How the Brain Works The Facts Visually Explained by DK (z-lib.org)

BRAIN FUNCTIONS AND THE SENSES

Smell

Receptor cell nerve axons detect odor and send information to olfactory bulb

Olfactory tract, a bundle of nerves that carries signals from olfactory bulb to olfactory cortex

Amygdala sends warning messages if odor is associated with danger

Olfactory cortex further processes signals sent by olfactory bulb

Capturing a scentWhen we inhale, odor molecules drift into the nose and activate receptor cells in the nasal cavity, triggering a reflex to breathe in

more deeply. In the nasal cavity, the odors dissolve in the mucus

that covers a sheet of neurons and supporting cells called olfactory epithelium. The molecules spread through the mucus to hairlike structures called cilia that are attached to receptor cells. These cells

send signals to the olfactory bulb—a structure located in

the forebrain that forms part of the brain’s limbic

system. Data is then sent to various parts of

the brain, particularly the olfactory cortex.

12 MILLIONTHE NUMBER OF

OLFACTORY CELLS

IN THE

HUMAN BODY

Olfactory receptorsEach odor molecule activates

a particular combination of olfactory receptors. The activated receptor cells send impulses up through nerve axons to the olfactory bulb for processing.

Inside the brainSignals then travel along the olfactory

tract to the olfactory cortex. The cortex is

located in the limbic system, which is responsible for emotions and memory. Signals are also sent

to the amygdala and orbitofrontal cortex.

Smell enters the noseOdor molecules are drawn up

through the nose and warmed to enhance the scent. The molecules dissolve in mucus produced by the olfactory epithelium and stimulate cilia that are connected to

receptor cells.

2 1

3

Receptor cell

Supporting

cell

Nerve axon

Mucus gland

Odor molecule dissolving in mucus

Olfactory bulb

Airborne odor

molecules enter nostril

Olfactory bulb

processes signals before passing to olfactory cortex

Orbitofrontal cortex involved in decision- making and emotions as well as processing smells

Cilia

NASAL CAVITY

Bone

Mucus

Dura mater

OLFACTORY BULB

AMYGDALA

OLFACTORY

CORTEX

ORBITOFRONTAL

CORTEX

LO

AF

TC

O

YR

E

P

TI

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