HUMAN BIOLOGY

the endOCrIne system 297

What do adrenal gland hormones do?

• The adrenal cortex produces glucocorticoids such as
  cortisol and mineralocorticoids such as aldosterone.


• The adrenal medulla makes epinephrine and
  norepinephrine.


• Cortisol raises blood glucose levels and suppresses
  inflammation. Aldosterone helps regulate blood
  pressure by adjusting reabsorption of potassium
  and sodium in the kidneys.


• Epinephrine and norepinephrine adjust blood circulation
  and the use of blood sugar in the fight–flight response
  to stress.

taKe-home message

Figure 15.9 The adrenal glands produce cortisol, the

stress hormone. Each gland rests atop a kidney. The

diagram shows a negative feedback loop that governs

the secretion of cortisol. Exercise and social activites

are good stress reducers. (© Cengage Learning)

Adrenal Cortex

C Cell uptake of glucose from blood slows in many

tissues, especially muscles (not the brain).

D Proteins are broken down in many tissues, muscles

especially. The amino acids are converted to glucose

and used in the assembly or repair of cell structures.

E Fats in adipose tissue are broken down to fatty acids

that enter blood as an alternative energy source,

indirectly conserving glucose for the brain.

A Blood level of

cortisol falls below

a set point.

Cortisol is secreted,

with these effects:

Anterior Pituitary

Hypothalamus

Stimulus Response

+

F Both the

hypothalamus

and pituitary

detect rise in

blood level

of cortisol

and slow its

secretion.

B CRH

ACTH

kidney

adrenal

cortex

adrenal

medulla

Nancy Ney/Photodisc/Getty Images

phthalates: endocrine disrupters

FOCUS ON OUr eNvirONmeNt

15.8

scented personal care products, soft plastics like vinyl,

food storage containers. these are just some of the

consumer items that may be manufactured using chemicals

called phthalates (pronounced thal-aytes). these artificial

chemicals are suspected endocrine disrupters—substances

that interfere with normal synthesis or functioning of

hormones. research with lab animals has shown worrisome

links between phthalates and skewed functioning of the

male sex hormone testosterone. Other studies linked high

phthalate levels in men with low testosterone and impaired

sperm quality. male babies born to mothers with high

phthalate levels appear more likely to have an undescended

testicle. Children who consumed food and drinks illegally

laced with phthalates were found to have abnormally low

levels of thyroid hormone (th). phthalates also are easily

absorbed through the skin. One result: many pediatricians

now advise parents to avoid using phthalate-containing

lotions, soaps, shampoos, and other products with children

under the age of 12, and to purchase only toys and food

and drink containers that are phthalate-free.

Because of mounting evidence of health dangers

associated with phthalate exposure, consumers increasingly

are advised to purchase only “phthalate-free” products.

© Kalinina Alisa/Shutterstock.com

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