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

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The thalamus

The word “thalamus” is derived from

the Greek word for “inner chamber,”

and this thumb-sized mass of gray

matter sits in the middle of the brain,

between the cerebral cortex and

midbrain. It is formed from several

bundles, or tracts, of nerves, which

send and receive signals in both

directions between the upper and

lower regions of the brain, often in

feedback loops (see p.91). It is

associated with the control of sleep,

alertness, and consciousness. Signals

from every sensory system, except

smell, are directed through the

thalamus to the cortex for processing.

The pituitary gland

Weighing about 0.01 oz (0.5 g), the

tiny pituitary gland produces many

of the body’s most significant

hormones under the direction of the

hypothalamus. The hormones are

released into the blood supply via a

network of tiny capillaries. Pituitary

hormones include those that control

growth, urination, the menstrual

cycle, childbirth, and skin tanning.

Despite having the volume of a pea,

the gland is divided into two main

lobes, the anterior and posterior, plus

a small intermediate lobe. Each lobe

is devoted to the production of a

particular set of hormones.

WEIGHING JUST 0.1 OZ (4 G),

THE HYPOTHALAMUS IS

NOT MUCH LARGER THAN

THE END SEGMENT

OF A LITTLE FINGER

Stimulation

The hormones produced

by the hypothalamus travel along

axons to the pituitary gland.

1

Release

The netlike

portal system collects

the hormones and releases

them into the bloodstream.

3

Production

The chemicals from

the hypothalamus stimulate

the pituitary gland to

release hormones.

2

Posterior

pituitary

lobe

Anterior

pituitary lobe

Hormones pass

into bloodstream

Network

of veins

Artery

Secretory cells in

hypothalamus

release hormone

HY

PO

TH

A

LA

M

U

S

PI

TU

IT

A

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(^) G
LA
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Thalamic nuclei
The thalamus is divided into three main lobes:
the medial, lateral, and anterior. They are each
further organized into zones, or nuclei,
associated with particular sets of functions.
Sense data from mouth
transmitted to medial
ventral posterior nucleus
Signals sent from
premotor cortex
received in lateral
anterior nucleus
Lateral nuclei
(pulvinar)
send signals
to visual
cortex
Incoming signals for
medial dorsal nuclei
are from prefrontal
cortex
Nuclei separated by
sheets of white matter

LAT

ER

AL

LO

BE

MED

IAL

LOB

E LOB

E

AN

TE

RI

O

R

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