and can cause pain

Prostaglandins

Enhance sensitivity of receptors to tissue damage and ultimately can induce more intense pain sensations, made by cyclo-oxygenase (COX) enzymes

Alldynia

Normally innocuous stimuli cause pain

Analgesia

Loss of ability to feel pain

Declarative Memory

Facts and events, "knowing what" --> primarily Hippocampus

Semantic Memory

General facts/data

Episodic Memory

Events