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

BRAIN FUNCTIONS AND THE SENSES

Neuroendocrine System

Neuroendocrine

System

Maintaining homeostasis (see p.90) requires the

brain and body to communicate. This is achieved

using chemical messengers called hormones.

The hypothalamus

At the center of the brain’s homeostasis system is the hypothalamus

(see p.34). It contains clusters of neurons, called nuclei, that perform

specific functions and has connections to the autonomic nervous system

(see p.13), through which it sends messages to control heart rate, digestion,

and breathing. When the hypothalamus receives a signal from the nervous

system, it secretes neurohormones, which in turn stimulate the pituitary

gland to secrete hormones. These affect organs all over the body and

prompt them to increase or suppress their own hormone production.

Nuclei in the hypothalamus

Most of the nuclei have distinct

functions. They secrete hormones

that act on the pituitary gland,

stimulating it to produce hormones

that will help achieve homeostasis

in the required part of the body.

When homeostasis is disrupted,

it can lead to disease, as well as to

our cells malfunctioning. The body

tries to correct the problem but

may make it worse, depending on

what is influencing the imbalance.

Genetics, lifestyle, and toxins can

all impact homeostasis.

OUT OF BALANCE

Inhibits eating and

reduces food intake

Body’s “clock”—controls

circadian rhythms

DORSOMEDIAL

NUCLEUS

DORSAL

HYPOTHALAMIC

AREA

L ATER AL

TUBERAL

NUCLEI

SUPRAOPTIC

NUCLEUS

L ATER AL

PREOPTIC

NUCLEUS

SUPRACHIASMATIC

NUCLEUS

OCULOMOTOR NERVE

MAMMILLARY BODY

PARAVENTRICULAR

NUCLEUS

PITUITARY GLAND

MEDIAL PREOPTIC

NUCLEUS

ANTERIOR NUCLEUS

LATERAL

HYPOTHALAMIC

AREA

POSTERIOR NUCLEUS

VENTROMEDIAL

NUCLEUS

Regulates blood pressure

and heart rate

Initiates intake of

water and food

Controls thermoregulation

Involved

in memory,

arousal, sleep,

and energy

balance

Synthesizes oxytocin,

vasopressin, and

somatostatin

30

HORMONES ARE

PRODUCED BY THE

ENDOCRINE SYSTEM

IN

SI

D

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TH

E^ H

YP

OT

HA

LAM

US

US_092-093_Neuroendocrine_System.indd 92 20/09/2019 12:35